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Interview of H. Richard Crane by Charles Weiner on 1974 June 18,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
Family background and early education; early science interests (telegraph and radio transmission), wins American Chemistry Society Contest in high school. Caltech for both undergraduate and graduate studies, 1926-1934, comments on courses, teachers (Richard C. Tolman, Paul Epstein) and fellow students (Chet Carlson, the inventor of Xerox). Joins Charles Lauritsen's group as graduate student (nuclear physics), gets involved in research projects. J. Robert Oppenheimer's interest in their work, Ernest Lawrence's interest and objections to Lauritsen/Crane work on the radiative captive process (Enrico Fermi), Merle Tuve's involvement. Involvement in building machines for the Kellogg Laboratory (Seeley W. Mudd); Ph.D 1934 (The capture of protons by Carbon-12). Accepts offer from University of Michigan at Ann Arbor; planning and building of a high voltage accelerator. Department involvement in applied work (GE, Ford), strong interest in biology; rising biophysics interest in the department. Wartime work. Recruited for MIT's Radiation Laboratory, later involved in Tuve's proximity fuse project; Manhattan District interest. Establishment of Biophysics Lab within Physics Department in Ann Arbor. The Racetrack Synchrotron. Also prominently mentioned are: Carl David Anderson, Ted Berlin, Sir John Cockcroft, John, Sir, Walter Francis Colby, James M. Cork, Leo Delsasso, David Mathias Dennison, William Alfred Fowler, Samuel Abraham Goudsmit, Halpern, Fred Hodges, Lampe, Otto Laporte, Gilbert Newton Lewis, Edwin Mattison McMillan, Harrison McAllister Randall, William Ralph Smythe, Robert Thornton, George Eugène Uhlenbeck, A. E. White, Robley Williams, Ralph Walter Graystone Wyckoff; and Randall Laboratory of University of Michigan.
We're resuming the interview with Professor Crane. I don't have the date of the last one, but it was at least a year ago, I guess, when I was out in Michigan.  This time we're at Dr. Crane's office at the American Institute of Physics.
Well, I just looked at the last page of what we did last time, and I mentioned that what I wanted to get into was the transition to Michigan. The letter from Randall reminds us that Lauritsen talked with Uhlenbeck at a meeting in Minneapolis regarding you, and the letter from Randall was some time between mid May and July 12, 1935, and you came out to Ann Arbor on July 13. This is by the letters. There was a conversation with Randall about the position, and then we have a little correspondence about what happened upon your return. But I gather that things were pretty well decided on that visit, because when you wrote a letter to him on August 1, two weeks later, it was pretty clear that you were negotiating for what kind of a setup you wanted, in terms of the high potential —
So let's take a look at that trip, your visit on July 13, 1935. Did you go alone or did you go with your wife?
No, I went alone. It happened to be a time when the summer session was in full swing. I don't remember how long I stayed, but I sat in on the summer session. That's what I remember mainly. I think Fermi was there. I can tell you from the list here, if you like, who was there at the time.
Rassetti was there too, I think, wasn't he?
Well, the official visitors form the 1935 summer symposium were Fermi, Bloch, and at that time Goudsmit and Uhlenbeck were there on the faculty. But I'm not sure about Uhlenbeck because at about that time he left to go back to Holland for a period of some years, I think that the reason that the money was available for two new positions — namely the one that was offered to me and the one that was offered to Robert Thornton — was because of Uhlenbeck's leaving to go back to Holland. So that probably, by that summer session, he had already changed his affiliation. He may still have been there. But anyway, those were the people who were there, and I think you're right, that Rassetti was there.
And as always happened with these summer sessions, a number of other well-known people showed up from time to time during the summer, in addition to the official members of the symposium. I believe that during this brief period that I was there, Gamow showed up. I'm not positive about that year, but I think so. Anyway, I was very favorably impressed, and everything went well with the discussions about what kind of research I might do, and so it was decided at that time that I'd come back in the fall.
The letter from Randall implied that he had you in mind to head up the entire program of nuclear research, which would include the cyclotron and the existing Van de Graaf, as well as the high potential tubes that you wanted to build for your own work.
I doubt that that was true, because when I got there, Cork was in the midst of building the new cyclotron. That goes back another year. I believe in 1934, E.O. Lawrence and Gamow and Oppenheimer were members of the summer symposium, and the subject of the summer symposium was mainly the new developments in nuclear physics. That got Randall and Cork and others quite enthused about nuclear physics, and that was the turning point for the department to turn its interest, or some of its interest, toward nuclear physics. And during that time, between the summer of 1934 and '35, when I came there, they had obtained a grant from the graduate school, from the Rackham Fund, to start a new cyclotron. That was under Cork.
So when I got there, that construction job was under way. They had also hired, or were in the process of hiring, Bob Thornton from Berkeley, who was a cyclotron expert, a fellow who just got his PhD and had done his work on the cyclotron.
So I would think that their expectations were that I would work in on that general cyclotron program. As it turned out, I had some other ideas, and in the end I set up a high voltage accelerator in parallel to the cyclotron. I worked on that and Thornton worked on the cyclotron.
That jibes with what I know. And yet, there was some place where he asked you to — (looks at letter) talking about all the experimental work, "As neither of our men will have had extensive experience, the responsibility for putting the entire program on its feet will rest to a very great degree upon the shoulders of the new men, each of whom will be given every opportunity to exercise his initiative..." That's the lower teaching load. He specifically offers you one of the two positions, with the idea of Thornton in the cyclotron part of it. I'll have to check where I found the specific things that I had in mind —
Well, Cork was one of the senior professors, and I don't imagine that the envisioned having a young sprout like myself come in and take charge of this operation.
He does speak in his letter to you, inviting you to visit, that they're interested in developing a satisfactory tube. They talked of the million volt Van de Graaf machine, and they talked about the work on the cyclotron, but they also had in mind other machines. I think that they had in mind a diversity of accelerators, a number of them, from this letter.
Well, I'm not sure they had in mind a diversity, before I came. It may have been because my particular interest was in the high-voltage accelerator type of equipment, and I talked them into having one of those in parallel with the cyclotron, after I got there.
All right, anyway, that's what they did. They had several going simultaneously. I gather from the letters that it was a question of whether one would be pushed ahead at the expense of another. There was some discussion on that. That is, that the aim was to produce radioactive isotopes for the medical department of Michigan, and the discussion was which of the machines could really fulfill that promise. And you ended up saying you agreed with Fermi, that the machine you had in mind could in fact be better for the radioactive isotopes, but the cyclotron was necessary to produce sufficient intensity for the medical work. That point is somewhat confusing.
I don't remember what the arguments were at that time. I know that the medical interest was very strong. In fact, Fred Hodges, who was in charge of the department of radiology at the university hospital, gave very strong support to obtaining the grant from the graduate school for building the cyclotron. He had been to Berkeley to see the experiments with neutrons, and was very enthusiastic about their possible application to cancer therapy. He pushed very hard to get the grant and get the cyclotron started at Michigan. The aim, in the early part of the cyclotron program, was the application to cancer treatment. They actually had quite a program of irradiating rabbits and mice and various things in the cyclotron soon after it began to operate.
Did they do direct neutron irradiation?
They did direct neutron irradiation of animals in the Randall Lab, at the cyclotron, very early after the cyclotron began operating.
With what results do you know?
I don't know. I don't believe there were any spectacular results, but I don't know what they found out. There was a lot of confusion in the early days about the effect of neutrons, a lot of wild tales about very startling effects, which turned out not to be true. I remember that there was a story out at Berkeley that mice were killed almost instantly by neutrons. The experiment was to shove a mouse down a small piece of pipe, into a position near the target of the cyclotron, and the mouse would always come out dead. Well, it turned out that he just didn't have any air to breathe down at the other end of the pipe. There were just wild stories like that. But in the end, I think it turned out that neutrons had not any very striking effect.
The major purpose of the cyclotron, I gather, was not so much direct neutron irradiation but to produce artificial radioisotopes for various experiments, medical and biological experiments, that were going on.
Yes, that was another use, a parallel use of the cyclotron, and they did make radioactive tracer elements for use in the medical school. I don't remember so much about the problems that they were working on with isotopes. I do remember very clearly the irradiation of animals in the Randall Lab at the cyclotron site.
Getting back to the original period, I'm looking at my notes and I think I can reconstruct what I was trying to say about responsibility. The thing I read from the Randall letter was that it would be up to the new men, which in this case meant you and Thornton, to take the major responsibility. It didn't necessarily mean the administrative responsibility, but that you had the major experience, although Cork was spending time at Berkeley, or was about to, to learn to build the cyclotron. And that in that case, your teaching load, because of this responsibility, would be six hours. This was the point — so it's not overall responsibility for the cyclotron...
That's true, and it sound like some words that were written in order to get us these half-time appointments. The reason we could have half-time appointments was that they got a grant of I believe $110,000 from the Rackham Fund, $25,000 of which was to be spent the first year, mainly for the capital equipment of the cyclotron, and then the rest of it was to be spread over the next four years. A total five-year program for the operation, and half of our salaries, half of Thornton's and my salaries, came out of that $110,000 grant.
Yes, he sort of spells it out in letters to Cork, at Berkeley, just how the budget is going to be made. What was your impression of Ann Arbor as a town, judging it as a potential place to live, compared to your California experience?
Well, I guess the first thing is I was quite adaptable. It was very different, naturally. My wife and I found the first winter quite an experience. In fact, it turned out that it was one of their hard winters that went down in history, 1935. We took the half a house, a duplex, that the Uhlenbeck's vacated, because the Uhlenbeck's had gone back to Holland for this several year period. It was very close to the campus, and we walked everywhere and just lived close to the campus. It was a completely different experience, but we found it interesting.
Where had you lived at Cal Tech, in Pasadena, in relation to the campus there?
Also quite close. Anyway, I got to like Ann Arbor. We both did. Wouldn't think of living any place else, now. It's a very rich town culturally, and a very fine place to live. The weather is not always good.
I guess after 39 years' residence, you know that.
Well, we seem to be talking some trivialities here. Maybe you'd like to get back to the department.
I was concerned really with your decision, once you'd talked with Randall — who else did you talk with on that visit? I'm trying to get the overall picture. Did you meet other people at the department, at the university, and have discussions about the work with them?
Oh, I met other people. Of course I talked to Cork and various other members of the staff, but mainly my conversations were with Randall.
This fits pretty much then, you know, on that visit...
Randall was very active and very much on top of everything at that time. He was the guy you talked to, and he was the one who really knew everything that was going on.
Did you make the decision then and there to accept?
I guess so.
It had to be right in that period, anyway. It's as simple as that. You wrote later on in August, you got in the apparatus, about the cloud chamber and tube and so forth, and somehow the estimate came up that $9000 would be needed to duplicate the Cal Tech high potential outfit. And they said that they would make that available, and that would include, I think, the chambers as well.
I don't remember the exact cost. I know we wrote to General Electric and Westinghouse and maybe others, about high voltage transformers .
And you said you'd write to Phillips as well. Your program, according to your letter, would be that when you got there in the fall and winter, you wanted to build a building which would eventually house a million volts or more; secondly, you wanted to build all parts for a large porcelain tube, including pumping system, ion source and so forth; then, to build cloud chambers, two different ones; then to assemble one section of the tube in the new building, and apply 200,000 volts to it. The purpose of it was to generate neutrons for the deuteron-deuteron reaction, as Professor Goudsmit was anxious to see done. And then the idea was to study the capture of neutrons by various elements.
Then you had a program for the following July. That would have been '36, I guess the money was apportioned out — a little bit available the first year, then a little bit more, which would phase in with the cyclotron development, which needed a larger initial outlay. So you were trying to get your plans consistent with what was needed from the fund for the cyclotron.
The following July — this is all written in August '35 — you'd buy a high voltage transformer, when more money becomes available. Anyway, it was a pretty well designed program. Two weeks after your visit, you're back, and you have a year's program, including how the budget would be used and the various stages of it. I think it's pretty impressive. Was this on your own, working with the information you got there? Or did you discuss it with people like Charlie Lauritsen at Cal Tech?
I don't remember discussing it with Charlie. I think probably on the basis of my discussions with people in Michigan, I went home and outlined the program. That would be my guess.
It's nice to know that the money's available and the program will fit the budget.
I remember you spoke of a building. I remember that when I was there, during that summer, I believe, Randall walked me around and showed me several possibilities, places for the machine to be built. One of them was the Alumni Memorial Hall, which was a stately building about 200 yards away that had been built as a memorial building for the alumni. It was not used for very much, but it had a big first floor room with a high ceiling, and he thought that might be a thing to use. Well, that turned out either not to be desirable, or else the alumni were not anxious to have it done.
We talked about building a small building near Randall Lab, in the L — Randall Lab is L-shaped. There's a piece of lawn in the middle of the L. We talked about building a building there.
It ended up that we had a very good room in the building itself, because during the year or two prior to that, Cork had built a large Van de Graaf which I think never was completed or never worked — anyway it was in a two story high room, about 25 by 50 or 60 feet, with two stories to the ceiling. So we decided to use that, and with Cork's permission, we cleared out the old Van de Graaf equipment, and it was built there. All we had to do was dig a kind of a basement room to use for the observation room. The high voltage part was up in the big two-story part. I think Cork had lost interest in the Van de Graaf by that time because he was then building the cyclotron. So that all worked out.
As to spreading out the program, the high-voltage transformer equipment that I ordered was in five pieces. It was a cascade million-volt transformer stack, in 200,000 volt sections, and I believe, now that you speak of it, we did space out the ordering of those sections, so that we got a couple of sections to start with, of the 200,000 volt sections, and then we bought some more. They were stacked, one on top of the other.
When was this complete? It seems as if you were writing about the million volts very soon. In 1937, a paper that was received in April, is a full description; I think there were abstracts before then, so you didn't wait.
No. No, I think that at most it was in two batches.
This site selection was done while you were there in Michigan, while you made that July visit?
My recollection is that we took that walk around, and looked at possibilities during the week that I was there. I may be mistaken, it might have been in the fall, but I believe —
It was a week, and during that time you also went to some of the sessions at the summer school.
Was the summer school similar to anything you had participated in before?
It might be good to get your first impression of that, in addition to the names you mentioned of some of these stars.
Well, it was very interesting because it was so informal. Some of the sessions took place on the lawn, out at the side of the building, and the rest of them took place in the second floor seminar room in the Randall Lab. The visitors were all housed in an old fraternity house that was turned to the purpose during the summer. I remember that was quite congenial. They had some seminars and informal sessions over there during the evenings. And there were trips to the nearby lakes for swimming. The whole thing was exceedingly informal, and not too high-pressured. There were a couple of major lectures every day, one in the morning and one in the afternoon, I believe, and the rest of the time people sat around and talked informally.
Was there any topic of special interest to you at the time that you remember? I wonder if you had a chance to —
I don't remember particularly what the topic was.
Fermi was involved in transuranics. I just wondered if there was anything in that.
Fermi actually tried to do some experiments in our basement during the time he was there. I remember one amusing incident; he needed some thin foil to absorb his radiation — 1 mil or 5 mil or something like that, aluminum foil. He found out the department didn't own any rolls of foil. So since Fermi criticized us for not having any foil in the laboratory, they went overboard and ordered huge rolls of several different kinds of foil. I imagine to this day you can go find those rolls of foil. It indicates that he did set up to do some experiments.
Yes, I did find a letter from him to Goudsmit, suggesting what they should have for him when he comes; because he wanted to continue his research when he arrived there. I don't recall what it was. But he came with the idea that he wasn't going to let any time get away from him, following a rather rigorous program at the time, of just going through the entire periodic table.
Well, you went back then to Pasadena, and I imagine got yourself packed up. Was it as simple as that, or was there some research that you were in the middle of at that moment?
I think I wound up my research activities pretty quickly after that. I remember clearly that we closed up the house, shipped our worldly belongings, about six weeks before we were due to show up in Ann Arbor. And we took the whole six weeks getting there. We drove, in other words, around through the Northwest and Yellowstone and various places, and we took that whole six weeks getting to Ann Arbor, so we must have wound things up pretty quickly after I came back.
There were still some publications that came out later, but that's understandable. That would have been work that had been completed. Some of the work with Lauritsen was published up through the end of 1935. The gamma ray work.
Most of the kinds of things we did at that time in Lauritsen's group were fairly short pieces. There were quite a few of them, but each research job, each measurement was fairly short, so there wasn't any long program that I had hanging over me, that I had to wind up. As you can see from the publications, most of them are just letters to the editors and brief things.
Yes, they average a page or two, something like that. When you got to Michigan, it would have been some time in late September?
What were the courses that you were asked to teach? You had to teach two courses.
Oh, all newcomers were given the same thing to teach, namely, recitation sections for the introductory course, and that's what I did.
These would be for physics majors, or for anyone taking physics?
No, for the service courses, that is the introduction physics that the department taught for the engineers and the pre-meds and so on. The typical course was a lecture and then sections of 20 or 25 students each, and those sections were taught generally by the younger faculty.
So you were doing six hours a week?
Yes. At that time, the full load for a junior faculty member was 12 hours. So half of it was six — I think, as I remember, it was 12 hours for instructors and assistant professors, 10 hours for associate professors and 8 hours for full professors. That was what I deduced from looking at the assignment board. Now it's about six hours for everybody.
It was a while before you could do any experimental work at all. I assumed that the first thing you'd do was to get busy on the construction, which would mean the site, then ordering the various components. Did you bring anything with you or purchase anything from Cal Tech?
No, I didn't. I think the first thing I did, aside from ordering things like the transformers, was to start building a cloud chamber. I started that right away. The department had a very fine shop. They had about five or six mechanicians, all Germans, trained in Germany — the shop was supported by the college entirely. All you had to do was just go in and ask them to make something. All the time up to the war, at least, the university supported the shop fully, and the physics department would just go in and use it. If there was a shortage of available time, the department chairman had to settle who got it, but other than that it was free. There was a glass blower, also a German, who was very expert. That budget for the shop, at about the end of the war, had gone up to where it was about $50,000 a year from the university, and aside from making a grating or a spectrometer or something like that for another institution, there was almost no income to the shop. Because there were no government- sponsored projects at the time.
After the war we began to have government-sponsored projects. Then the projects began to pay the shop for the work done, and apparently the college didn't catch onto the fact that the shop was becoming more and more self-supporting. They kept on appropriating this $50,000 a year for quite a number of years after the need for it had at least decreased, so that the shop bank account got up to credit balance of about — I remember at one time it was $110,000.
Eventually the college came to and cut back on their support of the shop, until in recent years, the college support of the shop has been very meager. They've forced the shop to support itself almost entirely in reimbursement from projects.
Well, of course it's expanded a great deal since then anyway.
Well, not a great deal. Partly because some of the projects themselves have started small shops, satellite shops. For example, the cyclotron has a pretty good-sized shop of its own. So it's sort of stabilized.
Talking about the department a bit — the faculty at the time consisted of Uhlenbeck, who was on leave or had left, Goudsmit, Duffendack, Cork, Randall, the two new people, you and Thornton — and who else?
Well, let me just try to give you a little rundown of the kinds of things that were going on at the time when I came there.
Infrared, both experimental and theoretical, was still very active and very strong at the time I came. Randall had several spectrographs in the basement, actively operating, and in fact a big new spectrograph was under construction at the time that I came. So the infrared was very much still going strong at the time I came. As you know, Michigan was one of the pioneers in infrared, and it continued to be strong for quite a number of years after I came — I would say, up until the war years.
Another kind of research was spectrographic analysis, mainly by means of spark spectra. This was an applied type of research mainly. It was a method of making fast analyses of the chemical composition of metals and various things. Sawyer and Ralph Wolf — Wolf was a faculty member — were active in that. I think they got some of their support from a steel company — I don't know which steel company, Bethlehem, I believe, because by their spark spectral analysis, they could monitor the composition of the steel, and get an answer within five minutes or so.
I did discuss it with Ralph Sawyer, that project, I forget the name of the company, but got some detail of how that was done.
So that was another thing that was going on. We've already talked about the beginnings of nuclear physics. An interesting line of work which had just closed at the time I got there was the work by Williams and Cleaton on magnetrons. They did very pioneering work in magnetrons which could go down to below one centimeter wavelength. In fact, I think .65 centimeters was the shortest wavelengths they got. They got it just by making the magnetrons microscopic in size. And of course, the power output went down to a microscopic amount also. But it was still possible to use it for research experiments, and one of the most interesting applications, in my opinion anyway, was that they were able to measure an infrared absorption line with this radiation which was generated by the magnetron. I think that was 1.6 centimeters wavelength. They made a grating that looked like a Venetian blind out of strips of aluminum, reflected this radiation from the grating, and sent it through a big kind of a balloon that was filled full of a gas which was the material whose absorption lines they were measuring, and measured a far infrared absorption line by radiation that was generated by the magnetrons. That was kind of a joining of radio waves with infrared.
This was in the thirties?
I think this was concluded just about the time I got there. Then Cleaton went away and Williams dropped it. I don't think he retired at that time, until a little later, but when I got there, it was a dead project. It had been a very interesting one.
At that time, the department had quite a lot of applied work. They had several people in several research labs devoted to work that was done for industrial companies on contract. The engineering college had a department they called the engineering research department, and that department brought in contracts from industrial companies and then parceled them out to various departments on the campus. The department of engineering research took an overhead on the contracts that they brought in. Then later on the department of engineering research would give the physics department a cut of the overhead, for buying apparatus and such things. This was all done entirely out of a little black book that A.E. White, who was the head of the engineering research department, carried in his inside coat pocket. He kept track of how much money each department had been given, out of the overhead, and it was all done on his personal say-so. Of course, it went through the business office, but no committees, nothing. You'd go to him and ask him for some money for a new spectrometer or something, and he'd get out his little black book and see how much money you'd had in the last year or two, and if he thought you deserved some more, he'd give it to you, out of the book. I wonder if this book still exists? It would be a unique document.
The overhead was not mixed in the general university funds?
I don't know how the business office handled it. Well, then, the infrared work at that time and in earlier years received a good deal of support from General Motors. General Motors, surprisingly enough, had a quite strong interest in research in infrared. They invented and developed the so-called chopper, which was adopted by most infrared labs. It was just a way of making AC out of the DC from a thermopile so it could be amplified and detected more easily. And I think the University of Michigan physics department got some financial help from General Motors.
Some of the applied work that was going on was for the Ford Motor Co., in trying to make automobiles more quiet. We had a couple of acoustics people, who were not faculty members but employed by these projects, working on Fords to take the noise out of them. I remember that this was done secretly between some of the Ford staff and the University of Michigan, and without the knowledge of old Henry Ford, because he didn't believe that universities had the capability of doing anything for anybody.
He demonstrated that it wasn't necessary, anyway. When you said outside people, would they be what we'd now call a research associate?
Yes. They were employed on the money that came in from the industrial companies who wanted the work done.
What was the role of the university then, other than supplying the space, if there was no faculty involvement at all, in the Ford Motor work as you've described it?
I don't know whether there was officially a faculty supervisor or not, but the guy that did all the work was not a faculty member. He was what we would now call a research physicist or something like that, on a long-time basis. He was not hired just for the job. He was there for most of his working life. Evidently they were able to get continuing industrial support, so that they supported two or three of these research physicists on a long-term basis.
I realize now, I've heard a story, they had someone in chemistry at the University of Chicago working not as a faculty member, but supported one day a week by the Universal Oil Products Co. for some particular chemical work, and I guess it may have been a pattern. Well, now, does that cover pretty much the research interests of the faculty? And projects going on in the department in the thirties?
Well, as I remember it, these applied problems in acoustics and the fast spectroscopic analysis of Sawyer and Wolf, and the infrared, both experimental and theoretical, and the beginning nuclear physics activity, the magnetron project which had just closed. Then of course there was theory, which was at that time naturally largely concerned with quantum-mechanical developments. Goudsmit, Uhlenbeck, Laporte and Dennison. Although as you know, Uhlenbeck had always had a very strong interest in statistical mechanics, and Laporte — I don't know whether it began at that time, but at least for a great many years he had a very strong interest in fluid dynamics, and eventually started a shock tube project which went for many years and turned out some very fine work. He built several quite elaborate shock wave tubes. I can't remember whether that had started by the time I came. I think it probably developed after I came.
You haven't mentioned Colby. What was he involved in?
Well, Colby was a theorist. I don't know, after I came at least, I don't remember anything that he did.
One thing he did was he brought Goudsmit and Uhlenbeck there. A talent scout, I guess you'd say.
We had another fellow there, Charlie Myer who had been there a long time. He was in optics. He taught an optics lab and again, I don't think he was doing anything in the way of research.
The nuclear physics group — I don't know if you referred to yourself in that way, but the people there concerned with nuclear physics, from the time of your arrival on would be (James) Cork, and Robert Thornton, who was new, yourself. Would Goudsmit be considered part of the nuclear group, or not?
He had an interest in it, and I think he did some work in nuclear physics. His main interest of course was in atomic problems, atomic spectra and such things.
So is there anyone else? These are all people concerned with accelerators, Cork and Thornton on the cyclotron, you on your setup. That's three people. That's about the size of the nuclear physics faculty group then? Now pretty soon, though, you're involved in research. Did you get graduate students from the start?
Yes. As I remember, when I got there, there were three graduate students sitting on the doorstep waiting for somebody to take them over. They helped me build the machine.
This would be Gaerttner and Turin? I know you published with them from '36.
Yes, Turin and Gaerttner, and then let's see, another guy, I've got a mental block now, I can't think of his name.
No, he was a little later.
They were looking for a thesis topic?
Yes, they were looking for thesis topics, and in order to get into some experimental work, ahead of the high-voltage tube, we pushed very hard on getting the cloud chamber operating. We did some work with the cloud chamber with artificial sources, before the high-voltage tube was operating, so they were able to get some experimental work ahead of the high-voltage tube.
Also in that early experimental work, you used some of the cyclotron sources, for example — (looking through papers)
I think so.
Well, that's '38 anyway. The radio-chlorine was supplied in one case, in the neutrino experiment, that's later on. That was supplied by the cyclotron. You acknowledge Cork and Thornton.
Well, in 1937, it looks as if Turin and Gaerttner I don't find Bayley in here, but I'm sure he also did some work —
Bayley did the beta ray spectrum of lithium -
— that would be with the high-voltage tube, so by the time they got ready for their thesis, the tube was evidently operating.
But their main job was to help you build the cloud chamber and to build the tube?
That was part of it, yes. They helped build the tube until it was ready to operate and then they did their experiments.
When did the tube first become useful for experiments?
Well, I can only go back to the dates of publication. (looking at papers) See, in '36, which was the next year after I came, we were still using artificial sources, because here is one about beta ray spectra of slow neutron activated substances, and Compton effect, gamma rays, that was done with radioactive sources. Here's one with Turin and Gaerttner on slow neutron activated substances, Turin, cloud chamber study with Compton effect, and so on. So in '36 we were still using artificial sources. Then in '37, the paper indicate that we were using the high-voltage tube.
They were still with you. That was the size of your group then. There were three graduate students — the three graduate students who were waiting for you on the steps. What was your interaction with the people working on the cyclotron?
We worked pretty separately. I didn't actually do any work on the cyclotron and they didn't do any work on my project. Of course we were associated, but we didn't work on each other's projects.
Were they housed in a separate building, or in your building?
The cyclotron was practically across the hall. We were both in the basement of Randall. It was across the hall, except it was on the next floor up. My room included the first and second basement, a double height room, and they were in the first basement. Fortunately there was some earth between the cyclotron and our observation room, because of the fact that they were on the first basement. There was not a basement under them.
Did the department have regular colloquia? I know they had regular colloquia and I'm assuming a journal club as well. Were there any special groups meeting on nuclear physics, any continuing thing which focused regularly on nuclear physics?
I don't remember if there was a nuclear seminar. We had the regular Wednesday afternoon general colloquium every week, and some of those colloquia were on nuclear physics. I don't remember the exact years, but soon after the cyclotron got under way I started a small seminar for the people in the university hospital radiology department, discussing biological effects of radiation and neutrons. A number of those people came over to Randall Lab once a week, and we had an hour and a half or two hour session on biological effects of radiation. I was quite interested in that subject for a period. I had studied it some before, and I was able to give them sort of the physics viewpoint in the action of radiation on biological materials.
Did they also contribute to that, from their physiology side?
They contributed some. They got up some papers on experiments that had been done with tracer elements and so on. But mainly I talked to them about the physics of radiation, and the way it disrupts molecules and atoms and so on.
Do you recall what year that was, '36 ? '37? Your first publication in the field is '39, when you have a very short thing on the use of radio- active elements as tracers in physiology, which is not the report of any specific experiment but just giving the physics background of this.
I think this would have been probably about 1936, maybe '37. I had quite a strong interest in biology from the time I came to Michigan. In fact, in about 1936, maybe '37, in the summer time, I attended the courses in the medical school on biochemistry and physiology. That was during the summer semester.
The biochemistry lectures were every day of the week at 7 o'clock. Then the physiology lectures were from 10 to 12 every day of the week. They were courses that were run at double speed for eight weeks instead of the usual 16, that's the way they did things in the summer — for those eight weeks I spent all my mornings going to these lectures. Then I read several books from cover to cover, like St. Darling's HUMAN PHYSIOLOGY and things like that. So I gave myself quite a dose of biology at that time. Then also I read quite a number of books on the biological effects of radiation. I think that was all before I had these people over from the radiology department to give them talks about it. I hope so.
That would be interesting. In other words, you took the general background and then with your own physics background gave specialized talks to these people from the medical school.
How many talks were there? How many of these seminars did you do?
I think we did it every week for the better part of a year. We missed some now and then, but it was fairly regular.
Have you notes for that or a record of that?
I don't have notes. I did it mainly from the chapters in some books that I have. It was mostly a course in elementary physics for them. Naturally I couldn't tell them about clinical effects. But I think they got something out of it. At least they were willing to walk over from the medical school once a week.
About how large a group on the average?
There were only four or five of them.
Were these some of the people involved in the joint physics-medical school program which the cyclotron was supposed to serve?
Yes, that was mainly the group. Fred Hodges was one who came. And Lampe, who was sort of his assistant at the time, came.
Was Lampe a physicist originally?
He got training in physics. I don't know whether he got his degree in it or not, but it seems to me he did.
It seems that I saw some correspondence at Michigan where they brought him in deliberately as a person trained in physics to work in the medical school. What about your own involvement, other than your own interest in learning about it and teaching about it? Was this part of your experimental program in any way? Did you envision getting involved in the application of nuclear physics to biology and medicine?
I think I thought seriously about it. But I never did. I wavered once or twice, I think fairly seriously about going into biophysics. You know, Michigan had a biophysics program, starting I think right after the war. You may not want to bring that in at this moment.
I'd like to hear about that. It seems the origins were in this period that we're talking about now.
I don't know who instigated biophysics in the physics department. I think probably Robley Williams. Robley Williams got his degree in physics at Cornell, on hydrogen spectra or something or other, and then he came and — I can't remember whether he was — I think he was a member of the faculty of the astronomy department when he came to Michigan. Because Al Hiltner, who is now a fairly well-known astronomer , (and now Chairman of Astronomy Dept. of U. of Michigan) was his student, and together they built a machine that would make intensity contours of photographic plates. I've forgotten the name of the instrument.
Then two or three other things happened about that time. Ralph Wyckoff, who was up to that time a well-known crystallographer, came to Michigan, and was attached to the School of Public Health. They brought him there thinking that — well, he had a strong interest in biological problems. Why they brought him there, I don't know, but he was there on a salary and had evidently nothing to do, but was supposed to enrich the School of Public Health in some way. Immediately he found that we wasn't very congenial with the people over there, felt a little isolated, so he started coming around to the physics department.
Robley Williams was in somewhat the same situation. He seemed to take more of a liking to the physics department than to his own department, astronomy. So he spent some time over there (in Physics Dept). And I think Ralph Wyckoff got Robley interested in biology. And also, another thing which happened independently, I guess, at about the same time; the bacteriology department persuaded the graduate school to buy an electron microscope, which was a new thing at that time. Since they didn't know how to operate any such gadget, they persuaded the physics department to have it located in the basement of Randall Lab, and persuaded the physics department to supply the technical expertise and employ a student to operate it. So it was used as a service machine for the bacteriology department.
It happened that I was put in charge of supervising the electron microscope and supervising the student operator. Robley got quite interested in both biology and the electron microscope, and he and I — well, it was at my suggestion — started the technique of shadow casting. Actually it was independently started by another fellow, I think at Dow Chemical Co., so we were not the only ones who started it. It was a fairly obvious kind of thing to do, as a matter of fact, at the time, but we started it, and it worked so well that Robley then got quite completely engrossed in using shadow casting for studying bacteria and things like that. He was interested mainly in the technique. I believe this was just after the war.
All these things, you see, happened in the physics department — Wyckoff coming over, Robley coming over, the electron microscope, and my past interest in biology — all this sort of resulted in the physics department making a commitment to biophysics, and hiring a little later ('50), Cy Levinthal who was a biophysicist. Also Gordon Sutherland joined the Dept. in '49 and with his post-doc Sam Krimm (now on the faculty) did work on biological molecules using infrared methods. You probably know him.
Yes, I met him.
So then the Dept. started in earnest and started a biophysics lab, which was a suite of rooms in the first basement of Randall Lab. Eventually they got another fellow, a young post-doc, I guess he came as an instructor, as a matter of fact, Charlie Thomas. Wyckoff was still around. So we had quite a little nucleus of biophysics in the physics department.
This continued. Levinthal left and Charlie Thomas left. Sam Krimm came, who was not interested in the same kind of biophysics, but anyway he was interested in the application of infrared and electron diffraction techniques to studying biological molecules. Later on, Worth came, who was interested in the same thing, and to this day we do biophysics in the physics department.
Identified as a separate group?
It's a group. It's not a division or anything like that.
Part of physics.
Now we have Sam Krimm and Venkat, the Indian fellow. Dick Sands is interested in biological type problems. They now have laboratories on the north campus, in the Institute of Science and Technology building. But they don't carry on what you'd call "wet" biophysics. That is, they don't work with virus and bacteria and such things, they work with the structure of biological molecules.
But crystallography per se that developed after the war, the protein work and so forth — that was not pursued? What happened to Wyckoff?
Well, Wyckoff finally left and went to the University of Arizona.
But it didn't develop in that way, the way other people, like for example Fankuchen and other people in crystallography went — in other words, there was nothing built up there as a result of Wyckoff's work?
Wyckoff never built up any crystallography work, as far as I know, after he came to Michigan. That was his prior work. At Michigan he was mainly interested in biological-type problems which I suppose involved some of the ideas from crystallography.
Then Robley Williams launched on a more ambitious program for biophysics at Michigan, and he wanted to have a Biophysics Institute established. He actually pressed hard enough so that he got the regents to create a Biophysics Institute, and to make him director of it. Then for some reason which I'm not clear about the whole thing blew up and he left and went to University of California, before the Institute ever got into action.
That's a separate study I hope someone does some day about the development of biophysics as a field of research, from the mid-thirties on, when people like Bacher were considering going into it because it was the only job available, and having great doubts as to whether there was a future in this field for a physicist — then the change in the field over time. It would be a very interesting thing to study.
Yes, it would be, because in the early days of biophysics, when Debunk and a few others started studying virus, they were able to just apply physics types of reasoning to these objects, and treat them like molecules, and just find out some basic things about them. They initiated a whole new world of biophysics. But I think within ten or twenty years, the field then became so highly professional that it's no longer possible for a physicist to just go into it and capitalize on his knowledge of physics techniques, without very much knowledge of biology, which is what these early people did. But now if you go into it, there's so much professionally complicated biology that you have to know, in order to compete successfully, that I think physicists can't any longer just make that simple change.
Well, there are degrees offered in biophysics, and have been for a long time, as evidence that one really needs to combine the two at a very early stage.
Looking at your research for the years in the thirties, you're continuing the things you'd started or in a general way — the papers with Turin, for example, on energy loss discrepancies, absorption of high-energy electrons. It seems to me that this is the kind of work that characterized your period — in the thirties in general. One of the things I notice in one of the papers is that you have correspondence with Rose, who was at Cornell I guess at the time; that there were some discrepancies with your work and the work that was coming from some of the cosmic ray results of other people, and that Rose came into the picture as a theorist. How did that tie develop? Was it through the Michigan Summer School?
Well, probably Rose came to the Michigan summer session one time or another. I know that Rose was actively working on the problem of multiple scattering, which is a horrible problem, extremely hard to solve analytically. Now it can be done by Monte Carlo methods, but it was just a quagmire, as far as trying to do it analytically is concerned. He was wound up in that kind of thing, we were doing experiments on multiple scattering, and it wasn't surprising that the experimental results didn't agree with the theoretical. We were probably both wrong. So that's where the correspondence developed. I think looking back on it, it was a kind of a fruitless field to be in. If we'd just waited for the invention of computers, it would have been solved.
That's like asking Rutherford to wait for the invention of the cyclotron.
How would you characterize the work of those years, from '36 through '39? There are things that come in the middle of it, that are individual papers, but what would you say your major concern was, what you were trying to accomplish in the various experimental work, toward that goal, in terms of the nuclear physics objectives? And how successful do you think you were in making contributions toward it? While you were building machines.
I guess in those days, work tended to be divided into two categories. One was the experiments aimed at finding energy levels in nuclei, energies of gamma rays emitted during bombardment, which all gave information about the nuclear energy level. That was a continuation of work from Cal Tech. Then we did quite a number of experiments on electron scattering, mostly multiple scattering, which as I mentioned turned out to be frustrating kind of a business
All these things were mainly done with the cloud chamber. We were able to do them with the high-voltage tube, either during bombardment or more particularly, we had the tube on a fast-operating relay, so that we could give the target a shot of protons or deuterons, and then shut the high-voltage off just before the cloud chamber expanded, so we'd get rid of all the x-ray background stuff that would have been present. For any kind of process that was a little bit delayed, we could do that kind of trick and get rid of the background.
So that's mainly what we did.
That technique was useful, for example, in '38 when you had the paper on the particle of intermediate mass. You described this technique of the cloud chamber, making certain of what you had — being able to demonstrate what I gathered was a verification. It was just after Street and Stevenson, it agreed somewhat with Street and Stevenson, but was significantly different from Nishira and other Japanese who had talked about some particles in that range.
Well, as I remember it, that particle that we had a picture of was just something that might have come in from cosmic rays or any other old place. It just appeared in the chamber, and was obviously a particle that had curvature in the magnetic field, so it couldn't have been an alpha particle. And it was much heavier than an electron. So it was just a curiosity, this one particle, and not knowing where it came from, you couldn't do anything.
You couldn't do it again. What was the response at Michigan? Do you recall discussions of some of the developments that were occurring in the mid-thirties? For example, the announcement by Fermi and his collaborators in Italy of the transuranic elements?
Well, I think we were interested, and we had seminars about it and all that, but I don't think we had much to contribute.
No one was doing that kind of slow-neutron work at Michigan?
Except Fermi when he came to Michigan during the summer. What about the meson itself, or as it was called, the mesotron? That's what Street and Stevenson's work led to, and Anderson's as well. There was no real cosmic ray program anyway at Michigan. Do you remember any discussion of the results there? This is all in the absence of theorists on the faculty who would be directly concerned about nuclear physics.
We have had an interest in cosmic rays ever since Hazen came on the staff. That was later. Hazen joined the staff from Berkeley in 1947. I think he worked with Bob Brode at Berkeley, and he started a cosmic ray program with cloud chambers and he continues to be interested in cosmic rays. Later Alfred Z. Hendel joined our department, and worked in cosmic rays also. So, dating from when Hazen came, we have had a modest size program in cosmic rays.
At that time, in comparison to active programs, for example at Cal Tech, there was nothing comparable at Michigan, except that you had a cloud chamber and were capable of finding some things.
No, up till Hazen came, there was no explicit program on cosmic rays.
One thing I find interesting was the neutrino experiment with Halpern. Was Halpern one of your graduate students?
No, Halpern was a postdoc who came and worked with me for two years. We were able to observe the recoil of the nucleus in beta ray disintegration, which was the first time that had been observed. Up to that time — oh, I guess there was no real doubt about the momentum conservation , but historically there had been a question of where the missing energy goes and where the missing momentum goes and so on. We demonstrated that the nucleus recoiled in such a way that it demanded a third particle. That is, the nucleus did not recoil in just the opposite direction from the momentum of the visible electron. It indicated that there was an unseen particle escaping also. So this turned out to be quite a significant experiment.
This probably was the first analysis of the momentum relations of an individual disintegration. Were you able to do that because of the setup? Was the importance of the experiment in the fact that you did it in order to get an individual event?
Well, we did observe individual events in the cloud chamber. We put the radioactive material in the gas of the cloud chamber, so that first of all, the disintegrations were in the gas of the cloud chamber. They were not from the wall. The recoil of the nucleus is so low-energy that it doesn't make a track, you have to observe it in some other way. It does make a number of ions, it has enough energy to make collisions and make a few ions. So by turning off the clearing field, and waiting a brief instant, after the disintegration, to allow the ions from the recoil to diffuse out in space into a little cluster — then the droplets were enough separated so that we could count the drops. Then, from that we worked back and determined the energy of the recoil.
How did you devise that experiment? First of all, it's a collaborative one, I gather, with Halpern. How did it come about that you got to the point which you've just described, which was the final experiment? Was it something you visualized from the start? You were looking for that kind of an event, with that result in mind?
Well, I think I'd been interested in the neutrino earlier than that. I believe it was before that time that I did an experiment trying to detect the neutrinos from the sun, by exposing a bag of salt for some period of time and then trying to analyze, extract the radioactive chlorine from the salt, which would have been produced by solar neutrinos. I think that was before that time.
Anyway, over quite a period of time I was interested in the neutrino and any ways to find out anything about it. And the question of the recoil of the nucleus was a fairly obvious unsolved problem. You could ask any physicist, "What are the things we'd like to know about neutrinos that we don't know?" he probably would mention that we'd like to see which way the nucleus recoils and how much energy it has, so we could be sure — whether there's evidence for some unseen particle escaping from the nucleus.
The question was, how to do that? I guess I just got the idea of doing this diffused droplet experiment. I think that was after Halpern came. I don't think he came to do that experiment. I think he came, and then I got the idea after he was there, and we got off onto that. It turned out that that was what he mainly did for the two years that he was there.
Was that a long running experiment?
That was quite a long term. We did two, we did it once and then we started all over again and did it better the second time.
Yes, I see a second publication was involved in this. Using in this case the radiochlorine supplied by the cyclotron. During this period, you were involved in the summer schools at Michigan, except for the summer that you were involved in the biochemistry school. You were also attending — your bibliography shows that you were presenting papers at the various American Physical Society meetings. In one paper you referred to the Washington (D.C.) Conference on Theoretical Physics. Had you attended that, or was it in reference to some other discussion that came out of it?
I went one year. I was invited to go down for a day or two. I was not a regular attendee of it, but I was invited down because they were talking about electrons, and the possibility that there are electrons of greater mass than the usual mass from radioactive decay. This would be an alternative to the neutrino hypothesis. The missing energy has to go somewhere. The question was, maybe it goes into the additional mass of the electron, instead of the neutrino. So I went down and described some of our experiments.
What was the atmosphere of that kind of meeting, compared to the summer school? Well, summer school was a school, this was a conference.
It was a conference. It was much more of a hard working type of affair.
It met for about a week, I guess.
It met for a week, and they had sessions essentially all day.
That was 1938, then. Was that the only one you went to?
Yes, just that once.
You just went to the sessions you were concerned with?
I believe. I certainly wasn't there for a whole week. I must have been for one day or two days.
Just a general question on the relationships within the department. Was there any competition among the various groups? There was the cyclotron group developing, and your work — was there any competition regarding results, time of completion, of getting into operation at a certain time, doing experiments with it?
I don't remember being competitive with the cyclotron. I think we were competitive with our own time schedule. We wanted to get things going as fast as possible and get some research going. The things we were doing were enough different so that we weren't racing to get to the same goals.
That's good. Were there any administrative kinds of meetings, I mean programmatic meetings within the department, concerned with the nuclear physics program in general? This is pre-war.
Oh, I don't know. I wasn't much involved. I wasn't on the executive committee and I wasn't much involved in administration. My only administrative job was that I was the advisor to undergraduate junior and senior physics concentrates. I was given that job when I came, and I had it for ten years. It was a rather time consuming and for me a boring job. There weren't many physics concentrates, but I had to counsel them.
In terms of their programs?
And you had that in addition to your six hours teaching which kept up steadily in this period.
Did you start switching to more advanced courses, after the first couple of years?
Yes, I guess the first course I took over that was different from the elementary teaching was a radioactivity lab that had been started by A.W. Smith, the guy who wrote the electrical measurements textbook. It was built entirely around natural radioactive sources, of course, and the instruments were just electroscopes, metal boxes with gold-leaf electroscopes, this had been run for years and years, you'd get radioactive material, uranium and things, and these boxes with the gold leaf in it. About the only experiment you could do was to collect some of the shorter-lived radioactive products of radium and uranium on little pieces of foil, and put those in the electroscopes and measure their decay. You can collect some of the short-lived products from these natural radioactive materials, with half-lives on the order of a half an hour or so, and you can collect enough to measure the decay curve. That's about what you get.
Well, I went along generally on those lines. I improved the electroscopes some, I thought up what I thought were better experiments. I ran that for a number of years. I taught a course in radioactivity for several years. I taught electrical measurements for quite a number of years. I taught the electrical measurements laboratory. I can't think of any others during that period, but I did teach some of the intermediate courses.
How about graduate courses?
I've never done much in the way of graduate courses. I've done courses that have been hybrid graduate and undergraduate courses. But graduate courses, really high-powdered ones, were always taught by Dennison, Uhlenbeck, Laporte, Goudsmit, the big theorists.
I see. But you were working directly with the graduate students in your research. There was some correspondence that you had with Willie Fowler, at the end of the thirties, characterized by the phrase, "To hell with gamma rays." I'm not sure they were all at the end of the thirties, because you had the terrible habit of not dating your letters. But there is one that I did find a date on. Anyway, it's still on the scattering of electrons and one is, I think 1939, anyway, perhaps you could take a look at this (looking at letters). Some are dated, some are '39, '40, but the earlier ones are not, maybe that will give you an idea what this was about. These are from Willie's files, your letters to him. I wish I could find his letters to you.
I don't see where it says "to hell with gamma rays" but I see how I might have felt that way at one time.
I'll show you that letter. That's the one.
Oh yes, I see it here. No comment, I guess.
It was pretty frustrating. I guess it was his expression to start with, at the beginning. "I join with you in the chorus, to hell with gamma rays." Anyway the point I'm getting at in this is that you kept up a correspondence, with him, at least on this subject. Was there anyone else that you corresponded with about your research during this pre-war period? Who would be more than a casual correspondent?
I don't think so. I think my only correspondence was with the group from which I came, namely the Cal Tech group, and I suppose that Willie Fowler was my contact there, and I wrote mostly to him.
You continued, you were working on the same subject as they were.
In these documents I have here, you say, "Since the completion of the high potential apparatus four years ago, "so I'd say this was 1940, estimating, or '41. Anyway, these are from the Michigan archives, from Randall's files. "Proposed Program of Research in Connection with the High Potential Apparatus," and that's a single sheet with your name on it, and yet there's also another one, "Program of Cyclotron in Physics," another one, "Application of Nuclear Physics to Biology at other Institutions," (a survey of what's being done elsewhere) and then "Present Status of Physics." Do these look familiar? There's no identification of it, but it looks as if it was kind of a recapitulation of what has been going on.
Well, I think that's the kind of thing that we had to get up to send in to the Rackham board for the renewals of our grant. These are like the thing you have to do for the NSF. Describe your program and your progress and tell them what you expect to do and why it's important, and ask for renewal of your grant. I think that's in the nature of that. I remember distinctly that at one time Randall was in the midst of getting up one of these progress reports or renewal requests, and he got kind of bogged down in it and had so many bits and pieces that he'd gotten from the various research people involved, that he was trying to put together, that I went in and spent I guess most of a day trying to piece this together and organize it into one of these things that was sent in. So I think that's in the nature of those, telling how good we were and how good our program was going to be.
For example you summarize it and say that the electron studies will furnish the material for three PhD theses and for eight publications — a kind of summing up —
— that sound like the kind of thing you do for that purpose.
Well, was there any crisis? The first Rackham grant was '35, for a five-year period. By 1940, which is about when I date this document —
we got some further money. That's what this was about.
This was really for the renewal for the next period.
I think it was a year-to-year business after that, but we did get some more money after the five-year period. That being 1940, that's just what that is.
Well, I'm estimating. For example, it says on one of the other sheets, "All Nobel Prizes in the last five years have gone to nuclear physicists." The thing I'm really looking for in here is any mention of fission. Anyway, it looks very much like an appeal to the Rackham Fund.
Here's an important thing. It says, "What can one hope from nuclear physics? Then it pointed out "the fundamental nature of nuclear research for the physical sciences is already stressed. Technical applications are still in the far future. The fission of uranium and the possibility of liberating enormous amount of energy in this way have given us an inkling of what one may expect." Third, application in other sciences, chemistry and especially biology, through tracers. Finally, there are the possibilities of using the radiation of the artificially radioactive substances and of neutrons in medicine."
I guess that's how one would have characterized the general state of justification for nuclear physics at about that time.
You're the expert on how fission got to be known. Wasn't that pretty well corked up, on account of the military applications? So that people weren't discussing it and publishing about it?
Well, when Turner from Princeton published his review article on fission in January of 1940, in REVIEWS OF MODERN PHYSICS, he had more than 100 articles listed, so it was still being very well published in 1939. It was only '40 that the secrecy started, and even then a lot of people were publishing and corresponding about it. It did mention fission here, but it talked of some time in the remote future something happening. That was before any real fission project was started, in terms of military applications.
I mean, fission was one of the aspects of learning about nuclear structure and nuclear behavior and so on. But the thing that would have set it apart and made it a very special kind of thing would be the mention of the possibilities of power and so on, nuclear power. So that aspect of it was not generally circulated around at that time, was it?
Well, the first announcements of fission were accompanied by big newspaper stories of potential energy developing from it, big stories about all this energy unleashed. So there was some really good open public discussion. Which seems to be a recurring thing, that any time anything happened in nuclear physics, the energy or the biology part was brought in. Even the first announcement of fission that I've seen in the papers said, "We don't know what use this will be, but there's an enormous amount of energy involved, so many times more than radium, and we all know that radium has been very useful medically and biologically." There was some discussion. There was a meeting at Michigan, I don't know if you recall, that Randall I think put together for industrial people, for a demonstration of fission, because he thought that this would be of interest to them. There was a conference planned, I think in 1940, I have a file on it, where you had people from various (places), heads of laboratories or people sent by those laboratories, from a number of industries throughout Michigan, not only the giant ones but a lot of smaller ones. There was a demonstration of fission put on and some lectures explaining it. Do you recall anything about that?
OK, some day I'll try to solve it. It's a fascinating thing, I think, the attempt to spread the word — I don't know what the motivation was. It seems to me it was to let industry know that something useful and interesting was going on in the physics department. It may have been a bid for some kind of industrial support for future work. There was a whole series of responses from the people there saying, how pleased we are, how interesting it was. But it wasn't obviously something that was going to result in a lot of grants. This was still before the military involvement. Now, how did you first learn of fission?
I don't know. That's a straight answer. I don't recall when I first heard about it.
Do you remember anything about the response at Ann Arbor?
You don't remember any colloquia, discussions?
I'm sure we had a colloquium on the subject, but I don't remember the circumstances.
OK. How did the war hit the department? What was the first intrusion of the national emergency into the normal physics situation at Ann Arbor?
Well, a number of people left right off. The MIT Radiation Lab was organized before the US went into the war. It was organized in the fall of 1940. And in the fall of 1940 or the late summer, I don't remember which, Ernest Lawrence took on the job of recruiting some people for the Radiation Lab, and I got a call from him, asking me to come to Cambridge to talk with him, so I did, and he persuaded me that I should — you know, you can't talk to Lawrence without being persuaded. He was the greatest persuader that ever was. So I immediately was persuaded to prepare to go to the Radiation Lab. I was one of the first arrivals. I think there were only a dozen of us, the first few weeks that I was there. So I stayed.
But prior to that time, or before Lawrence had recruited me, I had promised Merle Tuve that I'd come and work for him on the proximity fuse. He was still in the very early process of trying to get something going, and he wasn't even ready to have any helpers come and join him. He didn't even have the money. But anyway I promised him that he got something started, I'd go, so I had that prior commitment.
So I stayed at the Radiation Lab until February. By that time Merle Tuve was ready to go, so I left the Radiation Lab and went and worked in Washington at the Department of Terrestrial Magnetism for nearly a year. Then I broke off a project, a satellite project of the proximity fuse work and started that at Michigan. For most of the rest of the year, Dennison and I ran the laboratory, with a maximum of 20 people or 50 at Michigan, on proximity fuses.
This was under a contract with OSRD?
It was under a contract with the Bureau of Ordinance of the Navy. They supplied the money for Tuve's lab and also for us.
Did you move with your family first to Cambridge, did they come with you when you went up there?
No. We didn't move to Cambridge, because I knew I was going to be there only a few months. We did move to Washington.
But you did go on leave from Michigan from about the fall of 1940, until you returned there in — ?
'41, early '41. And then, of course, for a number of years after that I was on leave or partial leave from teaching. I was putting my entire efforts on the proximity fuse project. Do you want to go any further on this wartime —?
Yes, I'd like to.
Our work on the proximity fuse was scale modeling. We made airplanes of about one-eighth size or one-tenth size, and then made proximity fuses which were similarly scaled in wavelength and time constants and so on, and we flew these airplanes past the proximity fuses. By flying I mean we flew them on ropes, little trolleys, flew them past the proximity fuses and measured the electrical responses in the proximity fuses, and reproduced the actual pattern around the airplane on which the proximity fuses would fire. By changing the circuit constants of the proximity fuse, we could tailor that firing pattern around the airplane so as to give the maximum effect.
This turned out to be the only way in which the proximity fuse could be designed ahead of its use. Design it to have a certain burst pattern around the airplane. And it turned out that after they were in use and those burst patterns were measured, they came out very accurately to what we had designed. It was a good project.
Then, near the end of the war, the Manhattan District conscripted us to do some work in the Los Alamos. They thought that the proximity fuse would be a useful way of exploding atomic bombs at the right height above the ground, so they wanted us to try to modify our proximity fuses to be useful to the atomic bomb program. It turned out that nothing ever came of it. We modified them and made them so that they would fire at the desired places, and some were dropped in dummy bombs and so on, but the whole thing, it turned out, was never used. But you have to do those things, I guess.
Was there any problem in informing you what was going on at Los Alamos? Did you have full knowledge of it?
Oh, I went there a number of times, and they were quite open about — I found out pretty much what was going on. We had a liaison man between Los Alamos and our lab, Bob Brode. He came to Michigan fairly often, and occasionally I went to Los Alamos.
We served the Los Alamos project in another way, and that was if they needed very special kinds of materials and machine work from the Detroit area. Some of these were such as concentric spheres and cases for their bombs and such things, and they needed a fence, a blind. That is, they didn't want the Detroit manufacturers to know where these things were headed for. They needed a go-between who would insulate them security- wise. So they would tell me what they needed, and I would relay the orders to the manufacturers in Detroit. Somehow the specifications and drawings got to the people in Detroit. I didn't have to pass those along. I was only making the financial and business arrangements for them. From the government somehow, not Los Alamos but from some unknown place in the government, a lot of money would be placed in the University of Michigan accounting department, hundreds of thousands, a million dollars. Then it would be up to me to ask them to write purchase orders to certain Detroit manufacturing firms against this money. The only thing I could tell the business office was some phony name — they had all these names for the various kind of equipment, which were meant to confuse people so they wouldn't know what it was. All I could ask them to do was write a purchase order for 50 or 100 thousand dollars for something (off tape)
Well, here was the university vice-president of finance, sitting on hundreds of thousands of dollars over there, and I would call him up, call up the business office, and tell them they should place an order to a certain firm in Detroit, for five "fat boys" at $80,000, or something like that. That's all I could tell them. When the "fat boys" were manufactured, then they were shipped mysteriously to some location in New Mexico, actually through Jack Workman's laboratory, which was again a blind on the other end. Then the Los Alamos people were going to pick them up. It was an elaborate way of concealing where they were going. Finally, it made a nervous wreck of our vice-president for finances, having all this money go in these mysterious ways, so he rebelled finally. Then we had to get a delegation from the Defense Department to come, have a big conference with our president and vice-president of the University. They sent Captain Parsons, the guy who rode along with the first atomic bomb over Japan — they sent him with all of his gold braid and medals and things, to come and sit and confer with our president and our vice-president, and tell them that by golly, they are supposed to do this. And that they weren't risking bankruptcy of the university or anything. So after that, it went all right.
If the name "fat boy" was actually used — you thought that was all right? Was that the word you used?
As I remember, at that time — of course, it hadn't been used for any other purpose at that time.
Was that the name they suggested? You didn't make it up?
I didn't make it up. They told me what the name of the thing was. That was kind of a wild experience.
Did there approach a time, toward the end of the war, when you were concerned with what would happen in the department in the postwar period; not only the department, but changes in physics would take place, from the wartime experience.
Yes. I think I should mention also that during the war, some other people went away and worked for the war effort. I can't remember exactly all of them, but Dennison was associated with our proximity fuse project. Cork I believe went away somewhere. Research pretty much slowed down to almost a stop at Michigan during the war. People were involved with the war. Duffendack had a project at the university on some kind of an optical radar scheme and worked on that. I suppose we were typical.
Now at the end of the war we made a slow start in taking advantage of developments and opportunities. In the first place, we tried to hire a couple of new staff members from the (MIT) Radiation Lab. Uhlenbeck was instrumental in proposing a couple of the outstanding young people who had been at the Radiation Lab for faculty positions at Michigan. We tried to get those appointments from the Dean of the College and from the regents, and we ran into a great deal of just plain lethargy. They just plain couldn't be convinced that a new era had begun and we should be hiring people and doing things that fast. It got to be a pretty sticky situation. Uhlenbeck pressed very hard and the rest of us did too, and the college didn't budge, so it came to the point that we called a conference between the president of the university and the dean and I don't know who else, but the big shots, Uhlenbeck and Dennison and I principally and I don't remember clearly whether Laporte was also involved and Goudsmit, but I know Dennison and Uhlenbeck and I went over and in effect threatened to resign, if they couldn't open up some appointments. Well, things were better, after that.
When was this? Was the war over or was it coming to a close? Do you remember the date on this confrontation?
I think it was right after the war. You see, it had to be, because the people that Uhlenbeck had proposed were from the Radiation Lab, so it had to be at the time the Radiation Lab was winding up.
Was it in the fall of '45, perhaps?
Probably. Then on the matter of finances, we were a little slow on the uptake of taking help from the ONR and from other government agencies that wanted to give money to universities. Although the proximity fuse project that I had had, at the end of the war continued. The Bureau of Ordinance had supplied all the money through the Johns Hopkins Applied Physics Lab, so it was BuOrd money. We kept that money flowing for a few years after the war, and that was what we used to initiate the racetrack synchrotron. In fact, the BuOrd money paid for the racetrack synchrotron that we built there. So that government money continued. But that was not exactly free money. We were partly doing free research, but I also continued to do a certain amount of work on proximity fuses for them, and think about some of the problems they were interested in. But other than that, the department was pretty slow in grabbing onto money that was offered by the ONR and such agencies. They were a little bit leery of the permanence of them. They didn't want to take it and staff projects and hire people and so on, and risk that it would all peter out after a year or so, after the postwar enthusiasms had subsided. They didn't realize it was going to be a new way of life, here to stay. We should have — some other universities did grab it in a big way, and were right in doing so.
Was Randall especially conservative in this?
I don't know that I'd say he was the one. Maybe I was too. It was just the atmosphere.
On the racetrack modification of the synchrotron, you say that was supported by the Bureau of Ordinance of the Navy funds. Was it out of the proximity fuse contract, I mean, was it part of that contract?
Well, you see, Merle Tuve started the work on the proximity fuse at the Department of Terrestrial Magnetism, and then the administration of that project was taken over by Johns Hopkins University, called the Applied Physics Lab, and they moved to Silver Spring. As you know, that used to be a big garage or something, and they rebuilt that for the laboratory. All the time it was BuOrd money, as far as I know.
And at the end of the war, the Johns Hopkins Applied Physics Lab went right on. In fact, proximity fuse work continued, because the War Department considered that one of their useful weapons. So this continued, and certain people who were associated with the APL continued to be associated and continued to get subcontract money. And I was one of them. After the war was over, they allowed us to use part of that money for free types of research, and part for consulting with them with their military problems.
Did you have to justify or propose what the free part would be, in advance of getting the money?
Well, we had to turn in proposals and progress reports in the usual fashion, but so far as I know, it was our choice.
Suppose you had $50,000 from them and a certain amount of it is earmarked for "free research," say $10,000. Is that the kind of thing? You actually had the money to spend, and you could spend the $10,000 for this kind of free research or any other kind, and report to them what you'd done with it?
I don't know whether it was that much spelled out.
Not even that much? That seems to me very liberal terms. Anyway, there was enough in it, because the first two publications on the racetrack, yours and then the analysis of the stability of the orbits by Dennison and Berlin indicate that Bureau of Ordinance contract supporting you. It's the same number on each of them.
You remember it. I guess if you live with it so long, you don't forget. Let's talk about the origins of the racetrack. How did you first hear of the synchrotron, of the work of McMillan and Vekslar and others had done on that? Or had you thought of that idea before you heard about it?
I guess I read about the synchrotron in the Letter to the Editor in the PHYSICAL REVIEW by McMillan. Then a little later McMillan wrote that he acknowledged that Vekslar had also invented it. I think not long after that I talked to McMillan, and a little later still, I went out and saw the synchrotron at Berkeley that he built. Well, I got to thinking about the possibility of building a synchrotron, and some of the problems that were inherent in it — for example, the fact that you had to make a hybrid betatron-synchrotron in order to get the particles started. The synchrotron really only works after the particles are up to the velocity of light or very nearly so. If you inject them at 8/10 or less of the velocity of light, then they don't go around at the right frequency, until they get built up to the velocity of light or nearly so. And to do that, the only way at that time that was feasible was to make the machine operate like a betatron for the first part of the time, to get the particles accelerated up to where they were fast enough so that you could then switch over to the synchrotron mode of operation. That was a fairly ponderous way of doing it, because you had to not only build the synchrotron magnet ring, but you had to have a big core down through the center to furnish the betatron acceleration.
So I got to wondering whether one could accelerate them in the synchrotron fashion all the way up but changing the applied frequency to an appropriate value, during the first part, and making the frequency change in the right way so it would be followed up to where they went near the velocity of light. That sounded like a good idea, except that I then couldn't see how to put these RF electrodes into the machine. There wasn't enough room in just a ring-shaped synchrotron. Then I got to wondering whether one could put gaps between, make it in sections and have straight gaps, straight sections, and put the RF accelerating equipment in those gaps.
Well, that sounded a little horrifying to start with, because up to that time everybody had thought that a particle would be lost if you didn't have a perfectly circular and symmetrical ring for it to go around. Put straight gaps in it — it sounded a little radical. But Dennison and Ted Berlin, who was there at the time, understood some calculations which showed that, except for some resonances which one had to avoid, the thing should behave all right with straight sections in it.
In fact, it's interesting that they had the equations which would have shown the alternating gradient synchrotron, which was later invented by Snyder and company. If Dennison and Berlin had just stuck in different numerical values for their gradients, so that some of them were negative, they would have had the alternating gradient machine. But it didn't occur to them, or to any of us, to make some of the gradients negative. It was all right there in their equations.
But that's how the synchrotron got started. Then we did some work on modeling the magnets, and eventually we ordered a magnet from Allis-Chalmers in Milwaukee.
When was the decision taken to built it? An idea is one thing, but then what did you have to do to get the go-ahead to actually build it? Did you feel free just to apply part of your BuOrd budget to it? Did you have to get approval from the department or the university?
Oh sure, they knew what we were doing, and we got approval to spend money for it. They were quite flexible about it. Tuve was still in charge of the APL and he had a good deal to say about what they supported in the way of subcontracts. So it wasn't any big problem.
What did you have in mind, as to the physics uses of it, the justification in your mind for an experimental program on the machine?
Well, we thought that the high-energy electrons were going to be very interesting. They didn't turn out to be, really. There were things you could do with them, but it was not (in that energy range, a few hundred MeV) a fruitful kind of a machine. As you know, McMillan finally junked his 300 million volt synchrotron. The Cal Tech one, which was a higher energy electron synchrotron, was finally dismantled, and ours was dismantled. It just didn't turn out to be a really fruitful deal. But we thought it was going to be, and we thought it would be worthwhile building a machine to produce high-energy electrons. I think electrons of extremely high energy, in the many-billion volt range, have turned out to be somewhat interesting — the Cambridge, Harvard-MIT electron synchrotron that Livingston built, was in a much higher energy range, (almost 6) billion volt range, and I think it was more fruitful. But again, I don't think that was as fruitful as the proton machines of the same energy, by any means.
How was the energy choice made for the machine that you built? What determined the decision to go at a certain energy?
I suppose partly the money we had available. The magnet we bought cost $14,000. We bought a big condenser bank and some other capital equipment. I don't remember how much the whole thing cost, but initially maybe $50,000 or so. It was on about the scale that we thought we could undertake. Even things like the size of the room — it was built in the room that had been occupied by my high voltage equipment.
What happened to that?
It was dismantled when we started the synchrotron. It sat idle during the war, and then at the end of the war when we decided to build the synchrotron, we just took it apart.
You made no special application for funds, and made no fuss of it, the structure, in every sense — even the building structure.
That's what I meant a while ago when I said we didn't react very strongly to the opportunities, in terms of big financing. We could have gone out to the ONR or somebody and put in a pitch for a million dollars to build a synchrotron much bigger. We just didn't think in those terms, I guess.
Were you concerned with all the competition from other universities that were also going into large accelerators at the time? Were you aware of what was happening around the country?
Oh sure, we knew what other people were doing. I think we were really more interested in seeing whether this new type of machine would work, right at the start, than we were in the possible research program for it. And that being the case, I think we were as interested in a moderate sized machine — I mean, that would be just as interesting in telling us whether the principles worked as a bigger one. In fact, the whole thing, the whole idea of the racetrack, was just risky enough that it would probably have been unwise to build a big machine right at the start.
Yes, a machine of that size, that cost, was still really a model.
It probably should have been smaller — either much smaller, or much bigger, one or the other.
When was it first clear to you that this machine would have limitations in terms of its usefulness for experimental research, as it was developing in the field of particle physics and high-energy physics?
Oh, I think it became clear as soon as we got into using the electrons, and it was not just our conclusion. I think other people had sort of come to the same conclusion. For example, McMillan, with his 300 million volt machine. We did a few theses on it, but they were not very exciting. So we felt, along with other physicists around the country, that it was not really a very fruitful kind of a field.
When did it go into operation?
It took quite a while in the building.
You had the first paper reporting, in '46.
We started the idea, started the thing right after the war, about '46. It must have been three or four years in the building. And it wasn't just the length of time in the building, it was that we couldn't get the doggoned thing to work.
The first paper on it, along with the Dennison paper, April of '46 you submitted it. Then in '47 you have some stuff on magnet design relating to it.
I think the main use of the racetrack was that it showed that a machine with open sections in it would work. That principle was adopted for all the big proton machines, like first the Brookhaven cosmotron, and the Berkeley Bevatron. Well, all of the big proton synchrotrons have been made that way. So I don't regret the time spent on it, but it did take a long time. First of all, we designed it with too small an aperture. That is, the vacuum doughnut was a little bit too small in inside diameter, and we had a terrible time to get the electrons to go around without hitting the walls, because it was just too narrow a passage for them. We went through a long period of developing a doughnut that had more space in it. It was just sticky technical matters like that. We went through a long period of trying to get that RF to modulate in the right way to keep up with the change in he velocity of the electrons.
So, with the normal construction delay, it might have been '48, '49? We could check on it.
I think it probably was about three years before it really got into action.
Then you say after that its lifetime was — ?
Well, we turned out about three or four theses and then that was the end of it.
When did it go out of existence, when did it stop operating? What was the time on that?
I don't know. I would say, the last thesis was probably turned out in the early fifties.
How about the name? Whose idea was it to name it "racetrack?"
That was my name for it, and the reason was that the first concept of it was a figure with two straight sections, sort of an oval, two half circles with straightaways in between. It looked like a racetrack. Then very quickly it turned into one with four quadrants, four straight sections, and it didn't look so much like a racetrack. It turned out to be four quarter circles, with four straight pieces. The original one was two half circles, with two straight sections, and that did look like a racetrack .
Well, let's see what we're going to do about time. This is one logical point to break, but there are other things I wanted to talk about, and maybe we can do it. Subsequent research interests the radio dating, the g factor work. There may be others, things I want to get a little background on. Then I wanted to talk a little bit about your experiences with MURA — you know, your evaluation.
I think we should sit down again, at your convenience, and when I'm here, and talk some more.
Let's just say, it's enough for now.
 28 March, 1973
Some earlier expts. by Leipunski seemed to show it, but the data were somewhat borderline.
 At the end of WW II, the university launched the "Phoenix Project" for "peaceful uses of atomic energy." Many industrial corporations were approached for money. I suspect the above it's refer to that and that it occurred in about 1945 or 6, not 1940.
 e.g., names for bomb cases were "fat boy," "thin man" etc.
 Code for casing for uranium implosion bombs
 Office of Naval Research
 Midwest Universities Research Association