00:00:00NIER: [ . . . ] When I got your note, I did a little looking around to see where
things were, and I got out a number of things, reprints, that were, sort of,
significant, some of which you may want to take.
GRAYSON: Yes, any copies of reprints that we can have would be great.
NIER: Yes, and I have some photographs. I don't know whether I have duplicates
00:01:00of these. I could lend them to you or let you know which they are and have
GRAYSON: Well, I have arrangements in St. Louis [Missouri] for making copies of photographs.
NIER: Okay, there may be a few here that I don't want to give up.
GRAYSON: I understand.
NIER: So, we'll have to negotiate that; whatever's most convenient for
everybody. Also, since you raised the question about early meetings, were you
acquainted with this 1951 conference held at the Bureau of Standards [Symposium
on Mass Spectroscopy, National Bureau of Standards, 1951]?
NIER: That's the first meeting on mass spectrometry I ever attended. [The 1951
National Bureau of Standards meeting]
GRAYSON: Oh really?
NIER: I have a picture of the people at the meeting here, there was a group
picture taken at the steps. John Hipple arranged that. He was the guy who had
been at Westinghouse with Ed Condon and then went on to the Bureau of Standards.
00:02:00He was head of the section there; then he went to North American-Phillips, and
was at Penn State [University] for a while.
GRAYSON: But you say Hipple was at Westinghouse at the time?
NIER: Well, no, he moved to the Bureau of Standards.
GRAYSON: I see.
NIER: He had been at Westinghouse, and then Ed Condon became Director of the
Bureau of Standards, and brought Hipple with him. Condon had been director of
research for Westinghouse. But Hipple arranged this conference. It was a very
nice group picture. I bet, there aren't many of the groups in existence any more.
GRAYSON: Is it in the book anywhere?
NIER: I don't think the picture's there, but I have an eight-by-ten of it. It's
a very good one.
GRAYSON: That would be very excellent to go with the interview.
NIER: As a historical thing.
GRAYSON: Yes, and to identify the individuals that were there.
NIER: I have a standing list of these people. There were a lot. There were a
hundred or so people. It was a very nice conference.
GRAYSON: This work is referenced in your publication list, is that correct?
00:03:00NIER: Yes, because I gave a talk there. Maybe two talks.
GRAYSON: Yes, I believe there are two. Okay.
NIER: It's referenced there. I thought you ought to know about that.
GRAYSON: Yeah, that is an excellent point. Well, how do you want to proceed here?
NIER: Well, you're the one in control! [laughter]
GRAYSON: I have a number of questions . . . [laughter]
NIER: Well, why don't you go ahead, and then we'll have to pick up loose ends, maybe.
GRAYSON: I understand.
NIER: Well, now, tell me what's going to happen so we can see if that'll help us
decide how you're going to do it.
GRAYSON: Okay. The immediate plan with this recording is to have it transcribed.
And then, of course, you'll get a chance to edit . . .
NIER: Or censor . . .
GRAYSON: Yes, censor it, yes. I'm presently negotiating to arrange for the
Society [American Society for Mass Spectrometry] to become a partial affiliate
with the National Foundation for the History of Chemistry [NFHC, now the
Chemical Heritage Foundation], and I feel that eventually at some time or
00:04:00another, hopefully soon, this material will then be archived with the NFHC. And,
so doing, thus make it available, essentially to scholars and people doing
history of science work. So, that is the plan, and I believe, indeed, that's
what will happen. It's a matter of timing as to when it would happen.
NIER: So, it should be reasonably well-organized.
GRAYSON: Well yes, it should be, on the other hand, I think the important thing
here is to explore a lot of little nuggets that you don't get an opportunity to
explore in some of the review papers.
NIER: Since nowadays, you put these things on word processors, you can move
GRAYSON: Yes; the way these usually work is the transcripts are abstracted in
terms of titles of subjects, and so if a particular tape is of interest, that
00:05:00could be found out fairly rapidly. So, rather than worrying too much about the
organization, we might just kind of free run . . .
GRAYSON: . . . because if we spend a whole lot of time on how it's organized we
may end up missing the point. Well, what if we start with the very first
question I have here; how old are you now?
NIER: I'll be seventy-eight in May [of 1989].
GRAYSON: That's in a month. Then, can you recall your initial interest in the
areas of science; just when, how soon, how early in your life did that actually
become an interest?
NIER: Well, that's hard to answer because I don't think there was any really
definite time. The only thing I could point to is that I had done well in
00:06:00arithmetic in grade school. In high school, I was interested in the science
courses. I took physics and chemistry there, and I took all the math that was
available. And also, I took shop courses and drawing courses, which at that time
were things that were kind of standard for people. I entered high school and you
had to choose what kind of curriculum you were in. I went into the college
preparatory curriculum, because my parents felt that I should go on to college
GRAYSON: That was not common at that time, was it, for a young person to go on
NIER: No, I'm trying to think. One time, I was wondering how many of my
graduating class in high school, went on to higher education. [I graduated in
1927.] It turned out to be more than I thought it was after I looked at what had
00:07:00happened to some of the people. But I suppose a third, something like that. But
of course, as may be pointed out in some of the things I've written already, my
parents were immigrants. My mother had come as a ten-year-old, with her family
from Germany, and my father came as a teenager. They met, because he lived in a
rooming house next door to where they lived in St. Paul [Minesota]. Father had
gone to a trade school--he was a machinist by trade. My mother, I don't think
had much formal education. I would say the equivalent of grade school probably
was all that she had. But they were, like immigrant families, very interested
that their kids should get an education, and this was characteristic. This is
just a standard thing, if you look at the whole record. My wife came from a
00:08:00Norwegian family in upper Minnesota, and the same kind of attitude prevailed
among these people, too.
Keep in mind, my mother came in 1880s and my father came in 1890s. So this was
sort of the opportunity. I was always steered in that direction. In high school,
that was the time when radio was a coming thing. Keep in mind, this was the
middle 1920s and people built their own radio sets, and I had friends who did
this sort of thing. You could buy parts and tubes and crystals and whatnot, and
so I got into that kind of thing. By the time I graduated from high school in
1927, it was understood that I would go into electrical engineering, which I
00:09:00did, and I came here to the University [of Minnesota]. Unfortunately my folks
really didn't have much money, I carried newspapers when I was in high school to
help some, and I rode the streetcars dutifully, everyday, back and forth from
the other side of St. Paul over to here and back. I knew every bump on the
streetcar tracks. I continued for four years here, and graduated in electrical
engineering. That, sort of, seemed to be the direction I was going to go.
GRAYSON: Well, then, I gather that mass spectrometry interrupted that somewhere
along the way.
NIER: Well, I want to give you another thing I wrote. I received an honorary
degree here in 1980, and I wrote a blurb which I hadn't realized I'd written. It
00:10:00told a little bit about historical things. I made a copy of it, which you may
want as part of the interview.
GRAYSON: Excellent, yes.
NIER: But, the story's a kind of an interesting one, because it shows you how
you never know what's going to happen. All engineering students took physics in
their sophomore year. That was the standard thing, at that time. This department
was organized such that one person taught mechanics, another taught heat,
another taught electricity, and so on . . . this was the style of many places at
that time. Anyhow, the guy who taught the mechanics course was also the head of
the department. His name was Henry [A.] Erikson, and he was one of these very
tall, dignified sort of persons. I was in this class of probably two hundred
00:11:00students or something like this, and in those days, they kept track of your
attendance in class, and if you missed classes too often, you failed the course.
This was the standard thing that went on then. So, for these big classes we had
numbered seats in this big auditorium, and they had somebody going around five
minutes after the class started and seeing which seats were vacant. The
instructor knew where everybody sat. Well, after the third quiz just before the
class, this very dignified professor came up the middle of the room--I sat a few
seats from the aisle--and said he'd like to see me. He didn't ask what my name
was or anything else, he just came and said he'd like to see me. Well, then he
turned around and went back. He asked me at my convenience to come to his
00:12:00office. I didn't know what this was all about, and, the people around me began
to buzz. They wondered if I'd been caught cheating or something like that. But,
anyhow, I went to his office, and made sure he was talking to the right person.
And what had happened was I had gotten hundred's on the first three tests in the
physics course, so he raised the question, "Had I considered becoming a
physicist?" I said, "Well, no, I really hadn't." But he said I really ought to
consider it, and what's more, he gave me a job, working as an assistant, doing
some experiments. So this was my real introduction to physics as such.
GRAYSON: This gentleman's name?
NIER: Henry Erikson.
NIER: It's spelled with an E- [the Norwegian spelling] R-I-K-S-O-N
00:13:00NIER: He did this for a lot of young people. It was really an introduction to
science on a hands on sort of basis. For an undergraduate, it was quite a break.
Besides, I got fifty cents an hour, which was the going rate then, which was
high in 1935.
GRAYSON: That was high. I didn't earn that when I started working.
NIER: So, I did this and in the last summer I was an undergraduate, he got me a
job full-time with somebody else, working in X-rays. Professor [Joseph] Valasek.
V-A-L-A-S-E-K. By the way, he's the guy who discovered ferro-electricity. Didn't
get credit for it for decades, but he's been recognized since. [J. H.] Van Vleck
has officially given him credit for this. The J. H. Van Vleck. They had a
symposium in Valasek's honor some years ago. Valasek's still living--he's about
00:14:00ninety years old. But anyhow, I worked for him full-time in the summertime, and
part-time during the school year; so I saw a lot of what went on. Well,
Professor Erikson wanted me to continue on as a graduate student in physics, and
I said, "Gee, [this was my senior year] I wanted to really get out on the job
for a while, and I wasn't thinking of graduate work so I think I'll pass it up."
Well this was 1931, and jobs were not available for engineers. So, I estimate, I
think about five people out of our graduating class of eighty got jobs.
GRAYSON: But why? Was it because of the Depression then?
NIER: Yes, the Depression, people were being laid off right and left and
companies were not hiring. And there weren't many opportunities locally; there
was probably a job for one or two electrical engineers at the power company and
the telephone company and that was it, there was no industry. Honeywell
00:15:00[International] was still making dampers for stoves and things like that and 3M
wasn't interested in scientists. So, the jobs were with Westinghouse, GE, Bell
Labs, and so on and they just weren't hiring.
GRAYSON: But I would've thought . . . you probably graduated with good grades
and you were a pretty good student.
NIER: Yes. But I didn't have all the other things they wanted, so . . .
GRAYSON: What other things were they interested in?
NIER: Well, I mean, that you'd been active in school activities and things like
this. They were looking for these management types; leadership assistants, and
so on. The research opportunities were very limited so people who had that sort
of talent were very limited. Well, it turned out I was rescued, luckily, by a
man in electrical engineering who was really outstanding. His name is Henry
Hartig, who himself was a physicist and had come back to Minnesota. He had
worked at AT&T sometime before he came back on the faculty here in our
00:16:00electrical engineering department. This is, by the way, mentioned in my honorary
degree talk. And so, he rescued me and got me a teaching assistantship in the
electrical engineering department.
GRAYSON: So your good qualities, your good record was recognized by someone.
NIER: Oh yes, he knew who I was. He saved me when he found out I didn't even
have a job when I graduated. I spent two years there and got a master's degree
in electrical engineering. But they had so few courses available in engineering
departments in those days, that one took the courses in physics and math and so
on. So, except for having taken one course in electrical engineering in circuit
theory or something like that, I took just standard physics courses. It was just
as if I'd stayed in physics as far as my coursework and that's all you did the
00:17:00first two years anyhow. But I did spend two years there, and that was valuable
experience. I was always interested in instrumentation. As you can see the
thread of engineering runs through this. When I finished up in 1933 with a
Master's degree, Professor Erikson again offered me a teaching assistantship.
There weren't things like research assistantships in those days. The only avenue
was a teaching assistantship. So, he again offered one to me, which I accepted
then because I was now on the way. That's the history of that time.
GRAYSON: In these teaching assistantships were you actually teaching courses or
doing lab . . . ?
NIER: Lab--teaching labs. I think we had the standard load, which was called a
00:18:00half-time position. A standard load was four two-hour labs a week plus grading
the papers that went with these.
GRAYSON: And these typically had twenty or thirty students in each?
NIER: Well, probably less than that in our case, more like fifteen, or sixteen,
or something like that. You had so many stations they worked in pairs in many
experiments. I think it hasn't changed that much since.
NIER: So, that was, kind of, the way it was. I did that in electrical
engineering and it was very valuable. I taught a lot of different things, a
radio lab, and a transient lab where you did experiments with an oscilloscope.
This was one that had to be pumped down, crazy thing, never worked right; but
that was the one for doing high-speed transient phenomena, stuff like that. That
was kind of an interesting experience. Much more interesting than the
run-of-the-mill thing. It was quite valuable and the communications lab I taught
there was, kind of, fun.
00:19:00GRAYSON: To a large degree then, you had a foundation in electronic
instrumentation that you could carry with you into mass spectrometry.
NIER: Yes. Which most physics majors didn't have, by the way.
GRAYSON: Yes. It turned out to be an extremely valuable background.
NIER: A very valuable background, that's right.
GRAYSON: So, a little fortuitousness there.
NIER: That's right. As I say, you have to be in the right place at the right time.
GRAYSON: So, mass spectrometry. We were trying to get to the point where you
first became aware that such an activity existed and was worth pursuing or
looking into. When did you really . . .
NIER: Well, I had been in and out of the physics department for years since I'd
worked here as an undergraduate and the electrical engineering department was
just across the street. I'd gone back and forth and I was more at home in the
physics department actually, than I was in electrical engineering. Because I'd
00:20:00spent so much time here. I knew what the graduate students were doing. It was a
very interesting time; this place excelled in the study of the electron impact
of gases, thanks to John Tate. He was not head of the physics department. He
never wanted to be head of it. He was editor of the Physical Review for
twenty-four years. He got the job very young and he died quite young--he was
only sixty when he died. But, he was the leader of that enterprise which was the
largest research enterprise in the department here. A few students went into
theoretical physics, which this department pioneered because we had Van Vleck on
00:21:00the faculty at that time. He turned out some of the first students in quantum
mechanics in the country. Professor Valasek, in his work in X-rays and other
related things had students, but otherwise, it was mainly Tate who had students.
And they all worked on something related to electron impact and gases. There was
a real break-through at the time. There were several students who were very,
very good, they were predecessors of mine.
One that's really outstanding is Walter Bleakney, who was the man who first
recognized the importance in electron-impact studies of separating the
00:22:00acceleration of the electrons from the acceleration of the ions. (Figure 1) Keep
in mind that quantum mechanics was just coming in. It was the 1920s and there
was an interesting thing that people called the critical potential. It was an
interesting subject in the late 1920s. To do this quantitatively, you have to
know how fast the electron has to go to make an ion. You see, it isn't just any
old energy, you have to have a minimum energy or it doesn't ionize. Well, that
wasn't very well understood, and if you did it the way the conventional
spectrometers of the 1920s did it, where you accelerated the electrons in one
direction and used the same field to accelerate the ions in the opposite
direction, you got all mixed up and couldn't determine the potential of the
electron when it made the ion, because it wasn't a sharply defined thing. So,
00:23:00Bleakney came up with the idea of having the electrons go at right angles to the
ions. I wrote to him a few years ago--he's still living, well up into his
eighties--about what the history of that was. He says yes, he was the one who
really came across this idea. So, what you do is collimate an electron beam with
a magnetic field, so you get a tight pencil of electrons. You can control their
speed accurately by sending them through suitable diaphragms--a suitable gun
arrangement--so, when they come out, they're going at a very definite speed,
very sharply defined. Then you send them into a region where there is a small
cross-field, and draw the ions out at right angles. Then you can do tricks with
them, accelerate them, and so on.
00:24:00GRAYSON: So, this is essentially the beginnings of the electron-impact ion
source that everybody uses.
NIER: Everybody's used since. It was Bleakney's doing.
GRAYSON: I see.
NIER: And this was about 1929.
GRAYSON: But his primary interest was this very fundamental phenomenon related
to the ionization energy for different gases.
NIER: That's right, and he was the one who discovered quantitatively the
formation of multiply charged ions. Before that, it was a big mixed-up business.
His first study was on mercury, because we had mercury diffusion pumps and you
just adjusted the trap temperature to get mercury vapor. He determined the
ionization potential for singly charged mercury. He could tune to the mass 200
position and gradually increase the electron energy. You couldn't resolve the
isotopes with those early machines, so it was just about 200.
00:25:00GRAYSON: He was just looking at this lump in the vicinity of mass 200, a single lump.
NIER: Lump, that's right, the single charged mercury, around 200. And you got
nothing until the electrons were going 10.4 eV, or something like that. Then you
began to see the onset and generally reached a maximum around 100 volts or so.
You tuned to the position of doubly charged, like mass-100 m/e, and you didn't
get anything till you got to, I don't know what the number was, 35 or 40 eV
something like that.
GRAYSON: Yes, noticeably higher . . .
NIER: Then you turned to a third of 200, and you began to see those at sixty,
seventy or eighty or whatever it was, I think he observed up to quintuply
charged; that was the first time anybody had done that quantitatively. And this
guy was just a graduate student, you understand. Then, the other thing he's
responsible for is molecular ionization studies, which everyone's forgotten
00:26:00since. It really was a most amazing time. I was an undergraduate then and
coincidentally, Bleakney was my lab instructor. I never knew that I would follow
in his footsteps, but he was the teaching assistant in my first course in
physics; just a coincidence.
But anyhow, Ed Condon, who was one of the pioneers in what might be called
"chemical physics," especially the application of quantum mechanics to chemical
problems, was here a year or two on the faculty as a theoretical physicist
teaching quantum mechanics. I think he's one of the true pioneers of the middle
1920s, and he came here when Van Vleck left to go to [University of] Wisconsin.
And that was when he worked on this problem of what happens when you hit a
molecule, like a diatomic molecule, with electrons--what happens to the
00:27:00molecule? He was studying the quantum mechanics of this business, when either he
or somebody else, came up with this idea, that if you raised the molecule to a
higher energy level that it would fly apart. It doesn't start flying apart, you
have to go to the right energy and then it flies apart. And you have excess
00:28:00energy over what would be in the state of the particle, so the thing would fly
apart with energy. And so, if you take a neutral molecule, I think they worked
with nitrogen, or carbon monoxide and hit it with electrons that were going at
fast enough . . . you raise its energy up to the point where the ion and the
neutral fly apart. And so, he pointed out that you ought to be able to observe
these kinetic energy ions.
GRAYSON: Now, you said the second thing Bleakney was not known for was this
business with Condon and molecular ionization/fragmentation.
NIER: Yes, Bleakney was a graduate student here, and he knew Condon . . . of
course, everybody knew Condon. He was described like an old pair of pajamas: one
of the most friendly, wonderful guys that you ever wanted to meet and a
wonderful storyteller, just a terrific guy. Anyhow, he knew that Bleakney had
this spectrometer that could do these tricks, you see? So, Condon told Bleakney,
"Why don't you go downstairs and play with the apparatus, I'll teach your lab
00:29:00this afternoon." Or something like that. Well, Bleakney did essentially that,
and sure enough, found the energetics of hydrogen fragmentation.
GRAYSON: So, this represented additional work in molecular ionization,
fragmentation and so on as opposed to just the elemental ionization.
NIER: That's right. These were the two important things that Bleakney was
involved in. And then he got a National Research Council Fellowship, and went on
to Princeton [University]. There were two other guys who followed him shortly
who also were very good, P.T. Smith, who very few people ever heard of. He was
the most wonderful apparatus-builder, and my hero of those days.
GRAYSON: He was on staff here?
NIER: No, he was a graduate student, at my time. He had done this nice work, and
knew how to build instruments nicely.
GRAYSON: When you say, "he knew how to build instruments nicely," can you explain?
NIER: Well, he knew how you fabricate this stuff; making electrodes and so on,
00:30:00and putting them in a vacuum system. He had a real appreciation.
GRAYSON: He had a way of going from an idea on a piece of paper to something
that actually worked; that was a talent that some people had.
NIER: Yes. He had this peculiar sort of a talent, and he followed up things that
Bleakney had done; measuring total cross-sections, without a spectrometer, just
measuring the ions coming off, without trying to separate them by mass. And the
work that he did, about 1931 . . . people still, very proudly point out that
they checked Smith's values of l931.
That's how good
he was. I'm sure that there've been improvements, but in general, these guys did
NIER: The other guy, Wally Lozier, L-O-Z-I-E-R also had a National Research
Council Fellowship--there weren't many, maybe about two in all of physics and
00:31:00these guys got them and went off to Princeton. They followed Bleakney to work
with him. I knew them all, because I'd been around for a year. So, after they
were all gone I was casting around for something to do. I think I told this in
my reminiscences about geology or something. I thought the last thing in the
world I wanted to do was to work in that field. I thought I would do something
else, so I considered various things, I thought of working in microwaves,
because at that time, people were talking about the ultra-high frequency things
you could send through lenses made out of "pitch" and stuff like that. It
sounded like an interesting thing. And they talked about "plasma oscillations;"
00:32:00interesting discharges in gases.
So, I started out and set up the standard discharge tube where you have the
striations in it and stuff like that. Tate, was a very systematic guy, and the
students had great respect for him because he was so good, so you were sort of
afraid of him. He was so busy, he was then instrumental in setting up the
American Institute of Physics. He was editor of the Physical Review, the Review
of Modern Physics, and he commuted all of the time to New York [New York] to set
these things up. Remember you went by train, and it took two days each way, so,
he wasn't around that much, plus his editorship . . .
GRAYSON: We'll have to continue on another tape . . .
[END OF AUDIO, FILE 1.1]
00:33:00GRAYSON: Okay, we're on Side B of Tape 1, interviewing Al Nier. Tom Krick and
Mike Grayson are doing it. I meant to say that on Side A of Tape 1, but at any
rate, we've got it on Side B, and he was telling us about Tate's activities. [laughter]
NIER: Tate, while he was the advisor for most of the experimental graduate
students, he never spent much time with them. In particular, he didn't really
spend much time with you unless you were getting results. It was really a rugged
existence for people. I was batting around here, trying to work on something
that he wasn't particularly interested in, and he would come and see me once in
a while, and he'd look at the glow discharge and say "So, what're you going to
do with that?" and so on. I wasn't quite sure what I was going to do with it;
then finally, onetime he came down, and said "Gee, sounds a little like you're
working on something that General Electric did years ago and never bothered to publish."
GRAYSON: Real helpful!
00:34:00NIER: Real helpful! But, it was helpful. There was a message there. I batted
around a little more, and he suggested I might work with a guy by the name of
John Williams, who had just come here as a post-doc to act as an assistant to
Tate. Tate had prestige, he had money, so he could hire people full time as
post-doc assistants. John Williams, whose whole background was in X-rays, had
been with Sam [Samuel K.] Allison at [University of California] Berkeley and
then at [University of] Chicago. He came here, and was supposed to work on
electron impact, but by that time, the field was really drying up in the sense
that it wasn't terribly exciting for physicists to continue in the field.
00:35:00Chemists hadn't quite caught on, and couldn't build instruments, even though it
would turn into more of a chemical field; the study of the structure of
molecules and so on. Tate had lost interest. He, sort of, had a short
interest-span anyhow, because as editor of the Physical Review he knew
everything that was going on, and nuclear physics was just coming in. He had
Williams working with him, and they were going to build up a mass spectrometer,
sort of, picking up where P.T. Smith had left off.
Well, Williams barely got here and nuclear physics began to break forth, and
people were able to do nuclear disintegrations with relatively low voltages, a
few hundred kilovolts. You could perform reactions on the light elements like
lithium and boron. We had a 300,000 volt X-ray set here in the department, which
00:36:00really had never been used for anything before. So, Williams was encouraged to
go into nuclear physics and of course, he was anxious to do that anyhow. He
dropped out of the mass spectrometry entirely, and I was left alone; all on my own.
Well, in the meantime, I'd built an instrument taking advantage of all of the
work of my predecessors. All the early instruments that we're talking about were
180 degree mass spectrometers, and you had a solenoid that enclosed the whole
instrument. You accelerated electrons along the solenoid, because the magnetic
field collimated them and you drew out the ions sideways. You had a long glass
tube, which would be on one side of the hole in the solenoid, and a
horseshoe-shaped glass tube would come off it, which contained a 180 degree
00:37:00analyzer, Bleakney's instruments were housed entirely in glass, using a
four-inch diameter glass tube. (Figure 2) Smith came up with the idea of just
having an arm on the side for housing the magnetic ion analyzer, so you didn't
need the great big glass tube. You didn't have to have wax ends on it, so you
could seal it all up. And I should mention also that the thing that was
remarkable here was that they used ultra-high vacuum techniques in the sense
that there were no grease joints, no stop-cocks, no nothing else. They used
mercury pumps, and so you could pump down, bake the apparatus, and so on. You
didn't have all of the impurity problems, because many of the early people who
played with electron beams, had water present, and you formed hydrides and had
all kinds of stuff that led to confusion in your results.
GRAYSON: So, these were glass-sealed systems?
NIER: Pyrex glass-sealed, the electrical leads were tungsten, which you could
seal into the glass.
GRAYSON: So, you had to have some glass-blowing technology?
NIER: That's right. We had a very good glass-blower. But you also had to be able
00:38:00to do some of your own glass-blowing; I became a pretty good glass-blower.
GRAYSON: So, even as we're talking about the early 1930s, you're saying that the
vacuum technology that was being used in these experiments was comparable to
vacuum technology that was available many, many years later in other parts of
NIER: In most places. Except that the people who manufactured electron-tubes had
known this for decades, like GE, Westinghouse, Bell Labs and so on.
GRAYSON: Then, in 1930, electron tubes had been manufactured for how long?
NIER: Ten or fifteen years--1920 thereabouts. The good vacuum technology was
standard in factories, in places like General Electric.
GRAYSON: So, in a way, better vacuum practice was being done in industry.
NIER: Industry, but not in the universities.
GRAYSON: Not in academia, I see. That's interesting.
NIER: And very few people in the academia had good vacuums. There wasn't
00:39:00anything mysterious about it; it just was the way it was.
KRICK: They just worked with grease-seals in those days, and just did it that way.
NIER: So, anyhow, that was the kind of tube I inherited. I didn't work on
electron impact on gases. Although I had the first spectrum of benzene that
anybody ever had, and I was never encouraged to publish it. (Figures 3, 4)
NIER: Mass 78, 77, 76 and then, finally . . .
GRAYSON: Where is it? [laughter]
NIER: I have it around. I have a copy of it.
GRAYSON: You have it around?! [laughter]
NIER: But it was never published. I made a slide of it once and showed it at a
meeting, but that's as far as it ever got. The thing I missed the boat on was
the metastables because as you got down in the 20s, and you had some fractional
00:40:00mass numbers. I didn't try to interpret them. It wasn't until later, when
Hipple--John Hipple was at Westinghouse--and Condon, who had been interested at
the time, published something on the interpretation of these fractional mass
peaks--26.3 or there abouts.
GRAYSON: When did you put benzene in the mass spectrometer? I mean, that would
have been what year?
NIER: 1934 or 1935.
GRAYSON: Okay. What prompted you to put benzene in?
NIER: Well, it sounded like fun. The instrument I had was a larger solenoid than
people had used before. It was supposed to be part of a big electromagnet to be
used with a cloud chamber for some nuclear studies, but the electromagnet was
never completed, so there was a solenoid available with a seven-inch hole in it;
about so long. It weighed 500 pounds or thereabouts. I have a picture of it, by
00:41:00GRAYSON: Yes, we can hopefully get a picture or get a copy.
NIER: So, I had a larger magnetic field and a larger radius than had been used
before. A five-kilowatt generator was used to power it. I could get resolution
up to a hundred or so. I worked with the cadmium isotopes for instance, and so,
to work at mass 78 wasn't all that hard. I looked in the literature of the
chemists who had tried to build instruments in the 1920s. They had built
instruments and done some work on electron impact, but with their greasy, watery
systems, they found all kinds of crazy stuff. Also they didn't have nearly the
resolution I had. At that moment, I had the highest resolution mass spectrometer
in existence. There was nothing going on in Europe along this line, and there
00:42:00were a few places in America. Princeton and Chicago did some work in the
chemistry department. But nobody had as good an instrument as I had with this
solenoid that I'd inherited when Williams started out. There was a real break.
Again, it shows you what happens to people. One of the problems we had was, you
had to run the solenoid, which took a lot of power, five kilowatts, off a motor
generator. And motor generators weren't exactly the most stable things;
armatures would wander back and forth on the shaft, and the output voltage
changes a volt or two in 110, or there abouts.
GRAYSON: Sounds like mass spectrometry in China today .
NIER: [laughter] Yeah. Right. So, the question is, what to do about it, and it
was at this point that my engineering background and connections came in. To me
00:43:00it seemed hopeless to control the output voltage of the generator, because it
required stabilizing so much power. So why not be more subtle? It occurred to me
that, since the mass that you collect is proportional to the square of the
magnetic field divided by the accelerating voltage, why don't you fool the
instrument by monitoring the magnetic field, and changing the ion accelerating
voltage so that you stay on the peak. I went to talk to Dr. Hartig, who I'd
known so well, and who'd been my savior a couple of years before, about this.
Could we use a vacuum tube as a magnetron, and put it on the axis of the
solenoid, outside of the instrument, pick up the fluctuations, and modulate the
00:44:00high voltage in such a way that if, for example, "B" went up by 1 percent, the
accelerating voltage went up by 2 percent. B-squared over V. The result was, the
ions didn't know the difference, so the trajectory was stable. I could work with
heavy ions where you needed high resolution. It was my first publication, a
little note in RSI [Review of Scientific Instruments].
GRAYSON: Yes, I noticed that.
NIER: As far as I know, only one person elsewhere ever used the idea--someone at
Columbia. One of the guys there used the idea but I don't know whether it was
successful or not, because they had other instrument troubles. Anyhow, it was
the thing that got me started, because it made it possible for me to work with
our cumbersome apparatus. The magnetron gave us the stability we needed. To tune
up this apparatus you sat it on the side of a peak, and tuned the gain of the
00:45:00magnetron. You moved the position of it, with a slider. You slid it in and out
of the magnetic field, to get it so that it would just balance, so that it
didn't overdo it or didn't under do it, and you could sit there all day, on the
side of a peak.
GRAYSON: What you were really doing was taking the fundamental concepts in
electrical engineering such as feedback control . . .
NIER: That's right. That's what it was. Feedback control.
GRAYSON: And using it in the physics experiment to make the thing work.
NIER: To make it work, that's right. That is why it's so interesting how these
things overlap. It isn't quite clear which is which, you see.
GRAYSON: Well then, how does one get a spectrum with this machine?
NIER: Well, we changed the accelerating voltage. We had decade boxes, which was
all you had then, and put-and-take boxes, because it was just a potentiometer
arrangement. We used a put-and-take box so you didn't change the resistance of
the string; you just changed the tap on it, and you did it in a precise way. You
sit there, and turn the nobs, and follow the galvanometer spot that you had to
00:46:00look at . . .
GRAYSON: So, now, we're saying that taking a spectrum represented a day-long proposition?
NIER: Well, hours.
GRAYSON: Hours long?
NIER: Originally. And another great break came. Being born at the right time and
being around at the right time helped. The electrometer tube had just been
invented. One of the other graduate students had built, for a master's degree,
an amplifier using an electrometer tube. My first work was done with a quadrant
electrometer, where you have a little piece of aluminum foil shaped like a
four-blade outboard motor propeller hanging on a metallized-quartz fiber in a
hollow round metal box cut in quadrants, opposite quadrants tied together. A
potential difference between the pairs of quadrants sets up an unbalanced force
which rotates the little propeller-shaped object, which in turn twists the fiber
and attached mirror. You passed a current you wanted to measure through a
00:47:00resistor mounted between quadrant pairs. You couldn't buy commercial
high-impedance resistors then, so you took a pencil and a piece of insulating
material, such as fiberboard, and put pencil marks on it. You rubbed the pencil
on the insulator, and that was the resistor. If you got the resistance too low,
you erased some of the graphite. You adjusted this to get the amount of
resistance you wanted. And that was standard in those days. Everybody was doing
this in the 1920s and early 1930s. But I came in just at the tail end of the
quadrant electrometer era, so I had the privilege, if you want to call it that,
of working for only a short time with a quadrant electrometer!
GRAYSON: And so, basically, you adjusted the put-and-take box, as you call it,
to move to different portions of the peak, and . . .
NIER: That's right, and you would go over the whole mass spectrum, dot by dot.
GRAYSON: Okay, then the job of the operator constituted recording the
information at each point.
NIER: On a piece of paper.
00:48:00GRAYSON: Did you stay at a particular spot on the potentiometer for a minute, or
did you collect data?
NIER: Well, what one generally did was probably not much different from what one
might do today. You went over the whole spectrum to see what it looked like, and
then you went back and did peak-stepping.
GRAYSON: Okay. The mass scale was assigned in what way then?
NIER: Yes, inversely proportional to the accelerating voltage.
GRAYSON: So, if you knew the mass of a prominent ion, you could compute the
others as well.
NIER: Then you could predict every other one.
GRAYSON: And this was on a machine that had a resolving power, you say, of about
GRAYSON: And the peak shape looked like?
NIER: Well, not as sharp as nowadays, but not bad.
GRAYSON: Not bad. Do you have any data from those early experiments?
NIER: Yes, yes.
GRAYSON: Could we get copies of that kind of information?
NIER: Yes. You better write that down so that we remember to do all these things
I'm promising you. [laughter]
00:49:00GRAYSON: So, the benzene . . . you just put that in as, kind of as a lark.
NIER: Yes, but I said, "Look, my advisor isn't interested in this anymore, so I
better get in something to do with nuclear physics." And I said, "Gee, if I can
do benzene, I could do such things as argon." Argon-38 had just been discovered,
spectroscopically by some people in Holland, if I remember correctly, but the
exact amount of argon-38 wasn't known. Argon-36 had been known before that.
[Francis William] Aston may have even seen the argon-36 along with argon-40, the
most abundant isotope. We had standard gas we bought them from Linde or from Air
Products. Sure enough, when we introduce argon, there were three isotopes.
without any question. So I made the first measurements on argon-38 that showed
00:50:00the five-to-one ratio from argon-36 to argon-38, I did that in a half an hour
one afternoon. (Figure 5)
GRAYSON: This was with the machine that had the feedback control.
NIER: And the stability, so you could work effectively on isotopes.
GRAYSON: Then that represents really the, the discovery of the isotopes of
argon; all of them.
NIER: Not quite, they'd been known, but I made the first quantitative
measurements on all three.
GRAYSON: So you made accurate abundance determinations of the argon isotopes. I
noticed in some of the early papers the references to a "spectrograph" in the title.
NIER: Yes, we were loose, everybody used the word "spectrograph" because that's
what Aston had invented. But that was wrong; and later that was corrected. But I
used it for a long time, I didn't know any better. And a lot of other people
didn't know any better either, but that was corrected some time down the road
and instruments which use electrical detection are now called mass spectrometers.
GRAYSON: In essence then, you really never did any work with spectrographs.
00:51:00Could that be said?
NIER: That's correct.
GRAYSON: So, it was always been electrical detection.
NIER: It was always electrical measurement. That is correct.
GRAYSON: Okay. That's interesting. Even in your Mattauch-Herzog instruments, you
still were doing electrical detection.
GRAYSON: It's occurred to me, and this is just an aside, that you see
"spectrometrists" used some times but I haven't found that word in the
dictionary. You see "spectroscopists," but I don't know if I've seen "spectrometrists."
NIER: I may have. But it isn't common apparently.
GRAYSON: No, but I think most mass-spec people think of themselves as a "mass
spectrometrist" as opposed to a "mass spectroscopist."
NIER: Yes, of course. But you see, "mass spectroscopy" is broader. It would
include either spectrography or spectrometry; so that gives you more prestige in
this instance. [laughter]
GRAYSON: Well, now that we have those little nomenclature details taken care of,
00:52:00we do have a promise that you are going to supply us with a copy of your raw
KRICK: Right, benzene and other point-by-point measurements.
GRAYSON: That would be excellent, because I think, as you're well aware, with
instruments today, and computers and so on, so much of this type of activity is
just taken for granted and people don't even think about it.
NIER: Oh, yeah. Well, the strip-chart recorders of those days were very
primitive . . .
GRAYSON: Oh yes!
NIER: Even during the war, when we were building instruments for the Manhattan
Project. Electronic chart recorders were not yet available, at least at the time
when we needed them. So, we employed the old Leeds & Northrup devices where you
had a galvanometer and a needle that went back and forth and something bit down
on the needle. They were quite precise. Amazing instruments, by the way, but
terribly slow by modern standards.
GRAYSON: I just finished listening to a reminiscence from John [H.] Beynon who
00:53:00described a high-speed recorder they had in England. He said, at that time,
which I don't recall when it was, if the damping was a problem, you had to stay
away from it because it spread ink all over the place. [laughter]
NIER: I believe that. That's right.
GRAYSON: Well, I posed this question to you earlier; if you look at the mass
spectrometer as a series of different systems: a sample inlet system and an
ionization system, an analyzer, detector, data system and vacuum system,
starting back from when you first became involved, each of these systems were
kind of fundamental and basic, and today we have tremendous advances in each of
these. Why don't we just explore each of them with your early instruments. Like
sample inlet. Obviously, when you say "put benzene into this machine", how did
00:54:00you do that? How did you put samples in that early machine?
NIER: Well, we had all-glass systems. And, we didn't use stop-cocks and such. I
don't remember exactly, but we had a bottle of benzene--I still remember the
little bottle. We got it from somebody in organic chemistry, and it was very
pure stuff; that was part of it. I suppose I put a small amount in a glass tube,
froze it in there, and then sealed that onto the manifold system. This probably
had a u-tube. You could feed mercury into the bottom of a u-tube, a y-shaped
one, and you could seal it off that way. And I suppose that's what we probably
00:55:00used in place of stopcocks. The leak system at that time, the standard thing was
to send gas through a glass capillary. It was an art form to make the
capillaries. You took a piece of 8 millimeter Pyrex tubing, heated it locally
with a torch, and then drew out the tubing to a capillary. We worked entirely
with Pyrex, so it was easy in that sense. Then you broke off, say, six inches
from that part of the tube; and you hoped you'd drawn it at the right rate. If
you pulled very fast, you'd make a very small tube. If you wait long enough,
till it's just about ready to harden, you can make kind of a heavy walled tube.
00:56:00There was a lot of technique involved. You got pretty good at this. After you
broke it off, you would test it by putting pressure behind and putting the end
underwater to see if it bubbled. If it bubbled, it probably was too fast. So,
you threw it away. Then, if it was too slow, you'd break off some more. So you
got pretty good at this. Then you sealed it into a tube, which covered the
capillary, so there was a ring-seal connecting it and protecting it. You ended
up with a continuous length of, 8-millimeter tubing, with a barrier in it, and
the capillary sticking in one part. That was how you admitted the sample into
00:57:00We didn't worry much about fractionation, what it did to the sample. You were so
happy to get something going, so you didn't worry much about that then. This was
all sealed onto the apparatus, you pumped with the mercury pumps. In those days,
we couldn't afford liquid nitrogen, except in special experiments. We used dry
ice in alcohol or acetone for cooling. We got liquid oxygen in those days from
the Air-Reduction people who had a plant over here in southeast Minneapolis
[Minnesota], not far from the hotel you're staying in. I used to go over in my
own car and buy it by the liter. I would take a quart thermos bottle, and go
over there, and they'd fill it for me and I'd bring it back, and you nurse it
along. It would last you about 24 hours or so, and I would go back the next day
00:58:00and get another liter if I needed more. The department owned some dewar flasks
that would hold a couple liters. They were used for demonstration purposes, in
standard-run physics experiments.
GRAYSON: Do you have any feeling for the level of vacuum that was actually achieved?
NIER: Yes, we used a McLeod gauge. We didn't use ionization gauges; some people
did. In a McLeod gauge, you trapped a known amount of gas in a bulb and squeezed
it up into a capillary where its pressure could be measured using pV=p'V'.
Pressure was measured beyond the trap, because you didn't want mercury in the
system. We had a very good glass-blower. He made these McLeod gauges with a
sensitivity such that the first millimeter of the capillary was equivalent to
00:59:00about 2 x 10 -6 torr. So you had a 500cc bulb with a capillary that was about a
half a millimeter in diameter. And of course, there was the matter of selecting
capillaries that were uniform. But, since it was a squared scale, it didn't have
to be that accurate anyhow. But we didn't really use that very quantitatively,
the amount, it was just an indication that . . . .
GRAYSON: Essentially the vacuum system was usable.
NIER: . . . it was good. You could sense when the vacuum was good, because if
there was no air in there, the mercury would bang against the end and stick. So
you had what you called a "sticking vacuum," meaning that there was very little
01:00:00gas in there. That was like 10-7 [torr] or so, and I suppose that's as good as
we ever got.
GRAYSON: And so, this would be between the trap and the mercury diffusion pump.
NIER: That's correct, that's right.
GRAYSON: Then basically, with your trap you were pulling out the mercury so you
had a quite good vacuum.
NIER: I think we always worked with better than 10-6. But I don't think we ever
got down to 10-8 or lower. The mercury vapor pressure was enough, first of all,
that it would probably be around this range . . .
NIER: . . . and there must've been a little water. But it was certainly orders
of magnitude better than what most people were doing then. And, as I say, that
was standard technique in this lab.
GRAYSON: Okay. Now, if you were introducing a sample for isotope analysis, there
were two problems. One was getting the sample into the gas phase, and the other
was the problem of getting it inside the instrument. I guess getting it inside
the instrument would be similar to the way you would do for benzene.
NIER: Yes. Well, argon was a cinch.
GRAYSON: Oh, yes.
NIER: You just trapped some of it, that was easy.
01:01:00GRAYSON: Yes, gases would be somewhat easy. Now, for instance, for some of these
other isotopes . . . ?
NIER: Well, that took a little more technique.
GRAYSON: Did you have a chemist assist you in some of these.
NIER: No, not in those days. [laughter] But I stuck to things I learned to work
with . . . you see, the next thing I did after argon was potassium. (Figure 6)
NIER: That was interesting, and it really fit into the nuclear physics picture
because at the time there was a big argument about which isotope was responsible
for the radioactivity of potassium. That'd been argued about for years. The
potassium-39 and potassium-41 were well known, and many papers appeared in
Nature magazine in which people were speculating, is there another isotope? Is
there a potassium-40? Is there a potassium-42, or potassium-43, or some other
isotope? This was right in 1933 or so, when nuclear physics was just coming in.
01:02:00I said, "Well, this is just made to order, because if I'm going to get attention
around here, I need to be in nuclear physics, and here it fits in." [laughter]
So, what I did then, was to start working with potassium. And the way you did
that was you got some potassium chloride, and you heated it with calcium
filings, and you could make metallic potassium that way. We sealed off the
potassium in little tubes with break-offs on them. I did the same thing with
rubidium, for instance. That was kind of the standard thing that one did. Of
course, at room temperature, potassium doesn't have much vapor pressure. So you
had to run the spectrometer tube hot. But you couldn't run all of it hot--not
01:03:00the collector end--because the glass became, conductive. So, we had to separate
the ion gun and the acceleration part from the analyzer part. You only heated
that part of the tube, and some potassium would leak through the slit into the
analyzer, but not enough to make any difference, and it would fall dead since it
was cold there. It didn't bother you. It never got around to the collector
itself, and that worked.
GRAYSON: So, basically, the problem of a hot-ion source is what you had to deal with.
NIER: Yes, that's right.
GRAYSON: The fundamental technological problem that we all have with samples
even today. You had to devise a way of heating it, keeping it warm.
NIER: Devise a way of heating, correct
GRAYSON: Did you just wrap a heating tape around it?
NIER: Yes, just a heating tape around it. Well, we put a layer of asbestos on
01:04:00it. I should be dead! [laughter] I think the asbestos problem is badly
overblown. But anyhow, be that as it may, you got a roll of asbestos, got a
piece off the roll, wet it, let it dry on the glass tube, wound a nichrome
heater on it, put another layer of asbestos on, and waited until the next
morning and it would be dry. Or if you were not patient, you'd start putting
electric current in gingerly, and it would dry out more rapidly; sometimes we
put some water-glass on as a final coat to hold the asbestos in place.
GRAYSON: So, you didn't even wrap it with heating tape. You made your own heater?
NIER: I don't think heating tape was available in the United States. So we made
our own heaters. Besides, it was cheaper!
GRAYSON: You made your own heaters, on the spot.
NIER: That was standard. And sometimes, if you wanted to take them off, you made
a piece of aluminum tubing out of this aluminum sheeting, and wrapped it around
and put rivets in it. That made a slip-on furnace, a tube-furnace that could be
slipped on things.
GRAYSON: Okay, that's the end of this side.
01:05:00[END OF AUDIO, FILE 1.2]
01:06:00GRAYSON: [ . . . ] That was the primary way of volatilizing a sample?
NIER: Yes. Also, you could put a little oven into the source itself. A little
locally-heated oven; that's what I did later, but not here at Minnesota. I did
that at Harvard [University] when I worked with elements like calcium, and
strontium, uranium, things of this kind. I had a little box that I could heat
with a little heater right in the source.
GRAYSON: Kind of like a predecessor to today's solids probes that are heatable,
but they were a very, very fundamental kind of thing.
GRAYSON: Well then, what about that mass analyzer? Well we've, kind of, covered
that. At this point, the early mass analyzer you worked with was essentially the
solenoid design. Was this a derivative of your predecessor's instrument?
NIER: Well, there's P. T. Smith, Bleakney first, then Smith, who had come out
with the idea where the analyzer was an arm on the side of the tube.
01:07:00GRAYSON: And that was essentially the technology at the time?
NIER: Yes. I have a picture of that, my first glass tube.
GRAYSON: He's going to give us a picture or a copy of that picture, right? Make
a note of that, Tom. Now, you've got to detect this ion current at the other end
of the tube.
NIER: Yes, and I was fortunate. In the midst of all this, the electrometer tube
became available and we happened to have one. One of the other graduate students
at the time had built this amplifier and so I had the use of it.
GRAYSON: We're starting from a faraday cup?
NIER: Yes, a faraday cup. I think we still used the graphite on a little fiber
board for the resistors. But, about that time, you could also get S.S. White
resistors. S.S. White was a dental supply place and I've never understood why
01:08:00they made resistors, but you bought a little black thing that was about the size
of a fuse, like an automobile fuse. A little object about a quarter of an inch
in diameter and an inch and a half long. It had leads molded in. Well, the way
resistors have always been made. But this was solid, some black stuff, and I
have a feeling . . . I don't know, it'd be interesting to hunt that down
sometime . . . this was some of the stuff they made dental plates out of. They
probably put graphite or some other electrically conducting material in it to
make it dark. Somebody discovered that it had resistive properties. See, this
was some kind of plastic . . . and so then, they made these things deliberately
by just simply molding some wires in and you bought these things 109 ohm, 1010
ohm, 1011 ohm and so on. And if the resistance was a little lower than you
wanted, you would file off or grind off some of it to make it smaller in diameter.
GRAYSON: This was to get the feedback resistance for the electrometer?
01:09:00NIER: Yes, but there wasn't any feedback in those days. I mean, it was the resistor.
NIER: You had the current go through it to get a voltage drop across it and the
electrometer, just like any vacuum tube, measures voltage.
GRAYSON: Because you were working with small currents you needed a large resistance.
NIER: Yes, because the bigger the resistance for a given current, the bigger the
voltage. Of course, the virtue of the electrometer tube, was that it used very
low voltages. They're very well made. I still have some here by the way. Some of
the original ones, and . . .
GRAYSON: Is it possible to swipe one?
NIER: Well . . . you can look at it.
GRAYSON: Or look at it or take some pictures of it.
NIER: I don't think there are many of those around. And that was the standard
that everybody used for measuring small currents. The voltages on the tube . . .
instead of the standard vacuum tube in those days which had like 90 volts or 135
01:10:00volts or 200 volts on the plate--were 4 volts or 6 volts. So you never ionized
any of the gas that was left inside. They were carefully made, under a very good
vacuum. They used oxide-coated films, so it didn't get very hot, so you didn't
have X-rays or much ionizing ultraviolet. The result was the internal impedance
looking into it was very, very high, like 1013 ohms or 1014 ohms or more; so
when you put a resistor across the input, it wasn't shorted by the tube. They
used balancing schemes by making a bridge out of the tube. It was a pentode, so
it had several electrodes in it and you had a galvanometer between the screen
grid and the plate. The galvanometer measured, then, the unbalance of the
circuit when current flowed in the resistor between the cathode and input grid.
01:11:00GRAYSON: So, then, the output of the tube was measured by the galvanometer
deflection? Is that the way it was hooked up?
GRAYSON: How did the signal information get from the galvanometer to the recorder.
NIER: Well, the light reflected from the mirror on the galvanometer to a scale.
And you read the deflection.
GRAYSON: So, you read the scale off as you went along? And adjusted the put-and-take-box.
NIER: Yes. That's right. And then you took the reading. You waited till the
galvanometer got to equilibrium, five seconds or so. You had to have the right
damping resistor in the galvanometer so it didn't oscillate. It took time.
GRAYSON: Yes. [laughter]
NIER: Except for the long time it took, you could still make very good
measurements. You could also get by without a resistor and just measure the
charge build-up in the capacity of the system. You then got a rate-of-drift
01:12:00measurement, and you'd measure the rate. In all of my work at Harvard, where I'd
worked on very rare isotopes, I did just that. (Figure 7) I took the resistor
off and watched the rate of drift. You could measure currents about 10-16, 10-17
amperes. You waited, like, 30 seconds for the spot to cover the scale, and you
worked backwards for calibration.
GRAYSON: So, the drift measurement would be kind of like an integrative . . .
NIER: That's right, an integrative measurement.
GRAYSON: . . . integrative measurement, compared to the electrical detection scheme.
NIER: That's right. And that was used by people long before my time; there were
people doing ionization measurements with radioactivity. They had been working
with that kind of technique for years. I mean, that was nothing new. That was
the technology of the times.
GRAYSON: That was standard practice.
NIER: Right. We sometimes forget that individuals were doing some pretty
exacting experiments in the 1920s.
GRAYSON: They didn't have the technology we have today, but they were still
01:13:00using what they had to make very good determinations.
NIER: They were doing some very good measurements. Slow . . .
GRAYSON: That's interesting. As an aside, I talked to a friend of mine once, and
we were going to do a little discussion of . . . [beeper beeping]
NIER: Pill time. I'm sorry. Go ahead.
GRAYSON: Okay, we were going to do a little local course on mass spectrometry
for some of the people in St. Louis, and I told them, "I'll bring a spectrum
from a magnetic machine, you can bring a spectrum from your quadrapole machine,
we can show them the difference." And he said, "I can't get a voltage versus
mass signal out of my quadropole mass spectrometer." The computer takes
everything. How can you do that? You have to be able to look at the mass
spectrum in reality somewhere along the line but, in modern instrumentation, in
a lot of modern instrumentation, it's not available, you cannot look at it.
NIER: Black box.
01:14:00GRAYSON: So, I think the point that you mentioned about this early work is that
people certainly knew how their machines were performing every step of the way.
NIER: That's correct.
GRAYSON: Because if they weren't working correctly, you certainly were aware of it.
NIER: You knew it right away.
GRAYSON: What about some of those problems, incorrect performance? Obviously,
we're talking about experiments that worked. There were some that didn't work,
right? You had problems or difficulties.
NIER: I was very naive when I was here doing this work. One of the interesting
things that I ran into was mass discrimination. We didn't worry much about
discrimination in the instruments; I guess I didn't know enough. You sensed from
things that you knew, that it must be working. You'd put nitrogen in and people
had measured the nitrogen-14, nitrogen-15 ratio roughly. So, you knew it worked.
One of the things I encountered, but not really seriously until I went to
Harvard after I left here, was how to make sure that the ion source doesn't
01:15:00discriminate. I became pretty good at judging the performance of the source by
changing various parameters and seeing how an isotope ratio varied. For
instance, what I used as a standard when I was at Harvard, was mercury, because
there was always mercury present, because of the mercury vapor pumps. I would
compare the ratio of the mercury-204 isotope to the mercury-198. I think if you
look at a modern isotope table, the mercury-198 is very close to 50 percent
higher than the mercury-204. So I would look at the mercury, and I would diddle
with the ion repeller voltage that you used to push the ions out of this
ionizing region and fool around with other things. If you used extreme values,
01:16:00you might get funny ratios; instead of 1.5, you'd get 1.6 or 1.7 or 1.3 or
something of that sort. So, I got to be pretty good in estimating when it was
working right. Keep in mind, we had no standard isotope mixtures that you could
go against. It was just your intuition and experience.
GRAYSON: Well, at the very least, though, you were tuning the instrument to a
point where the ion source operation would be standard.
NIER: Standard, yes, and not critical. For instance, you could change some of
these parameters so that the values you got didn't change much over a big range,
and then it would drop off the end. You worked in the middle of the range. It
was always a system of compromising. And this was . . . experience, I mean you
had to learn and it took a lot of feel, you couldn't have a technician come in
and take data tomorrow morning. You had to do it yourself.
GRAYSON: Right. So all this data that was acquired with regard to the isotopes .
01:17:00. . there were a lot of little techniquey things that were done . . .
NIER: It was just full of it!
GRAYSON: . . . in order to make sure that when you got to the end, and there was
an answer, that it was indeed an answer which represented a measure of reality
as opposed to just measuring something that came out.
NIER: That's right, that's right . . .
GRAYSON: You've got a source discrimation problem that you had to deal with.
Tuning it so that it wouldn't discriminate between the various isotopes. What
other kinds of problems did you have to deal with to ensure that you had an
answer that you could put in the literature and not have someone come after you
with a . . . [laughter]..blunderbuss.
NIER: Well, you worried about impurities, of course. If you were talking about
rare isotopes, you were always worried about interference. You did tricks like
change the electron accelerating voltage. In potassium . . . see, I found
potassium-40 when I was here.
That's what really set
me up in business because it was only abundant one part in 8,600 I think,
something like that. And that was really very difficult, but I remember we did
01:18:00tricks. When you ionize potassium, it takes . . . I don't know what the
ionization potential is--about 3.8 volts or some number below 5 . . . way, way
down. And so, if you ran the electrons slow enough, you'd eliminate most other
impurities and interference. You'd do tricks like this. Or if you're dealing
with vapors, such as potassium, I'd change the vapor pressure by heating the
source or cooling it and seeing if the potassium-40 tracked to 39-41. You did
various tricks of that kind, you worried about doubly charged ions interfering
or whether you got doubly charged when you wanted them. You did all these kinds
of tests. And again, as I say, this represents experience. You got a feel of
when things were right.
GRAYSON: Well, you're keeping a very critical eye on what you're doing, every
step of the way, to ensure that you're not making assumptions which will get you
01:19:00in trouble later on.
NIER: That's right, that's right.
GRAYSON: And, purity would be a problem. Did you rely on, for sources of these
materials say . . . for instance, potassium, did you rely on a chemical house or
did you have special samples made?
NIER: Well, both. But most of the stuff came out of bottles from chemical
houses. It wasn't till later that I had lead samples made for me when we were
doing the geological work, but that was because you had to make those. But most
of these things just came out of bottles. You could do a pretty good job making
potassium and rubidium, for instance. When you made it yourself out of the
chlorides, with calcium, you automatically got a pretty pure assay on it.
NIER: The process itself did it. And then the vapor pressure; other things were
not that volatile, so you'd distill the stuff over, and get pretty good stuff.
GRAYSON: There were a number of different things that helped you to get it. And
01:20:00it was, again, another aspect of the whole measurement problem that you took
into account as you proceeded to do this work, and to determine these isotopes.
NIER: That's correct, right.
GRAYSON: So, now your recorder in these days was really, the person
individually. He wrote down the results.
NIER: With a pencil . . . and a notebook.
GRAYSON: [laughter] Then you did what--did you plot the data?
NIER: Plot it on graph paper, on 8-1/2 x 11 graph paper, 1/2 inch standard
GRAYSON: And took into account all of the multiplication factors?
NIER: You had a shunt on the galvanometer to cut the sensitivity so you could
change scales. So, we'd have steps like factors of two and a box that you
switched. And generally you made the shunts yourself. You could also buy these,
01:21:00but I think we made our own. We had precision resistors and you bought multiple
point switches--and you wired resistors between the points; and that was it.
GRAYSON: So, basically the technology of the vacuum system was there, pretty
much to the same level as we have it today. Some of the detection was getting
there with the advent of the electrometer tube. In terms of recorders and sample
inlets and actually mass analyzers, the technology was kind of not where it is
in modern-age, yet. I mean, there was a lot of evolution that had to be done.
But fundamentally, the vacuum system and some of the electrical detection was
pretty far along.
NIER: Yes, was really quite far along. As I say, I came in just at the right
time on that. The interesting thing is that, nobody used inverse feedback
01:22:00amplifiers yet. And the first ones we used were during the war or just at the
beginning of the war. They ended up in all of the Manhattan Project instruments
which we developed. There had been very few publications on inverse feedback amplifiers.
GRAYSON: What we know today as the operational amplifier.
NIER: The operational amplifier . . . that's right. Of course it was all vacuum
tube stuff in those days so it was sort of tricky the way you wired stuff
together. But we started using them in about 1940 for our work. They were never
as stable as the plain electrometer, so at first we used them only for measuring
large currents; for example, we used them when we did a multiple collection with
the instruments used for analyzing uranium in the Oak Ridge [Tennessee] plants
used for isotopic separation.
01:23:00Actually, we started using feedback amplifiers here in 1940, well more like
1941, when we separated carbon isotopes for biological
We had to do a lot of analyses, so we
built the first system where we could measure the 44 peak, CO2 with the inverse
feedback amplifier and then balance a fraction of the current against the
current from the 45 peak. You would have a low impedence output on the feedback
amplifier; put a decade box across it and then take a fraction of that and
balance it against the 45 peak. Then you used the galvanometer as a null reading
device. And that's when we started measuring ratios directly.
GRAYSON: So, that really represented, for the isotopic abundance work, a
technological step forward.
NIER: That's right, a real step forward.
GRAYSON: A step of real significance. Because the answer was almost there and
01:24:00basically, it was just a matter of getting some stability.
NIER: There were a few publications on inverse feedback amplifiers at the time
when I was at Harvard, from 1936 to 1938. The people there in electrical
engineering were very good, and they knew all about inverse feedback systems and
I learned a lot about how you build inverse feedback amplifiers. There were two
guys by the name of [F. V.] Hunt and [R. W.] Hickman who were faculty members
there, who had worked on inverse feedback circuits for high voltage
They had a publication on it and I learned
from them how to build inverse feedback devices.
GRAYSON: Do you feel that your background in double-E [electrical engineering]
helped you here again?
GRAYSON: Because you were able to pick up where they were right away and you
could see exactly what it was they were doing.
NIER: I understood right away what they were doing. And there were tricks, like
especially in the power supplies because you had high voltages and you had
01:25:00problems isolating things and getting it down to a low voltage. There were all
kinds of tricks, so unless you understood circuit theory you couldn't get very far.
GRAYSON: I would gather, then, the dynamic range of these instruments--even the
earliest ones you worked with--was really quite good.
NIER: Yes, it was quite good. You see, at Harvard, I had a standard glass
galvanometer scale 50 cm long and you could read this to a fraction of a
millimeter. The light spot was focused and it had a hairline that projected an
image on the scale. You could read that to say 2/10 of a mm. Then your shunt on
the galvanometer changed the range a number of times. And if you used drift
methods for very small currents, you picked up another factor of 100 or 1,000.
So I suppose, we were playing with million to one dynamic ranges. It was
cumbersome, but it worked.
01:26:00GRAYSON: Yes, but essentially, mass spectrometry has inherent in it the need for
that type of dynamic range capability.
NIER: That's right. Yes.
GRAYSON: And even though at the time, the technologies were not as advanced as
they are today, you were actually making use of the full dynamic range then.
NIER: Yes, that's right.
GRAYSON: You mentioned Harvard a number of times. Maybe we should move on to
Harvard for a minute. But first, you were encouraged by Tate to get into a
different area. Were you, kind of, kicked into a different area? [laughter] Did
he recognize that what you had gotten into was valuable?
NIER: Well, indeed. When I was able to do the argon in one afternoon, and then
01:27:00moved on to potassium and found K-40 [potassium-40], then I was really high on
GRAYSON: So, you moved up from the bottom to the top? [laughter]
NIER: Yes, and there was another fortuitous thing that happened in connection
with that, which is most interesting. Tate was editor of the Physical Review and
we published in the Physical Review. I'd made the K-40 discovery in spring of
1935, just about the time he was ready to leave for the summer to go to Columbia
where he taught a course in summer school. My paper on K-40--it was a letter and
I have copies of this by the way--went into him as editor. So, here he was, my
advisor, and also the editor. [laughter]
GRAYSON: That's an interesting situation. [laughter]
NIER: And I was his student. He was very cautious and did not like students
GRAYSON: He had your whole life in his hands. [laughter]
01:28:00NIER: Well, he accepted the paper as editor, and it was in press. You couldn't
stop the presses. As I say, this was an interesting field at the time. There was
a guy at the Department of Agriculture, his name was [A.] Keith Brewer, who was
really a pretty good physicist. He was working on isotope abundances in the
alkali metals and used thermal ionization in his work. You heated up a salt of
the element you were interested in and got ions out. Brewer also was working on
potassium, which I didn't know at the time. He had a nice instrument, and with
thermal ionization you didn't have the impurity problems; at least of the kind
01:29:00we might have. While my letter to the editor was in press, Brewer sent in a
manuscript to the Physical Review in which he stated that potassium-40 could not
exist with an abundance [of] even a tenth as much as I said was there. So, here
was my advisor and the editor of the Physical Review. [laughter] I don't think
he called me, but I think he wrote to me. I may even have the correspondence.
GRAYSON: That would be worth looking for.
NIER: It would be worth looking for, because this was most interesting. But
anyhow, I know I was quizzed, "Did I do this, did I do that, am I sure on that?"
And I convinced Tate that what I had done was all right. So, he wrote back to
Brewer and told him of my work and that this was being published and wouldn't
he, Brewer, like to do his work over again to check. Whereupon Brewer did it
01:30:00over again and he got 1 in 8,300 instead of 1 in
Well, I only claimed an accuracy of 1 percent.
So, we agreed. What had Brewer done wrong? He had nice flat-topped peaks. His
resolution wasn't as good as mine. He had nice flat-topped peaks, so if you're
looking for a little bitty thing in a valley between two big things, between
potassium-39, potassium-41 if you have a nice flat-topped peak, all it does is
raise the level in the valley. And he didn't see as sharp a bump in there as I
saw. So, when receiving Tate's letter, he did something; probably narrowed his
slits, and of course, he found K-40. Then, he published a value confirming the
value I had turned out. His letter to the editor is in the literature, a few
months after mine.
GRAYSON: So, basically, Tate was kind of in a tight spot. Because, he had work
01:31:00from his student, who was very young, that said X . . .
NIER: Who was very young. [laughter]
GRAYSON: Yes, who was very young, that said X, and here was a fellow . . .
NIER: Who was experienced, he was an older man. And he had a very good
reputation. He had done good work . . .
GRAYSON: And who had published before in this area . . .
NIER: He was an authority . . .
GRAYSON: Was recognized, and so, he must have asked some pretty incisive
questions before he sent this back to Brewer and said, "Do it over again."
NIER: Well, this didn't hurt when it was all over with, as you can imagine.
GRAYSON: Yes, definitely. [laughter]
NIER: So that's what really was a decisive factor, I'm sure, in my getting a
National Research Council Fellowship. After all, here I was, twenty-four or
twenty-three years old and had found a new isotope and it was an important one
because of the radioactivity business and so on. I'd demonstrated that an
authority in the field had done it wrong, so what more do you want? [laughter]
01:32:00So, that was very helpful.
GRAYSON: I assume Tate had the connections inside the system that would have set
your . . .
NIER: Yes, he was a wheel. He was the editor, and he was on the council of the
American Physical Society, and everything else, and on the board of the National
Research Council. So, he could write letters and say this is a guy you ought to
support, and soon, and so on.
GRAYSON: So, you were going from the low man on the pole, so to speak, to the
top of the pole. It was almost fortuitous wasn't it?
NIER: That's right. Well look, I've been retelling you these things that
happened. You had to be there to take advantage oft he opportunity. It's always
true, but, you know, the opportunities were there, that's just the point. That
was a very fortunate break because there were only two fellowships in physics,
two in chemistry, two in biology. That wasn't very many--in the whole United
01:33:00States. I got offers, then. I had the fellowship, and of course the schools said
they'd like to have these people come as post-doc's, it didn't cost them
anything except for their lab expenses.
GRAYSON: At this time you were a post-doc?
NIER: Well, I had just gotten my degree in 1936 here. So in the spring of March
or thereabouts I got word that I'd been awarded a National Research Council
Fellowship, 1,600 dollars the first year and if you were appointed a second
year, it would be 1,800 dollars. That was a lot of bucks. So, where to go? That
was the next step.
GRAYSON: Okay, then you had, to choose . . .
NIER: Yes. Bleakney got in touch with Tate or with me and said "Why don't you
come here, [to Princeton] and carry on the tradition?" See, two other guys had
already gone there and why not me? Meantime, [Kenneth T.] Bainbridge, at
Harvard, who was in mass spectrography in the business of measuring precise
01:34:00masses, had built this beautiful double focusing machine, together with a guy by
the name of Ed Jordan who had gone to Harvard as a post-doc to work with him.
Bainbridge was one of these wonderful people that you wish you could meet all
the time because he was very generous and very interested in helping people. He
assured me money from their private funds. After all, Harvard had endowments.
There was a fund called the [William F.] Milton Fund--named after somebody, some
benefactor. I think they offered me, for my lab 5,000 dollars. Which was a lot
of bucks in those days. That'd be like 100,000 dollars or something like that today.
GRAYSON: And it was prestigious institution.
01:35:00NIER: Right, and free shop-work and the like. They had machinists. So, he
offered me that opportunity. And told me about all the wonderful things: I could
come there, I could supplement their mass work, I could be the abundance guy. He
had a good reputation, he was real first-class scientist. Bleakney on the other
hand was also very good. Well, Bleakney said if I came Princeton, I could build
a super-duper spectrometer using their cyclotron part time. They were just
building a cyclotron. And, I could build a bigger 180 degree spectrometer than
anybody. Everybody was thinking in terms of 180 degree deflection in those days.
I could have had a radius of curvature of 2 feet or more. Cyclotrons magnets had
a diameter of 6 feet or more. The idea was that I could have the magnet part-time.
01:36:00Well, I thought about the matter a little bit and decided, for a variety of
reasons, that I should go to Harvard rather than Princeton. One of them being
that to be realistic, to think that I could have the magnet for much time . . .
to have them take all of the guts out of the cyclotron and replace it by the
spectrometer at a time when nuclear physics was really hot just didn't seem very
realistic. Not that they wouldn't have treated me well, in other ways. But the
whole scenario didn't seem very realistic. Also, I thought, maybe instead of
everybody from Minnesota going to Princeton, somebody ought to go to Harvard for
a change. Tate didn't discourage me. He agreed that was a good idea. This was a
very happy thing for me. I think it would have been a more friendly atmosphere
at Princeton. I would have felt much more at home there, because Harvard, at the
time, had a reputation of being . . . I wouldn't say "unfriendly . . . but it
was, kind of, New England cold, and they were pretty formal.
01:37:00[END OF AUDIO, FILE 1.3]
GRAYSON: Okay, we're recording Side B of Tape Two, and Harvard was a cool place. [laughter]
NIER: Cool weather-wise and cool otherwise. [laughter] Well, I found Bainbridge
extremely friendly. The people I met were extremely pleasant. The people were
01:38:00not all New Englanders. True, the atmosphere was a bit formal, but friendly. And
I found everybody to be extremely cordial.
GRAYSON: Even then, the Midwest and the Northeast Coast have this difference of
. . .
NIER: Oh yes, there's a different culture.
NIER: But, it turned out a lot of the Harvard people were Midwesterners and
Westerners. True, you had a lot of hangers-on from the East that stayed there.
One of my very good friends I shared a lab with was working on high-pressure
stuff there. It was a big lab, and I had one side of it and he had the other
side of it. He was from California, for instance. So, there were people from all
over. It was really quite cosmopolitan. And Bainbridge was very helpful.
At the same time, I also got an offer to work at General Electric. They were
01:39:00interested in hiring people who had just gotten degrees for summer jobs and also
graduate students. So, I was offered a job at GE, working for the summer before
my fellowship started in Fall. I went to Schenectady [New York] for the summer
months, and my boss was [Chauncey] Guy Suits, who later became the director of
research for General Electric. But he wasn't at that time. He was a promising
young man in the lab. I worked on arcs or something like that. He was interested
in vacuum arcs, and the techniques I had, of course, fit right in. It wasn't the
most productive summer. I don't know if I did him any good, but I certainly
learned a lot.
GRAYSON: And, you probably made some connections there that helped you later on, perhaps.
NIER: Some. I got to know him, I got to know [Saul] Dushman.
GRAYSON: Okay, that's a nice guy to know. [laughter]
NIER: A nice guy to know. We became good friends later on. I met everybody else:
01:40:00Albert Hall, who was the associate director, I met [Irving] Langmuir, even
[Willis R.] Whitney, who was the pioneer in the lab. So, I met all these people
. . . I'm sure they didn't remember me. But, Dushman did. I met other young
people like myself, I got to know people. I knew Fred [Frederick] Seitz, he was
one of those working there in the summer also, and stayed on. There were quite a
few. John [P.] Blewett, one of Bleakney's students in mass spectrometry, also
had a job there, working on something else. So, I got to know other people.
GRAYSON: GE had a number of summer appointments.
NIER: Yes, working in basic science.
GRAYSON: Okay, do you know if they had an ulterior motive.
01:41:00NIER: This was a recruiting scheme, if that's what you mean. You know, get a
line on young people . . .
NIER: The standard thing that goes on at many places.
GRAYSON: But they had to commit to the concept that these people had valuable
talents and assets for the future of General Electric and its products.
NIER: That's right. They wanted to look at the young people, and see, they
didn't have to make any commitment.
NIER: It was a neat way to do it. Very good.
GRAYSON: Well, the same thing is done today.
NIER: Oh, it's done everywhere. The government has a lot of post-doc positions
at the Bureau of Standards, and at the Naval Research Lab, and places like that,
with the same kind of idea where it's a one or two-year thing, except that in my
case, it was three months.
NIER: So, that was a good experience.
GRAYSON: And then you went on to Harvard?
NIER: I went to Harvard in the Fall. But, more important than that, before I
settled at General Electric, which was around 1 July that summer, the summer of
01:42:001936, I went to Harvard to meet Bainbridge. I had never met him. I had an old
car then that just barely got along. He and another family from the electrical
engineering department at Harvard shared a big house in New Hampshire. This was
the standard thing, you rented houses on an abandoned farm or something like
that. So, they had me as guest over there for a weekend. I met him very briefly
at Harvard, and then he went up to New Hampshire, and invited me to come up
there later on in the summer. We sat around for about a half a day, and talked
about what I ought to be doing. This was the beginning of July, and I wasn't
going to be coming until September. We came up with the design of an
electromagnet--this 2-ton electromagnet--which became the basic magnet for the
01:43:00instrument. The decision was, we should make something bigger, get away from the
solenoid, and then you'd get a stronger magnetic field by having an
electromagnet with a smallish air gap. So, we came up with a magnet that had a
two-inch air gap, and I think it was 12- inch diameter poles. Something like
that. (Figure 7)
GRAYSON: This was still 180 degree deflection.
NIER: Still 180 degrees, yes. And so we built it, and it had a five-inch radius.
That was the original 180 degree tube that fit between the poles of the magnet.
This whole thing was sort of designed there, between us. I don't know how much
my contribution was and how much Bainbridge's was. He certainly contributed a
lot on the magnet design. He knew about how you built magnets.
GRAYSON: The basic idea of a 180 degree deflection instrument, was that in the literature?
NIER: That's what everybody had used. [laughter]
01:44:00GRAYSON: The idea of putting the ion entrance right at the edge of the magnetic
field was already used?
NIER: No, you had the whole thing immersed. And what I had to do was to build an
ion source that would squeeze into a tube that would fit into a two-inch air
gap. And this is where the modern ion sources came from really. From that
everybody else has pretty much copied. You see, the ion sources that I was
acquainted with, which Bleakney had used, which P.T. Smith had used, which Wally
Lozier had used. You had a long electron accelerating system because it was in a
solenoid. The ion sources were five or six inches long. You accelerated the
electrons in stages, and you had diaphragms to screen the sections. You did a
very careful job of defining the electron beam without having stray fields. That
01:45:00was important if you were going to do electron-impact work quantitatively. But
if you were just going to play with isotopes, it didn't matter. It was a matter
of compressing the source enough so that it would fit into the tube. So, we used
a 45 or a 48 millimeter tube--48 millimeter, I think it was--which would fit in
a two inch air gap, along with an oven around the tube. I still have one of the tubes.
GRAYSON: Well, I'll need to get a look at it.
NIER: You can look at it. I have some old tubes up here.
GRAYSON: I need to get a picture of all these wondrous old things.
NIER: It was a matter of designing the source to fit that gap, which I did.
GRAYSON: What you're saying is that there was a point of departure here, and,
you were trying to take all the stuff your predecessors had done and squeeze it
into a smaller space?
NIER: Squeeze it into a smaller space.
GRAYSON: Or were you trying to actually redesign the whole concept of the
01:46:00NIER: No, I think the idea which they had was sound. It was a matter of
squeezing it, so it would fit in there.
NIER: Without losing too much.
GRAYSON: Okay. So you were still trying to get some of the capability of their design.
NIER: Oh yes, very definitely. And so, you didn't do as good a job of separating
the fields which accelerated the electrons and the ions. It didn't work that
well. But it was good enough for the isotope work. And that was what I was going
to work on, was isotopes, see?
GRAYSON: Now, when was that design was worked out? Over the summer, or when you
started working at Harvard? In the summer you had decided on the . . .
NIER: The magnet, that's right.
GRAYSON: Having established that, then you had to deal with fitting the ion
source in the air gap.
NIER: That determined how much space we had.
NIER: I suppose I thought about it during the summer. And when I came back in
September, I started working on it. Because I got there right after Labor Day,
01:47:00or Labor Day weekend, in September, and I had spectra before Christmas.
GRAYSON: Okay, that was 193 . . . ?
NIER: So, in three months, I had an instrument running. Now, Bainbridge, in the
meantime, once we'd decided on the magnet, had gone back to Cambridge
[Massachusetts]--I think he commuted--and had got the magnet started.
GRAYSON: Sure. Because that would be a pretty substantial piece of work.
NIER: Yes and they had a good shop. First-class guy at the head of it. And
industry was interested in jobs. Of course, Bainbridge's idea was: you had only
the best, you had to have special materials. So, he got hold of Armco iron with
low carbon . . . good magnetic properties; and he contacted whoever it was in
Ohio on how these things were made. They cast a big yoke, a big C-shaped yoke,
01:48:00and prepared coils on it. Remember, this was using about five kilowatts. They
had water-cooling tubes; they drew square copper tubing for cooling tubes.
Square copper tubing!
GRAYSON: Sounds like a first-class operation. [laughter]
NIER: First class. But, industry was interested in jobs. Boy, I'm telling you
there was a Depression, it was in the middle of the Depression.
GRAYSON: So, if you had money, and . . .
NIER: If you had money, boy, you were king . . .
GRAYSON: And if you wanted square copper tubing . . . [laughter]
NIER: You got square copper tubing. [laughter] They didn't mind drawing square
copper tubing on special order. So, by the time I got back, in September, the
magnet yoke may have even been delivered. It was being machined--they probably
01:49:00machined it at the factory. Certainly, that magnet was running by November.
GRAYSON: Now, the pole faces for that . . . were they 180 degree?
NIER: Full circular. Everything was symmetrical. Full circular.
GRAYSON: But the ion path was 180 degrees.
NIER: 180 degrees.
GRAYSON: So you had that tube in there.
NIER: And I have a good picture of that instrument, by the way.
GRAYSON: Yes, yes. [laughter] We've got to add that to the list of things to
collect. Did you put a glass tube in this machine?
NIER: Glass. It was sort of horseshoe-shaped. The ion source was in a
cylindrical part, and attached to that was the 180 degree analyzer, and you
brought out an arm at right angles to that; I have a reprint on that.
GRAYSON: The glass-blowers must have loved you guys.
NIER: It was wonderful! And they would do these beautiful ring seals so you
could separate the source part from the analyzer part. Now, I did all the
glass-blowing on the little stuff. Like, you see, if you wanted to change the
01:50:00source, you cracked the tube off. As I think back, I think it was 45-millimeter
tubing. See, it took a little skill to heat 45 millimeter tubing and not have
strains in it.
NIER: And you weren't always successful, so you sometimes had problems. But we
had a very good glass-blower at Harvard, as we had here.
GRAYSON: Was it pumped by a mercury diffusion pump?
NIER: Yes, all mercury. I had two systems. One for the inlet system and one for
the mass spectrometer.
GRAYSON: Did they use liquid nitrogen there or were you still using that carbon
NIER: Both. But, I think we used liquid nitrogen more frequently.
GRAYSON: It was easier to get there . . .
NIER: It was easier to get there than here.
GRAYSON: And so, by December, you were actually getting spectra.
NIER: Yes, I got my first spectrum of mercury.
GRAYSON: Did the detection scheme use the faraday cup-electrometer tube?
NIER: Very much like I'd used here. I built the thing up, and they knew about
01:51:00this technique. But I built my own amplifier; I had some help from the shop. But
I did all the wiring myself.
GRAYSON: Okay. Could you also do the integrating type of measurement?
NIER: That's right, that's right.
GRAYSON: Charge drift, was that you called it?
GRAYSON: Was there anything in the literature about how that was done, this
NIER: I suppose, if you look back to 1915, or sometime like that . . . but it
was understood. You simply charged up the capacity of the system. And the
voltage was equal to the charge divided by the capacity. So, you just built it up.
GRAYSON: When did the first publishable data come off the machine?
NIER: Pretty quick. In the Spring.
GRAYSON: And that was done on?
NIER: Well, I played with krypton and xenon, and mercury, about the first thing
. . . so, my first paper involved a number of elements.
01:52:00GRAYSON: Mercury . . . you mentioned it before. People looked at it because it
was in the vacuum system.
GRAYSON: I guess there was information in the literature on the isotopes of
NIER: Not as good as I was able to get.
GRAYSON: That's around 200, and the performance of this machine at Harvard was
absolutely better than anything you had before.
NIER: Oh yes, 200 was a lead-pipe cinch. [laughter] No, I worked up in 300, when
I was working with uranium and such.
NIER: So, there was no problem. I got another break at Harvard. It was a
marvelous place. In addition to the people, they had marvelous facilities. They
had a 100,000 volt storage battery, which had been used by a guy by the name of
Duane, for precision X-ray measurements. The battery was used to get the voltage
01:53:00accurate for X-ray studies. It consisted of 50,000 little glass cells, each
having one or two watt-hours capacity. When Duane completed his research the
cells were emptied and dried out. If people needed a low capacity storage
battery for research, there was a technician who reactivated the cells by
filling them with sulphuric acid. So, I had 2400 volts of battery. It was a
little dangerous. [laughter] I got a nice burn on it one time. Got across it . . .
GRAYSON: Yeah. There was no current limit.
NIER: No current limit . . . this is how you get electrocuted. So, aside from
that hazard . . . everything went well. [laughter] Most of the time I
accelerated ions by at least 1200 volts, and I guess at times, I used up to
2400, but I don't remember . . .
GRAYSON: So, let's see, for the higher masses, you'd go to the lower
accelerating potentials anyway.
NIER: Well, you had to use as high an accelerating potential as possible,
because that's what helped your resolution.
01:54:00GRAYSON: Sure. This was a fixed-field . . . the magnetic field was fixed?
NIER: Oh, no . . . electromagnet.
NIER: Then I had a problem with my magnetron scheme; it wouldn't work. I thought
it would be a lead-pipe cinch but the stray field outside of the magnet would
not track the field in the gap, because of the hysteresis in the iron. So this
was when I had to build an amplifier to control the field of the generator
itself. It was a DC generator, and they employ a fixed magnetic field, which the
armature turns in. One adjusts the output voltage by changing the DC current
through the field coils of the generator. So I had to build an amplifier that
would control that, using the output voltage of the generator with a feedback
system, and that's when I made use of these wonderful people there in the
01:55:00Electrical Engineering Department, Hickman and Hunt, who knew all about feedback
amplifiers. I got a lot of good tips from them about how to build it, but I had
to build it myself.
GRAYSON: Well, you had the technological know-how.
NIER: That's right; it wasn't easy by the way, because of the hunting of in high
gain feedback systems. There's a lot of time-lag in a loop involving a
generator. So, feedback is all good and well, but you get into oscillations if
you don't do it right. A lot of effort went into perfecting the circuitry. But,
it was possible to stabilize the generator well enough, that we got the
stability we needed.
GRAYSON: So, what you really were using here was a stabilized power supply.
NIER: DC. That's right.
GRAYSON: As opposed to the method with the solenoid.
NIER: That's right. So, I had to stabilize the output of the generator. The
thing that worked to help you, was that the magnet itself had a high inductance,
so it didn't respond rapidly. All you needed to do was to make sure that the
average of the voltage you pressed on it stayed pretty good. There was still
01:56:00ripple, because you never get rid of that in a DC generator. But we got it down,
so it was pretty damn good.
GRAYSON: The whole concept of that magnet and its size and the power required to
drive it, obviously, you wanted a magnet with a fairly high magnetic field.
GRAYSON: You just looked at the technology at the time, and decided the
parameters you needed to make this particular thing.
NIER: Well, I think once we made the decision to have a five-inch radius of
curvature for the instrument; then, it told you what the relationship between
the magnetic field and the accelerating voltage had to be. We wanted to use, a
couple thousand volts accelerating potential so you knew what the magnetic field
had to be. We pushed this up, I don't know, 8,000-10,000 gauss, something like
that. It was very good magnet material.
GRAYSON: It was very high for that time.
NIER: Oh yes, very high for that time, that is correct. But that's what pushed
the whole thing up to something that was different.
01:57:00GRAYSON: So, basically, there was a decision to get a certain performance, and
then, given that; you had a certain accelerating potential required, and so on,
and that's what drove the design.
NIER: That's what did it.
GRAYSON: The earliest work that was published was on xenon and mercury. In the
case of mercury, you were measuring the isotopic abundances?
NIER: Well, there were values in the literature--I've forgotten exactly--but I
think the only values in the literature were produced by Aston. This was
accomplished with a photographic plate as a detector, measuring the density. How
this guy ever got anything out of that, I don't know. It was amazing how well he
did, you know. But, on rare isotopes, he usually was off. Because, remember, his
apparatus had lots of grease and wax joints and water was present. Ions were
produced in an electrical discharge. So, Aston missed the boat on rare isotopes
01:58:00generally. He either found things that weren't there, or didn't find them or had
other problems. There was some question about his mercury results. The
mercury-196 isotope, for instance, is a very rare one, and he was off by a
factor of five or thereabouts in the amount--I don't remember exactly, but he
was off. I could show there were no other isotopes such as mercury-197,
mercury-195, mercury-203, and so on. I was able to establish that beyond any doubt.
GRAYSON: So as late as 1937, even though mercury had been in mass spectrometers
probably from the first year, that was probably the first time it was really
accurately known what the isotopic abundances were.
NIER: And the amount, that is correct. And those values we got then are still
pretty good, you know. The people since then have done it with separated
isotopes and precision calibrations, and so on, but if you look at the original
values, they're not bad.
GRAYSON: Now, you spent several years at Harvard?
NIER: I was there two years.
01:59:00GRAYSON: Did this collaboration with Bainbridge work to his satisfaction?
NIER: Oh, he was very happy.
GRAYSON: So, he was pursuing the mass measurement problem?
NIER: Mass measurement, yeah. That's right.
GRAYSON: And you were pursuing the abundance measurements.
NIER: And he'd gotten into other things, also. They were going to build a
cyclotron at Harvard, and he'd gotten involved in that. He was very happy. As
long as I was getting along, he felt his role was to see to it I could do what I
wanted to do. It was an assistant's utopia.
GRAYSON: It was an ideal situation. [laughter]
NIER: [laughter] Really, an ideal situation. A most wonderful person . . .
GRAYSON: Much better than having your advisor tell you that, "Gee, you did it,"
and publish it . . .
NIER: No, and he, he was just wonderful.
GRAYSON: So, what do you feel were the most important things that came out of
your stay at Harvard?
NIER: Well, to be sure, determining the isotope abundances was interesting and
important, because it was the first time people had done reasonably precise
02:00:00measurements of abundance. Now, I might say, at the very same time, by
coincidence, Bleakney, and several students at Princeton were doing similar
things, but hadn't moved in the direction that I had. They did some other nice
things on isotopes at the same time I was at Harvard. They were working on
different elements. There was never any overlap.
NIER: So, I continued with that work. But then the significant thing that
happened in that period was the introduction to geochronology. It happens that
this was a heck of a good place to be for this. First of all, T. W. [Theodore
W.] Richards, who was the atomic-weight chemist of the early part of the century
and got the Nobel Prize [Chemistry, 1914] for his work on atomic weights, had a
02:01:00marvelous collection of stuff that he left behind when he retired, or died, or
whatever happened to him. And his successor was a guy by the name of Gregory
Baxter, who had all of this material. You have to remember that after the
discovery of radioactivity in 1897 or 1898, or whenever this was, people became
interested in geochronology when it was realized that uranium and thorium
decayed to form lead. So, measuring the atomic weight of lead was important.
That became a hot field in 1910 or so. That's when Richards did his work.
Chemists showed, that if you had common lead, you got an atomic weight of
02:02:00207.21. And then, if you had uranium-lead you got a weight near 206, because 206
and 207 came from the decay of uranium. From thorium, you get close to 208. So
the chemists were measuring the atomic weight of lead to tell how much common
lead impurity was present in these different specimens.
Then there was a guy by the name of Alfred Lane, a geologist, who was retired
and lived near Harvard. He had been at Tufts College--it's now called Tufts
University--which was in Sommerville [Massachusetts]--a suburb next to
Cambridge. He was one of the very few persons in this country interested in
quantitative geological age measurements. Not just stratigraphy, but numbers.
GRAYSON: This would be in 19 . . . ?
02:03:00NIER: 1936. I was introduced to him, when word got around that I had a mass
spectrometer that could work on lead and uranium, and other heavy elements. I'd
suddenly made a lot of new friends, you see. Lane was a wonderful guy. He was a
funny guy, but wonderful.
GRAYSON: In what way?
NIER: Well, sort of, peculiar. He bustled around, and really had interesting
mannerisms. First-class scientist, and a very well-known geologist of his day.
He used to come around with a little bag, and he was getting a little absent-
minded, and his mind would wander, and he had a little notebook he wrote in. He
had very interesting mannerisms. Wonderful guy. And, so, he was very interested
in my work, and tried to promote it, getting samples and things for me to work
on. So I spent most of my time, or a very large part of it, working on things
related to geochronology.
GRAYSON: And Bainbridge felt this was fine?
02:04:00NIER: Oh, he encouraged this, he thought this was terrific. That was one of the
attractions, why he said I should come there; because I had opportunities to
enter the field of cosmology.
GRAYSON: Okay. In some cases, a guy like that would try to commandeer your
abilities for his own pursuits.
NIER: Oh, no, no. He wanted good science to be done, and he saw that this was
good science. Through him, I met Baxter who provided me with very pure samples
of lead, and made it into lead iodide for me, which was volatile. You could put
it in our instrument, and heat the part which contained the sample. Baxter made
wonderfully pure lead iodide for me.
GRAYSON: So, these samples at Harvard had been collected by a fellow who was
more interested in the decay scheme between the radiogenic elements.
NIER: Well, in the geochronology thing, in using atomic weights for telling how
02:05:00much impurity was present in common lead.
GRAYSON: Okay, it was the whole business of using isotopes from radiogenic
sources for dating. Was that concept pretty well fleshed out at the time?
NIER: Oh, yes. It had been done for years. You measured the amount of uranium
and the amount of lead. From the atomic weight of the lead, you tried to decide
how pure it was. From alpha-particle counting measurements of uranium and
thorium, one knew the rate at which these elements decayed to form isotopes of
lead. From the amounts of lead and uranium isotopes in a uranium mineral and a
knowledge of the decay rate of the uranium, one can compute the age of the mineral.
GRAYSON: So, your ability, to look at the isotopes of these elements was really
opening up the door.
NIER: It was a new dimension.
GRAYSON: It was a tremendous experience.
NIER: Yes. I could do one sample in a day. Actually, the measurements took me an
hour, but I had to clean the instrument up because you filled it with lead
iodide vapor that had to baked out of the system between samples. So, I could
only do a sample every other day, but the actual analysis took me about an hour.
02:06:00I could do in an hour for which the chemists, in making atomic weight
measurements, needed weeks. Everybody was very much interested and supportive.
And Baxter--and this was quite a break for me, again this business of being in
the right place at the right time--Baxter became intrigued with mass
spectrometry. He was an analytical chemist of the very highest-order in wet
chemical methods. But he became interested in the mass spectrometry business
that could do the determinations in so short a time. So, he fed me common lead
samples that they had accumulated way back even before his time. From T. W.
Richards' time. I ran a dozen or more of common lead samples and I found that
02:07:00the isotope abundances varied, although the atomic weights were the
Well, his first reaction was, "The mass
spectrometer has to be wrong, because after all, we chemists have done this so
carefully for so long, with so many people. What could be wrong?" The reasoning
didn't take into account that you could have a coincidence: that the variations
with isotopic abundances were such that the average weight remained the same.
Just a crazy coincidence. I mentioned this in my story in the reprint I sent you.
NIER: On my reminiscences of . . . I don't know if you have that or not, if you
know about it, Tom.
GRAYSON: Yes, I think I sent Tom a copy.
NIER: Okay. At the same time, there was a guy by the name of Arthur Holmes, a
very famous geologist, a very good geologist, at the University of Edinburgh. He
02:08:00was interested in quantitative geological measurements. Are we coming to the end
[of the tape] here?
GRAYSON: Yes, I think we better stop on this tape, we're about to run out.
[END OF AUDIO, FILE 1.4]
[Nier and Grayson are looking at cartoons taped to the doors of a cabinet in Dr.
NIER: This one was given to me by a friend who sat in front of me at the
02:09:00football game after Minnesota had lost. [laughter] He thought it was appropriate
for me because in the cartoon one character says to another "Anyway, we have a
better physics department than they do!"
GRAYSON: Speaking of football and mass spectrometry, I was up at the University
of Nebraska once, and the person [Michael L. Gross] who runs the mass spec
center there takes out an ad in the football program.
NIER: They take out an ad?
GRAYSON: Yes, they have an ad in the football program. How's that for getting PR?
NIER: That's interesting, isn't it . . . yeah.
GRAYSON: You have to do everything you can.
NIER: Right. There's some wonderful ones. There's some German ones [cartoons]
02:10:00that are wonderful. See, she says to this dog with the sad look. "What is more
important--that you should not catch a cold, or that the people shouldn't laugh
at you." [laughter] Then, I think this one's wonderful. "This is reality,
children. We simply can't switch on another program." The man said as he changed
a flat tire on the car. [laughter]
GRAYSON: [laughter] Yes, life is not a TV. When would be a good time for a photo
opportunity? Would you want to take a couple of pictures?
NIER: Anytime, whatever you say. You can take some in the lab if you want.
GRAYSON: Well, I wouldn't mind getting some in here. I was just kind of looking
at your organization of books and papers.
NIER: Well, it's not very good.
GRAYSON: "Not very good"?! I think it's excellent. It's a lot better than mine!
[laughter] Mine is simply a file, and . . .
NIER: Yes, the things I haven't sorted are over there.
GRAYSON: Yes. Oh, I see some old ASMS [American Society for Mass Spectrometry]
bound volumes over there. That's encouraging.
02:11:00I like that arrangement with some general order to the shelves.
NIER: Yes, that's right.
KRICK: What's great is that they can be archived later on.
GRAYSON: Now, are those your own personal copies of the journals? So, you get to
take off all of this on your income tax, right? [laughter] You subscribe to all
of these journals. I guess you can't deduct much anymore unless you have a
substantial fraction in journal subscriptions.
NIER: I don't even try. I'm trying to stay off the list of people that should be
investigated regularly. [phone ringing]
GRAYSON: Let's continue with, Tape 3, Side A. Does anybody recall where we
NIER: Oh, yes. We were talking about Holmes.
GRAYSON: Okay, Tape 3, Side A and we were talking about Holmes. So we'll pick up
with Holmes. In the meantime, I'll be taking some pictures. Do you suppose it'd
be okay to close the door. The typewriter is making a lot of noise.
NIER: Yes, I think we should . . . of course.
02:12:00GRAYSON: Holmes. And I may just move around and take an odd picture or two while
we're chatting, in kind of an informal situation. So, Holmes . . .
NIER: Yeah. Well, um, let me think for a minute. Holmes had just come out with a
paper, and this is mentioned in the article that I wrote for the Annual
He had just come out with a paper in which he
said that the lead ores could not have a magmatic
I believe the argument went that they always
had the same atomic weight, and therefore, the same isotopic composition. In the
magma, the lead would be in contact with thorium and uranium, and you ought to
be generating uranium-lead and thorium-lead at the same time. Therefore, the
02:13:00atomic weight of the lead ought to be varying. What he didn't take into account,
which nobody took into account, was that you had the crazy coincidence I
What happens is that the half-life of thorium is about four times that of U-238
the principal isotope of uranium, and the abundance of thorium, in the earth, is
about four times that of uranium. So, you generate about equal amounts of Pb-206
and Pb-208 when the two decay together. You see, if you think of a couple of
hour-glasses, the sand gets piled up at the same rate. Okay. The atomic weight
of common lead, 207.21, is about halfway between. There's a little bit of 207
also from the decay of U-238. So, you generate not only U-206, but a little bit
02:14:00of U-207, and the U-206 and U-207 balance off the U-208. You can have various
amounts of radiogenic lead but you always get about equal amounts or uranium and
thorium lead, so the average atomic weight doesn't change. Now, if you made real
precise measurements of the atomic weight, you'd find it changed, but within the
precision of the chemists atomic weight determinations, it was not measurable.
GRAYSON: So, this is another case where your data is flying in the face of some
expertise that's out there. This is the second time now, right?
NIER: That's right.
GRAYSON: So, what happened then?
NIER: Well, when this first happened, Baxter didn't believe me. He gave me
unknowns--as I told in this article--as if I were a freshman in analytical
chemistry. And after doing three or four of them and coming out with consistent
answers he said, "Well, it has to be so." Then he made the interesting comment,
he said, he was glad that he was nearing retirement. [laughter] He was a
02:15:00wonderful guy. He was quite formal, very stiff in a way, but very friendly, and
very nice, and had a real sense of humor.
GRAYSON: The competition was getting too tough, huh? [laughter]
NIER: Getting kind of tough, so he was glad he was getting near retirement.
GRAYSON: So, what about Holmes?
NIER: Well, I wrote to Holmes and I described this in the article a little bit.
There was a professor at Harvard by the name of Gratton. He was in economic
geology, and they'd been teaching their students about the origin or lead ore
all this time. And here Holmes, also an authority, comes out with a
contradictory idea on the origin of lead ores, and Gratton was just fit to be
tied. And there were others the same way. So, Gratton was just delighted that
I'd come up with the data which refuted Holmes theory. I wrote to Holmes, and he
was delighted, too . . . or other reasons. And I met him later, as I've
mentioned in the article, and we talked about it a little bit, and he said,
02:16:00"Gee, how was he to know that there was this coincidence, that it would be this
sort of thing," and so on. He was very friendly to me. We exchanged Christmas
cards for years. I visited him in 1954, had a nice afternoon with him and his
wife, also a geologist. Very friendly, and we even did analyses of lead samples
for him afterwards, so we kept in contact with him for years. He died in the
1960s, so that was the end of that. But it was one of these cases, I wish I'd
got to know him before. You know there's so many people like this, that you wish
you'd gotten to know, but it was too late.
GRAYSON: But, at least, he was enough of a scientist to realize . . .
NIER: Oh, yes. Well, he told me . . .
GRAYSON: . . . that even though his work was correct, that there could possibly
be another explanation.
NIER: Yes, well, he jumped on the bandwagon then and was very much a fan of the
isotope work. As a matter of fact, he was the first one who pointed out, what I
should have done a long time ago . . . Although I'm trying to figure out why I
02:17:00didn't . . . that you ought to make use of these variations, somehow, to tell
you something about the age of the common lead minerals. I did do things like
this, starting with the older, the most primordial minerals and so on, but I
never took the real step of tying everything together. I don't know why, but I
have a feeling that somebody restrained me. Because it had occurred to me, but
they said "Well, you better not stick your neck out that far," [or] something
like that; so I never did. But, Holmes jumped on the bandwagon.
At the time the earth was believed to be two billion years old. And he said, on
the basis of these measurements, it ought to be at least three billion years
old. Others came up with 3.3 billion years. And later on, when Clare [C.]
Patterson did this precision work on meteorites, that's where the 4.6 billion
figure we now use comes from. But it's making use of the variations in common
lead, and working backwards. I was starting to say that, if you take a
primordial sample and add to it various amounts of other lead of known age you
can work back and figure out how long the addition must've been going on. So,
that was really the start of the lead isotope field. I was very happy to be
02:18:00involved in it.
The other interesting thing which occurred at that time, of course, was the
measurement of the uranium isotopes.
I had lead
samples, both common lead and uranium-lead and thorium lead, which I'd gotten
from Baxter and also through Holmes. Not through Holmes . . . I mean, through
Lane. There are actually two uranium series. There's the U-238, that decays to
U-206, and the U-235 that decays to U-207, each at a different rate. So, you
have like two hourglasses, running at the same time, see? So, if you measured
the isotopes of lead accurately, and you knew the isotopic composition of
uranium accurately, you could then determine and compare the ages by the two
02:19:00methods. But one didn't know the relative abundances of the isotopes of uranium
accurately. Aston had observed the isotopes on his photographic plates, and
showed that for U-235 there was a little smudge on the plate. But that's as far
as he got. So, people had guessed at the relative abundances of the uranium
isotopes, but I think they were off by a factor of three or some amount like
that. It was realized then that we could now accurately measure the uranium
isotopes. Bainbridge was certainly in on this thing. We'd all talked about it.
And Lane, of course, was just delighted at the prospect that I might measure
uranium isotopes. So the question is, how do you do it? So I'd looked back and
seen what Aston had done, and he had used uranium hexafluoride; so I said "Well,
gee, that's the thing to use." Well, UF6 was a rare commodity in 1937.
GRAYSON: You didn't just go buy that, did you? [laughter]
NIER: You didn't just buy it by the kiloton as one can now. So, Lane said "We'll
find somebody to make some." He got a grant from the Geological Society of
02:20:00America, to have somebody make it, but he couldn't find anybody who was willing
to take on the project. He had 500 dollars, but he didn't find anybody who was
either willing or able. Probably not willing. Because there were people who
could do it. But it wasn't easy. So, the money reverted. And the question is
"What else should I do?" And then I looked, and I went over to . . . what is it?
"Mellor," is that the chemistry book, the one that tells you how to make
Used to be kind of a bible, in two volumes. It
showed you how to make all kinds of compounds. I went into the chemistry library
at Harvard and looked up how to make other compounds of uranium. And what you
did was, you took uranium oxide and mixed it with carbon, and pass chlorine over
it, doing it at 1000 degrees, or some awful temperature. I was hoping to make
some uranium tetraflouride or bromide, which was volatile at my oven
02:21:00temperatures. See, I'd already had the "oven technique" of putting little ovens
in the source, so I could introduce the uranium that way.
Well, I told Baxter about that, and the story I like to tell, which is a bit of
an exaggeration, but probably not much, was that he was so offended by the
technology that I was describing that, as a good chemist, he decided that he'd
better take charge. [laughter] Baxter taught class at Radcliffe College and he
often dropped by my lab on his way there. One morning I came in and there on my
02:22:00desk were several sealed quartz tubes containing uranium tetrabromide and
uranium tetrachloride. It was very hygroscopic, so you had to rush to get a
little bit into the oven and then into the vacuum system. I worked with both
compounds and made the first measurements of the uranium isotopic abundances,
and that's where the 139-to-1 came from.
GRAYSON: That is, in 19 . . . ?
GRAYSON: And so, the relative abundances of the various isotopes of uranium
NIER: In addition to U-235 I was able to measure U-234, which is in equilibrium
with the U-238. Its abundance is only one part in about 17,000.
GRAYSON: Okay. This was done on either the bromide or the chloride or both?
GRAYSON: And so, that would've required working up around, what? Mass 340, 350?
02:23:00NIER: Not in this case, It turned out we got an abundant number of metal ions so
we worked with these.
GRAYSON: It probably was simpler to work with the metal, because of the many
isotopic peaks from chlorine and bromine.
NIER: The isotopes are both lousy.
GRAYSON: You would have all kinds of other information.
NIER: The spectrum at the uranium position was very clean and I have a reprint
of it here for you.
GRAYSON: Oh. Excellent.
NIER: Knowing the U-235/U-238 ratio [was] important, because that added a whole
new dimension to age determinations. Also, I could come up with a number that
was not known at the time: the ratio of the activities of the uranium and the
actinium series. The uranium-series referred to the decay of U-238 going to
U-206. The actinium series came from the U-235 going through actinium to U-207.
02:24:00And the number I came up with was 4.6 percent, which is still a good number,
fifty years later. The uranium isotope ratio I gave was 139 to 1. I said it was
good to 1 percent. The latest accepted value is 137.8. So the early value is
still within 1 percent. I was lucky; the uranium measurements were pretty
ragged, but I took a lot of readings and averaged them. I think I was a little
lucky, in that I came out within 1 percent of the presently accepted value,
which is really pretty good when you stop to think of the difficulties with the measurements.
GRAYSON: So, a lot of these little experimental details were particularly
02:25:00critical in doing these measurements, making sure the ion source was not
discriminating, and making sure that the samples didn't have impurities that you
were getting confused by, and so on. So, you always had a healthy skepticism
about what you saw and were willing to look for all other possible explanations
and eliminate them: variation of ionization potential, etc . . .
NIER: As many of those things as you could perform. Of course, with the little
oven in there, you see, it was easy to heat or cool it, and you could run
different pressures, and see if things tracked.
GRAYSON: So, a common experiment was, then, just to change the amount of sample
entering the ion source.
NIER: All the parameters you could lay your hands on, yes.
GRAYSON: And make sure that you got several determinations and do the statistics.
NIER: Yes. It worked out quite well, but again, experience was terribly
important in this, because you got a feeling of what flew and what didn't fly.
You'd get this feeling.
02:26:00GRAYSON: Then, would you say that that represents the major thrust of the work
that occurred when you were on the NRC Fellowship at Harvard?
NIER: Yes, it turned out to be, in retrospect, to be the main thing that I did
at that time. I was pretty busy doing that, by the way. [laughter]
GRAYSON: What other things were you doing at the time?
NIER: Well, the other thing that was interesting. One of my friends was a guy by
the name of Earl [A.] Gulbranson, who was an instructor in chemistry up at
Tufts. And he was interested in carbon isotope variations in nature, and we
collaborated on an experiment. And I always felt I let him down, because I
didn't follow up on the work as I should have.
NIER: I didn't follow up on the variations we discovered in carbon isotopes.
This probably took place in 1938. Things overlapped into 1938, from 1937. We
found that natural carbon isotope abundance ratios vary by about 5 percent. In
02:27:00limestones, the C-13/C-12 ratio was 1 in 88 or so. For a piece of wood or other
organic compounds it was more like 1 in 93. Gulbranson was a very good chemist.
He made the samples, and I analyzed them as CO2. We even looked at the CO2 in
air. I remember driving down a side road, outside of Cambridge one dark night,
with a funnel sticking out to bubble the air through a tube dipped into a
solution containing calcium hydroxide. We precipitated the CO2 to form calcium
carbonate. And later Gulbranson would change it to CO2. This is how we obtained
air samples. We studied, about a dozen different sources of carbon. That was the
beginning of looking for variations in carbon isotopes. That was done so long
ago, most people today don't realize the first measurements were made over fifty
GRAYSON: Now, did that work get into the literature then?
NIER: Yes, it was published.
GRAYSON: And this was with, I'm sorry, what was the guy's name?
02:28:00NIER: Gulbranson, Earl Gulbranson. The paper is in my list of publications.
GRAYSON: Okay. So, that was kind of a seminal work, but you really didn't do any
more along that line of study--the C-13 type work.
NIER: Yes. We followed up and did some more of it here, later on, with a
graduate student, a chap by the name of Byron Murphey.
GRAYSON: Do you have a feeling for the number of publications that came out of
your NRC Fellowship time at Harvard? Were there three, four, six, eight?
NIER: Six or eight would be more like it. They're all kind of interesting, in
that they all had something that was related to isotopes. It's in the list, you
can pick them out easily.
GRAYSON: I guess that was a two-year appointment?
GRAYSON: Bainbridge, I guess, had an opportunity to ask you to stay there if you wanted?
02:29:00GRAYSON: Did you have that opportunity to stay at Harvard?
NIER: Yes, yes.
GRAYSON: But you elected to come back to Minnesota?
GRAYSON: Okay, could you kind of explain that one? [laughter]
NIER: [laughter] Well, it was a difficult decision, and it was not based
primiarily on scientific reasons. My wife was an only child, whose mother had
been a widow for many years. My parents were getting quite old. They were almost
old enough to be my grandparents. I had a sister who died very young, I was the
only one. Neither family had very much money. And the problem of staying there,
when I could come back here and help, played a very important part in the decision.
I had an offer of three jobs in 1938. Condon wanted me to come to Westinghouse
to the research lab. Harvard said I could stay on as an instructor, but there
02:30:00was a problem. This was when Conant became president, and the tenure situation
was very uncertain. So, the young people had a real serious morale problem.
There were two retirements here in the department. And, Tate had become Dean of
the Liberal Arts College and was anxious that there be some continuity in the
work he had started. Also, the people here knew me, and I had done well at
Harvard, so, they were anxious for me to come back. I had to choose between
these three jobs. I decided against Westinghouse, fond as I was of Condon, whom
I liked very much. He was director of research at Westinghouse. Harvard made it
attractive, and you never know: Should I have stayed or shouldn't I? It
certainly would've been a happy situation. There was no question of that, but I
02:31:00didn't see how we'd ever cope with the problem of the family, with both of us
having the problem of parents who needed us. So, I decided that I'd come back
here. Financially, the offer was about the same as Harvard. I knew my way
around, felt more comfortable, and I felt living here in the Midwest was
preferable to living in New England. Anyway, I felt more at home. So, all these
things added up, and I made the decision to come here. While my initial
appointment was as an untenured assistant professor, the chance for promotion
seemed a lot better, because Harvard had been dropping people right and left.
GRAYSON: Really? What was the reason for that?
NIER: Well, there'd been a lot of hangers-on who were on as instructors at
02:32:00Harvard, for whom there was no future. And they just hung around, hoping
lightning would strike. In fact, the young people there whom I knew thought I
was out of my mind turning down a chance to stay at Harvard. They may have been
right, I don't know. But it's just one of those things, and how do you judge?
Certainly, professionally, I'd have done very well there, because they had all
the support for me. Better than here, as a matter of fact. However, Tate was
awfully good about helping when I came back. Bainbridge was always good to me,
no matter what. When I left he felt badly, but he let me take my spectrometer
tubes with me. Tate, out of his research budget, got money for me to build a
magnet like the Harvard one, and so on. So, I had, you know, six in one hand,
and half-a-dozen in the other. Teaching loads here were awful, so I had to do a
lot more work, whereas at Harvard it would've been much lighter.
GRAYSON: So, tell me a little more about the teaching loads.
02:33:00NIER: Well, you had two full courses that you had to teach, plus some extra
things, and so on, and that took a lot of time. Especially starting out from
scratch. The first year was very rugged, very rugged.
GRAYSON: Would these be like introductory physics courses?
NIER: Yes, I taught an intermediate course and an introductory course, but a
large class: a couple hundred kids. You give a speech every morning. Four times
a week plus a quiz. Plus all the kids bellyaching about the quiz grades and
working with the graders.
GRAYSON: And then they want partial credit. [laughter]
NIER: They want partial credit of course, exactly. [laughter]
GRAYSON: We'll have to get a copy of that cartoon, so that those people who hear
this tape and look at this transcription will be able to understand "partial
NIER: I think that's a marvelous cartoon. (Figure 8)
GRAYSON: So, basically non-scientific or non-professional things drove your
choice to come to Minnesota at the time. So you made that decision, and did come
02:34:00here, and essentially, by that time, I guess your reputation was pretty well-established.
NIER: Yes, yes.
GRAYSON: And you didn't have any trouble with Tate coming around giving you
left-handed hints about where you were going.
NIER: Oh, no. Everything was wonderful. They did everything they could. I was
GRAYSON: Okay. So, did you just, kind of, continue along the lines of your work
NIER: Well, I had to set up a new apparatus again. Tate had arranged for the
magnet, so we copied the Harvard magnet. In the meantime, they had improved
techniques in casting metal, and so on. I had to wind the coils myself. It was
"Number 8" wire or some size like that.
GRAYSON: So, how does one do that?
NIER: Well, you learn how. You go to a lathe, and have spools made, great big
brass spools. I can show you the magnet. We still have it . . . it's used in
GRAYSON: Yes, we need to take . . .
NIER: . . . and you can get a picture of that, too. And, so with the help of the
guy in the shop we wound this magnet.
GRAYSON: This was an enamelled wire?
NIER: No, this was cotton-covered stuff that we had.
GRAYSON: Oh, wow!
02:35:00NIER: And then we had to paint it with black caulk for making it thermally
conducting, sort of like tar. It was a mess! But you did this on the lathe to
get a better space factor because the heat conductivity was important. As in the
Harvard magnet, we used water cooling tubes to keep the coils from getting too hot.
GRAYSON: Did you say you used square tubing too, or? [laughter]
NIER: No, we didn't use square tube. We had round tube. [laughter] I became an
expert in winding coils, which I didn't have to do at Harvard, because they'd
had it all done for me. There was a lot of brute work I had to do here just
getting started again. But I had an instrument running by Christmas.
GRAYSON: So, you came here, when? At the beginning of the summer? End of the summer?
NIER: In the middle of the summer.
GRAYSON: Middle of the summer.
NIER: I left there about August.
GRAYSON: And brought?
NIER: I had the spectrometer tubes that Bainbridge gave me, and the magnet was
02:36:00being built during the summer. I'd sent the details to Tate, and he had arranged
it for me. So, the magnet was delivered in Fall, but the coils had to be made
yet, and I had to participate in that, so I spent a lot of time with the
machinists in the shop winding coils. Well, it wasn't that bad, but you know, it
GRAYSON: Yes. Well, definitely. It's a time-consuming job. How many miles of
copper wire do you suppose you had?
NIER: Well, it was pretty heavy stuff, so it wasn't that many miles, but it was
a lot. When you see the coils you'll understand; they weighed 500 pounds apiece
GRAYSON: So, even though you were rebuilding your whole apparatus and
instrumentation, you were able to do things in a very short period of time.
NIER: Yes, well I had help, and I got some money for it. Then I had to build a
regulator for the generator. The generator here wasn't as good as the one at
Harvard. It wasn't as steady. So I had to build this thing all over again, the
regulator for the generator. But then, I had some help. I had a grant from our
02:37:00graduate school so I could hire undergraduate students, who were good. They were
kids who knew how to build electronics devices. So, I had people building these
things for me. By that time, we also could get away from using batteries. We
built, I think it was a 1200-volt power supply for accelerating the ions, which
was electronically controlled. I had a very good student working on that.
GRAYSON: That kind of electronics technology . . . were people building
high-voltage power supplies at that time, or, was that a common thing to buy those?
NIER: In some limited cases. People had Geiger counters and instruments like
that. To be in physics, you had to build devices of that kind. This was
different than high current supplies and things like that. By that time, I'd
learned how to do it, thanks to my connections with the Harvard electrical engineers.
GRAYSON: So, all that business about feedback was put to good use again.
NIER: Oh, yes. Good use, that's right. See, there's a real advantage to having
an engineering background.
02:38:00GRAYSON: Well, it's one of the things that's becoming obvious to me. If you'd
had a straight, classical physics background, a lot of this instrumentation
would've never come to pass.
NIER: Never done. Never come to pass.
GRAYSON: Because you would have hit a brick wall. You knew that you needed an
XYZ, but you didn't know how you were going to get one, and you didn't know
anybody who was going to be able to do it.
NIER: That's right. You didn't even know who to talk to.
GRAYSON: Yes, but with the double-E background, you immediately knew what to do.
NIER: That's right, that's right. It's just terribly important. You can't
over-estimate this at all. [laughter]
GRAYSON: So, a nice combination of fate.
NIER: Yes, yes.
GRAYSON: I think we're about to the end of this tape, so why don't we stop
before we go any further.
02:39:00[END OF AUDIO, FILE 1.5]
[END OF INTERVIEW]
GRAYSON: We're starting Side B of Tape 3, and Dr. Nier is talking about an
article published in the Physical Review, 1935, in which the potassium
telling us about the lettering on the figure.
NIER: Well, Professor Tate, who was the editor of the Physical Review, was
accustomed to doctoring up documents that came in that fell short, in one way or
another. Often this was the case in the lettering. And especially, when he got
02:40:00foreign things--the Germans especially, I think, were not accustomed to doing
their own drawings. They would send in just a rough draft of the drawings, and
expect the editor of the journal to do the finished draft. So, he was accustomed
to fixing up figures. But he didn't like the lettering I had on my drawings. So,
the result was, he did it over. If you look at random at the Physical Review of
that era--the 1930s when he was active as editor--you'll find many papers in
which the lettering will look like that in my article, which appeared in the 1
August 1935 journal. This is all hand-lettering, you understand. We recognize
his very distinctive lettering. You saw a lot of that in the journals of that time.
GRAYSON: This was a free-hand lettering that he did?
NIER: Freehand, yes.
NIER: He was very good at it.
GRAYSON: It is very good, and it is clear and legible.
02:41:00GRAYSON: Okay. Let's see. Where had we ended?
NIER: We were back in Minnesota . . . just a minute.
GRAYSON: Oh yes, you'd decided to move back to Minnesota.
NIER: Well, I was just getting going, wasn't that it?
GRAYSON: Yes, you'd finally gotten your equipment together again, and were
working on it. You had it ready to produce results again. So, at this point,
what exactly did you get involved in initially, when you first started again in Minnesota.
NIER: Well, when I came back, I wanted to pursue the work on isotopes, which I'd
been working on originally here, but more so at Harvard. And, I had, as I said,
two mass spectrometer tubes which I'd built at Harvard, which Bainbridge allowed
me to take back with me. And I had additional lead samples which I'd gotten at
02:42:00Harvard also and then some that I got from our geology department. I wanted to
look further at variations in common lead. And then I also had samples of
uranium lead that had come from somewhere or another, I suspect through Alfred
Lane or maybe through Harvard, I don't remember. One of the things we continued
was the work on the variations of the lead isotopes. Also at the time, I gave a
paper at the American Physical Society Meeting in Washington in April 1939,
which would be fifty years ago on the iron and nickel isotopic abundances.
I'd gotten my instrument going in time, around
02:43:00Christmas or shortly after, and the abstracts were due in late winter.
[laughter] So, I made it.
GRAYSON: The game then, was the same as it is now. When the abstract deadline
comes around, that's when the work really gets done.
NIER: Really gets pegged, you see. [laughter] So, I had a paper on that. And
that's what I reported on there. Now, there was an interesting story about that
paper. The secretary of the American Physical Society at the time was quite an
elderly man, who was a little bit out of touch, and was getting a bit senile.
So, he didn't know exactly what these different fields were, where the papers
fit. And, my paper on the isotopes of iron and nickel didn't seem to fit
anywhere. But there was a solid-state section on the kind of things solid state
people worried about--phase diagrams, and so on, in metals. This was on Saturday
afternoon, the last afternoon of the meeting, you understand.
02:44:00And my paper, which didn't seem to fit in with phase diagrams and stuff like
this, was the last paper of the afternoon. So, it turned out that that session
had a small group. As things were, there were a few dozen people there when
things started. But when my paper came on, everybody walked out, except the
chairman, my wife, and somebody else. And I remember the chairman of the session
was Ed Condon, who I knew already, as I said, the man who was later going to be
the Director of the Bureau of Standards. So, I had this small courtesy group who
listened to me tell about the isotopes of iron and nickel at the American
Physical Society meeting. So, that was the crazy thing that happened there.
However, that was the meeting right after nuclear fission was discovered and
02:45:00where I met [Enrico] Fermi. I knew John Dunning already, who was the man in
charge of the Columbia cyclotron, and was interested in nuclear physics, and
through him, I met Fermi at that meeting.
GRAYSON: At that meeting?
NIER: At that meeting. That was April of 1939, and fission had just been
discovered a few months before. It was one of the things that was talked about a
lot at the meeting. And that's when I got acquainted with Fermi. So, that was a
positive thing that came out of the meeting.
GRAYSON: Well, my feeling of meetings is that more than half of the meeting may
actually be in the contacts you make. The papers That you attend are a small
portion of the meeting. [laughter]
NIER: I think more than half. It goes on at lunchtime or in the corridors.
Dunning had figured out that, if I just souped up the spectrometer a little bit,
I could collect enough separated isotopes of uranium to make possible a
determination of the fissionable isotope. He knew how much uranium it would take
02:46:00to detect fission if they bombarded my samples with neutrons. I don't remember
the exact conversation, but he pointed out that if I could collect some fraction
of a microgram of uranium-235, they ought to be able to verify it was the
Now, it had been predicted by [Niels] Bohr and [John A.] Wheeler, that
uranium-235 ought to be the one responsible for the slow neutron fission. But it
had never been demonstrated experimentally. That was the whole point of it. So,
we went through this calculation. Then, in the meantime . . . a lot of things
were happening. I had gotten interested in isotope separation. In particular,
C-13 which seemed to be useful as a tracer for biological purposes.
GRAYSON: When did that start?
NIER: Well, you see, there were several papers published in about 1937 or 1938
02:47:00in Germany. [Klaus] Clusius and [Gerhard] Dickel, C-L-U-S-I-U-S and D-I-C-K-E-L,
published something about the thermal diffusion
You have a hot wire in a vertical tube and a
cold wall around it. If you want to do it in quantity, you'd have to water-cool
it to get enough power in. Then, you put a gas in, anything you want to. And
what you have between the hot wire and the cold walls is a gradient--a
concentration gradient of the isotopes, of the isotopic molecules. It's a
phenomenon that you can't explain by elementary kinetic theory. It takes a more
sophisticated theory, because it depends upon the law of force between the
02:48:00molecules. The molecules coming in one direction encounter others from the
opposite direction with different temperatures and speeds. It's a subtle sort of
effect. It'd been discovered many years ago by [Sydney] Chapman and somebody by
the name of [David] Enskog, I believe it was, in 1910 or thereabouts. But it had
never been put to use, as best as I can determine. And these guys, Clusius and
Dickel, pointed out you might use a column like this as a fractionating system.
It would repeat itself, and because you'd get a convection flow up and down with
the gas moving like a roller-towel and you'd keep concentrating heavier
molecules at the bottom of the column in this way. I don't think they enriched
isotopes initially, but they separated some gases this way. It seemed natural to
use methane gas for separating carbon-12 and carbon-13. It was light, and
So, I built a column, and as a matter of fact, if I remember correctly, it was
02:49:00started before I left, and Jay Buchta, B-U-C-H-T-A, who was head of our
department, was awfully good about taking care of everybody. He could never turn
down anybody who asked a favor, and he would try to help, and he saw to it that
the shop continued working on this in my absence when I went down to the
meeting. So, when I came back, a lot of the column was completed. I proceeded,
and showed immediately that we could separate carbon isotopes in small--very
small--amounts. And then, of course, the column was made longer and longer. We
had an empty elevator shaft downstairs. So, my original column was 24 feet long,
and we enlarged it to 36 feet, got another floor in, and we had another column
in parallel finally, where you circulated between the top and the bottom of one,
but that came later. Anyhow, I was producing enriched carbon, and thinking it
could be used for nuclear experiments, separate targets for bombardment, and so
on. But also, I knew a lot of people in the biological field who were just
02:50:00anxious to get their hands on separated carbon isotopes for tracers. So, I began
producing enriched carbon.
GRAYSON: Now, what was the whole concept of doing this? Why did you want to do
NIER: Well, it sounded like fun. [laughter] And it seemed like a useful thing to
do, I don't know. And, as I say, I knew people in the medical school, I knew
people in the biology departments who were interested in the possibility of
this, doing tracer work. See, carbon-14 was not yet then available.
GRAYSON: So, you had a kind of inkling in the back of your mind what you would
like to do with this if you could get it, if you could enrich it.
NIER: That's right, there'd be uses for it. I might not use it, but somehow or
another, I always had these friends who could use it. I belonged to the faculty
club, where people from one department used to sit with people from other
departments. It was very interdisciplinary. Nowadays, the organic chemists sit
at one table, the historians at another, and my physics friends are all sitting
02:51:00at a certain table. They never sit with anybody else. I usually try to sit with
other people, but that isn't done much any more. So, I got to know a lot of
people in other fields, which is one of the important things about a faculty
club, I suppose.
GRAYSON: So, you're saying that, maybe, over a lunch, at one time or another, a
problem was posed to you, "Could you do this?" And you thought, well, maybe not,
and maybe you thought about it some more, and . . .
NIER: That's right, there were a lot of connections like that, and I did get a
lot of people started on work of this kind, through this sort of informal
contact, which is one of the wonderful things you can do in the right
environment. So, we were producing C-13 and I had very good friends in
chemistry, who were friendly competitors in this, they got into it also. Ivan
Taylor, who used to be active, was a very good analytical chemist. He died too
young, of cancer some years ago. And another fellow by the name of George
02:52:00Glockler, was interested in this, too, because the physical chemistry of the
whole process was an interesting one. So, they built a column in the chemistry
building around an open stairwell. They used to have open stairwells.
So, we were friendly competitors in this business. They didn't have as good of
machine-shop facilities as I had, so my column worked better. You had to have
precision between the center wire and the tube. We didn't use a wire, because we
wanted to get more throughput, so we had a tube, a heated stainless-steel tube,
with a heater inside of it, about an inch or an inch and a half in diameter. And
then, there was a water-cooled brass tube outside, with the spacing about a
quarter-inch between the hot and cold walls. But it had to be very precise,
because if it wasn't symmetrical, then the thing wouldn't work right; the
fractionation wouldn't continue on. If I remember correctly, my colleagues used
pipe instead of tubing. I used tubing, which was precision stuff, and had fancy
spacers to center the hot tube. A lot of the parts I had to make myself. But the
02:53:00shop gave me wonderful help. So, we built the columns, and were producing
carbon. When the plant was expanded in a year or two after that, we were
producing routinely 10 percent C-13 from 1 percent. So, you could do some pretty
decent tracer experiments.
GRAYSON: Now, did this thing start out evacuated, or did you charge it with gas?
NIER: Well, you started with it evacuated, of course, and then you filled it
with methane. We got pure methane, natural gas, from some particular well in
California, and they gave it to us free, because it was cheap. We'd get
cylinders, and we'd just have to pay the shipping costs.
GRAYSON: And then, once the system's charged, then you'd turn on the heat?
NIER: You'd turn on the heat. At first we did it batchwise, but then later we
fed fresh methane continuously into the top of the column, and then took out
02:54:00enriched stuff at the bottom. Actually, you shouldn't feed in at the end in a
fractionating column, you feed in someplace in between. So, one end takes out
one kind of component and the other takes the other. That's the way you'd run a
fractionating system, but I don't think we ever got that efficient. I think we
just had fresh methane going past the top, and took out the heavy at the bottom.
GRAYSON: When you were doing this in a step-function charge type thing, how long
did it take for the separation?
NIER: Pretty slow. [laughter] The output, I don't remember what it was now, but
the output was about a liter of gas a week. This ran at, I think, just about
GRAYSON: That was about 10 times concentrated?
NIER: That was about 10 percent concentration. That's the order of magnitude.
02:55:00And, friends of mine in physiology used it for tracer experiments in metabolism
studies, I think, with mice, something like that. And then, I had other friends
in botany, who grew radish plants in a bell jar with this, and then they could
make sugars, that were labeled, because they let the plants do things for them,
GRAYSON: Were they trying to get to the labeled sugars, or were they trying to .
. . ?
NIER: Yes, labels.
GRAYSON: So, there were actually taking your product and reducing it further?
NIER: Making other things out of it, making further things out of it.
NIER: But this was what led to the 60 degree instrument, rather than the 180. It
became apparent that not everybody could have a 180 degree instrument that
weighed two tons, and took a five kilowatt, stabilized generator to run it. And
of course, we had expanded needs. I had graduate students working on different
projects and we were pursuing several programs at the same time, and the
02:56:00capacity of the spectrometer wasn't enough to do what we wanted.
GRAYSON: Okay, so now, we're talking about the late 1930s, early 1940s?
NIER: That's correct.
GRAYSON: You had gone to the APS [American Physical Society] meeting, and met
Fermi, and shown this iron-nickel work that had been misplaced, and at the same
time you were also doing this work with the carbon, both producing it and
NIER: And analyzing things for people. And I had students to help me on the
analysis, of course.
GRAYSON: Okay. But all of this work was all being done on one machine?
NIER: One machine. The 180 degree machine, with a two-ton magnet . . .
GRAYSON: Which was a biggie, okay.
NIER: That's right. Yes, sir.
GRAYSON: So, we're, kind of, poised here in a period where there's a lot
happening all at once.
NIER: That's correct. And I was teaching eight hours a week. [laughter]
GRAYSON: [laughter] Of course, by this time, you had the course material down
pretty well. [laughter]
NIER: Better. [laughter]
GRAYSON: [laughter] And still giving partial credit. [laughter] So, I did see a
02:57:00copy of the letter from Fermi that he had sent to you. The impression that I got
from the letter is that he was kind of gigging you, like "Hey, kid, get to work
on my project!" [laughter]
NIER: Well, it's interesting. I never met him again, which was too bad, because
I never got to Los Alamos [National Laboratory] until after his death [in 1954].
So, I never saw him. I may have seen him in Chicago [Illinois] after that, but
never had a chance to visit with him again, because it would have been
interesting to our earlier contact review at that point. But certainly, he was
interested in it. And see, they had a very good group there at Columbia. First
of all, there was Dunning, and there was Herb [Herbert L.] Anderson, who made a
name for himself, as an assistant to Fermi, and the other people around there,
so they were very interested in all aspects of the fission problem. And Fermi
was never that convinced, you see, about the uranium-235 business. I raised the
question with Wheeler a few years ago, and he acted as if they always knew that
U-235 was responsible for the fission of uranium. But nobody had ever
demonstrated it. So, I don't know. Well, I'm sure they were quite sure of what
they were doing, but still it needed demonstration. And that, of course, was the
02:58:00interesting thing. And to demonstrate that you could separate enough that way
that you could actually do something with it. That was an important point, you see?
GRAYSON: Okay, I'd like to take a little bit of time then, and just explore that
whole experiment. I understand that initially, you finally did get some UF6,
which you hadn't been able to get before. Is that correct?
NIER: That's correct.
GRAYSON: But then, when you did actually try and do the experiment with UF6, it
NIER: It didn't work.
GRAYSON: And what was the problem there?
NIER: Well, I met Fermi in April of 1939. During that summer, I was working away
on the diffusion studies. Actually studying the thermal diffusion of gases by
having two bulbs at different temperatures, and studying how much the isotopic
concentrations varied. This was basic stuff. And that's when I got started on
the wedge instrument, the sector instrument, at the same time. And, we were
carrying on the lead work at the same time as well as running analyses for
02:59:00people who were using our carbon. So, you see, we had a full situation here.
Well, I had been in touch with Dunning, on and off. I don't know if I still have
the correspondence. I lost a lot of that after the war, because it got mixed up
with classified things which went to Oak Ridge [National Laboratory], so I may
have even lost it. Or it may be buried somewhere, or have been thrown away by
this time. But anyhow, I certainly was in touch with Dunning. There was a guy by
the name of [Aristid von] Grosse--von Grosse, actually--who was a very, very
good inorganic chemist, who'd been with Universal Oil Products in Chicago, and
gave up his job there, and went to Columbia to work with Dunning on fission
after it was discovered. He knew all of the chemists who knew something. And so,
they arranged for me to get some UF6. Where it came from, I don't know. Maybe
03:00:00the Naval Research Lab was manufacturing it then, because they were going to
[use] liquid thermal diffusion as a possible separation method.
Anyhow, I got some UF6. And this would have been in the Fall of 1939. I don't
know exactly when, now. And just put it in my instrument like any other gas. We
tried to see what we could get on targets, placed at the end of the magnetic
analyzer. In place of the faraday cup, we just put some little strips next to
one another at the location of the normal outlet slit of the instrument. We
found that you couldn't tell the difference between the targets I called
uranium-235 and uranium-238 because the UF6 is, sort of, a sticky substance, and
it went on everything. And the amount that just diffused around the whole
spectrometer tube was just too much. It was a gas at room temperature. And so,
03:01:00you couldn't tell anything.
It was at that point then, and I think this final decision was made over the
Christmas holidays, that we decided that we would have to approach it someway
differently. Get rid of the UF6 and use a relatively non-volatile substance like
uranium tetrachloride or bromide, with an oven in the source, and then when the
vapor hits a cold surface, it falls dead. It will never get around to the
collector in a 180 degree instrument without ionization and separation. So, that
was the decision.
GRAYSON: So, basically, you're going back to use the same type of materials . .
NIER: At Harvard. In fact, I could have done the separation at Harvard years
before. [laughter] For the final experiment, I built an instrument with a
03:02:00seven-inch radius glass tube. We covered the inside with Aquadag, the colloidal
stuff which you baked on. It made a nice black surface and was a good conductor.
The whole source, the electron bombardment system, the little box with the oven,
etc were on the end of a stem that went in through a ground joint. And I have
pictures of this, by the way. This was the first time I departed from using
all-glass systems. We actually used a grease joint to put this in. And the
collector, the same way, had a ground taper with the collectors in it, coming in
from the other side. Well, we got it going, and were able to soup up the heater
in the source and get a higher pressure. Actually, I don't think we had a real
arc. But we probably had a glow discharge in the source. I had much bigger ion
currents than I'd ever gotten before. Within about a day's running or
03:03:00thereabouts we managed to get enough uranium-238 so you could actually see it on
the target. A little smudge.
GRAYSON: So, you could actually see the sample build up as the experiment was running.
NIER: You monitored it on the uranium-238 collector. I had a meter connected to
it and measured it with an electrometer.
NIER: So, then you do a calculation. It's so many amperes for so many hours, how
many atoms in Avogadro's number and all of this stuff. You can figure out,
predict how much uranium-235 should be there. You just add a fifth.
GRAYSON: So, the collection arrangement was essentially two independent collectors?
NIER: Two independent collectors. They were little strips of nichrome or
platinum. And the resolution wasn't all that great, but it was good enough.
Uranium-235 and uranium-238 are, you know, three mass units apart.
03:04:00GRAYSON: Yes. So, basically, the machine essentially just ran.
NIER: You had to babysit it, because it would drift off of the peaks. You
couldn't just leave it overnight or anything; and you had to keep watching the
current because the material would be depleted, so you'd have to soup it up. Or
if it got too warm or something . . . because it wasn't just a straight
electron-impact ionization, there was some kind of a discharge there, the
pressure was high enough. So, it was, kind of, erratic.
GRAYSON: In order to actually get this thing to go in a length of time that was
reasonable, you were really pushing the whole instrument.
NIER: You were pushing everything. When it was run as an analytical instrument
an ion current of 10-10 amperes would have been a pretty hefty current. This was
more like 10-9 or 10-8.
GRAYSON: Significant . . . yes.
NIER: And you began to get a space-charge problem, though, because, the ions
weren't all that fast. I remember now, the voltage supply on this machine was
1200 volts. It was the power supply that accelerated the ions. You do the
03:05:00calculation in that range, and you find that the space charge . . . the
repulsion between ions begins to be a problem.
GRAYSON: So, basically, you were right at the edge of where you could work.
NIER: Just about. Oh, and the vacuum really was bad. You see, the decomposition
of the compounds gave you icky chlorine and bromine in the machine. The vacuum
wasn't as good as it could have been. That's one of the things that limited you, too.
GRAYSON: Then, at the end of the experiment you removed the collector and sent
NIER: That's right. And the stories that were told are really so. On a Friday
afternoon, which if I remember correctly, was 1 March 1940, I wrote a letter,
and pasted the little targets on the margin of the letter. I went down to the
Minneapolis Post Office--in those days it was open twenty-four hours a day, you
03:06:00could mail letters--and sent it "Airmail/Special Delivery" to my friend John
Dunning. This was before the days of Scotch tape, and I don't know how I
fastened it on, but I think it probably with a piece of a Dennison label.
Dennison labels go back, way, way back. The letter still exists, but I don't
know its whereabouts. I should have asked, since I kept no copy.
GRAYSON: You didn't take it to the Xerox machine?
NIER: [laughter] I didn't take it to the Xerox machine, that is correct. And
since it was a long-hand letter, I wanted to get it off in the afternoon,
because there was a plane that night. And, so I mailed it. And Dunning called
me, woke me up on Sunday morning. I was still in bed, it was very early Sunday
morning, and they had worked all Saturday night, and had demonstrated that,
03:07:00indeed, the one that I called uranium-235 gave fissions with slow neutrons, and
the other one didn't. It was very definite. And that's the story.
Well, then, the letter. I saw Dunning hundreds of time, literally, afterwards.
And I never asked him for the letter or a copy of it. There were copying
machines existing later on . . . I can see why he might not have wanted to give
up the original letter, but after all, it was my letter. But be that as it may,
I never got a copy of it. And, it turned out, he died some years ago, and his
wife guards all his stuff jealously. And I've put it up to one of the historians
at Columbia to see if they couldn't get their hands on it and get a Xerox for
me, at least, but there's no hope. He tried, as he was interested. So, as long
03:08:00as she's living, this is not possible. She was very devoted to John and had some
strange notions about the value of something like this. You know how people get.
NIER: So, you just don't know.
GRAYSON: But for the sake of anyone who might want to follow it up at a later
time, there's a good chance that . . .
NIER: It's in his papers, because he saved everything, and I know he had it,
because he had that and many other things.
GRAYSON: Because that would be a quite an interesting document to try to locate
some day for posterity.
NIER: Indeed it would, indeed it would.
GRAYSON: Mailed . . . hand-carried and mailed, probably for less than three
cents . . . well, air, special-delivery, it might have been ten cents.
NIER: With special delivery it was ten or twenty-five [cents] or something,
which I paid myself.
03:09:00[END OF AUDIO, FILE 2.1]
GRAYSON: . . . talking about John Dunning's relationship to the Manhattan Project.
NIER: Well, that was the beginning, you see. John was very interested in this
all the time. He was the one that started the ball rolling. He was always
interested in the electric power aspects of the problem, and of course,
recognized, with the war coming on, that a bomb was a real possibility. But I
03:10:00know he always stressed the power situation and felt that in the long run, you
had to have some way of separating U-235--that you would do it in large
quantities--to make it practical. He had a very, very good group of young people
and some not so young with him there at Columbia. In particular Gene Booth,
Eugene [T.] Booth. John was a very imaginative, flamboyant type, a real
entrepreneur who might wander off into the wild blue yonder. Although he was
very sound in every respect, he was always on the optimistic side of things,
whereas Gene Booth was a young, very conservative-type person. This was a
wonderful team because Booth would hold Dunning down to practical things,
because he could sometimes find flaws in John's extrapolations, and so on. So,
03:11:00they worked together, it was just a marvelous team, wonderful people to work
with and I just loved those guys. Gene and I are still very good friends. I
haven't seen him for a long time.
Later they pursued the diffusion separation process. I got into the Manhattan
Project through them, as I mentioned in this historical article I wrote for the
Chemical Society. But I don't know if you want to include that now or if you
want to talk about the sector instrument.
GRAYSON: Well, I suppose, probably, while we're started into the nuclear
fission-type thing, perhaps we can continue to explore some of the details of
that, as it . . . basically, you're saying, in the 1940s, in early 1940 period,
Dunning had a vision of what was coming?
NIER: Yes. Well, I think we've got to talk about the sector instrument first,
because that plays an such important part in the Manhattan Project, later on.
03:12:00Coming back to our previous discussion about all the activities we had that
required mass spectrometers . . . it became obvious we couldn't do it all with a
single 180 degree machine, so we needed more capacity. I remembered so well that
Bainbridge's mass spectrograph had a combination of 127 degree sector
electrostatic analyzer followed by a 60 degree magnetic one. That's the way they
did their mass analyses. I also remember reading papers of a guy by the name of
Bill [William] Stevens, who was I think at the University of Pennsylvania at the
time, and somebody by the name of [Michael] Barber in England. They had
03:13:00published papers in the early 1930s about focusing charged particle beams with
sector magnets. They pointed out a general theorem if you have a source of
charged particles emanating from a point and send it through a sector magnetic
field, if the apex of the sector and the source of the ions and collector are in
the same line, then the diverging beam will focus at the collector. The 180
degree case is just a special case where you open up the apex angle to 180
degrees and the straight line is the diameter of the circle. Theoretically, any
angle would do. If it wasn't for the fringing fields, you could have a 1 degree
sector. It seems like the question is if you're going to do this, what angle
should you choose? And I thought about this a little bit, and choose 60 degrees
(Figures 9, 10, 11, 12) because the 60 degree deflection worked so well in the
03:14:00Harvard machine of Bainbridge's; and in part because of other considerations.
When I thought about other angles, it turns out that it would have taken quite a
bit more magnet for 90 degrees. If you stop to think of it, going from 60 to 90
is quite a bit more. Also, if you were going to have a flattened tube that you
fit between the poles, it was a lot easier to bend something through 60 degrees,
rather than 90. Flattening tubes isn't the easiest thing in the world. Later, we
perfected the technique of bending and flattening tubes to any angle but at that
point, we didn't know how to do it well.
GRAYSON: So, now you're thinking about making metal flight tubes, at this point?
NIER: Yes, metal flight tubes.
03:15:00GRAYSON: Even though glass was primarily what had been used up until then?
NIER: Yes, but now, you see, if you wanted to use an electromagnet, you had to
have a narrow air gap to exploit it. So, there wasn't room for a glass tube. I
never built a sector glass one.
GRAYSON: Okay, so the technology forced you into this.
NIER: But then you had to have glass to metal seals at the source and collector
ends. In the original tube, of which I have a photograph, we had a copper tube
which went through the analyzer. Five inch lengths of Kovar tubing were
silver-soldered to the copper tubing. The source sat on one end, the collector
on the other. Glass tubes which encased the source and collector were sealed to
03:16:00the Kovar. Now the presence of the Kovar really buggered things because the
Kovar is very magnetic and you had a big piece of Kovar right next to the
source. You wanted to use a magnet for collimating the electron beam but the
magnet magnetized the Kovar and affected the ion trajectories. This didn't work
too well. Subsequently, we changed that and all the tubes we built afterwards we
continued the copper tubing all of the way to the source and collector and made
the glass to metal seals through Kovar cups which fit over the copper tubing;
well away from the source and collector.
GRAYSON: So, you moved the glass-to-metal sealing arrangement as far away from
the magnet as possible?
03:17:00NIER: Yes, it was quite far away; anyhow, you no longer had a problem. The only
difficulty you had was working with the Kovar. You had to be careful because it
cracked if you didn't anneal it properly. So, there was a lot of little
technology we had to learn.
GRAYSON: Yes, It sounds like a mess, to be quite honest with you. [laughter]
NIER: It was. [laughter] But it worked.
GRAYSON: I've done enough of that kind of stuff to not like it at all.
NIER: But that's the way the thing went. We standardized on a 6-inch radius for
the magnetic analyzer.
03:18:00GRAYSON: And so now we've got 6-inch radius, 60 degree sector instruments.
NIER: That is correct.
GRAYSON: And for the magnet for these, you still used an electromagnet.
NIER: Electromagnet. But you could run it off of a couple of automobile storage
batteries instead of a motor generator.
GRAYSON: Okay, that's a big change in power requirements.
NIER: That's right.
GRAYSON: Was this because of physical size?
GRAYSON: The magnetic fields weren't as high?
NIER: We didn't go quite as high with the batteries. In the case of higher
fields, we had to still use a generator but I had the stabilized generator by
then. But for light molecules, such as carbon dioxide we could use batteries.
Those were the days of 6 volt automobile storage batteries and I think we had
two or four of them.
GRAYSON: What would high mass be for this type of machine?
NIER: Well, at first, we were just shooting to do carbon dioxide, but then we
extended the studies to heavier molecules.
03:19:00GRAYSON: That was still with the battery . . .
NIER: No, when we went to the heavy elements we had to use a generator.
GRAYSON: Okay, so, somewhere the battery power supply was not adequate, I mean,
you had to use something else to get to higher masses.
NIER: That's right.
GRAYSON: It was probably around . . .
NIER: And I think we maybe even tried having the batteries on and charging them
at the same time they were being run, using them as a capacitor, but I don't
GRAYSON: But basically, the whole concept here is that the machine was certainly
simpler and more useful.
NIER: And more people could have it.
GRAYSON: Now this prototype machine was in 19 . . . ?
GRAYSON: 1940. So, was this being developed simultaneously with the problem of
measuring the uranium?
NIER: Yes, in another part of the room.
GRAYSON: How many graduates [students], how many people, did you have working
for you at that time?
NIER: Well, I had one or two undergraduate kids working as technicians. They
03:20:00were very good ones because you could choose. Also, I probably had one or two
graduate students working with me at the time, so I think the total group,
including myself, was around five people.
GRAYSON: You had shop support?
NIER: Shop support, yes. We built a lot of the apparatus ourselves but the shop
did the precision machine work. And we had by that time a machinist, who later
became head of our shop, who was an utter genius, R. B. Thorness,
T-H-O-R-N-E-Double-S, known as "Buddy". He started working in the University
shops when he was just a kid out of school, so the older men there called him
"Buddy". He carried that name until his death. He was a little older than I was
03:21:00and died, unfortunately, some years ago of a heart attack. He had very little
formal education. He may have gone to vocational school instead of high school.
Maybe he graduated from high school, I don't know. He had a sense of what was
appropriate. When you used a hacksaw to get something done or when you used a
grinding wheel to get the surface smooth and precise. He had the sense for what
was appropriate and he could design mechanical things for which he didn't have
any formal training--levers and moments of inertia of cross sections, and so on.
I would have trusted him more than any mechanical engineer who did this
professionally. [laughter] He knew where you made things hefty and where you
03:22:00didn't. It was very important to take him into your confidence, so that he
considered himself part of the project.
This is something that's missed by some scientists. We are very dependent on
people of this kind, and you'd better make them part of the team, if you want to
get their cooperation. We would explain the experiments to him; and he might not
have fully understood what we were trying to do, but he got the gist of why it
was important, why he should do a good job. As a result he was very, very
cooperative. He would come up with new ideas on how to do things. He was very
interested in finding better ways of fabricating things. The problem of the
Kovar cracking was so frustrating for him, he just about went crazy. It just had
to be licked, so he just kept working on it until he perfected the proper technique.
03:23:00GRAYSON: Now, was he on the staff?
NIER: In the physics department we had three men to help on mechanical things. A
machinist who was supposed to do fancy machine work for everybody in the physics
department, faculty and graduate students. He got the job when his predecessor
retired. His predecessor was pretty good but he had a real personality problem.
We couldn't get anything out of him if he came in and felt bad or had a real or
imagined problem. He always seemed mad at something. But he was a very good
machinist and when he did things, they were good. But Buddy was better and was a
nice guy you could work with. Then we had a man who did general work who was a
03:24:00combination glass-blower-photographer, and machinist, whose job was more or less
to help graduate students in their problems. He was very versatile and very
good. He was a half-time instructor and also taught courses in laboratory arts,
as it was called. I got to know him very well and that's where I learned how to
blow glass and how to make tungsten-to-pyrex seals and all such things. Then we
had a third man who came a little later on, who did carpentry and some machine
work. So, that was the whole mechanical staff. But all the fancy things we're
talking about were done by Thorness.
GRAYSON: Did he become the machinist when this other fellow left?
NIER: Yes, he became the machinist. He had been in a University shop before
that, which happened to be housed in our basement next to our shop.
GRAYSON: Oh, I see.
NIER: So, he just came and changed workbenches.
GRAYSON: Okay. All these people then were employed by the physics department?
NIER: Yes, we had three employees in the physics department then at that time.
03:25:00Actually, he technically was still part of the central shop assigned to us, so
it was always a touchy thing. But later the payroll item was transferred to us,
but as far as we were concerned, he had always been ours. During World War II,
he came with me when I moved to the Kellex Corporation in New York. He headed my
shop, because I had a development laboratory there. But that's another story.
GRAYSON: Yes. We were picking up on the development of the 60 degree sector
machine and the fact that there was obviously a need to make these machines and
have them in other places. Anyway what happened to these machines that were made?
NIER: He then built tubes for a few other labs before the war. I don't remember
where they went. But he built a few of them, I know.
GRAYSON: Did you have in mind, at the time, increasing the number of analytical
instruments available here, or did you have in mind creating . . .
NIER: We were not interested in going into the business of building instruments
but tried to help others. If somebody wanted to have a mass spectrometer tube
03:26:00and would pay for Thorness' time, we would do it. I know we built at least one
tube for Harold [C.] Urey, before the Manhattan Project was formalized. We also
built one for the people at Princeton, Hugh Taylor, who was a very well-known
chemist and also dean of the graduate school. They had built a tube which didn't
work very well. They were working on isotope separation problems related to the
uranium program. It wasn't called "Manhattan Project" then. It was still under
the aegis of the National Defense Research Committee as it was called headed by
For all practical purposes, we were in the war before 7 December 1941. It was
03:27:00fairly obvious. I was going to build a house that summer, and so I knew about
the difficulty in trying to get materials. There was a fair amount of activity
in the uranium program. Urey saw the need for developing methods for separating
isotopes and for analyzing the results. He was in the chemistry department at
Columbia then, and Dunning was in the Physics department. Work was supported by
the Office of Scientific Research and Development, OSRD, which was the agency
that did things for the National Defense Research Committee. I obtained a
contract to separate some more uranium-235 by electromagnetic means. This would
03:28:00have been the summer of 1941. We worked very hard on this and got larger
quantities of it but not nearly enough to be really useful. We simply didn't
have . . .
GRAYSON: Was this being done on the larger 180 degree machine?
NIER: No, it was done on a 60 degree, which was put aside for the purpose. The
180 degree instrument was being used at that time for uranium isotope analyses.
It was the best machine we had and we were monitoring the work of the people who
were trying to separate uranium by various methods. And we had the only
instrument in existence that could measure uranium isotope ratios.
GRAYSON: So, this machine was reserved for the real important work.
NIER: That's correct.
GRAYSON: Because these people trying to enrich the fissionable material . . .
this was the only machine in the States . . .
NIER: In the world!
GRAYSON: Yes, you did it . . . or no you didn't?
NIER: Yes, yes.
GRAYSON: So, you reserved that exclusively for the . . .
NIER: Well, almost exclusively, I may have done some lead work at the same time.
03:29:00GRAYSON: Okay, because it had been demonstrated, it could clearly do it properly.
NIER: And so we didn't tie up the magnet for the electromagnet separation of
isotopes. We built a 60 degree instrument for trying to separate more uranium.
It didn't work as well as it should have. It wasn't as good as the 180-one that
we had at the time. Part of the difficulty was the vacuum problem, I think.
GRAYSON: In that you needed a better vacuum or . . . ?
NIER: That was the main problem.
GRAYSON: Essentially, you could get a pump of . . .
NIER: Well, I couldn't do as well with the 60 degree instrument. I didn't have a
big enough magnet to get a high enough field. We couldn't have energetic enough
ions, and if you didn't have energetic enough ions, the space charge bothered you.
GRAYSON: So, it was well-suited for lower mass work.
GRAYSON: But not at all for higher masses.
NIER: Yes, at that time.
GRAYSON: A number of these were built then. One was shipped to Columbia and I
guess there were a number of others.
03:30:00NIER: There was the one that we built for Urey, I know that. There were several
others but just where they went I can not say at the moment.
GRAYSON: You obviously used some of them here. Did you have a couple of them here?
NIER: We had one for the analysis of CO2 and later we had a second 60 degree
instrument. We still weren't building instruments on a very systematic scale. In
about 1941 or 1942 I also had a contract to try to separate uranium isotopes
using thermal diffusion with a column having a hot wire in a cool tube. In the
elevator shaft, I remember we had a piece of . . . I think it was quarter-inch
copper tubing 36 feet long. We stretched it to make it straight and put a wire
down the center if you can visualize this. The wire was supposed to stay
centered. It never worked very well, and it was never pursued. It turns out the
method itself wouldn't have been very good, but it was a separation project
which I thought would be worth trying.
03:31:00GRAYSON: So, this would fall into the category of experiments that you tried,
but really weren't quite successful?
NIER: They weren't successful, no. And I gave that up then. That was the end of
my attempts to separate uranium isotopes. Except in the fall of 1941, when
Ernest [O.] Lawrence at [University of California] Berkeley got into the act.
He'd been concerned with the radar development. He was one of the wheels that
got the Radiation Lab started at MIT [Massachusetts Institute of Technology],
and was, you know, high up in advising the government on research. He decided
that Berkeley, with their beautiful facilities, ought to get into the uranium
program. He visited me, as a matter of fact, in the summer of 1941 and looked at
our facilities, and saw how pitiful they were, and must've gone back and said,
"Oh my God . . . ," or something like that and they then proceeded to set up the
03:32:0037-inch cyclotron as an isotope separator. He had many able assistants such as
Emilio Segre, for example. I spent two weeks there, overlapped Thanksgiving Day,
in the fall of 1941. I came home on 4 December 1941 three days before Pearl
Harbor Day. I helped them with the design of the 180 degree separator they
installed in the cyclotron magnet. They had big pumps because of the cyclotron
as well as high voltage supplies for accelerating ions, etc. They immediately
began to get currents that were 100 or 1000 times as big as ours ever were able
to get. They continued the development after I left and that led to the thing
they called the Calutron. It was essentially a blown-up version of what I had
here. It was my last direct association with trying to separate isotopes.
03:33:00Then Pearl Harbor Day came along. Urey had been beating on the powers-that-be
before that, saying "Look, if we're going to work on these things you will have
to have decent analytical facilities to measure what you are doing." I remember,
he took me in to see Vannevar Bush at one time, pointing out how important it is
that the OSRD ought to support instrument development so they could tell what
they were doing. They were spending all kinds of money on separation methods,
but nobody thought of spending money on the analysis of the product. So selling
Vannevar Bush on this, and I don't know what influence he had, whether it was
even necessary. The uranium project had been under the direction of Lyman
Briggs, who was the director of the Bureau of Standards.
03:34:00If you want to get some insight on that problem, you'll want to read Richard
Rhodes' book on the making of the atomic bomb.
a worthwhile book owning, by the way, or borrowing from the library because it's
a whole history of the atomic business, going all the way back to the discovery
of radioactivity, and it's got a lot of the personal notes on the people. It's a
very interesting . . . terribly long, but he discusses this period very frankly
and doesn't have very kind words for Briggs, which I could verify. Briggs was a
real nice man, a real southern gentleman, but slow moving, and he didn't see
that this was all that important. He was completely out of tune on the urgency
of the war.
GRAYSON: What was his background? Was he a physicist?
NIER: He was a physicist, and apparently, a fairly good one in his younger days.
03:35:00But he was director of The Bureau of Standards, which was a desk job after all,
and I don't know what he had done. I'm sure he had done some good science
before, at one time.
GRAYSON: But he just really wasn't able to grasp the fundamental concepts?
NIER: And didn't understand the era we were living in. So he didn't push on
these things, everything was so slow and I was so mad at him, at one point,
because he could have gotten support for me--I could have done something. I was
so mad after going to Berkeley and found out how they had taken over on things I
could have done just as well months before.
GRAYSON: With just some support.
NIER: Support, you see. But he didn't see the importance of it, you see. But a
lot of other people didn't either, so you can't fault him alone. But Rhodes
really takes out on him. You've got to read that. It's just worth reading by
itself. But anyhow, be that as it may, everything changed when 7 December came
along. Among many people, I was invited down to Washington [D.C.] for a
03:36:00high-level meeting either at the beginning of January or late in December--a
discussion of what ought to be done. And following that, we had all the money we
could ever use for the analytical end. Urey was my boss. I reported to him,
because he was in charge of some phase of the isotope separation business. After
all, he was a very prestigious guy--a Nobel Prize winner [Chemistry, 1934] for
his separation of heavy hydrogen. He was a hard guy to get along with in some
ways, in other ways, very easy. He and I were always very good friends and he
always respected my opinions and requests. The decision was that we immediately
ought to build four mass spectrometers for doing uranium isotope analyses.
(Figures 13, 14)
GRAYSON: This came following Pearl Harbor?
NIER: Following Pearl Harbor. So there's no problem. Within weeks, we had a
03:37:00contract for building four 60 degree instruments for uranium analyses. These
were to be sent to other parts of the project.
GRAYSON: Which was in addition, or above and beyond, the ones you already had.
NIER: Already had, yes.
GRAYSON: So, you researched the design in 60 degree instruments ahead of time.
NIER: That's right. Even before the push for uranium analyses instruments came
along we had built a complete 60 degree instrument for carbon tracer work. We
called it the Rockefeller instrument because it was built with some money left
over from a grant the Rockefeller Foundation had given the University to build a
Van der Graff generator to help on biomedical research presumably to make
radioactive isotopes. At the time there was the question of do you do it with a
Van der Graff generator or with a cyclotron? The cyclotron was, of course, much
better for production of radioactive isotopes but at that time that wasn't
established. So we got money here; I think it was 25,000 dollars from the
Rockefeller Foundation to build the Van der Graff and the tank outside of our
building, which hadn't been used for decades. The money was for perfoming
03:38:00nuclear physics experiments and producing radioactive isotopes. But that all
came to an end pretty much when war time came. There was money left in this
budget, so I was able to get some thousands of it for building an instrument
exclusively for the isotope analyses--for the carbon work to help the biological
people. We built an instrument. I have a picture of that. [laughter]
GRAYSON: We need to get a copy of that. [laughter]
NIER: Yes . . . it was built exclusively for the work to help my biological colleagues.
GRAYSON: So, even though the money was supposedly for the generator, the fact
that it was still going to be used for biomedical work . . .
NIER: We got permission to divert it for medical applications.
NIER: We had an instrument then, devoted entirely to analyzing C-13. I hired
03:39:00students to run it. We built the instrument . . . I did a lot of the
construction myself, but we had electronics help. Kids who could build
electronics boxes. The shop built the tube and other parts requiring skilled
machining so it wasn't too bad. We had it operating in the fall, maybe
earlier--I don't know the exact date. We had that operating certainly before the
end of 1941 on a routine basis. It was there that I came up with the
null-detector business, which we never published, because the uranium problem
came up at the same time and I thought it was too important to publicize. So,
this was quietly put aside and appeared in the uranium instruments during the
war, where we used the same trick. The uranium-238 went to a collector which had
03:40:00a slit in it, and uranium-235 went through the slit to a collector behind. We
used the null method of balancing a fraction of the uranium-238 current against
the uranium-235 current. And so, we transferred that whole technology to the
uranium instruments which were now being built, starting in January of 1942.
GRAYSON: Okay, now you came back from this meeting with the people in
Washington, and essentially, was this a planning meeting?
GRAYSON: I mean, you had scientists from all . . . I mean, were they physicists
or . . .
NIER: I don't remember
GRAYSON: But basically you had a fairly large group of prestigious [scientists].
NIER: Some dozens. I was a nobody in that crowd.
GRAYSON: [laughter] That's hard to believe. But anyway, and what was the format?
I mean did you just sit around and talk about the problem?
NIER: Well, they talked about a lot of problems. And there was a lot of side
03:41:00conversations because not everybody was let in on everything. For example, they
were talking then about uranium reactors for making plutonium.
[END OF AUDIO, FILE 2.2]
GRAYSON: We're starting Side B of Tape 4. There were a number of people, then at
this meeting in Washington who knew different things about what was happening.
NIER: Yes. I don't remember the exact connection between my getting the contract
to build more machines and that meeting. But certainly, it was related. And of
course, from a technical standpoint I dealt entirely with Urey from that point
03:42:00on. We dealt with the administrative office at the Office of Scientific Research
and Development on the contractual side. I more or less lost contact with other
people then, except for John Dunning.
GRAYSON: Then you came back here and very shortly started working on these machines.
NIER: We began building four of them immediately.
GRAYSON: 60 degree sectors for doing the uranium?
NIER: Uranium, that's right. Also, we still had the only facilities for making
uranium analyses so we carried on the analysis. There was centrifuge work going
on at [University of] Virginia by Jesse [W.] Beams and his colleagues. There was
the work at Columbia--the diffusion studies through membranes. There were other
experiments going on in some other places. There was Phil [Philip H.] Abelson,
03:43:00the guy who became editor of Science. He was then working at the Department of
Terrestrial Magnetism but I think he also had some connection with the [U.S.]
Navy in Philadelphia [Pennsylvania]. They set up a liquid thermal diffusion
column there using liquid UF6.
So, there were at least these three programs directly involved with the uranium
separation. Quite independent of all this, the development was going on at
Berkeley on the Calutron but they used radioactive counting methods so I no
longer interacted with them. I never saw any of them again. I knew Lawrence
quite well. We were friends, but I just had no contact with them at that time.
So, my contacts then were exclusively with either Urey officially, or John
Dunning officially and unofficially.
GRAYSON: Now the next generation of 60 degree sector machines, had some
03:44:00modifications to analyze uranium because, as we mentioned earlier, the first
generation didn't do as well.
NIER: Well, we had bigger magnets than I had for the original one, the 1940 one.
Bigger magnets were employed and we used stabilized power supplies, electronic
ones: that time we could build these things; you had to wind very fine wire,
miles of it. Remember we used high voltage with vacuum tube regulators which
were high voltage, low current devices; unlike the solid state things these
days. We could get pretty decent fields. The magnets were heavier, everything
was beefed up. But it was still a basic 60 degree machine and we perfected the
manufacture of the spectometer tubes so that the Kovar seals no longer cracked
most of the time, and so on.
GRAYSON: Again, your electrical engineering background probably came in handy
for applying the latest and greatest electrical techniques.
NIER: Undoubtedly because I kept up with electronic things of the times.
GRAYSON: Okay. Then, now, basically, this was a contract of four instruments?
03:45:00GRAYSON: And having these four machines, what happened to them?
NIER: I got to know Arthur [H.] Compton, who was at Chicago at the head of what
was called the Metallurgical Lab. And I knew all the people who were in charge
of things. I knew [J. Robert] Oppenheimer for instance too. The decision was
made some place, and I'm sure Compton had a lot to do with it, that they would
send me, Mark [G.] Inghram, I-N-G-H-R-A-M, who was a graduate student of [Arthur
J.] Dempster's at Chicago who was getting started in mass spectrometry. They
would send him to me to help us with our uranium analysis. He and Ed [Edward P.]
03:46:00Ney, N-E-Y, Edward Ney, who was an undergraduate, they did the bulk of the
uranium analysis for the country. Inghram, a graduate, a beginning graduate
student, and Ney an undergraduate.
GRAYSON: This was with those four instruments?
NIER: Well, with one of them, plus the old 180 degree one. Four weren't built
yet. But they were being built. Gradually, by the end of spring, we had built at
least two and maybe three of the four. And we were doing analysis then by that
time routinely on one of the 60 degree ones, the 180 was no longer used. We
worked out the whole manifolding system and everything was more convenient, it
was designed to do the job. So, that was the first of the instruments where it
was a self-contained package. It had a frame of its own and I have pictures of
that too, so you can see that.
03:47:00Well by the summer of 1942, Ney graduated, but he had been working for me a
couple of years and was the best experimental student in the department
including all the graduate students. He was just a natural. He's a full
professor in our department, a very distinguished guy now. So, the question is
what do we do. The decision was to send him to the University of Virginia with
two instruments to help on the centrifuging work which looked very promising but
wasn't pushed as hard at Virginia as it might have been. They didn't quite push
it. Two of the instruments with Mark Inghram went to Columbia, and set up in the
03:48:00physics department as part of that program. So, he was in charge of the mass
spectrometers at Columbia and did all the UF6 analyses at Columbia.
GRAYSON: So, these gentlemen were in on the building of the instruments?
NIER: Of the instruments, yes. They worked part-time building, part-time running
analyses. That's right.
GRAYSON: They had a full knowledge of what needed to be done to make it work correctly
NIER: That's right, they knew it from A to Z. It was during this period,
sometime in 1942, that the critical experiments were performed at Columbia
determining that the diffusion method indeed was promising. I think they had
either a 6- or 12-stage system. Their little barriers were little disks about
03:49:00the size of a penny or so they had developed--Dunning was in this with
everything he had, plus a very good staff of people. They had even developed
pumps for pumping UF6. These used sylphon bellows for seals. UF6 is a very
corrosive compound. You had to have an all metal system, but not any old
metal--it had to be Monel or nickel. They had built pumps that could pump UF6 up
to pressure. They had been working on valves that you could use. You couldn't
buy valves that didn't have string packing; I take that back, refrigerator
valves didn't have string packing, but they had brass housings which were
terrible things for UF6. You couldn't even buy miniature valves that were any
good. At Columbia they had some very good people in the physics group working on
uranium separation with Dunning as the leader.
03:50:00Until the middle of 1942 we made all of their isotope analyses. I wish I still
had the telegram which I got from Gene Booth after they had sent us some
critical samples. They never told us which samples were critical so as not to
prejudice us. I got this wonderful telegram from Gene saying that either I could
read minds or we did a good job. It was to tell me that everything was as it was
supposed to be. The measurement confirmed that the diffusion method was
performing as hoped for and could be developed further. We had built four
03:51:00machines. I sent two to Columbia and two to Virginia.
In the meantime we got a contract for three more. At that point I was going to
fold up things here and move to Columbia to help out on their activities, but
their machine shop was already booked to capacity and I couldn't live without a
machine shop if I was to develop new instruments. What was I to do? So, I stayed
in New York for two weeks, I think it was, and finally got frustrated. I talked
to Urey and Dunning and said, "Gee, I could do so much more good if you let me
go back home again, where I have a machine shop that I can do anything I want
and with people to do things. We need more instruments, so why don't you let me
03:52:00go home?" So, I came home. Stayed another whole year. That was a very productive
year. We were out of the uranium analysis business then and worked exclusively
on the development and construction of new instruments.
NIER: We built three more uranium instruments. We then built ten heavy hydrogen
instruments for doing HD [Hydrogen-Deuterium] analysis. These were all glass
with magnets mounted inside the glass housing. I now have one which Charlie
Stevens discovered at Argonne [National Laboratory]. (Figures 15, 16) It was a
leftover tube. They were going to throw it away. It used to be here in my
office. I put it in our storeroom. We built these for HD analysis. They were a
lot simpler than the uranium instruments. They had permanent magnets, which were
small since you were doing hydrogen. (Figures 17, 18, 19) We had only 3- or
03:53:004-hundred volts accelerating voltage; for stabilized voltage we used the drop
across VR tubes. These were glow discharge tubes that would give you a fairly
steady voltage. By that time we had emission regulators--automatic emission
regulators--that used the emission current to tell the filament how hot it
should get to keep it steady.
There had been something published on an ion-gauge regulator by Louis [N.]
Ridenour, a physicist at Princeton, in The Review of Scientific Instruments
during the late 1930s or early 1940s.
We adapted the
circuit for use on a mass spectrometer filament. Before that we used a storage
battery and a heavy slide wire resistor for controlling the filament
current--one of these things that you bought from Central Scientific. Because
you had to pass 5 amperes through the filament. You had to use some care in
03:54:00adjusting the current. We had the first stabilized emission regulators on mass
spectrometers, and that was standard equipment on all our stuff here. That was
the only tricky thing we had in the spectrometer. But anyhow, we built about ten
hydrogen instruments. Three went to Trail, British Columbia. You had to take the
train or plane to Spokane [Washington] then you took a bus the rest of the way.
It was like going to Shangri-La on a little road that hung on the side of a
mountain. I remember because I did this a number of times. But, anyhow, I went
up there myself and set up three instruments there.
GRAYSON: This was for deuterium determination?
NIER: Deuterium. They had a heavy water plant there. Three instruments went to
Morgantown, Virginia where DuPont [E. I. du Pont de Nemours and Company] had a
03:55:00plant. And three more went down to Indiana where somebody had a plant. I don't
know if I ever went to that plant, but I did go to Morgantown.
GRAYSON: What was the interest in deuterium?
NIER: Well, they thought heavy water would be part of the reacting business, the
bomb business, which turned out not to be. But that was one of the things being pursued.
GRAYSON: Yes, at that time, anything that looked like it might have a possible
application . . .
NIER: Yes, was being pushed. Like isotopes.
GRAYSON: [laughter] Yeah.
NIER: Then, at the same time there was this other interesting development. I
travelled quite often to New York. I went to see how Inghram was getting along,
to visit Urey because I was supposed to report to him.
GRAYSON: Were you still being paid by the university
03:56:00NIER: I was on a regular university appointment but OSRD paid my salary. They
reimbursed the University. I just got my regular salary.
GRAYSON: But you were able to use the facilities here.
NIER: Yes, and they may have paid some overhead even. This was before the days
that overhead was such an important thing. You don't even use the word overhead
anymore, it's "indirect costs," you know. [laughter] On second thought, I think
there probably was no overhead. While all of this was going on I was relieved of
GRAYSON: I see, what year were you relieved of teaching?
NIER: Starting in the summer of 1942, for sure.
GRAYSON: So, the word was . . .
NIER: Maybe even earlier than that.
GRAYSON: . . . that you were supposed to work on these problems.
NIER: Yes. And my labs, then, had special keys, not everybody could get in . . .
03:57:00only the people who had business there. In the midst of all this construction, I
was going back and forth to New York and I knew Dunning very well because after
all, we had helped them on their method. By coincidence, a very close friend of
mine, Manson Benedict--whose name became very important later on--was hired by
the M. W. Kellogg Company. He was a very, very good chemical engineer and was
part of our gang at Harvard. He was a post-doc as I was, but working in
geophysics, and subsequently he was hired by the M. W. Kellogg Company as a
process engineer. You see, Kellogg was a company that built oil refineries and
03:58:00power plants and other industrial plants. When the decision was made to go the
diffusion route as one of the ways for separating uranium, and Kellogg was given
the contract, he ended up as the chief process engineer.
He in turn hired another old colleague from Harvard days, a guy by the name of
Bob Jacobs, who had shared a lab with me at Harvard. He then was working on high
pressure phenomena with Bridgeman. We all knew each other well. He was given The
responsibility for getting the big diffusion plant uranium tight. Getting the
plant vacuum tight was important because, if the thing leaked, the UF6 would
plug the barriers and that'd be "bye-bye plant."
GRAYSON: I hate to interrupt, but UF6, you say, would plug all the barriers if
03:59:00there was a leak in the vacuum system. I think we need to expand on that some.
NIER: Well, if water from the atmosphere got in, as was very likely if there was
leakage, it would react and form UF4 which would plug the holes in the barriers.
GRAYSON: Okay, so the important point is that this plant, whatever size and
however operative, had to be held under vacuum. There could be no leaks.
NIER: That's right. It ran at below atmospheric pressure, I've forgotten the
exact amount. It was 1/5 of an atmosphere or thereabouts. So, air could leak in
if there were leaks. Everything had to be tight; the welds, and people didn't
know how to make welded joints that were really tight in those days. At least it
wasn't of concern for steam applications. A little bit of seeping didn't matter
for steam. What is more, because of the corrosion problem, stainless steel,
nickel and Monel were used. Those materials were hard to weld. There was a whole
lot of technology that had to be learned. And then there were many thousands of
04:00:00valves in the plant, all with welded bellows; because you couldn't use packed
valves. These were made out of Monel, with welded bellows in them, and so on.
This all had to be vacuum tight.
GRAYSON: Not so much that you had to get that good of a vacuum, it's just that
you had to keep any possibility of water out.
NIER: That's correct.
GRAYSON: You could probably get by with a little bit of air in there.
NIER: That's right, yes.
GRAYSON: That wasn't a problem.
NIER: That's right. In fact dry nitrogen was let in. In operation of the plant,
UF6 was forced through porous metal tubes and the pressure dropped. You had to
pump it up again for the next stage. They had big centrifugal blowers for pumps
and how do you run something with a rotating shaft that's 4 inches in diameter
into a vacuum-type system? So, they had seals which they had perfected with
carefully honed surfaces which used a film of dry nitrogen as a lubricant. So
04:01:00there was slight leakage of very dry nitrogen into the plant.
GRAYSON: You had to keep the water out.
NIER: You had to keep the water out. Also you worried about other leakages as
well . . . various refrigerants for example. Because of the pumping, the UF6 got
hot so you had to have all kinds of refrigeration equipment to cool the gases.
Also because of the size and complexity of the plant you had miles of welded
joints. Then, the question came up, "How can you find leaks if you're going to
have miles of welded pipes and joints and couplings?" There must have been . . .
maybe a million joints is too many, but the number of joints that had to be
welded was way, way up in the tens or hundreds of thousands. So, how do you test
all this stuff? Well, you had to find some way to do it. You could use the usual
stunt . . . you could pump down and have an ionization gauge and read the
pressure; or you let it stand and watch the pressure rise with a bourdon gauge.
04:02:00Well, these were all far too crude. So, in kicking this around, and I don't know
exactly whose idea it was, but in one of many brain-storming sessions the
question came up, "Could you use a mass spectrometer as a leak detector?"
GRAYSON: Was this down at Oak Ridge?
NIER: No, this is all up in New York.
GRAYSON: All up in New York, okay.
NIER: I'd never been there, to Oak Ridge at this point. We're talking now, 1942,
when I had more time, since we were no longer doing the routine analysis. And,
so, when the question came up it appeared feasible to develop an instrument for
the purpose. In practice you used the leak detector as a sophisticated
ionization gauge. You tuned it to helium. There isn't much helium in the air and
you could sniff around with helium. (Figure 20) Well, at the time, we were
building the hydrogen instruments, which were for light masses. So, it was
04:03:00simple for us to adopt a hydrogen instrument for the purpose. In a month or so
we threw together a portable instrument (Figures 21, 22, 23) that could do
analysis. Now this first instrument had a glass tube. We played with it and
showed that you could detect very small leaks this way. We built four such
portable instruments, is my recollection. We shipped a couple of them to
Columbia, where they were doing all the pilot plant testing so they could
experiment with the procedure. There were people on the job doing all kinds of
04:04:00pilot plant studies. The decision was that the instruments should go into
production. (Figures 24, 25, 26) General Electric received the contract for the
construction. This followed shortly after the decision was made to pursue the
gas diffusion method of isotope separation on a large scale.
GRAYSON: This was in 1942, or sometime?
NIER: Late, sometime in 1942, yes. Everybody was concerned; how can we help
K-25--that was the name of the plant, K-25. How can we help K-25? The feeling
was they had to have many hundreds of helium leak detectors. GE had the
contract, a blanket contract for instruments of that kind. So, they got the
contract for building helium leak detectors. Now before that, they had received
the contract for building uranium analysis mass spectrometers. I should have
mentioned that, after we built those first ones, one of the seven we built went
04:05:00to GE as a prototype.
GRAYSON: Okay, did you just ship the instrument there or did you supply drawings
of the circuits?
GRAYSON: Did you supply mechanical drawings of the components?
NIER: Yes, drawings as well as a prototype instrument.
GRAYSON: Basically, you were in an instrument development research design mode
at that time.
NIER: That is correct, developing and building prototypes.
NIER: Now this period overlapped my moving to New York. By the summer of 1943 in
Minnesota we had built seven uranium instruments, about ten hydrogen
instruments, and four leak detectors. We may have built a few other things in
addition that I have forgotten about now. A uranium instrument went to GE as a
04:06:00prototype and they went into production on those and built, I don't know how
many dozens of them for the project. One helium leak detector went to GE to
serve as a prototype for the hundreds to be built. Following this, the question
arose, what should I do from here on? We're now to the summer of 1943. I was
faced with a dilemma, what would be the best thing for me to do. Lawrence wanted
me to come out and help at Berkeley, Oppenheimer called me to ask me to come to
Los Alamos which was then being set up. Compton raised the question, "Wouldn't
you like to come to Chicago?" Nobody put any real pressure on me, but in talking
it over with Urey I thought the most good I could do would be to work for
Kellex, the Kellogg subsidiary, which had the big responsibility for building
04:07:00the Oak Ridge gaseous diffusion plant. There were a lot of potential analytical
problems in this plant.
GRAYSON: Was it known at that time that diffusion was the answer?
NIER: Centrifuging had been dropped, they had not gotten far enough by the time
a decision had to be made.
NIER: It may have been the superior method, but it hadn't been demonstrated that
you could do it, whereas the Columbia people had demonstrated that the diffusion
method could be scaled up and produce substantial amounts of concentrated U-234.
GRAYSON: And the idea of electro-magnetic separation . . . ?
NIER: Ernest Lawrence was pushing that full-blast.
GRAYSON: So, he was still pushing that at the time.
NIER: And it was being developed full-blast.
GRAYSON: Would it be fair to say the government had decided to pursue both of those?
NIER: Yes, that is correct.
GRAYSON: But you elected to cast your lot with the diffusion method. I think
it's an interesting area, an important area. Your natural background would be,
to a certain degree, with the magnetic separation work.
04:08:00NIER: Yes. But I thought that was hopeless for a big production thing.
GRAYSON: Okay, in your own mind even though you knew that that was a good
technique, you didn't think it was going to be able to produce the quantities necessary.
NIER: Certainly not large quantities. But remember, the first bomb was made that
way. They got enough for one bomb.
GRAYSON: Yes. So then what you did decide at that time was that your talents and
abilities would be better off spent working to support the gaseous diffusion plant.
NIER: Yes, that is correct.
GRAYSON: Even though your own native background lent itself to magnetic separation.
NIER: But the diffusion plant offered a tremendous challenge. There were real
problems ahead. [laughter]
NIER: Now this was a very practical kind of thing, you see. I got out of science
at that point. We were all out of science. I don't know if it would have been
any different if I'd gone to Los Alamos. Maybe I would have worked on exotic things.
GRAYSON: It would have been more scientific?
NIER: Much more scientific. The other people came out of that experience
04:09:00pursuing science because Los Alamos was run like a high-powered university
thanks to Oppenheimer.
GRAYSON: Whereas the problems that you were dealing with . . .
NIER: Were very engineering.
GRAYSON: . . . were much more engineering oriented.
NIER: Very much engineering.
GRAYSON: And more mundane? But the end to which they would be applied was effective.
NIER: I think what I did was more important to the effort.
NIER: In reaching the decision you can't forget the personal angle. I was a good
friend of John Dunning's. He had been very generous with me in giving me credit
for demonstrating the first fission property of U-235. My name was first on the
paper announcing the result.
There were four of us
that were on that paper. Also, I knew Manson Benedict of Kellogg who was a very
dear friend of mine. I also knew Bob Jacobs. And a very large problem was
looming for the diffusion plant. That was how to monitor the performance of the
entire plant for all the impurities, all the refrigerants, and every other damn
04:10:00thing that could leak into the process stream. So, it looked like a challenging
problem to monitor a whole huge plant like this for all the crazy stuff that can
happen to it. Dunning really doesn't get the credit he deserved, because he had
the imagination to foresee all the problems that had to be solved to make the
plant successful. "Gee why don't you monitor the thing with a mass
spectrometer?" I don't know who said this first, but certainly, Dunning was all
in favor of it; so that was to be my big assignment when I went to work for
Kellex in 1943. I took a leave of absence from the university. I'd been on the
university payroll--to be sure paid by the government but on the unversity
payroll. So, in the summer of 1943, I entered the commercial world as an
employee of Kellex, it was a subsidiary of M. W. Kellogg set up to build the
04:11:00diffusion plant. So, I moved to New York City.
GRAYSON: This is the second time you went to New York?
NIER: The second time I went to New York. This is now in August of 1943.
GRAYSON: But you also took along your machine-shop man with you didn't you?
NIER: Yes, I had my shop which was needed for further development. I had with me
several of the students who had worked with me. But I had lost my best and most
experienced people. Both Inghram and Ney were gone. But I had several other
people who were coming along, including Charlie [Charles A.] Stephens who is now
at Argonne Lab. He's done very well, he was one of my good people then. He
worked on the development of the hydrogen instruments that were sent to the
various hydrogen plants during the war. He came with me as did [Wallace T.]
Wally Leland and Donald [L.] Drukey, two other undergraduate students.
GRAYSON: So, there were a number of people from here that went to Kellex and . . .
NIER: Including our electronics man who'd developed and built our electronic
04:12:00units at Minnesota. He headed up an electronics shop for me at Kellex and
Thorness, headed up the machine shop. We had a nucleus to start with. We got
started in the fall of 1943. Nothing happened for a while, it takes time to get
started. We didn't have tools and we didn't have this and we didn't have that,
so I spent a lot of time in the library at Columbia trying to figure out how to
analyze all the things they want us to look for. And I was the last one in the
world that wanted to use a large number of mass spectrometers to monitor the
plant. I thought of the complexity of trying to keep dozens of these things
going all at once. It seemed very formidable. And the project manager . . . is
this the end of it?
GRAYSON: Yes, why don't we stop here, because this is a good place to stop, and
we'll pick up on the next tape.
04:13:00[END OF AUDIO, FILE 2.3]
GRAYSON: We had just left off with the discussion of . . . this is worse than
bridge, nobody can remember who dealt last, but you can remember the play of the
last four hands. [laughter]
NIER: Well, as I was saying, I went down to New York, and we were in a building
called the Nash Building. It had been the Nash Motor Company's warehouse for
cars in New York City. It was just above Columbia University at 133rd and
04:14:00Broadway. Kellex had several floors in the building; and the group at Columbia
that pursued the diffusion-related problems were on other floors of the
building. So, we saw the Columbia people all the time. But we had several floors
of our own there. And I had half of a floor of that building, for our
development group. When I first went there, I had time, because I arrived in
August and it was some weeks before we could actually get started doing things.
I spent a lot of time in the library, trying to figure out ways which could
avoid using mass spectrometers.
GRAYSON: You knew too much about the instrument. At that time, running one was
more of an art than a science.
NIER: [laughter] That's right. Finally, the Project Manager and the right-hand
man to the president of the company entered the act. He was an electrical
04:15:00engineer by background and was intrigued with the idea of a mass spectrometer
doing things. He thought it was just wonderful. So, in one of our conversations,
I was told him about all the things I was trying to do to avoid using mass
spectrometers. I don't know the exact words he used, but the effect was, "Look,
we hired you to do something about mass spectrometers, and here you're trying to
get away from them!" It was something like that. [laughter]
And so, he became one of my great fans. Al Baker was his name. And I suppose his
background was designing power plants for oil refineries and other large
installations. But he was very interested in electronic devices. Anyhow, the
decision was made at that point that we should analyze the process stream with
mass spectrometers. Now, there were conversations between other people, of
04:16:00course. There would be around fifty sections in the large building, which was a
huge, U- shaped structure--one-half mile from end to end. There were fifty
different sections which could be isolated from one another. I don't remember
how many diffusion stages there were in each section; probably dozens of stages.
And, you could isolate these different sections, in case something went wrong.
There was to be a mass spectrometer in each one of these. (Figure 27) There
were, I think it was something like fifty-four locations where we were going to
put mass spectrometers, and each one would be backed up by a duplicate. It was
so important that there was a spare instrument. There were thus one hundred and
eight mass spectrometers set up there. We called them Line Recorders since they
made a continuous on-line analysis of the process stream.
GRAYSON: We knew that mass spectrometers were difficult beasts, so we put two of
them there. [laughter]
NIER: Later, after the war, and after they got going, they found that they
didn't need nearly that many, but at that time, we didn't know how closely the
process stream had to be monitored. The spectrometers were all pumped with
glass-mercury pumps. The spectrometer tubes themselves were metal. The
04:17:00instruments only needed to go up to mass 69. Why 69? CF3. Because they used a
lot of flourocarbons in the plant. This was the first large scale use of
flourocarbons as refrigerants, lubricants, and whatnot. The CF3, just like the
CH3+ is an important ion. If you have hydrocarbons, you have a CH3+ so we'd have
CF3+ That's all the heavier we had to go really. We didn't attempt to do the
uranium on them. In fact, we didn't want the uranium in the instruments. We took
the uranium out. When we let the gas in, in fifty-four locations each with its
own instrument, we passed the gas over a little pool of mercury, whose
04:18:00temperature was controlled. [laughter] The UF6 reacted . . . I won't say
violently, but decisively . . . with the mercury, it fell dead. And the other,
the impurities in there, which were inert gases, were not affected and went into
the spectrometer. When UF6 is admitted to an instrument molecules are adsorbed
on surfaces. When the electron beam in the source struck a surface, the UF6
decomposed to UF4, an insulator. So, the uranium analysis instruments had to be
turned off, taken apart, and the sources cleaned regularly. It was part of the
ritual in running them.
At Oak Ridge, you had dozens of uranium isotope instruments in the diffusion
plant for analyzing the products of the plant; both in the diffusion plant and
in the electromagnetic plant, which was being built in the next valley. You had
helium leak detectors all over the place. Some were on the foundry floor at
Crane's Plumbing to check valve castings. Others were in factories all over the
04:19:00country to check other products, plus many dozens at Oak Ridge, for checking the
plant as it was being built. The Line Recorders were located in fifty-four
places in the diffusion plant. The problem of monitoring continuously in so many
places was a bit of a project, and the guy who was my immediate boss, fellow by
the name of Thomas Abbott, was an engineer from GE. He had been a superintendent
at one of their plants, and understood instrumentation of all kinds; he felt we
ought to have a central control room. At each Line Recorder we had a strip chart
recorder with a slave run off of it in the central control room. (Figure 28) You
had fifty-four recorders in a room, around the walls, so at a glance a single
04:20:00operator could see the composition of the process stream at every place
throughout the plant. Now, we had to freeze the design on all of this in 1943.
This was before the days of electronic recorders. So, the best thing we could do
was to buy recorders from Leeds & Northrup which employed galvanometers as
sensing units. When the galvanometers got off balance, there was a mechanism
which would turn a slide-wire to indicate the balance. Also these were
multi-point recorders. So, we could record . . . I've forgotten whether it was
eight or twelve different signals selected by a commutator. We performed
peak-stepping on the spectra, and picked out the things to see. We recorded
04:21:00oxygen, nitrogen, [untranscribed material, 4:20:54-4:21:11] HF CF3 and a few other ions.
And that's the way the plant was monitored continuously. This became very routine, to
be sure. There were terrible maintenance problems, but the technicians got pretty good at this
thing; and the instruments were actually pretty reliable. Now, there was one
interesting incident . . .
GRAYSON: Now, was there an individual responsible for each pair of instruments?
NIER: Yes, there was an instrument department that [Union] Carbide [Corporation]
had which maintained and operated the instruments. There were some interesting
unpublished stories in connection with that whole operation. One refers to the
period when the original leak detectors were put into operation. Since our use
04:22:00of helium leak detectors was a pioneering effort, we said "Well, they're sort of
experimental." The people in the instrumentation section of Carbide, looked upon
this as a license to try to rebuild the instruments themselves. [laughter] And
they had a fiendish time with the maintenance of the leak detectors, because
they got pretty rough treatment. They'd lose vacuum, burn out filaments, and all
kinds of things. So, you had hot-shots in the instrument department who thought
it would help if you replaced the battery-operated amplifiers by
electronically-run ones. And you ran into ground loops, and all kinds of
electronic problems. We designed the amplifiers to run off of a six volt
automobile storage battery and two 45-volt radio-B batteries, because it was
felt this ensured reliability. You changed the batteries regularly, and there
was no problem. It was a nuisance, but it was reliable. Well, the hot-shots
04:23:00wanted to replace all of this stuff. Then they decided there ought to have been
more stages in the feedback amplifiers; and then they ran into problems with the
feedback. Things were just going to hell on wheels.
Tom Abbott and I always traveled together, he as a manager-executive-type, and I
served as a technical consultant on our visits to Oak Ridge. We had long talks
about the maintenance problems and finally decided we would go to the management
of Carbide and say they should get rid of the people who headed up the
instrument department, and put in someone who would follow rules. There was
terrible soul-searching on this, but we persuaded them that the two high-level
04:24:00people responsible, should not be in charge of maintenance of instruments. They
should move them to some place where they could do their inventing, and get
somebody who was a bit more pedestrian and who would follow instructions and be
faithful, and so on. The management of Carbide was just aghast that we'd make a
suggestion of this kind. But they followed it and the down-time dropped from 50
percent to three percent, or something like that. The leak detectors were more
reliable than your automobile after that. So, that was just one of the little
side things that came along.
All of the mass spectrometer instruments worked pretty well. We also developed a
number of other instruments. We had chemical work going on in our lab. We had to
work closely with GE who built production instruments based on our prototype.
04:25:00This was very interesting. We often disagreed with the GE people, but it was
never on a personal basis. We were the best of friends with all of the engineers
there, but there were a lot of disagreements. We would curse each other during
the hours of the day, but at the end of the day, they would take us out to
dinner and we were all palsy-walsy. Like the lawyers in a court case. They may
be on opposite sides, but they go out and have drinks together. So, it was very
interesting to see how the people could separate work issues from personal ones.
After all, the GE people were accustomed to this; they were accustomed to
dealing with customers who had problems, so they knew how to be smooth, and
friendly, and so on. We had very good relations with the engineers.
They didn't like a lot of our designs, often for good reasons. In the lab we
were getting by with specifications that were marginal. We would use vacuum
tubes beyond their ratings, and a lot of similar things. If you had to put the
04:26:00GE label on it, you would not do. So, they were much more conservative in their
designs. Some things they sometimes redesigned for the sake of redesigning. But
most changes were made for good reasons. So, it worked out very well in the end.
We built several instruments that way.
At Kellex, when I went down there, one of the first things we did was make an
all-metal version of the leak detector--it had been glass before--and handed
them that. And they followed it pretty closely, and it worked very well. And
they did a good job on that. One of our responsibilities was to monitor the
radioactivity coming out of the stacks of the plant. [laughter]
GRAYSON: You mean, there was an environmental concern?
NIER: Oh, yes, But it may have been more of a security matter, of not letting
04:27:00people know what was coming out. So, we had to monitor the stuff that was coming
out of the stacks. So, how did you do this? Well, we were going to use
ionization chambers. I knew they were working at Chicago at the Metallurgical
Lab with ionization chambers, but we got no cooperation in learning about their
designs. This was the compartmentalization business. We had to go back to square
one and develop our own ionization chambers, which was probably a good thing.
You know the way you do this, you have an of an insulated structure with high
voltage on it in a container. Ions are produced by the radioactivity and you
measure the ion current. The instrument had to withstand corrosive atmospheres,
04:28:00which I'm sure the Chicago people never had to worry about. So, we had teflon
insulators and nickel structures. We started out fresh, without any
pre-knowledge of what had been done, and built big chambers, as large as garbage
cans. We were trying to measure very low levels of radioactivity--the
alpha-particles from UF6 which might be leaving the stacks was what we were
trying to detect. We had those big tanks which had something which looked sort
of like a birdcage inside, with a high-voltage on it for collecting ions.
Who was going to build this at GE? Well, it turned out it was the mercury
rectifier department that normally built big, power rectifiers for power plants.
[laughter] They were low in work at the time, and so it was assigned to them.
The man who was in charge was really a top-notch engineer, an older man, who was
04:29:00nearing retirement. Our meetings were interesting because before, we were
dealing with mainly these young people, who had to be eager beavers to prove
something or the other. This guy didn't have to prove anything. So, he said,
"Tell us, what is it that works right, and what is it you're having problems
with, and we'll do what we can to help out." We outlined the status of the
thing, and they followed our recommendations exactly, and didn't feel they had
to re-invent the wheel. It was a very interesting experience. The devices were
very successful because there was no monkeying around.
GRAYSON: I get the impression, quickly going back in time, from 1944 to 1934 . .
. you started up essentially three or four, four or five different times, in a
way. You started up here with your graduate work, and then you went away to
Harvard, and then you came back here, and then you went to Kellex. And each of
04:30:00these moves represented an almost a complete new beginning experimentally.
NIER: That's right. Of course, the mass spectrometer was, sort of, central to
the whole thing. And at Kellex, we had various assignments. I had several
chemists working who were pursuing other analytical problems along that line. It
was an interesting job in the variety of things going on.
GRAYSON: But a reasonable amount of your time was concerned with bringing
yourself up to a certain level of performance.
NIER: Oh, yes. I had to learn about ionization chambers for example.
GRAYSON: Right off the bat, you're faced with re-building equipment or spending
a reasonable amount of time learning new things.
NIER: Well, we had to develop all kinds of things. One of the devices we
developed, long before anybody else had, was for measuring the pressure of a
corrosive gas. We could measure the pressure of UF6 at low pressures, a couple
of torr pressure. We had bellows instruments, just like the ones that you buy
now. Whatever they're called . . . they're made by some company who made the
04:31:00pressure gauges with diaphragms that deflect. We had devised a balance gauge
with which we could make absolute measurement of pressure. We had a pair of
bellows and you had a vacuum in one of the bellows, and sample pressure on the
other. We put weights on a scale and in effect "weigh" the pressure. That was
part of the development. One of my assistants, Charlie Stevens, whom you may or
may not have met worked on measuring low pressure of UF6 on flow measurements,
etc. He is now in the chemistry section at Argonne, and has done a lot of
interesting things there. He was one of our undergraduates. He never pursued
graduate work, although he was as good as any of our graduate students. He
finally ended up at Argonne, in a very responsible job and was very good. At
Kellex he worked on all these crazy things.
GRAYSON: The activity associated with that plant represented a consortium of
04:32:00different large companies, General Electric, Kellex, etc.?
NIER: DuPont, Union Carbide, and many instrument companies helped.
GRAYSON: Westinghouse was probably involved as well. You alluded to the fact
that in dealing with different companies you ran into different problems. Were
some of these companies jealous of the information that they had?
NIER: I don't think so. I think that everybody worked together. They weren't in
competition on particular things. They had different assignments. For example,
we dealt with the people who made hydraulic instruments. Pneumatic
instrumentation is a tremendous field. They'd been using unusual feedback
devices before the electronic people had discovered some feedback. You know, it
was amazing, the interesting pressure gauges and stuff these guys had developed.
What is it? I've forgotten the name of the company . . . someplace in New York
04:33:00State. And I was amazed to learn about feedback schemes they had: flow meters,
precision flow meters, that they knew about long before people applied feeback
to electronics. So, there was a lot of interesting things. We dealt with them
because we had a lot of pneumatic instruments that we worked with. So, we
interacted with a lot of different groups. GE had the prime contract for the
electrical instruments for the plant, so that's who we dealt with there. The
DuPont people were concerned with some of the plastic, the flourocarbons and
such. It was all different groups.
GRAYSON: Yes. You mentioned teflon. I didn't realize that Teflon was used in
this plant, or developed for it.
NIER: Well, Kel-F came out of it. It was called Kel-F because Kellex had
something to do with it. And I don't know who they worked with. With DuPont, I suppose.
GRAYSON: Well, DuPont is definitely the flourinated carbon company.
NIER: Yes, that's right.
04:34:00GRAYSON: I'd just assumed that teflon had not come about until somewhat later in time.
NIER: Well, maybe the thing you think of is teflon, but there were these
compounds that were fore-runners of that, that were being used. I think that the
flourocarbon business got a real boost as a result of the Manhattan Project, and
the need to work with corrosive halogens.
GRAYSON: Because it represented a material that was inert to the corrosive environment.
NIER: That's right.
GRAYSON: And then, of course, for the refrigeration side.
NIER: You had C8F16, and various compounds of that kind.
GRAYSON: How come Kellex became involved in the naming of Kel-F Was that just
because the work was done in conjunction with Kellex?
NIER: They had something to do with the development. I don't know for sure.
04:35:00GRAYSON: And so, that kind of got put all together. [beeper beeping] This whole
thing says that leak detection started--the idea of a helium leak
detector--really started in this period. You were very much the father of it.
NIER: Initially, we were the only ones who had leak detectors. What happened
was, hundreds of the instruments were distributed among the many vendors of
components for the plant. Their existence was supposed to be real secret, but so
many people knew about it, it was no longer secret. A lot of the other people
got into the act. For instance, the Consolidated [Engineering Corporation]
people in Pasadena--Consolidated Electrodynamics, or whatever they call
themselves--at the end of the war, started selling leak detectors. GE tried to
04:36:00keep on, after the war, selling them. But neither they nor the Consolidated
people had the knowhow or provided the service necessary to employ them. And
this led to a couple of guys, who worked for us at Kellex, a guy by the name of
Al Nerken, N-E-R-K-E-N to be exact, and Frank Raible, R-A-I-B-L-E, starting a
little company, called Veeco. They sold leak detectors and told people how to
use them. It became a very successful company.
GRAYSON: I understand that the University of Minnesota owns or holds the patent
NIER: We had the patent on them, but it was later shown it wasn't worth fighting
for. We got royalties for a number of years.
GRAYSON: Oh, you did?
GRAYSON: You actually did get royalties?
NIER: From both Veeco and Consolidated. But then they decided they didn't need
to pay us anymore, because it could be established that somebody may have used
04:37:00the principle sometime before. At first it was simpler to pay the royalty . . .
a kind of blackmail in a way. It's a fuzzy-wuzzy area. And, rather than cause
trouble, they paid us five percent, or whatever it was. I got a fourth of it, I
think, from the University. I got a couple tens of thousands of dollars out of
it. And the University got the rest.
GRAYSON: Do you have a copy of that patent anywhere?
NIER: Oh boy. [laughter] Maybe.
GRAYSON: [laughter] Maybe.
NIER: I must have, but I don't have it right here.
GRAYSON: That would be an interesting document. I'm sure we could dig up a copy.
NIER: Yes. But that was one of the things that came out of it. And that was
about the only thing that we really got a patent on. The problem was, once we
got mixed up with the government, then we no longer had any patent rights. But
see, we'd been using the principal well before. But the first actual
04:38:00instruments, the ones with wheels on them and so on, were built as part of the
government work. As I say, we got a patent, obviously, we got the patent. But it
doesn't do you very much good if people really start to contest it.
GRAYSON: Yes. Well, then it becomes a problem with the legal beagles to fight out.
NIER: Yes, it really is. A patent gives you a license to sue somebody.
GRAYSON: Right. Now, I missed that point about whether or not you trained people
to run each station where Line Recorders were located.
NIER: Yes. We had people located at each station who knew enough to operate the
instruments as "black boxes". Then you had some very good people in the control
room. In particular, I remember well one very good young chemical engineer, who
was very much on the ball. He was one of the people on the shift. The plant
04:39:00operated twenty-four hours a day, you understand. You had crews on shifts. He
was very much on top of the situation. He was very good. We had one incident
that isn't in the textbooks where the whole plant was shut down one night in the
spring of 1945 through an error. What happened was, that at some important
place, something went wrong. A bellows joint or seal broke. A lot of the plant
was protected in that you had jackets containing dry nitrogen over practically
everything in the plant. But anyhow, something went wrong, and a big leak
04:40:00developed, about halfway through the plant. Well, the instruments in the central
control room showed you exactly where it happened. It was just a textbook case.
It was the kind of thing you would publish in a textbook to show how the
instrument monitoring system worked. And this poor young chemical engineer,
screamed bloody murder, telling the powers-that-be "to isolate section
such-and-such, this is where the problem is!"
But the people, the old-fashioned engineers who had the ultimate authority
thought they knew better how to run plants; they didn't believe him. Their idea
was, the way you tell when something goes wrong, was you look at the ammeters
that were in the lines that drive the pumps . . . and if you change the
molecular weight of the gas that you're pumping in a centrifugal pump, the load
changes on the pump. So, you look at the ammeters and measure the sensitivity of
this. Well, the problem never showed up well enough on the ammeters. The result,
04:41:00was the whole plant filled up with air and nitrogen. The whole plant! The spring
of 1945. By coincidence, Al Baker, the project manager for Kellex, came to town
that morning on the train, and was confronted with the situation. Now, I wasn't
in on the details of these operating problems at the plant. I never lived down
there. Anyhow, I was just in and out, but I happened to be there too when the
accident occurred. [phone ringing]
NIER: I'll take it. Excuse me.
NIER: Al Baker immediately got to the bottom of the problem and the negligence
of the Carbide people who operated the plant. And remember, he was a great fan
of the spectrometers. The strip charts off of the recorders showed exactly what
had happened. Well, I don't know what happened to those in authority. I don't
think any heads rolled, but some were certainly bashed in. After that, the young
04:42:00chemical engineer had a lot more say in how the plant was run. That was one of
the things that came out of it. Just that one incident showed why you had to
have a sophisticated analysis system.
GRAYSON: Well, the whole idea of instrumenting the plant . . .
NIER: Yes . . .
GRAYSON: . . . with the mass spectrometers was . . .
NIER: . . . was just this very reason.
GRAYSON: . . . was just for that purpose.
NIER: But you see, it was a whole new technology. Keep in mind, this all
happened so fast.
GRAYSON: I know, yes.
NIER: And they had all of these old engineers who had been very competent in
reading ammeters and the like. But their idea of the way you monitor something
was a little out of date. It was a perfectly good way to do things at one time,
but it wasn't under those conditions. And they'd never worked with such
corrosive stuff before. Luckily, the plant was not damaged, so it resumed
production in a few days. That was in spring of 1945, as the war was nearing an
end, and they wanted U-235 enriched, and here the plant was shut down. So, it
was shut down for a number of days. But luckily, what happens when something
like that occurs . . . you only lose the production during the time it is down.
04:43:00You don't have to build up the concentration gradient in the plant, as you would
if you started from scratch. This is like any fractionating system. If you just
shut it off, everything picks up where you left off. Within a few days, they had
the plant more or less back again to where it was, and luckily, no permanent
damage was done. But that was a very good example, and you won't find this in
the textbooks. [laughter]
GRAYSON: Well, that's what we're here for. As you mentioned, a lot happened in a
short period of time. Something that occurred to me in looking at this . . .
04:44:00from 1940 forward, a tremendous amount of work had to be done. From the point
where it was known that you had to enrich U-235 until the time when all of this
was actually happening. I know you're talking about five years later. When did
it really go on line, initially?
NIER: Well, the electromagnetic plant was running ahead of any of these others.
That was already producing stuff in 1944. And that started out with normal
uranium, so anything you could do to enrich the starting material helped. If you
started with double, it was like doubling the size of that plant in the output,
because you started at that much of a higher level. So, I'm sure what they were
doing was feeding stuff into that plant very early.
GRAYSON: Sort of, piggy-backing between the two plants.
04:45:00NIER: Piggy-backing . . . also they had the liquid thermal diffusion plant,
which Phil Abelson had been involved in. It was producing material also. Not
terribly enriched, but nevertheless of help. I don't remember how enriched the
material from this plant got.
[END OF AUDIO, FILE 2.4]
GRAYSON: You were speaking of the thermal diffusion work of Abelson's?
NIER: Yes, I'm sure some of that material went in as feed for the
electromagnetic plant, which was called Y-12. That was the code name for it.
Also, our gaseous diffusion plant was feeding material, I'm sure. You see, when
they got this plant started, they started bit by bit. It wasn't really running
04:46:00full-blast until maybe mid-summer of 1945 or so. Perhaps even as early as late
spring. But they certainly had sections running, so they had doubly-enriched or
triply or quadruply-enriched stuff, months before. The output of this plant was
so huge when it got going, that they could divert large amounts to the
electromagnetic plant, and it would never be missed, in effect. This was
actually the situation. So, I'm sure a lot of that went into the electromagnetic
plant as feed. I don't know the details on that. I'm sure it's no longer a
secret. I was not privy to that kind of information, and never bothered to find out.
GRAYSON: As an interesting aside, this morning on the news, I just heard that
[Soviet General Secretary] Mikhail Gorbachev has unilaterally decided to cease
production of uranium.
NIER: Really, I didn't see that. Oh, my gosh!
04:47:00GRAYSON: He announced it in England, while visiting with the Prime Minister
[Margaret Thatcher] and the Queen [Elizabeth II] there.
NIER: Oh boy, how interesting!
GRAYSON: Yes. Well, maybe, we've just completed the cycle in the production of
NIER: Well, they've got so damn much of this stuff that it's just awful.
GRAYSON: Yes, that is most definitely true. So, you stayed with this Kellex
activity for a number of years . . . about three, I guess, was it?
NIER: Well, two. A little over two. My job was really done with Kellex in about
September. The war had ended. It officially ended about Labor Day.
GRAYSON: That was 1945?
NIER: My job was done. Anything more was too late to affect the war, you see.
So, I didn't see any reason for hanging around. People were giving up new
efforts. The Kellex engineering effort was shutting down and the plant was
04:48:00turned over to Carbide. Kellex built it, and Carbide was the operator. For
years, they had the contract for running it. We worked with the Carbide people,
in training them, in helping them, and so on; there was a lot of going back and
forth. By now the plant was entirely in their hands. So, I got out in October,
1945. A lot of my guys had already left. The whole operation at the Nash
Building was closing down. Everybody was going home, or doing something else.
There were lots of jobs around, so people were scrambling everywhere. And I
decided to come back to the University at that point, and came back here in the
middle of October 1945.
GRAYSON: Okay. Before we start on that, I'd like to just explore one idea. In
the beginning, when you first were faced with doing the analyses for this plant,
you were looking, casting about for some other way to do it, and kind of got put
04:49:00back on the path of mass spectrometry. But, in retrospect, could you say that
without mass spectrometry, without that technology that you had provided in your
group, that this plant maybe would have been a lot slower coming on stream.
NIER: Well, I think so. The helium leak detector was certainly spectacular. This
was orders of magnitude better than other methods for finding leaks. And they
had really good guys who applied the technique. My friend, Bob Jacobs, was in
charge of that, and, as I said earlier, some of the key people he had were Al
Nerken and Frank Raible, who ran the vacuum testing, and of course, trained a
lot of people who did a lot of the maintenance and testing. The helium leak
04:50:00detector saved many months, if not years, in getting the plant running. It turns
out, the line recorder, which was the big thing we worked on after I went to
Kellex, you probably could have gotten by without. You'd have had more incidents
like the one that I talked about. But, it was not a life-and-death matter. And
of course, the uranium isotope analysis instruments, which we worked on earlier
. . . without them, you wouldn't have known how any of the enrichment plants
were behaving. And you had to be able to do this properly. You could have made
rough measurements with alpha-particle detectors. The people at Berkeley were
doing some of that. You could do rough measurements that way, but you could not
do precise ones. The spectrometers really were important in that.
GRAYSON: So, between the helium leak detector technology and the ability to get
precise measurements . . .
04:51:00NIER: Of the uranium. I think that there was no other way to do it decently.
GRAYSON: It would have been just impossible to do, almost. You're really talking
about a significant contribution to that whole effort. And, had you elected to
go to Berkeley?
NIER: Someplace else?
GRAYSON: I guess this stuff would've got done eventually.
NIER: Well, it isn't likely it would have been done very well. You know,
nobody's indispensable, but there wasn't anybody else in the world who had the
experience I had. It was certainly the right place to be, for me to be, because
I had the background. Keep in mind, there weren't many mass spectrometers in the
world at that time. We were the only people who could even make measurements of
these kinds. True, there were people coming along. Consolidated was
manufacturing instruments, 180 degree instruments, which were used in the oil
industry. They sold them to big oil companies, where they could do routine
04:52:00analyses of hydrocarbon mixtures in their plants in one percent of the time
needed by the old methods of analysis. So, there were spectrometers available.
But, the companies that made them . . . you were supposed to use them in a
certain way. It's just like when you buy an instrument now. Unless you use it
the way it's made for, it isn't too useful. There weren't many people who had
the flexibility that we had, in that if a new problem came up, I said, "Sure,
we'll go home and try it." and next week, we'd probably have an answer. And
that's the way we lived during that time. There certainly were many clever
people who could have done the same thing, but they didn't have the mass
spectrometry experience. That was really the unique thing that we had, that
other people didn't have, was the combination of experience and ability to
develop new instrumentation.
GRAYSON: Okay, I think that's the important point that I wanted to draw out
04:53:00here. This fundamental contribution, which may get overlooked, or may not even
be considered to be important by a whole number of other people who are not
familiar with this activity, should be brought out. Because of the problem with
leaks, and the insensitivity of the leak detection methods of the time and the
insensitivity of other methods for measuring isotopes to determine how well the
plant was performing . . . these were fundamental problems that needed a
solution for the plant to be successful.
NIER: At that time, it was important. Once you get the plant running, fine, you
don't need these sophisticated techniques. To get it started, you need to know
what you have. There's really no substitute. And certainly, the uranium mass
spectrometers were very important in monitoring the electromagnetic plant as
well as the diffusion plant. In the electromagnetic separation plant they used a
large number of 180 degree separators. It was a batch process so a large number
04:54:00of analyses were required. A friend of mine, Gus Cameron, Angus Cameron, was in
charge of these analyses during the war. He was originally at employee of
Eastman Kodak, and was transferred to Tennessee Eastman, which ran the Y-12
facility for the government during the war. He did a superb job. He learned
about mass spectrometry at Columbia. I met him there. He learned how to run them
from Inghram, who had two of our machines. Soon he was buying dozens of them for
the electromagnetic plant in Oak Ridge. You had banks of instruments with people
running samples twenty-four hours a day. I think they had twelve instruments in
continuous operation. Sometimes the electro-magnetic separation units didn't
work right, and you didn't want to mix the product from a malfunctioning unit
04:55:00with another one that was working right. You had all kinds of problems like
that. So, the analyses were very important. There is no getting around it.
GRAYSON: Speaking of Columbia at that time, there was a fellow by the name of
Vince [Vincent G.] Saltamach? Do you know Vince?
GRAYSON: Could you just give us a little insight as to what he was doing at that time?
NIER: I don't know. I've only met him since. He worked for Ivan Taylor, who was
a very good friend of mine. Ivan, by the way, helped out during the war. He was
at the Bureau of Standards. He was in our Chemistry department and left
Minnesota and went to work at the Bureau of Standards during the war. When we
had problems with developing the line recorder, he worked on the problem of
taking UF6 out before it got into the spectrometer. He was a very good chemist
and he guided some of these young people that I had. He was a most generous
person with his time. He moved to New York to help us out; a wonderful guy and
04:56:00one of my very dear friends.
GRAYSON: Ney and Inghram came through here. What became of them? I did get a
chance to look at some of the interview that had been done in 1976. I think you
referred to these gentlemen as being very young, responsible people.
NIER: Yes, they were good. [laughter]
GRAYSON: Their responsibilities far outweighed their age. What exactly did they do?
NIER: Well, Inghram was a graduate student at Chicago whose education was
interrupted by the war. From 1942 to 1945 he was an employee of Columbia. He was
in another building in New York, but I saw him regularly. Following the war, he
went back to graduate school and finished up at Chicago, got on the faculty
04:57:00there, and retired last year. A very distinguished person. When the centrifuging
business came to an end at Virginia, Ney had more time to pursue graduate work.
He did that during this period and got his Ph.D. at Virginia. He was added to
the staff there and we lured him away in about 1947. He's been on our faculty
ever since. He's now nearing retirement age. And is a very distinguished--the
most distinguished person in our department actually. Not everybody agrees on
that, but I think I know better.
GRAYSON: So, the responsibility of these young men was devoted to making sure
that the analyses were done properly.
NIER: That's correct; and in the development of the instruments. They played an
important part in that.
04:58:00GRAYSON: This problem is important because it was the period when they were
still sorting out which of these separation techniques was going to be pursued.
They had to provide accurate results.
NIER: That's right. We were the key ones. The samples came to us. And of course,
after the summer of 1942, there were instruments at Columbia and Virginia, but
until then, the only instruments were here.
GRAYSON: So, with the instruments at the other locations, they were able to do
NIER: That's right.
GRAYSON: After the war ended, you returned to this part of the country. As I
recalled from the tape that I viewed, there was a question about your going to
Wisconsin at one time. And you had, kind of, gotten talked out of it by Tate.
His argument essentially was that he knew what you didn't, perhaps . . . that
you were going to get sucked into the war effort.
04:59:00NIER: Yes, well, I was at Berkeley during the last two weeks of November 1941
and 4 December, I came back to Minnesota. Now, I always had a terrible tendency
to get airsick. Earlier in the Fall, I'd been invited to Wisconsin to give a
talk and meet people--the standard visit. You invite people to come and see
whether or not you want to offer them a job. The connections there were kind of
interesting too. This is related in part to the biology activity. I had provided
heavy carbon to a man by the name of Harland [G.] Wood, who is now a biochemist
of some note. At the time, he was a post-doc at Iowa State [University], working
in the bacteriology department. We had provided him with heavy carbon and did
05:00:00the isotope analysis. He demonstrated a very fundamental thing about how certain
bacteria can incorporate inorganic carbon in certain places. It was apparently a
real breakthrough. This was known in the biological community. Wisconsin has
always had good biochemists, and I think the dean of the Wisconsin Graduate
school, Dean [Edwin Broun] Fred, was a bacteriologist by training if I am not mistaken.
The physics people knew me and what I had been doing. So, when was an opening in
the physics department everybody there thought it would be a good idea for me to
come down there because it would help their biology program as well as physics.
In any event I came back from Berkeley on 4 December, sick as a dog. I got
05:01:00airsick on the trip. It was a DC-3 that went up and down . . . we had stormy
weather. I remember there was a guy on the flight who didn't have a belt on as
we came near Salt Lake City [Utah] and he got thrown against the ceiling, and
had to be bandaged up. Oh God, I was sick. I came home, and my wife was having
the inside of the house painted! Well, it turns out that the president of the
University of Wisconsin was visiting on the campus and he'd said that he wanted
to talk to me. I called when I got in, and told him about my flight and that if
I had a chance to rest for a little while perhaps we could talk. I hadn't eaten
anything for twenty-four hours which didn't help any.
So, I slept for about an hour and ate a bowl of soup. I felt fine, and then I
went and interviewed him. Out of that came the offer of a job. But Tate was then
05:02:00head of division six of the National Defense Research Committee which was in
charge of anti-submarine warfare. He commuted regularly between New York and
Minneapolis. See, he was a wheel in science in this country. He was also dean of
the college that we were in, so he was wearing several hats. It was a decisive
thing . . . should I go to Wisconsin which offered me a very attractive job.
They had lots of money from the [Wisconsin] Alumni Research Foundation or should
I stay here. I really didn't want to leave here, although, Madison [Wisconsin]
was not as far as the East and I could still handle my parents' problems.
Also, they had certainly treated me very well here. So I think the clinching
thing . . . in those days people had ethics on this job business and if you
05:03:00accepted a job somewhere, and they held it open for you for a long time, you
were on the spot. You were supposed to honor the commitment. And Tate was really
a very proper, sort of, person, and he emphasized this. This was on or about 1
January 1942--after Pearl Harbor Day. He said, "Look, you're not going to be
doing anything normal for the next few years." It wasn't clear what I was going
to do next, but he didn't think I was going to be around here during that time.
"If you accept a job to go some place now, five years from now you may not want
to go there." He knew the war situation, he knew everything that was going on,
he was on top of the whole thing from his involvement with the anti-submarine
program. "If you accept a job someplace else now, you will be obligated to take
05:04:00it afterward, but if you stay here, there are no obligations." And I believed him.
GRAYSON: Well, it was a good argument. Shortly after that you ended up leaving
here just as he suspected.
NIER: And I came back, picked up where I left off. I was welcomed back and
everything. Now there were a lot of people who accepted jobs someplace else
during the war and never took them. I can't say that I was solely motivated by
the ethical argument but it certainly was a part, and when you add it together
with everything else, it was a convincing argument. Tate was so sincere and so
honest and so decent. When he said something, you listened. [laughter]
GRAYSON: Like when he said they were doing this research at GE and didn't
NIER: Yes. [laughter]
GRAYSON: So it was 1945 that you came back to Minnesota.
NIER: I came back in the Fall of 1945.
GRAYSON: And once again you had to start building instruments.
NIER: Yes, and we were in worse shape than we were before. It turned out most
05:05:00other people had contracts with the Atomic Energy Commission and got the
instruments that I had built. And we didn't have such a contract. So, we didn't
have any instruments. We really had to start from scratch, which was not all
bad. But it would have been useful to have some of the components. We picked up
where we left off, and I was lucky. I got some money from the Graduate school
and I got some money from the Research Corporation which doled out small amounts
for people starting out. They were very sympathetic to youngish people. I was
still young then! But I had some money to get started and had several very good
graduate students at that time. We built an instrument very similar to the
uranium instrument. That's when [L. Thomas] Tom Aldrich was a graduate student
looking for things to do and we made the first accurate measurements of the
05:06:00He-3/He-4 ratio. (Figure 29) It had been measured at Berkeley with the cyclotron
by [Luis] Alvarez and [Robert] Cornog before the war, but they were off by a
factor of ten on the relative amounts.
GRAYSON: What was the interest in that ratio.
NIER: Well, it was interesting for many reasons. For instance, we showed it
varied a great deal in nature. We were able to do that. They had found at
Berkeley also that the atmospheric He-3 was about ten times what it was in oil
wells. There was this kind of geophysical interest in the ratio. When you have
anything that varies that much, it certainly is interesting. Tom Aldrich worked
on problems such as that. Initially it was kind of hard to find problems to work
on. We didn't have the "in" that people who'd stayed in science had. Inghram had
a tremendous advantage because he went back to Chicago which had connections
05:07:00with the Argonne lab. He had access to instruments we had built and was able to
start right out. He was still a graduate student, but they had a lot better
instrumentation than we had. We then looked for other problems, and the question
of the radioactivity of potassium was looked into. It had been shown in the
meantime that potassium-40 was the radioactive one. I forgot who, but he used a
mass spectrometer to collect the ions with a target at potassium-40 and showed
that that was the radioactive isotope. Enough was known about nuclear physics
that it decayed into argon and calcium. So, the question was, is this really so?
If you have a potassium mineral, does it really have argon in it. So, we worked
05:08:00on that and Tom showed, well sure, if you have potassium in the mineral, you
find excess argon-40 in it. And that set the stage for the potassium/argon
method of geological dating. We never pursued it beyond that.
GRAYSON: There is an Aldrich chemical house. Is there any relationship between
NIER: When he finished here, he went to the physics department at the University
of Missouri. Later he got a job at the Department of Terrestrial Magnetism at
the Carnegie Foundation in Washington. Merrill [A.] Tuve, the Director, was a
very imaginative guy, interested in all kinds of things especially geophysics.
He went there working on geophysical problems. He retired a year or two ago.
05:09:00GRAYSON: There is a period then when you went back to measuring isotope
abundances. It seems that there was a switch-over to atomic mass measurement
where you are looking at the precise mass. Why did you suddenly make this change?
NIER: The time seemed right for it. We knew how to make electrical measurements.
After all, we had a lot of experience. We had built more spectrometers than all
the people in the world combined had ever built. All the mass measurements at
that time were being done with photographic plates as detectors. They had
perfected this very highly--it was beautiful work.
GRAYSON: This was the work that was still a derivative of Bainbridge's work?
NIER: Well, Aston, originally. And then Dempster had an instrument, and later
Bainbridge and [E. B.] Jordan had instruments for measuring masses. So, these
05:10:00were some of the mass measurements going on at the time. But somehow or another,
the business of putting a photographic plate in a vacuum, adjusting the machine,
taking the plate out to see if you were right, and developing the plate,
measuring it with a comparator to see where the peaks were and so on; didn't
appeal to me! Of course the interest in nuclear physics, and the binding energy
of nuclei, the whole question of atomic energy after World War II made it seem
like mass determination was a logical thing for us to work on. We decided to go
into the precision mass measurement as a part of nuclear physics development of
1945, 1946, 1947. I said, "Gee, there's got to be a better way to do this." The
thing that occurred to me was that the people with photographic plates had to
05:11:00focus ions along a whole focal plane to be useful. But if you had an electrical
detection instrument, then you only had to focus at one place. You didn't have
to make the compromises the plate people had to make. So, it occurred to me that
you ought to be able to soup this business up somehow, taking advantage of the
fact that you only had to collect ions at one place.
I had a graduate student by the name of Edgar Johnson, who was the most
wonderful, handy guy in manipulating mathematical expressions. He never made a
mistake. God, I couldn't divide one fraction by another fraction without making
a mistake. This guy never made a mistake. He was looking for a Master's thesis
problem, I said, "Why don't you investigate how we could put together a
double-focusing arrangement so we could have energy focusing--velocity
05:12:00focusing--and maybe higher order angle focusing. There ought to be a way to get
higher order angle focusing if you only had to focus the ions at one place. So
he went to work on this. And within six months or so he came up with all the
equations. Remember, this was before the days of computers, even hand
calculators. He came up with the equations which demonstrated indeed there was a
whole family of geometries that would do this job and do it well.
GRAYSON: Okay. So, he was able to divine that there were a number of different
geometries that could be used.
NIER: Yes, well, an infinite number if you wanted to change one degree at a
time. So, we went ahead and built an instrument according to his computation. He
never participated in that part. He didn't want to go on. He got a Masters
degree and he really didn't want to go on in this sort of thing. I got him a job
with Harold Urey at Chicago. Urey by that time was at Chicago. So, he worked
05:13:00around the lab there. Urey was always looking for young people to work in the
lab as technicians. He must have been bored running mass spectrometers, I can
understand this. Johnson wasn't terribly interested in advanced work, which was
a tragedy because the guy was bright.
GRAYSON: Its interesting because if you think about the Nier-Johnson geometry
and this was work done on a Master's thesis. Probably that affected mass
spectrometry more than many, many, many Ph.D. dissertations. It's just a curious
fact of life that it worked out that way.
NIER: That's correct. That's correct.
GRAYSON: When it came time to design the instrument . . .
NIER: Well, by that time, he had all the equations ready.
GRAYSON: But the equations were general in form and you would pick the, say for
example the magnetic sector radius . . .
NIER: Well, I had a feeling that we ought to stick with the 60 degree magnets of
which we had some on hand.
05:14:00NIER: And instead of the screwy 127 degree electric analyzers where you had to
have the exit slit in the field and come out at some other angle we employed a
90 degree analyzer. Johnson worked out the second-order angle aberration for the
general sector case. That was a unique contribution which nobody had ever made
before. 90 degrees seemed like a good electrostatic analyzer size. The machine
shop could build something that was a fourth of a circle. So how do you do it
with 90 degrees electric and 60 degrees magnetic?
GRAYSON: So, basically, he had worked out the general case. So, you applied this
to your particular angles.
NIER: And he contributed, obviously, to the decision. We came up with an
asymmetric geometry because the angular aberrations were not quite equal in the
two. But if you had the electric sector analyzer have a different magnification
than the magnetic sector analyzer, one could cancel out the angular aberrations.
05:15:00So, you deliberately put aberration in to cancel out another aberration. Well,
its just like optical lenses with color compensation. Its the same principle. So
we came up with that, and that would have been in about 1949. Johnson had left
by that time. Later, he came back to Minnesota Mining and worked on a color
printer or some other similar devices. Spent his career there. He's retired now
and has moved away. I don't know what's happened to him. I saw him a few times;
we were very good friends over the years. But he just didn't want any part of
GRAYSON: That's interesting.
NIER: Following the development of a practical instrument, we saw the
possibility of doing mass work and we started a systematic program. This would
have been about 1949. I had a series of students who worked in this area.
GRAYSON: This was using the Johnson geometry instrument. So, it was a high
05:16:00NIER: Yes. With the second-order angle focusing we could employ a bigger angle
than other people were able to use before. One other thing we put into this
original machine; we used a second mass spectrometer tube as a monitor. This is
going back to the magnetron at the end of the solenoid concept. What we had was
a sector magnet that was big enough that you had a second mass spectrometer tube
next to the main one. The second one was just single focusing. You needed
double-focusing when you worked with fragment ions because if you were dealing
with fragments, you might have kinetic energy ions. You couldn't compare a
fragment with the molecular ion and obtain a correct mass measurement. In the
monitor mass spectrometer, you had a split collector. If the beam wandered one
05:17:00way or the other, it sent a signal which told the high voltage to correct itself
to keep it centered. Since both instruments used a common ion accelerating
supply, the trajectories in the double-focusing mass measuring instrument were stabilized.
[END OF AUDIO, FILE 2.5]
GRAYSON: We were talking about a method of regulating the magnetic field in the
NIER: The original instruments had a second mass spectrometer tube, which acted
as a standard or stabilizer. What was used as a reference was the constancy of
the mass that you chose. We used inert gases and so on, which were nice. And you
didn't have to have the reference any particular mass, because you could adjust
the relative voltages for the two mass spectrometers, so it was easy to find a
mass that was appropriate. This arrangement was used in our early measurements,
05:18:00and we used a strip-chart recorder, too. I've forgotten who made the recorder.
It had a pen that moved in an arc so that instead of vertical lines across the
paper, there were arcs. The graph paper, the strip chart, had curved lines on
it. That's the way it was, because these were relatively high-speed recorders
that could do the job. We took our measurements right off the paper. You had a
pair of peaks at different mass, and you measured from the half-height on the
left-side, here, to the half-height here. And then you went to the other side,
took the averages of the two, and said, "That must be the center." This gave you
the mass difference. The measurement of mass to was reduced to a measurement of
resistance, because you had changed the accelerating voltage to scan the
spectra. So, you had to have precision resistors.
We went to the Bureau of Standards to find out how to get precision resistors.
Well, of course, one could go to Leeds & Northrup or a similar company and buy
05:19:00cumbersome things in boxes. This was just as computers were coming in. There was
a little company in a loft in New York, near the Medical Center, up on 168th
Street. They were upstairs in a warehouse building, and they made precision
resistors there for computers. They cost a fraction of what Leeds & Northrup's
charged. What's more, they had special temperature compensators. It was really a
small company, but very imaginative. I went there, and talked to the owner of
the company. He's one of those enterprising guys who started the business,
selling resistors to computer manufacturers. Not that Leeds & Northrup wouldn't
have done a good job, but this guy did it cheaper and much more flexible. He
05:20:00wasn't yet in the business where the resistors had to be in special boxes, and
stuff like that. You'd just buy resistors from him. So we bought all of our
resistors from him. Plus, we had some other precision resistors here. So, we
were able to reduce the measurement of mass to a measurement of resistance. So,
, for the mass measurement.
NIER: And then I had a very fortunate thing happen. A guy by the name of--of all
the things--Tom [L.] Collins came as a post-doc. He came from the University of
British Columbia. A very, very clever guy. He later was on our faculty for a
while. He went on to a research position at Harvard after he left here. He ended
up, I think, at the National Accelerator Lab as a top electronics man, if I'm
not mistaken. Just awfully good . . . very, very clever. And, during that
period, we worked on a scheme for improving the inverse feedback system we were
05:21:00employing. The problem with inverse feedback is, while it's wonderful, it's not
perfect, because it doesn't quite go all the way. You see, you miss the mark by
1 over g, if g is the gain. You don't quite get there, and that wasn't good
enough for our measurements, because if g changed, which it is apt to do, your
delta m over m equals delta r over r with the little bugger factor . . . the
bugger factor would change a little bit. This wasn't quite good enough for our
measurements. So, I think it was Collins who came up with the idea: "Why don't
we have an infinite gain arrangement?" Then the g goes to infinity, and the
bugger factor doesn't come in. So, we used the mechanism out of a Brown strip
chart recorder. These were electronic recorders which had very high gain
amplifiers in them.
GRAYSON: This would have been 19 . . . ?
NIER: 1952 or 1953.
GRAYSON: 1950s, okay. We're getting into the 1950s.
05:22:00NIER: The 1950s now. Maybe even a little later than that . . . in the early
1950s. In addition to the normal inverse feedback circuitry we used the Brown
recorder mechanism to do the final balancing. It was something that you relied
on to remove the error signal remaining after the normal feedback circuit had
done all it could. So, then we really had delta m over m equal to delta r over
r. We proceeded to make measurements for a period of time that way, and that's
the way it went. In the meantime, other people also came along. Another Johnson,
Walter Johnson, who was a student of mine, who is now on our faculty came back
05:23:00from GE where he went when he finished up here. He worked on other improvements.
And there were other graduate students at the time that I had, a whole series of
them: a guy by the name of Tom [T.] Scolman, Karl [S.] Quisenberry, Clayton [F.]
Giese, Jay [L.] Benson, and others who were very good at all of this stuff.
In the midst of all this, the multi-channel analyzer became available. You could
store a bunch of signals, different things, all at once. We got one of those and
made use of it for accumulating data. Lincoln Smith, whose name may or may not
mean something to you and mass spectrometry, was interested in the mass business
right after the war, also. He had been a graduate student of Bleakney's at
Princeton in the 1930s, at the same time I was a graduate student. He'd gone to
05:24:00[University of] Michigan, where he taught for a while, and then came back to
Princeton. He was independently wealthy. He was not on the faculty at Princeton
but he worked in the Forrestal lab, I think it was called. It was a research lab
set on the Princeton campus. He came up with some ideas for some radio frequency
mass spectrometers, with very complicated schemes for sending ions around
torturous paths. A very clever sort of thing, but terribly cumbersome. He had
also been at Brookhaven [National Laboratory] for a while, I guess, and come up
with schemes whereby you'd take your mass signal and have it on an oscilloscope
screen. You'd have a signal for one peak and one for the other in a mass doublet
and would superimpose them by switching techniques; reverse the sign of one of
the peaks to get a null signal. He was really the first one to use that scheme;
05:25:00the time had come for us to follow suit. So, we adopted this same thing. You had
one signal, and you took the other one, and turned it upside down, and bumped
them against each other. If they were exactly matched, you didn't see anything.
And if they were a little bit unmatched, you got a funny little wiggle, because
it was on one side and it would go like this, and on the other side, it would go
like that. You got very skillful at it if your eyes would stand it. Then, that
was the way that masses were measured afterwards. You still had the resistance
boxes and all of the tricks with this, but you now had a visual scheme, where
you looked at the signal on an oscilloscope screen.
GRAYSON: This was the concept of peak-matching?
NIER: Yes, that's right. Now, the Enhancetron entered in, too, because then you
could store the data. The Enhancetron was the name of the multi-channel
05:26:00analyzer. You had the multi-channel analyzer take data for you. I was out of it
by that time, so Walter Johnson carried on. He had some very good students. If
you look at the table of accepted precision masses, the ones that are in the
handbooks, you will find they were determined by our students.
GRAYSON: So most of all that work was in the 1950s to 1960s?
NIER: Our early work was done with an instrument having a 6 inch magnet. In the
early 1950s we built a larger instrument employing the two ton 180 degree magnet
bought for me in 1938. The poles were replaced by 60 degree sectors so we now
05:27:00had a radius of about 18 inches. That was used for a number of years, and they
did some very nice work on masses of a lot of elements; the rare-earths, for
example. As well as many elements throughout the table.
GRAYSON: So, you weren't an author on a lot of this work.
NIER: Not at all. I'd turned it over to Johnson.
NIER: He'd come back on the faculty, and he and his students carried on.
GRAYSON: Okay, so a great body of detailed information about the accurate masses
and a whole series of elements, was done with that equipment here, under Johnson.
NIER: Walter Johnson, not Edgar Johnson.
GRAYSON: Right, yes, Edgar forsook mass spectrometry, much to all of our
regrets. So, here you are getting out of mass spectrometry. What happened?
05:28:00NIER: Well, even before that . . . remember, I was chairman of the department in
GRAYSON: Okay, well, that's new. I didn't know about the chairmanship.
NIER: I taught classes. I was chairman from 1953 to 1965. Twelve years, and I
was acting chairman once before, I think it was thirteen years I was chairman of
the department, with a lot of headaches plus teaching classes. Now they relieve chairmen.
GRAYSON: You mean the chairman still had to teach?
NIER: I still had to teach, like everybody else.
GRAYSON: Did you teach the full load, or did they give you some consideration.
NIER: Well, there wasn't much difference. It was a little easier than other
people. I only taught a single five-credit course, instead of two three-credit I think.
GRAYSON: I see.
NIER: I finally got it down to a four-credit course, I think it was, for the
last couple of years. But I did that for quite a few years.
GRAYSON: Then, with your responsibilities in that regard, did you forsake your
NIER: No, I'm a little bit like a three-year-old that has a limited attention
05:29:00span. In 1954, on my first trip to Europe I went to Germany, and I became
acquainted with [Josef] Mattauch, we became very good friends. I visited
practically every year after that, until his death, I kept up with him.
GRAYSON: Do you have any pictures of him?
NIER: Oh yes.
GRAYSON: Would it be possible to get a copy or arrange to get some?
NIER: Maybe, if I can find it, you can arrange it somehow.
NIER: Yes, they were doing precision mass work, too. And they had various
instruments . . . after all, Mattauch-Herzog, etc.
NIER: So, we were competing with them on the mass work, but he was still hanging
on to the photographic business. They had built a super-duper big machine.
05:30:00[Heinrich] Hintenberger, who was his right-hand man, built an instrument which
was supposed to have perfect focusing, perfect to the second order. But it had
some other serious problems with it, so the machine never really worked.
GRAYSON: Now, is that the Hintenberger of Hintenberger and Koenig that did the
whole series of different things.
NIER: Yes. Hintenberger was really good.
GRAYSON: But anyway, the machine didn't really work, though.
NIER: Didn't work, and it never really measured masses. And they were out of it
then. So, we did most of the measurements. [Henry E.] Harry Duckworth--at
McMaster [University] originally, later he went to Winnipeg, the University of
Manitoba--did mass measurements as did Ogata in Japan. Was there anybody else
doing it? That was probably it. And those were about the only mass measurements
that were made. But you see, what was happening. The shell model of the nucleus
was established and by the end of the 1950s, mass measuring didn't look very
interesting. I'm sure you could get another decimal point, but there wasn't any
05:31:00real good reason to get another decimal point. If there'd been a tremendous
breakthrough in theory, or something, it would be worth getting another decimal
point, I guess it would have been worth pursuing. It was getting tough. We got
masses out to seven decimal points or thereabouts. But it was getting tough!
GRAYSON: Now, was this all based on a C-12.
GRAYSON: As opposed to . . . ?
GRAYSON: Were you involved in getting C-12 as the standard?
NIER: Yes, yes.
GRAYSON: Could you give us a little about how that came about?
NIER: Well, there's an article that came out in honor of Beynon's birthday. It
is a very good review article that Harry Duckworth and I
I have a reprint of that here. There was an
issue devoted to that. And we wrote the lead article in this, they put us at the
head of the list. Harry is so good at writing, so he wrote most of the article,
he corrected all of the things I wrote. [laughter] We communicated between here
and Winnipeg. He's retired now, he ended up the president of the University of
05:32:00Winnipeg. He'd always wanted to be president of a University. He was only
Vice-President of the University of Manitoba, but he became President at the
University of Winnipeg, which was a smaller, private school. But anyhow, Harry's
very, very good with writing, just marvelous at it. So, we wrote this together.
I was on the Atomic Weight Commission in the 1950s, late 1950s. The Atomic
Weight Commission still exists. They don't do much anymore, but they still
exist. And [Edward] Ed Wichers, who was head of the chemistry part of the Bureau
of Standards, a very, very good analytical chemist, was chairman of the
Commission. I was on it, they wanted to have a mass spectroscopist on it, and
05:33:00several Europeans . . . Mattauch was on, and some analytical chemists from
Europe. I think it was an Englishman and a Norwegian at the time--I've forgotten
the exact names, you can look back and see what they were. Anyhow, they were
groping around . . . and this would have been 1955 or 1956, that era . . .
groping with the problem. Actually, several problems. First you had the chemical
scale, with the mixture of oxygen as 16. The physical scale, with O-16 and then
the oxygen isotopes with varying abundance in nature. So your conversion factor
does funny things. So, how can you make this better? Well, the ordinary chemist
said "You just define a mixture and call it that, and let it go at that." But
Wichers was not satisfied with this. He said we ought to be able to do something
05:34:00better. "Can you find another standard?" Mattauch was interested, and said "It
ought to be carbon." Since masses of the elements were made using hydrocarbon
fragments for comparison, it made sense to use cargon as a standard rather than
oxygen. The matter wasn't really thought through until an international meeting
on isotope separation in Amsterdam [Netherlands] in April 1957. My family and I
were over there. We brought our American car over, and I had a leave for a
quarter plus the summer, so we would have spent five months. I went to the
meeting in Amsterdam. We had just arrived in time for it in April, and the
05:35:00Atomic Weight Commission was meeting in Paris [France] later that summer. And,
so I saw Mattauch there in Amsterdam. I saw him again in Mainz [Germany], where
he was the director of Max Planck Institut fuer Chemie, and of course, saw him
in Paris, later in the summer. I saw him three times that summer, and as I say,
we were very close friends. In Amsterdam, we were already talking about the mass
standard question, since we were on the Commission. It was the problem of what
do you do, and Wichers was interested in unifying the scale somehow. Various
people made the suggestion that you use flourine, which had only one isotope.
GRAYSON: Selecting a mono-isotopic element certainly has an attraction.
NIER: Fluorine is a poor choice since it is hard to refer to. There was a good
reason for choosing oxygen in the first place since it reacted with so many
05:36:00elements. The problem was, do the physicists give up their scale? They already
had O-16 equals 16. The chemists had the mixture, and so many atomic weights
were based on that. To drop the chemist's scale seemed impossible, from a
practical standpoint. So, we had to find some compromise, and this we did. As
the result of a conversation which I had with Mattauch--and this is really
so--in the bar of the American Hotel in Amsterdam one evening, I pointed out to
him "If you chose C-12 equals an even 12, the problem disappears". By
coincidence, the amount that C-12 isotope differed from an integer 12 on the
O-16 scale was just about the conversion factor between the physicists' and
05:37:00chemists' scale. So, all you needed to do is have everybody agree on C-12 equals
12. The only thing chemists had to do was to go to their lecture rooms, where
you had a chart, a periodic chart on the wall--either painted on the wall, as it
usually was in chemistry lecture rooms, or curtains--where it says oxygen equals
16, you just erase that part and write C-12 equals 12.00000. And the chemists
don't have to change a damn thing, because the change was so small that it
didn't effect any of their procedures that led to all of these combining weights
for molecules and so on, which had always been.
For the physicists, it wasn't so convenient. Duckworth and I tell the story in
05:38:00our paper. It's been told in other places, too. By coincidence, the mass
measurements, in mass spectrometry, were in a state of flux at the time. There
were two separate scales that had sprung up. There was the one done by the mass
spectroscopists, in terms of O-16 equals 16. And then there was the one the
nuclear physicists had built up based on reaction energies--knowing the energy
of alpha particles and beta particles as you went from one element to another.
They could build a whole chain of masses based on reaction energies. There was a
group at Caltech [California Institute of Technology], who were very active in
that. [William Alfred] Willy Fowler was one of them, and there was a young
fellow by the name of Ward Whaling, who was in this sort of thing, and they were
coming out with precision tables of masses, based on reaction energies. And they
didn't agree with the mass spectroscopic ones.
Here we are in 1956. We had a conference in Mainz, a mass spectroscopy
05:39:00conference in honor of Mattauch's sixtieth birthday. And this really came out,
because we had the nuclear physicists, who represented their view, and the mass
spectroscopists representing their view. It was clear, there was a problem. So,
this was all in a state of flux and neither scale was right. But measurements
were improving all of the time, and they were coming together. Mattauch had been
a Rockefeller fellow. He was an Austrian, you understand . . . he came from
Vienna [Austria]. But in the 1920s, he was, for a couple of years, at Caltech.
And he was really a Texan-American at heart. He was a real flamboyant-type guy,
just full of beans. And he knew all of the important people at Caltech from his
The Atomic Weight Commission met in Paris in August--I think it was 1957 at the
time of the IUPAC [International Union of Pure and Applied Chemistry] meeting
[Congress and General Assembly]. The possibility of adopting C-12 as a standard
came up at the meeting of the Commission. Mattauch, after all, was a wheel. He
was the director of one of the Max Planck Institut in Germany, so he was a wheel
05:40:00in Europe. And he knew people who were at the heart of the mass business at
Caltech. So he came on a missionary visit to Americas in the spring of 1958, and
talked to them about the problem, and they were amenable to something like this.
And so, between him and Harry Duckworth, who was kind of the Canadian big wheel
on this sort of stuff. He was great on this Commission business and always
represented Canada. The problem was worked out. IUPAP, the International Union
05:41:00of Pure and Applied Physics, met, I think, in Canada, about that time. IUPAC,
the chemistry group, met someplace else as well. Between these several guys,
they sold it to their respective bodies. At that time, you erased oxygen equals
16, and changed it to C-12 equals 12, and it's been that way ever since. So, we
no longer can give problems to kids in class on how to convert from one scale to another.
NIER: Except you could give a hypothetical problem: "If you were still a student
then, how would you do this?" [laughter] But, I mean, this came about that
simply. It was just fortuitous that they were able to work out these problems.
GRAYSON: Yes. It's probably also fortuitous that the one guy, Mattauch, who
talked to you, knew the right people . . .
NIER: That's right. Knew the right people, he knew all the right people, that's correct.
GRAYSON: . . . because, without that, I could see a committee forming, and
everybody getting bogged down.
05:42:00NIER: Wichers had a lot of prestige. Ed Wichers, after all, was head of
chemistry for the National Bureau of Standards, and he had a lot of prestige. He
was nearing the end of his career, he was getting older then--and he was anxious
to settle this problem in his lifetime. He was just delighted at the solution.
The thing that made me hesitate in the first place, I appreciated that even
before, was I said "Gee, the chemists will never accept as a standard, something
that you can't put your hands on". You ought to have pure C-12 in your hands in
order to do it. Well, it didn't really matter, you see; because you knew the
relationships well enough. They didn't balk on this, and they were so relieved.
As I said, everybody bought it, and that was the end of it.
GRAYSON: Well, I wonder if with today's various machinations, anything like that
could have happened.
NIER: Well, there's personalities involved. And, as I say, the people who
05:43:00deserve credit for putting it across were Harry Duckworth in Winnipeg and
Mattauch in Germany. I just was a bystander at that point. If there was anything
I wasn't interested in, it was to get into that argument.
GRAYSON: So, your measurements were good. It's just that that was an aside to
the whole problem of selecting a reference to define the accurate mass of
something. Obviously, you have to settle for some standard.
NIER: Yes, and of course, C-12 . . . since we used hydrocarbons for comparison
masses for these precision mass . . . that's where you find something at every
mass number. This was very handy, and Mattauch was just delighted with that
prospect, you see, because there was a big argument. One of the things we
couldn't agree on, was the difference of mass between O-16 and C-12, He-4.
That's a doublet that you measured. And there was some disagreement. This way it
05:44:00was actually resolved, both the nuclear measurements and the mass spectroscopic
measurements finally came together. But it was fortunate there was this
discrepancy at the time, so nobody had an entrenched position.
NIER: This was important.
GRAYSON: You're probably right. I would suspect, that the chemists had the
largest entrenched position of any group.
NIER: Yes, you couldn't change that very well.
GRAYSON: And, the insight that you provided.
NIER: And the number of people in physics, who were really interested in the
problem of precision masses; it was mainly people like at Caltech and a few
other places, who were doing these precision energy measurements to get mass
differences and so on, and a handful of mass spectroscopists.
GRAYSON: Well, that work that Johnson was doing . . . how did he report his results?
NIER: We didn't care. I think at first we reported them both ways.
GRAYSON: I see, okay. Because, it didn't matter, but you had to report it one
05:45:00way or the other, so you just selected both, which probably was maybe the nice
way out of the problem.
NIER: Yes at the time . . . so, you could convert it. It didn't really affect us
very much. We found our error. We had a mistake in the measurement of the
doublet, and that was part of the discrepancy between the mass spectroscopists
and nuclear reaction-based scales.
GRAYSON: We did talk about one or two experiments that didn't work, like, for
instance, the one with the UF6 measurement initially, the one with the thermal
column that you were going to try. I'm sure that there were others. Would you
care to maybe just talk about some of the more interesting, or less interesting
of those that didn't work? [laughter]
NIER: Well, one I remember was when I was a graduate student. I was essentially
done, I had my thesis done, essentially a year before I was going to get my
degree. And after having found potassium-40, it would have been interesting to
05:46:00try to check into the radioactivity of it. And we had, on the campus, a young
instructor, by the name of Donald Hull. Where'd he come from? Well, he was a
student of [Willard F.] Bill Libby's in California, and knew all about soft
beta-ray counting . . . such as potassium and stuff. He came here as an
instructor, while I was still a graduate student. We thought if we could somehow
bugger the isotopic composition of the normal isotopes, we might see which
isotope the radioactivity goes with, An experiment had been done by [George de]
05:47:00Hevesy in Denmark years before, where he changed the isotopic composition of
potassium by free evaporation. You just evaporate a lot of potassium, and the
lighter isotope comes off easier, and finally you're left with a residue
enriched in the heavier isotopes. They'd done this and demonstrated--I think the
experiment worked--that they get a slight difference in atomic weight. All they
could do was measure atomic weight change. Here we were, and we could measure isotopes.
So, I thought, wouldn't it be interesting to do this, and especially since the
other guy was an expert on beta-counting. So, a fellow graduate student, a very
dear friend of mine, who I had known for years--we were undergraduates
together--by the name of Andrew Hustrulid, was working on something else. And I
05:48:00had free time, so we set up an apparatus where we had what was like a fountain
of molten potassium. We had to develop a pump that would pump the potassium, a
little iron piston pump. You see potassium doesn't react with iron, so we made
the mechanical parts all out of iron. Just like a pump on the farm for water. It
would come up and flow over a surface and down, and we had cold walls, so the
potassium would stick. So you'd keep it mixed, which was important, and the
lighter one would remain close to the surface, so you'd keep evaporating until
essentially it disappears. We took what was left, and gave it to the expert in
beta counting, and tell him, "Here, measure the activity of this stuff." And you
see, we knew the isotopic composition from making isotopic measurements.
05:49:00[END OF AUDIO, FILE 2.6]
NIER: So, we had produced potassium with altered isotopic composition and Hull
was to measure the activity. Well, like everybody else, he had his hands very
full. He was a new instructor with a heavy teaching load, and he had trouble
getting a lab started. He had other interests, so it was never done. I finished
up my degree, and left, and so did Hustrulid.
GRAYSON: And you had this nice sample.
NIER: A nice sample. I still have the residue. I've got a bulb in the cabinet
right behind you, I think. I'm sure the safety people don't know about it. A
sealed-off bulb of solid potassium that we used--about 250 cc's. I've forgotten,
05:50:00we got about 10 percent enrichment of the K-41 and 5 percent of the K-40 which
should have been enough. Our measurements were good enough. The counting
measurements were not that easy. You see, these were such soft rays, you had to
put the stuff in the counter.
GRAYSON: Oh wow. You had to be right there.
NIER: Yes. But Hull was capable of doing it. You see, he worked with Libby who
was the first person to measure radioactivity in tritium, for instance.
GRAYSON: Well, it, kind of, never really got completely finished.
NIER: No, never finished.
GRAYSON: Were there any other kinds of things like that; kind of blind alleys,
or skeletons that you care to discuss. [laughter]
NIER: Well, there were lots of them, but I don't recall them all now. There were
never a lot of big things that really went wrong. It was usually just sort of a
05:51:00little side thing which wasn't really a failure. It was just never completed. I
suppose there were a number of things of that kind that we never finished up. At
one time, I had wanted to look for the neutrino, before they found it, and I had
some support from the Office of Naval Research. Right after the war, they
supported nuclear physics things generally. I had some support, and got a very
potent alpha-particle source. The idea was to measure some darn thing or
another, measure conservation of momentum, and so on. So, I tried that, and
never did very well on it. I never finished up.
GRAYSON: Yes. Like so many things, it was an idea that you explore, and it just
doesn't pan out.
NIER: You don't really do anything with it. There were a number of false starts
like that. And some of our instruments never worked. You only heard about the
05:52:00ones that worked. But, there were a number of things like that. We, of course,
had failures in rocket flights. I got into rocket flights, and had failures there.
GRAYSON: That was a little more spectacular.
NIER: Those are a little more spectacular. I have pictures of some of those
GRAYSON: Did you happen to see that most recent big failure, where this huge
rocket took off and did a couple of cartwheels? That was impressive.
NIER: I started flying in about 1960. I decided, "Gee, this is the space age
that's coming along, we ought to get into that." The problem of studying the
composition of the upper atmosphere was an interesting challenge. So I thought,
"Gee, with all of the experience we have, we ought to build mass spectrometers
to do this." And so, we built miniature instruments. And I pursued that for
quite a long time.
GRAYSON: I'd like to explore that, but we've been at it almost a day. It's
05:53:00getting close to four p.m.. As a matter of fact, I think it is four. Would you
want to break now, and maybe call it a day.
NIER: Well, it might be useful to do that, because then we could talk about some
of this documentation I have. Maybe I should have a little bit of rest if you're
going to go on.
GRAYSON: Sure. Okay, and I would like to explore the business with the other
things, and do a lab tour, too.
NIER: Well, we'll pick up tomorrow morning.
GRAYSON: Okay. What would be a good time to start off in the morning?
NIER: Well, nine o'clock?
GRAYSON: Nine o'clock.
NIER: I'm up early, earlier than that, if you wish.
GRAYSON: Well, I had this problem that we would either not get enough material
or get too much, and I think I know that we don't have the first problem. I
would be willing to meet earlier, but I don't want to wear you out or down. I
think we're getting a lot of excellent material.
NIER: Well, there isn't that much more. I mean a little while longer, I think.
GRAYSON: Okay. Well, why don't we just plan on starting at nine.
NIER: Because I think the rocketry is, sort of, interesting, too: Mars. And the
05:54:00various things I've done since.
GRAYSON: Okay, we can start it and then plan for nine in the morning.
NIER: Nine in the morning. I think the building's open. If not, go to one of the
front doors, because I think there are classes here, but sometimes they have the
side doors locked.
NIER: But if not, I'll look for you, if you can't get in.
GRAYSON: Well, it's a simple walk.
NIER: And come in the front door, fine. I'll make it my business to be here then.
GRAYSON: Okay. Then we'll conclude this part of our activity at this point, and
pick up tomorrow.
NIER: Very well.
[END OF AUDIO FILE 2.7]
[END OF INTERVIEW]
NIER: [ . . . ] Well, do you want me to just list what I have here? [Papers and
photos are being examined and discussed in Nier's office.]
GRAYSON: Well, yes, let's just talk about it the way you would as if we were not
NIER: Well, I have here some reprints, or copies of reprints that I'll give you
05:55:00that are relevant. I have the one on the discovery of potassium-40. And I'll
give you the first one. And then, here's a picture that appeared in what is
called The Journal of Applied Physics of our 1940 instrument. Now, I have better
pictures than that. Now let me see what this is here. Then, here's one of my
instrument at Harvard, the one that fit in the electromagnet. With this, the
first work was done with a number of different elements. On the other side, it
GRAYSON: Now, was Tate still in charge of the Physical Review then?
NIER: Oh yes. Now, let's see how the figures were. [laughter] No, I think we had
a lettering set then. Yes, this was done with the lettering set.
GRAYSON: You used a Leroy Lettering Set, right?
NIER: Yes, that was done with that.
GRAYSON: Leroy must have sold a tremendous number of those to physics
NIER: They had an engraving machine at Harvard, and they owned a Leroy set, and
a guy in the shop on a moonlighting basis would make sets for us. [laughter] And
they charged 50 cents or so for a strip. I have a Leroy set of my own that was
05:56:00home-made. Here's the paper by Edgar Johnson.
GRAYSON: Okay. This is the double-focusing work.
NIER: The double-focusing one, yes.
GRAYSON: Now even though this particular design is used quite a bit in the
organic analytical business, you never received anything from that, monetarily.
NIER: No, we never patented that. We should have.
GRAYSON: Yes, I mean in remuneration, in terms of dollars.
NIER: Well, there's another interesting angle on that. Here's a paper that you
may not be acquainted with. I was invited to talk to the Bunsen-Gesellschaft in
That was the occasion of my being in Germany. I
gave a review on isotopic masses and abundances. This is where I presented some
of these results. Here is the instrument, with the second spectrometer tube.
This was our single-focusing wedge instrument. The significant thing in this
05:57:00whole paper, however, is one sentence in here . . . which Beynon picked up, " .
. . instrument of this type will undoubtedly prove useful in the field of gas
analyses in the future. Molecules having the same mass numbers, but differing in
weight by an amount determined only by the difference in binding energy of the
nuclear particles, may be clearly resolved as in this example. Extension of the
use of this instrument to resolution of heavy hydrocarbons should prove
fruitful." [laughter] Beynon read this article.
GRAYSON: Well, it has . . . proven quite fruitful. [laughter]
NIER: This is where we showed the mass difference between CO2 and hydrocarbon
ions. I talked about the comparison of the scales. See, this was in 1954, before
05:58:00we changed to the C-12 scale. So, that was, kind of, an interesting paper. The
history of this, the important thing, is buried there, in that one sentence.
[laughter] Here's the paper on common lead, variations in common lead, the first
thing we came out with.
In which we showed that you
could consider common lead as a mixture of a primordial, plus varying but equal
amounts of uranium and thorium lead. This was the thing, which, as I say, the
geologists were gaga about. Here's the original 60 degree instrument. before.
And here's the Kovar tube that came all the way up here, and then this is silver
soldering on the top to keep it on there.
GRAYSON: I see.
NIER: Here's the magnet, and so on . . . Here's some uranium lead, from the
05:59:00first lead samples. And then there's the related uranium measurements where the
first uranium ratio of 139 to 1 came from. Here's 139 plus or minus one percent.
Here's the isotopes of uranium, and the spectrum even shows the isotope U-134,
which I gave as having an abundance of 1/17,000 of U-238. They've measured it
more accurately since. It's 1 in 16,400 or something like that, but when you
consider the difficulty of making the measurement . . . [laughter] And then,
here's the first carbon isotope paper. I worked with Earl Gulbranson on this,
and we showed that the 12/13 isotope ratio in nature varied by some 5 percent.
GRAYSON: Okay. That was in 1939. It seems like a large number of these papers
are very close together in time.
NIER: Well, it was finishing up work done in 1938 at Harvard.
GRAYSON: I see, okay.
NIER: And then, there's a delay in publication . . .
NIER: Then, this was this first paper on the device for compensating for
magnetic field fluctuations in a solenoid mass spectrometer. It has a diagram of
06:00:00the circuit. A simple circuit is all you need. As far as I know, only one person
ever used it. We used it very successfully. Then at one time in about 1950, I
built a portable instrument for the people in surgery. And this was before
transistors, so the thing was really cumbersome. I have a picture of that thing.
The medical school, had an anniversary a few years ago. It was their hundredth
anniversary and they remembered this instrument, and they asked me, "Did I by
chance have a picture?" And sure enough I did. (Figure 30) So, I lent it to
them. This showed how you used this. This appeared in the Journal of Thoracic
Surgery. You had this connected to people to monitor respiration, you see. We
also have a photograph of the 180 degree mass spectrometer tube used with the
instrument. (Figure 31)
There were some other people doing similar things in other places. I think we
06:01:00had a better instrument, but I didn't have time, and none of the medical people
knew how the thing worked. I provided them with a guy to help run it, but this
is a case where you ought to buy an instrument that's all done. Because, see,
they don't have any time or sympathy for the concerns of this sort of thing. So,
it was never pursued. Although, it saved one life, at least, that I know of.
Something went wrong, and they weren't giving the guy enough oxygen.
GRAYSON: Oh, really?
NIER: I think the machine told them that. So, that's a story there. I have some
other things, but those are the ones that I found in particular. Here is
something that you don't have. I got an honorary degree from the University in
1980. I had to give a little speech. And that gives some background on things.
Repeats some of the things I told you this morning. So, you can have that to put
06:02:00NIER: You have that?
GRAYSON: "Reminiscences of the isotopic . . . " Yes, yeah . . .
NIER: You don't have this, I bet. Did you see this? I got a medal--the [V. M.]
Goldschmidt Medal from the Geochemical Society [in 1984]. And Harmon Craig of
[Scripps Institute of Oceanography, University of California San Diego] La Jolla
[California] gave the introduction, and I gave a little talk, which repeats some
of the same stuff that we were talking about here, but you should have that for
your file. Harmon Craig was such a character, that just reading this is an
interesting aside. Here's something which you may not have. This is the one I
mentioned before. Duckworth and me on the unified scale. That came out just recently.
GRAYSON: 1988. That's pretty recent! [laughter]
NIER: Yes. It that reviews that whole history of the standardization on C-12.
06:03:00Probably with more detail than you're interested in.
GRAYSON: Oh, no.
NIER: It's all there. But it tells it very well, and Harry deserves an enormous
credit for getting that out. Here's the conference in 1951 at the Bureau of
Standards. And here are all the characters that were present. There's a map of
all of them. (Figure 32)
NIER: Now, ASTM E-14 probably already existed, but maybe it didn't. There was a
group in England, Institute of Petroleum-sponsored thing . . . this I don't want
to lose now.
GRAYSON: Right, we'll have to make some arrangements to ensure its safety.
06:04:00NIER: I could lend this to you if you want. I did a little research on this a
few years ago. There was a meeting of mass spectroscopists in England, who were
interested in that sort of thing about 1949. This group then met every three
years and this developed into the international meeting. I went to the first few
of those. I was not at the original one, but I was at later ones; several of
them. I got to meet quite a few of the people. They were mainly English and then
it was broadened to include the Continent. At first, it was just a handful of
people, it seems like it just snowballed. You'd be interested in this meeting,
since you're not an organic chemist. John Hipple organized
He was then head of something at the Bureau of
06:05:00Standards. And he was so afraid that it would be swamped by organic chemists,
with all of their things, that it would be like the E-14 meetings. They
deliberately excluded--that's too strong. They didn't deliberately exclude them,
but on the other hand, they didn't make much of a point of inviting them. The
meeting was by invitation. But they had practically everybody in mass
spectroscopy in the world. Leading Japanese people, Ogata, was there. Mattauch
was there, [Paul] Ewald, Hintenberger, all of these people were there. I met
them for the first time in 1951. [Jaap] Kistemaker, from Holland, who was a
wheel there, plus countless others. I don't remember everyone who was there at
that meeting. And it was the first time I had ever met other mass
spectroscopists, you know. I knew a few but it was the first time that I'd ever
06:06:00met a lot of these people. And I think for a lot of them, it was their first
time. Certainly it was the first time I met the Germans.
GRAYSON: Okay. We'll have to work out some mechanism here to get copies of this photo.
NIER: You ought to know about that meeting, no matter what. I'd be glad to lend
you the whole business. But, as I say, I don't want to lose it.
GRAYSON: No, I understand.
NIER: Maybe the thing to do is take it with you.
GRAYSON: I could. I just want to make sure it is safely transmitted. This tape
that John Beynon did with Graham Cooks, Beynon tells this horror story where
some English scientist was doing some research in the history of mass
spectrometry, and Beynon sent him all of his early ASMS booklets in the mail, so
he could go through them, organize them, and so on. And the guy never got them.
06:07:00They're somewhere in the English mail. He had all of these fantastic things,
that I would like to look at myself--the early ASMS proceedings--but they were lost.
NIER: Well, can you make some arrangements? You know, we could have them done at
our photo lab, here, at North Hall.
GRAYSON: Right, I thought about that, with Tom [Krick] being here, that would be
NIER: Yes, I was going to say, and you could make some financial arrangements
there and have them done.
KRICK: I could get them to you. I could even put them in my budget.
NIER: So, whatever you could do. You and I could work it out. There may be other
things like that we could do here.
KRICK: And then they'd be physically located right here.
NIER: Right here, at North Hall, and they do beautiful work over there.
KRICK: They do real good work over there.
NIER: See, they copied this thing. And I've got the stuff that goes with it.
Look, isn't this a marvelous thing.
KRICK: Yes. That's unusual.
NIER: With this sheet, you have all of these people in the group portrait
identified. (Figure 32)
GRAYSON: Yes. That would be absolutely excellent.
06:08:00NIER: Here is the foreword. It gives you an introduction. And this is the book;
with the index, and so on. You should have all of this. Well, we can xerox this
for you later. These are things, I think, you don't want to miss.
NIER: I'll keep it now, and you and I can work this thing out and have copies
made, if you want to. You can see some of these people here. Here's Bleakney.
I've got a current picture of him. I say current . . . he's now about
eighty-five or eighty-six years old, and this was, as I say, in 1950, so that's
forty years ago. He was at Princeton. Here's Ed Condon. He was then Director of
the National Bureau of Standards. Here's Bainbridge.
GRAYSON: Oh, wow!
06:09:00NIER: And here I am with these people. A lot of wonderful people in this
photograph--good, good photograph. It was done by somebody who was a good
photographer. But these were the people who were doing mass spectroscopy or
closely related things, at the time. And there are a few chemists involved,
there are a few here, but if you read the papers, there's nothing here about
fragmentation of molecules or radicals or fragments. [laughter] It was really .
. . well, the title of the meeting was "Mass Spectrometry in Physics Research."
NIER: Well, we should organize this material a little more.
GRAYSON: Yes. I think that the point you make about getting a little break
before you go out tonight is good. It's getting a little late, and I don't want
to push things.
NIER: There's my first instrument. The one with the solenoid.
NIER: Here are the mercury pumps. The tube is inside here, with the asbestos
06:10:00wrapped around it, heaven forbid!
NIER: There's asbestos up there on the shelf, by the way.
GRAYSON: What's this? Does this say "thermos" on it?
NIER: Yes, it's a thermos bottle. [laughter] We didn't even have pyrex ones, we
had ordinary ones. You had to be damn careful. Otherwise, they imploded. Here
were the traps for the mercury pumps. The scale is back here. The galvanometer
you can't see; it's hidden behind some stuff here. Then, I have a picture, from
the Harvard instrument. Now, this is the so-called Rockefeller instrument, that
we built specially for the carbon work. Here's the magnet, here's the tube, and
that had the first null measurement feature. The galvanometer is hidden behind
it . . . here's the scale, you sat behind it. On the other side, was the
06:11:00console, where you sat. And then, the Harvard instrument is here somewhere . . .
I'll have to check . . . oh, here's that surgery instrument.
GRAYSON: Yes. That is fascinating.
KRICK: Portable too.
NIER: Here's the first commercial leak detector.
GRAYSON: Now, there is a conference in France, I think, in the Fall. A fellow
[Pierre Duval at Alcatel in France] has contacted me, asking me for pictures of
this type because he's going to be presenting some material on the history of
leak detection. [Duval died before the meeting and the paper was presented by
one of his co-workers.]
NIER: Well, whatever you want to do, you're welcome.
GRAYSON: What I'd like to do is tomorrow sit down and go over all of this.
NIER: We better do that. Are you going to be free tomorrow, Tom?
GRAYSON: We can go through these pictures and make some notes on them.
KRICK: Well, I was thinking you could even take the pictures and xerox them, and
then make notes on them.
06:12:00NIER: I think that would be very good. That's very important. And, if somebody
doesn't break down the xerox machine this afternoon, I can do this tomorrow.
NIER: But unfortunately, the xerox machine, if somebody buggers it, then it
won't be available tomorrow. Otherwise it's available, and I have keys to everything.
NIER: Here's the first spectrometer.
KRICK: We could copy them on 11 by 17, so you'd have more room on each one to write.
NIER: Something I wanted to show you is the Harvard machine. But I've got our
first leak detector also. Sure, by all means, you're certainly free to have it.
Now, let's see. This I got at a symposium.
GRAYSON: There's even some negatives there, I see. Aha! [laughter]
NIER: No, I've misplaced a lot of stuff. There should be one here on the
06:13:00Manhattan District instruments. Here was the Consolidated Instrument tube . . .
sixty degree hydrogen spectrometer. Here is the instrument where the panels were
first introduced. There's one with me on it, though, which was really a very
GRAYSON: So, this is looking at that machine from the front, as opposed to the
back, and this represents the scale . . .
NIER: Yes, the scale is there.
GRAYSON: . . . that you would look at. It was all very neat and organized.
06:14:00NIER: Here was the machine that the first work was done here, in 1938, 1940.
GRAYSON: That's a plywood panel I see.
NIER: Plywood panel, yes. I made that myself. But, we didn't have all that help
in those days, you know.
GRAYSON: You've got this nice little convenient business where there's a little
cowl over the light, so you can see your controls, when you turn out the lights. [laughter]
NIER: Well, you had to see that electrometer spot. The spot was up on the scale.
GRAYSON: Yes, but you also needed a little light to know which knob to turn. [laughter]
NIER: What to write down, and things like that. You know, I think I have most of
the pictures that would be interesting.
GRAYSON: Okay. Well, like I say, we will have tomorrow, and if we're going to be
going out this evening, which I think we'd really like to do, I think it would
probably be a good idea to wrap it up for today.
NIER: Okay. Now, my wife and I can pick you up at some time which is convenient.
KRICK: Or, if you want me to come with you, I'll pick you up.
NIER: Well, fine, whatever you say. Where do you live?
06:15:00KRICK: Right next to St. Paul campus.
NIER: Well, so do I.
GRAYSON: Everybody's right here, so maybe we don't have to pick up anybody.
Well, it depends on where we want to go.
NIER: Well, where do you want to go? You had thoughts of where you wanted to go?
[END OF AUDIO, FILE 3.1]
[END OF INTERVIEW]
GRAYSON: [ . . . ] Professor Nier and I are going through some, photographs that
we're going to have copied, so that we can . . . include them with the
interview. And this particular picture here is?
NIER: Well, shortly after World War II, I got a grant from the Committee on
Growth which was some money put up by the American Cancer Society for promoting
research related to cancer. And they'd given the money to the National Research
Council, and who in turn, gave the grant to me. And this was to develop a new
mass spectrometer which might be useful for tracer work. And, we developed such
06:16:00a machine in 1947 or thereabouts, and then the design was given to the
Consolidated Electrodynamics people in Pasadena [California], who proceeded to
manufacture these. I don't know how many they made and sold, but it was a number
of dozens, as far as I know, and they were used by people in biochemical
research, where they used tracer isotopes.
GRAYSON: There are two people in this picture. (Figure 33)
NIER: Yes. Myself, and Harold Washburn, who was the director of research for the
company, and responsible for the development of various instruments for the
company. And that picture would have been taken in about 1948 or 1949. (Figure
33) It has the name "Consolidated Nier" on the instrument, and by the way, in
the British Museum, in South Kensington, there is such an instrument, on display there.
GRAYSON: Oh, really? Excellent. My son is there now. I'll ask him to go by that
museum and take a picture of it for me. (Figures 34, 35)
06:17:00NIER: [laughter] Good. Well, these are details of the instruments. I don't know
if we need anything more of this. This is the developmental model. (Figure 36)
GRAYSON: Okay, so basically, it was a 60 degree sector instrument. The ones with
some people on them, perhaps those would be more interesting.
NIER: Well, here's the prototype from which the Consolidated people based their
instrument. I've forgot who the individual is there, with me. It may have been
somebody who was visiting or a Consolidated person.
GRAYSON: Physicists didn't wear suits in the laboratory, did they, in those days?
NIER: Not always. [laughter]
06:18:00GRAYSON: Why don't we just put it in the copy pile. [Untranscribed material; 6:17:48-6:18:22] So, this is essentially the prototype design for that particular instrument?
NIER: Yes; here are the people. There were three of us on it. [laughter]
GRAYSON: This was taken in this building, I guess.
NIER: Yes, it was . . . in our sub-basement, where the instrument was set up.
There are names on the back of this one.
GRAYSON: Oh good!
NIER: Howard Ecker and Ray Hopper. They may have been Consolidated people.
06:19:00GRAYSON: This one has more people on it.
NIER: And it shows more of the instrument. The recorder and the flight tube. And
you can see the inlet system.
NIER: Now, here's another view of the instrument. And here's a profile view.
GRAYSON: Actually, a profile view might be interesting it shows a lot of detail
on the analyzer side.
NIER: Well, why don't you take that one. Here's the negatives. I think that's a
nuisance, to go separately through the negatives, isn't it?
GRAYSON: I don't know, if they're in good shape, it's easy to just print from
06:20:00the negatives, if we have them. Oh my, there's more stuff in there.
NIER: These are schematics of the spectrometer.
GRAYSON: Okay. That's a double-focusing machine.
NIER: Let's see what this is. This was when we were doing our meteorite work.
Comparing the helium-3 to the helium-4. You see, here we had a multiplier and a
collector. It even says helium-3. We took a fraction of the output. It shows it
here schematically. When it balanced, we used the recorder to note the
difference. (Figure 38)
GRAYSON: So, because the helium-3 was so much less abundant, you used an
NIER: That's the way we did it.
06:21:00[END OF AUDIO, FILE 4.1]
[AUDIO FILE 4.2 MISSING]
[GRAYSON: [ . . . ] There's so much good material here. So, this was the Kovar problem?
NIER: Here's some console pictures here. But there's one like this with me on it.
GRAYSON: Well, pictures with people on them are worth more than those without anybody.
NIER: Well, I have to look through these prints. [paper shuffling]
06:22:00GRAYSON: So, you obviously documented the stuff pretty thoroughly during the
years . . .
NIER: It all depends. [laughter] Some things, yes.
GRAYSON: Probably depended on how big a hurry you were in at the time.
NIER: Yes, that's right. That's usually the way it is.
GRAYSON: You have some good negatives there, I think we could certainly get some
NIER: Yes, this is the original 60 degree instrument.
GRAYSON: Okay. I'm sure that can be printed up readily.
NIER: Yes, Well, let's see. Here's the console. I don't know if this is
important. This was a hydrogen instrument made after the war, with one of my
students. It was all metal, and it had multiple collectors for mass-2, 3, and 4.
GRAYSON: I see . . .
NIER: That's just a little diversion.
06:23:00GRAYSON: I like the battery there. What's the battery doing?
NIER: Well, at the collectors, you had a suppressor plate, to knock back the
secondary electrons. It was just a 22 and a half volt battery.
GRAYSON: You just plugged the battery in.
NIER: To get the voltage on the suppressor plate.
GRAYSON: Well, here's some interesting details of the guts of an instrument.
GRAYSON: Showing all the slits and so on. Is this a dual-slit?
NIER: Apparently yes, there are the two cup-pieces.
GRAYSON: Okay. And the framework.
NIER: Yes, see we did document that well.
GRAYSON: Yes, all kinds of good bits and pieces, there.
06:24:00NIER: We had a glass pump on this instrument; a little 180 degree instrument. It
may have been a version of the portable one for the medical people. This was a
spherical joint, so it had a glass ball on the end of the diffusion pump. It was
sealed with black wax.
GRAYSON: That was where the diffusion pump was.
GRAYSON: Then was this for water-cooling the little coil?
NIER: Apparently yes, that was the water-cooling.
GRAYSON: What where you trying to keep cool there?
NIER: Well, the wax . . . see, because you baked the rest of it, and this was to
keep the wax from melting.
GRAYSON: Okay, I see. That's an interesting bit of detail. That was on the
GRAYSON: It says . . . what is this? Somebody [Byron F.] Murphey?
NIER: Hydrogen machine . . . Murphey, from his thesis . . . Byron Murphey . . .
that was right after the war.
GRAYSON: I see, thesis work plus one Phys. Rev. [Physical Review] publication.
06:25:00NIER: Yes, that's right. [laughter] It was published in Phys. Rev. By the way,
that had in it the leak system which was adopted by the people in Chicago . . .
Harold Urey, and others. I don't know if that shows in the instrument. You could
switch back and forth from one gas sample to the other. Well, it doesn't show on
this picture. There were little glass valves. Yes, there it is!
GRAYSON: These were magnetically operated?
NIER: Magnetically operated, and you could switch between them. That became
standard practice. Here's a good picture.
GRAYSON: Yes, let me take one of those, too.
NIER: One of Urey's people came up to look at all of this, and they adopted it
on their instrument, and published on it, and so it became known as the
06:26:00Urey-McKinney leak system, but they saw it here first. We had been using it and
published it before them, but it's very seldom that people acknowledge this.
That where the idea came from.
GRAYSON: That's the problem with letting people into your laboratory.
NIER: Yes, well, it was published in a different place, so it was in a different context.
NIER: Nobody did anything deliberately; it was just one of those things that
happens. I think I refereed a paper once, where I called an attention to
somebody on that, and in that particular paper it was corrected. That's the only
publication. This was Tom Aldrich, who worked with me, and that was his work
there. This would have been in 1946 or 1947.
GRAYSON: Okay, can we go ahead and get a copy of this one also?
NIER: Sure, just write it, "L.T. Aldrich."
NIER: Are you recording this?
GRAYSON: What we'll do is make xerox copies and then we can write on them.
06:27:00NIER: Right. That's L.T. Aldrich, who did the original work on the abundance of
He-3 and He-4 and identified the Ar-40 in potassium minerals.
GRAYSON: Batteries seem to be a common.
NIER: Yes, we always had these 45-volt batteries for various things. Usually,
they had a 22 and a half volt tap, and that was convenient to use, as I said,
for the suppresser voltage at the collector, to stop secondary electrons.
GRAYSON: Is this, then, the inlet system?
NIER: This would be the inlet system on that, yes.