Notice: We are in the process of migrating Oral History Interview metadata to this new version of our website.
During this migration, the following fields associated with interviews may be incomplete: Institutions, Additional Persons, and Subjects. Our Browse Subjects feature is also affected by this migration.
We encourage researchers to utilize the full-text search on this page to navigate our oral histories or to use our catalog to locate oral history interviews by keyword.
Please contact [email protected] with any feedback.
This transcript may not be quoted, reproduced or redistributed in whole or in part by any means except with the written permission of the American Institute of Physics.
This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.
Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event. Disclaimer: This transcript was scanned from a typescript, introducing occasional spelling errors. The original typescript is available.
In footnotes or endnotes please cite AIP interviews like this:
Interview of M. Stanley Livingston by Charles Weiner and Neil Goldman on 1967 August 21, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/4746
For multiple citations, "AIP" is the preferred abbreviation for the location.
Fundamental work in developing the cyclotron and other accelerators. Early life, education prior to graduate studies at University of California at Berkeley from 1931; work with Ernest O. Lawrence at Berkeley and with Hans A. Bethe at Cornell University. Work on the 42-inch cyclotron at MIT in 1938, subsequent war work, later role in development of new high energy installations at Brookhaven National Laboratory, CERN and University of Cambridge. Also prominently mentioned are: John Paul Blewett, James Chadwick, Eric Clark, John Cockcroft, Donald Cooksey, Ernest Courant, Robley Dunglison Evans, Malcolm Henderson, Marshall G. Holloway, Robert Eugene Marshak, Edwin Mattison McMillan, Mark Oliphant, David Sloan, Hartland Snyder, Tileston, Merle Antony Tuve, Robert Jamison Van de Graaff; Associated Universities, Inc., Atoms For Peace Conference, Cavendish Laboratory, Comptes Rendus, Federation of American Scientists, Massachusetts Institute of Technology Radiation Laboratory, Ministry of Aircraft Uranium Development Committee (Great Britain), National Committee for a Sane Nuclear Policy, Office of Medical Research, United States Atomic Energy Commission, University of California at Berkeley Journal Club, and University of Rochester.
I’d like to start by commenting on something of personal interest to me. I notice in your family background that your mother’s maiden name was Ten Eyck. I’ve come across that name in other connections.
Yes, it’s from the New York State Ten Eyck family.
Was Philip Ten Eyck related? There was a Philip Ten Eyck in Albany who was associated with Joseph Henry on some experiments on electromagnetism.
I don’t know that connection. I do know that the Ten Eyck family is a very early one in this country, and I have a family history that goes way back to 1640 on that side.
Philip Ten Eyck was Henry’s close collaborator on some early electromagnet work at Albany. The name stuck in my mind. You lived in Wisconsin, but I’m not at all clear, from the information we have, when you moved to California.
My family took me to California when I was about five years old, and I have no memory of that earlier period at all. My father was a minister in his earlier years, and the family was closely connected with the church. Later, he went into high school teaching and for years was a teacher of economics and history. My early days were spent in small towns, first in Burbank and then in Pomona and San Dimas, California, with this family background of a father who had been a minister. For several years he was a teacher or principal in high schools in those towns and in Claremont, California. My mother died at a rather early age when I was about 12, and Father remarried and had a big family. I have three sisters and five half-brothers, and they make quite a collection when we get them together occasionally in the West at family parties and picnics.
Most of them are still in the West?
Was there much discussion in the home that you can say related to your later interests?
Well, my father was an educated man. He had a Master’s degree, which was quite advanced for those days, as well as his Bachelor of Divinity degree. He was always intent on all of his children going through college. We knew that from the early days, and we all did get through somehow, although there wasn’t very much money to put us through. Most of us had to earn our way or part of it to get through college.
How about science? When did you first become interested in it?
Let’s say I got interested in the mechanics of farm tools, instruments, Fords, and did a lot of the work around the orange grove in repairing tractors and trucks — all that sort of gear — and had quite a background of mechanical ability picked up that way before I went to college. Then I went to Pomona College, which was natural because it was close by. For one or two years I lived at home and commuted, and then I went up to the campus and supported myself other ways with a room on the campus. I was headed for science all the way through and took a chemistry major. I finished my formal courses for a major and for my degree in about three and a half years, and during that last year I became acquainted with physics. It happened this way: My roommate was Victor Neher, who has gone on and is well known as one of R. A. Millikan’s students and colleagues for many years at Caltech. We still keep in touch. But we were roommates in college, and I was intrigued by his descriptions of the kind of things he was doing as an undergraduate student in physics and an assistant to the professor for setting up laboratory equipment and so on. And that last year I became disenchanted with the chemistry being taught; it seemed to be getting pretty routine. So I arranged with the physics professor, Professor Tileston, to take some special courses. During that last year I doubled up and took all the undergraduate courses in physics and got a physics major as well. When he saw that I was really interested, he got me an appointment as a teaching fellow at Dartmouth for the year following my graduation, and I went on from there.
What had you expected would be the result of your degree in chemistry when you originally started out with that as your major?
I think that I had the concept of research from the day I went into college as a freshman. I had always intended somehow to get out to the boundary of knowledge and to push forward any way I could. I remember my concept of it was that in order to be able to get to the edge of knowledge I was going to have to narrow my scope and to push on a very narrow field. That was my intention — to specialize and do one field in order to prepare myself enough to go beyond the boundary of knowledge — although I had no clear idea as to what that meant or what sort of life it would be.
But chemistry seemed closest to this goal?
Well, when I started, yes. Chemistry, remember, got a tremendous boost at the end of the First World War, in much the same way that physics did after the Second World War. It was the reigning favorite of the sciences in those years, and that’s why I started. On the other hand, by the time I was a senior in college I had lost my certainty that chemistry was the research field I wanted to go into, and found that physics would be better.
Had you had chemistry in high school?
Oh, yes. I’d had the usual chemistry course in high school. Maybe that was one reason why I continued in college.
But how about physics?
No, I didn’t have any course in physics in high school.
Where did this general impression of science, as you entered college, come from? Had you been reading any of the magazines? Was it in the air? Was there some discussion in the community? How aware were you of what was going on?
The place we lived was on a ranch, and it was out in what was in those days a rather poorly developed part of the West. It was a place where the whole tradition was that of young people coming out and investing their energies in some field and succeeding. It was obvious from the start that I was going to do something like that. Just why I picked science I don’t really know, except it became interesting to me. It’s just possible that it was connected in a certain sense to my disillusionment with what I had seen in the way of religion, and perhaps represents a kind of rebellion that I went through against my father’s urgings and training.
This disillusionment or disappointment with religion — was this because of the difficult economic situation?
No, it was a purely personal thing. I just didn’t find the kind of conviction that my father and most of my relatives seemed to find in their personal religion. I just slowly slipped away from it and finally decided that I didn’t have their faith. I was going to search for another kind of information on which to base my own life, which was, I though on the facts of nature.
What was your father’s attitude?
Oh, he was in favor of my plans for college and supported me all the way through. He was a little bewildered that I went into science, but, on the other hand he understood and appreciated the mechanics part of it very well.
In the physics part of your college program — which you advanced into in less than a year — what sort of courses did you have to take to qualify you at the end of that time to take a position at Dartmouth as a research fellow?
I don’t recall their names and titles too well, but there were courses in mechanics and electricity and I think heat and sound — the things that normally were being taught. I remember assisting my professor, Professor Tileston, in setting up a phonodeik system for displaying the voice sounds on a graph with a needle working on carbonized paper so that you could see the tracks of the voice tones and fluctuations on paper.
Was this after Miller had done his work on it?
Yes, it was following his work, and the acoustics of the human voice was rather an interesting field at that time.
Was that his special research interest?
That was one of his interests. He had many. This was one of the methods he used in his courses, the use of special projects to help train us in the use of tools and techniques.
Other than Victor Neher, who else went on to graduate work in physics from that group?
There has been quite a sequence. For example, Norris Bradbury was a graduate of Pomona College a few years later. He went on to be director at Los Alamos. I can’t recall the names, but quite a sequence of people were trained in physics, inspired into physics, by Professor Tileston. He was an excellent teacher, and he was the one who really got me interested in and excited about physics. His history, I understood, was as a teacher at Dartmouth College, at Colorado College and Pomona. He had these connections, which he used to send his students on to get teaching fellowships so that they could go ahead in the field.
Was he up in years at that time?
He would have been about 40, 45, in those years.
He stayed on at Pomona?
Yes. I don’t recall when he died, but it was about in the early ‘40s, I think.
It’s very interesting to see how one man in a small college can play an important role.
Another connection here is Victor Neher. Victor’s home was in Eugene, Oregon, and he had spent some time at Reed College. We heard quite a bit about Reed College during those years. Knowlton, I think it was, was a professor at Reed; and he also sent a whole group of students through into graduate work. In fact, as I recall, this was fairly typical of the times. A few professors in some of the smaller colleges were inspirational enough to send their students on into graduate work in physics.
There was one at Whitman College. I think his name was Brown. He had a connection with Brattain and Bleakney and a whole group of them.
Right. Well, I wish always to give full credit to Professor Tileston for getting me interested in the field and giving me the chance to start.
Then he selected Dartmouth because of his relationship to that institution?
And what type of a position was it?
It was a teaching fellowship. I went back there and started working on a Master’s degree, which I completed in two years. My professor was Professor Meserve, who was a Rhodes scholar and a physicist. The job he assigned me — which proved not to be a practical success but was an interesting experience in technique — was to observe the effect of magnetic fields on iron and other ferromagnetic ions in solution using X-rays — that is, trying to observe changes in the X-ray diffraction patterns of such liquids due to the presence of a magnetic field. As I say, it did not pan out. Perhaps that indicates that Dartmouth wasn’t a very advanced graduate school at that time. In any event it gave me a lot of good experience.
When you came there did you have a specialty in mind in physics?
No, I was just going on to get more training, to get my Master’s degree from Dartmouth. At the end of that time I had a request to stay on at Dartmouth as instructor for one year because Professor Gordon Ferrie Hull, who was the leading physicist at Dartmouth, was going on leave of absence. I helped him set up the equipment for the demonstration lectures my second year there, and they asked me to stay on and do the same for the professor who taught the course the following year. So I stayed another year at Dartmouth as an instructor. During that third year I made application for teaching fellowships in other graduate schools and was accepted at Harvard and at the University of California at Berkeley. By this time I’d been away from home across the continent for several years. I suppose I wanted to get back to the West so I chose the University of California.
Why had you narrowed it down to those two?
I didn’t need to apply to very many places. I selected the ones I wanted.
Why did you want these?
The two big names in science to me were the University of California and Harvard. Those were the ones I knew at that time.
Did you associate any individuals with those names?
Well, Professor Bridgman at Harvard had been doing a tremendous amount of work at very high pressures which intrigued me. I knew a little bit about it, since I had stopped at the Harvard laboratories and looked around on a trip to Cambridge. But this was just a matter of my selecting the schools I wanted and applying. There was not nearly as much competition then.
Now, this meant you were accepted as a graduate student?
As a graduate student and with a teaching fellowship to pay my way. I didn’t have to depend on the family for funds. I earned my way through college and graduate school. In college it was by chore jobs during the school year and in the summertime, and in graduate school I always had teaching fellowships.
Do you know the source of the fellowship at Berkeley?
It was one of the department teaching fellowships. We actually assisted in the teaching. We had sections in the laboratory and graded papers in the big courses.
Had you known that Lawrence was at Berkeley?
No, I didn’t know until I arrived. I met Lawrence when I was a student in his electricity and magnetism course at Berkeley the first year. I had the Master’s degree from Dartmouth, which meant that I had a little bit more than the bachelor’s level of courses. So when I went to Berkeley I entered their higher-level courses and took all the major courses in the first year: electricity and magnetism, thermodynamics, mechanics, the mathematics of physics, and a course by Leonard Loeb in gas discharge. I got to know the professors through their courses, and I was moving fast in those days. I wanted to make up the year I’d taken off as an instructor, so I was headed for a doctor’s thesis after one year of courses. I went around to the various professors to ask their suggestions. Lawrence suggested the resonance of hydrogen ions with a radio frequency field in a magnetic field that proved to be the cyclotron. I talked with others — with Loeb, Brode, and several others — to get suggestions for thesis topics. I finally selected the one Lawrence had suggested because it seemed to be more exciting; he seemed to be a very confident person with a real knowledge of the problem. He gave everyone a feeling of enthusiasm and confidence; that was the thing that drew me to him.
Was anyone else working with him at the time?
Yes, he had been there for two years before I arrived. He was still an assistant professor. He had come from Yale where he had been a Sterling Fellow, I think they called it, a post-doctoral appointment, and he’d come to Berkeley as an assistant professor. He had several people working on photo-electric problems, mercury resonance lines that could be excited by ultra-violet light; early stages of spark discharge, that was Frank Dunnington’s work. He had quite a few things going. And when I approached him it was just exactly the right time, because he had this idea and he knew it was good. He was obviously aiming — as I recognized after a short time — at the goal of millions of volts for nuclear studies. The word being used in those days was nuclear excitations. It was considered similar to the excitation of atomic spectra of earlier generations. He was aiming at that and thought this new technique would do it. He was so confident of success that he swept me right along. So I started immediately — in fact, that summer — on the experimental work. I should perhaps go back and say that one of Lawrence’s other students named Edlefsen had finished his doctoral thesis and was waiting for the date when they gave their degrees in June. He had a job waiting, but was just hanging around the laboratory. Lawrence urged him to try out this idea. So he set up a rather sketchy apparatus with a small laboratory magnet to study this magnetic resonance. Lawrence thought that his results were quite promising, but he did not get anything very definite. Then he had to leave. So the problem was waiting for the next graduate student to come along, and I just fell into it.
You had completed your course work by this time?
Yes, by this time I had completed my course work. So I could spend full time on research, except for the time I was assigned as laboratory assistant for the teaching fellowship.
What requirements were there other than the course work and the successful defense of the thesis? Were there qualifiers?
There were qualifying examinations, yes; in special fields. One exam was in the field of electricity and magnetism; another in mechanics; another in thermodynamics. I think there were about four qualifying examinations that I passed in the spring term of ‘30, so I was ready to go for the thesis.
Were these written or oral?
They were written, rather thorough written qualifying exams. The defense of the thesis which came later was oral.
Was there anyone else on the faculty other than Lawrence who took an interest in this project?
Oh, yes. I talked with Leonard Loeb, for example, whom I respected and enjoyed because he had a tremendous and enthusiastic personality. I asked him what he thought of Lawrence’s idea; he didn’t think it would work. He conceived that these particles would go around many revolutions and that just a slight perturbing effect would make them spiral upward or downward instead of stay in a flat plane and they’d all be lost before they could get to the edge. He conceived that this long mean free path was impractical, and warned me against it. He said I’d be wasting my time. But I went back to Lawrence and got recharged with enthusiasm and went ahead.
Did he have an alternate project in mind?
No, I didn’t talk about any alternate project with him. To me this was so exciting that I wanted to take it on.
I see. You couldn’t be deterred from doing it.
You started then in 1930?
Wait a minute. Am I right in my dates on that?
Well, the dissertation was completed in ‘31.
In ‘31, that’s right; it took me less than a year to do my thesis.
So this is the later part of ‘30?
Now, during this time did you work pretty much alone? Or was it a question of Lawrence checking and supervising the work periodically? Or was it a day-to-day contact?
Well, quite a few other students were doing experimental work in the laboratory for their thesis subjects — some of them working with Lawrence and some with others. And we were a very close fraternity. We talked a lot to each other about our problems, about how do you do this and what do you do to get around that problem and so on. Then, of course, Lawrence was always around and would drop in practically every day to see how we were getting on and make suggestions.
Did the students live together? Did they have some common dorm?
No. This mutual aid society developed mostly around the laboratory. One man that I relied on very heavily was David Sloan. He was a ham radio operator and also a graduate student at that time; his very strong specialty was electrical devices, particularly radio systems. He helped me tremendously in building the first oscillator circuits I used for the cyclotron model, the first prototype, and other things of that nature. I got a great deal of help from him. He was quite inventive and started several projects on his own. Although he was nominally Lawrence’s student, he was the instigating spirit behind the linear accelerator developments at Berkeley, which didn’t succeed because they we e ahead of their time. We didn’t have adequate high-frequency sources of radio power at that time. What Sloan did was accelerate heavy ions, such as mercury; but he made the first linear accelerator run.
Can you recall when this was?
It’s in this reference here. In fact, I quote his first paper here. 
He also developed the medical X-rays.
Yes, another thing Sloan did was to invent the resonance transformer X-ray tube. I had a connection with that later, but I’ll insert it now. Two years later when Lawrence couldn’t get my instructorship extended, he provided my salary by offering me the job of chief designer and constructor of a resonance transformer X-ray tube in the San Francisco Hospital. Milton Chaffee was with me; the two of us built it. We had it running in six months and producing one million-volt X-rays, the first in history.
This was what year?
That would have been about ‘32.
Where did the source of funds come from for this particular application? It must have been enough to keep you on the payroll.
This came from the hospital. A roentgenologist, Dr. Robert Stone, wanted such high-voltage X-rays for deep therapy work. Probably Lawrence made the connection and put the ideas together. Medical funds supported the construction of the hospital unit and paid my salary for one year.
Perhaps it was foundation funds for medical purposes.
I don’t think so, not in those days. I think it would have been hospital funds. We have jumped ahead a couple years, but mostly to demonstrate Sloan’s ability. He was a graduate student at that time as I say, but with a different kind of experience which matched well with the places in which I needed help. So I got a great deal of help from Sloan. There were other students doing special work from whom I got information. Frank Dunnington was doing early work on spark discharge with Kerr cells, optical system long transmission lines and things of that nature, which was helpful. And Jim Brady was working on a thesis on the photo-electric effect from thin films of potassium and sodium, in which he was using a very high vacuum — the best vacuums developed at the Berkeley Laboratory in those days. So I learned the techniques of high vacuum from him. I was able to call on this kind of experience from others in the laboratory to help me in the development.
Was there a great deal of borrowing of apparatus?
Assistance in actually building —?
Yes, for example, Bob Holzer had a much stronger laboratory magnet than I had. It would go to about 13 kilogauss, and the one I had would only go to about 5 kilogauss. I did the early work on my thesis topic with this small 4-inch diameter poleface laboratory magnet with noncooled windings that went to about 5 kilogauss, and first observed resonance with it. This result, by the way, came rather early. I think I had the system together and was observing cyclotron resonance by about November of that first year.
Was that about ‘30 —?
Yes, ‘30. I had started in the summer term. There was a little more to it than this. One of the things I found at an early stage was that Edlefsen had observed something, but it was not cyclotron resonance. It was a special kind of single acceleration of heavy ions, residual ions in the gas in this chamber, which (ions) were bent in arcs or partial circles and reached the collector plate at the edge after one acceleration. I could check this because it showed a broad, rather flat resonance when magnetic field was varied. It persisted even when I turned off the hydrogen in the source, so it was due to some other gases. So the first thing I did was to show that Edlefsen had not observed cyclotron resonance; then it was my job to do just that for my thesis. As I say, I built a new apparatus and devised new techniques that Edlefsen hadn’t had time to do. There are photographs of this first cyclotron around that show what it looked like. That much was done in the fall of 1930. Then I borrowed Holzer’s magnet, the bigger one. I was able to get it for only two or three weeks; he was also using it in his experiment. During that time I tuned up to the highest field (13 kilogauss) and observed resonance up to this higher field. The highest energy calculated with that first model was 80 kilovolts. I used an orbit radius of maybe three to four centimeters; the source was a filament emitting electrons which ionized hydrogen gas inside the chamber near the center. That result of 80 kilovolts, which was the maximum the little model could do, was obtained sometime in January, ‘31. By this time Lawrence was really excited. You see, we’d proven the point.
He was off to the races. He went angling for funds and other support. I didn’t know what he was doing exactly, but I could see that he was spending a lot of energy searching for support to make the next step. Then came one of the most crucial moments in my life. I had been doing a lot of other things trying to confirm the results, observing focusing (for the first time) with the electric fields, the magnetic fields, measuring the energy, etc. Then one day at the end of March he suddenly said, “Stan, you’ve got to stop now and write up your thesis.” He said that there were only two weeks before the thesis deadline date for a degree that June. He had made an arrangement with Professor Birge, the Chairman of the Department, to give me an instructorship the next year if I could make that degree date and get my doctorate. They had the practice of requiring a doctorate before one could get onto the staff, even as an instructor. So I had two weeks to write my thesis, and I did it. It was two years from the time I had arrived in Berkeley — or rather less than two years — a very short doctorate. By this time Lawrence had already found the money for a larger machine. And so, that spring and the summer I was busy on the next-sized machine, which produced over a million volts.
Let me just backtrack. What about the defense of the thesis? When we talked informally here, you mentioned that that was of particular interest —
It was interesting and also embarrassing to me, because Professor Birge was a precisionist. He started asking me questions about nuclear physics of that day, which was essentially natural radioactivity, and I didn’t know much about it. He asked me the outright question: had I ever studied Rutherford, Chadwick and Ellis, the most famous book in the field? And I had to admit that I had not. I hadn’t had time. I was pretty shaky when I came out of that examination, fearing that I had made a poor impression because I certainly had not been able to demonstrate a background in my chosen professional field of nuclear physics. And yet I passed. I imagine that Lawrence was persuasive. So I got my degree and everything went right along.
Do you remember who was on the committee. Birge and Lawrence, I imagine. Who else?
I think that Jenkins and Brode were there. There may have been others, possibly Victor Lenzen, the mathematics specialist.
You mentioned that about this time in the winter of 1931 Lawrence became quite excited about the prospects for getting higher energies and that he was 1eginning to gather financial support. In some published account you mentioned that he was successful and got a thousand dollars from the National Research Council.
That’s my memory. I believe he got a thousand dollar grant from the National Research Council for the machine that he had calculated would be large enough to produce a million volts. That’s what he set me to building.
What I’m interested in here is if you have any recollection of what arguments he advanced in order to get that grant.
None at all. You’ll have to get into his records, if there are any —
There are, extensive ones.
I don’t have anything more than vague impressions of his funding activities. He was a very active man. He had four or five graduate students, he was carrying a full load of teaching and he was doing this promoting of funds on the side.
Were you aware at this time of other attempts to reach high voltages.
Yes, we had been vaguely aware of the work going on in England in the Cavendish Laboratory, where Cockcroft had published in 1930, I think, his first report of the machine that was used to get nuclear disintegrations in ‘32. This was basically a rectifier system, limited by the high voltage breakdown of air and materials. Lawrence was aware of this and we discussed it frequently; he claimed that our method would avoid this limitation. In fact, in our early papers we featured the development of high-energy particles without the use of high voltages. Those words were used because of our awareness of the limitations on high voltages due to insulation breakdown. We didn’t expect anybody could go to a million volts with straight rectified power. Of course, by now it’s clear that you can exceed that figure if you have suitable conditions.
How about the work of Tuve or Lauritsen —?
Lawrence knew about Tuve personally, and I heard a little bit about it. Tuve was Lawrence’s neighbor and classmate in North Dakota, and they had kept in touch. Lawrence knew that Tuve was working on tesla coil techniques for producing high voltages during that same time. I’m not at all familiar with what Lawrence knew about Van de Graaff’s activities. He could have been but I wasn’t aware of it until about a year later — after we got our first million volts.
I think it was only in 1931 when Van de Graaff came back from Europe from a trip with this idea, and it was perhaps Tuve who built the first one really.
Yes, possible. In the year when I was doing my first one, in the winter of 1930, I don’t think Van de Graaff had anything yet.
No. How about Lauritsen at Caltech?
Yes, we knew about Lauritsen. I knew about activities at Caltech because I knew Victor Neher, who had gone to college with me at Pomona and had gone on for his doctorate at Caltech; I was in touch with him personally. My home, by the way, was in Pomona, which was nearby, and I visited the Caltech laboratories with Vic Neher several times and knew what Lauritsen was doing with his transformers. He was working with a set of transformers turned over to him by the Southern California Edison Company that had been used for spark breakdown studies at high voltages for transmission of power; and he was trying to adapt those to developing a high voltage source. He needed a rectifier tube to rectify it; and, as far as I recall, in those days he had not achieved rectification at anything like a million volts. So we knew there was competition. This was a race and Lawrence was very much aware of it.
Other than that factor — which I think is an essential one, I’m not minimizing it — was there a feeling of what one would do when you achieved the high voltages?
I’m sure that Lawrence had much more of a picture of this than I had. He had a more thorough graduate training than I did and must have been very much aware of Rutherford’s work on disintegration. I knew about it but only in the more or less casual way in which a student is aware of one field out of fifty. Lawrence must have been very much aware that this was a new field of science: the study of the excitation of the nucleus. That was one of his major interests. There’s no question about it. I soon recognized his interest and it became my goal, too. Although I didn’t know very much about the field, I was pushing enthusiastically to get there, or at least to prepare the tools.
Would you say this was a correct characterization — to describe your interest at that time as the physics of the machine and his perhaps as the physics of the nucleus?
That’s right, very definitely so. I was the mechanically minded person who could make these things happen — frankly I was much more adept with tools and techniques than he. He was quite aware of this and trusted me completely to do the technical development work. With my background experience in mechanics and what I had learned from other students I became quite adept also at all of the techniques required.
And yet you apparently didn’t have a background ham radio.
No, I didn’t. I picked that up — learned it though Sloan — as I developed the first cyclotron.
What about the availability of parts? You just made everything yourself?
We used a 10-watt vacuum tube as an oscillator. That gave us about a thousand volts across a resonant coil, which was applied to the electrode. To obtain 80 kilovolts with a thousand volts required 80 accelerations or 40 revolutions. That was the maximum we achieved with this small machine, which was used on my theses. We used a much more powerful tube for the next one, the one million volter. Now, these developments came fast. It took less than a year to build my first model, and it took less than a year to get the next million volts. That was with a square box chamber with a single dee; and a more powerful radio tube. I think we used a 20-kilowatt transmitter tube obtained from the Federal Telegraph Company. Lawrence had made a connection with Mr. Fuller of the Federal Telegraph Company and was given a lot of parts and components to help out his research. Mr. Fuller was one of the vice-presidents of Federal Telegraph located in Palo Alto at that time. Now to go back, while doing my instructing duties in ‘31 - ‘32, I was building the one million volt model, which was the first working cyclotron, and the first one that had enough energy to disintegrate nuclei. It was completed in the middle of the winter or early in ‘32.
We have some dates here.
I also have some records.
We could look at the bibliography, too. [Paper is dated 1932.]
Well, in any event, I had a million volt particles in the cyclotron by the early spring of 1932, and I was busy tuning it up. We had currents at that time of around 10-9 amperes, mostly of molecular ions, but we had tuned it up for protons also, which took a higher frequency and the highest magnetic field, and had reached 1.2 million volt protons. By this time I’m sure that Lawrence was busy on the next stage, but I don’t have very much memory of what he was doing during the times when I was so intensely engaged in making this million volts. We were both working in our special fields; when I was in the laboratory he was out promoting the next one. He raised the money and support in various ways. For example, he got a gift of a bigger magnet from the Federal Telegraph Company; it was installed sometime early in 1932 in the old radiation laboratory while I was still working part-time on the 11-inch (one million volt). Probably to make this story understandable we ought to complete the 11-inch story and then go back to what Lawrence was doing. With the 11-inch we had resonant particles of full energy in a collector cup at the edge of the pole in early spring — in January or February.
Our first publication was sent in to the Physical Review on February 20th reporting 1,200,000 volts. Cockcroft and Walton’s paper came out a little later that spring and showed that they had disintegrated nuclei with even lower energies. My memory of their first report is 400 kilovolts — the disintegration of lithium with 400 kilovolt protons. Well, we weren’t ready for experiments yet. We didn’t have the instruments for detection. I had built the machine but had not included any devices for studying disintegrations. So we had to rebuild it. Now, Milton White was a student at that time, following right along behind me. He joined with me that spring in helping to rebuild the machine, and Lawrence also put in an emergency call to his friend Don Cooksey at Yale, who came out. Franz Kurie, a graduate student, also came out with Cooksey for the summer. Meanwhile we re-equipped the chamber with a target mounted inside where it would be hit by the beam, and a thin-foiled window on the side where we could mount counters. I think the first devices used for detecting the product particles were Geiger point counters. We set the threshold low so that they wouldn’t trigger with X-rays or ultra-violet and they would count with particles. It wasn’t long before we started to observe disintegrations, too. The date when we observed disintegrations for the first time was sometime in the early summer of ‘32. The first paper came out during the summer of ‘32. That’s right, it was by Lawrence, Livingston and White and described the first disintegration results.
Do you recall the reaction when you published, in 1931, the papers on the cyclotron? Was there much stir about it?
Yes, there was a great deal of stir. There were newspaper stories in the local press and also more widely. We had newspaper people around frequently. Karl Darrow came out, and got very much excited. He and Lawrence became very good friends — were for many years. He was writing up this sort of thing for Bell Labs at that time. By this time we had also learned about Van de Graaff’s activities, about Cockcroft and Walton’s techniques, about what Tuve was doing — all the rest. So we found we were second in observing disintegrations in the world, and this time with protons of over a million volts — 1.2 million.
Was there any reaction when you did your early cyclotron work in 1931?
Yes, it was being talked about and published and I gather was being discussed as an interesting idea.
I wonder if you got any sense of excitement there that this had really made a splash.
Oh, I knew we were heading for something big, definitely. Lawrence made that very plain. He said, “We’re making history.” He knew it. He wouldn’t let me take a minute’s time off for anything else. In fact, he wouldn’t allow me to take time off to study for my orals at the time of my thesis exam because he said we just had too many things to do. He said I could study later. I think this pressure had a direct effect on a later part of my life. Now, let’s see, we’d reached the place where the 11-inch had performed disintegrations, although by this time I had left it. I turned it over to Milt White, went over to the old Radiation Laboratory to build the next one early that spring of 1932. Lawrence was raising support for the next and larger machine. But meanwhile Milt White used the 11-inch as a tool for his thesis on proton scattering. He got his thesis in the following year. That was the end of the 11-inch, except that it’s now of historic interest. Lawrence sent the 11-inch chamber to Cockcroft who had it put into the Kensington Museum of Science in London.
I’ll be there in ten days to look at it.
You have to climb four flights up to find it. It’s way up in the attic.
That’s the science museum at Kensington Park.
That’s right. It’s way up on the top floor along with some of Cockcroft’s early apparatus.
This puts you in 1932. Had you learned at that time of the discovery of the positron?
It came later on in ‘32, I believe.
The Cockcroft-Walton was August and this was later on that year.
I suppose the reason why the positron didn’t impress me was that it was a cosmic ray result. Now, we knew about cosmic rays and were professionally interested, but we were working with artificial particles. What was being discovered in cosmic rays was only of peripheral interest — to me at least. Maybe others such as Lawrence had a broader vision and saw the significance. I don’t remember much discussion.
I ask the question because there is considerable question in my mind of whether or not that was regarded as a significant part of nuclear physics.
I think it was regarded as being a part of cosmic ray physics, which at that time was not connected up with nuclear physics at all closely. Cosmic rays were known to be radiations and had been studied for years, but were more associated with natural radioactivity than with what we were doing in accelerating particles.
There’s a point I’d like to have cleared up. It seems that in some of the accounts I’ve read about the early days of the cyclotron, there are stories told that you found the first 1 MeV beam the same day you received the report from the Royal Society Proceedings about the Cockcroft-Walton work. Is this a valid story?
No, that can’t be valid because I think if we looked up the date of publication of that Proceedings of the Royal Society, that it would be in ‘32. The issue probably didn’t reach the States until late spring.
If I recall, April 28th is the date on that paper on Cockcroft-Walton. I had a brief interview with Cockcroft and so I remember the date mentioned. Anyway, that fixes that date.
The published report that you had about the disintegration of lithium was in October of 1932.
Yes, but we had the high-energy particles earlier. Also, I was pulling out of the 11-inch more and more. The reason, although my name was on that paper with Lawrence and White on disintegration, I didn’t do much of the actual work. I was building the next cyclotron at that time. This was a case where my contribution in having built the instrument was being recognized; but I was away building the next one. So this first disintegration work with the 11-inch was done during the summer and was published, as you say, in October.
When you were a graduate student, did you get a chance to attend many seminars or go to many meetings away from the University you were attending — either at Dartmouth or at Berkeley?
At Dartmouth I don’t recall going to any meetings. At Berkeley, yes. There were some local meetings. The AAAS met there. I went to Pasadena one year — drove down to a meeting of the American Physical Society at Caltech. And I believe there was another one in Berkeley during the years I was a graduate student. Seminars? Yes. Locally there was what they called the Journal Club, discussions of the current journals in physics, which met once a week — Monday evenings — and all the physics graduate students and the physics research professors were there: Oppenheimer and Lawrence arguing out things between them. I remember Lawrence’s attitude at that time. He was never afraid to ask a question which showed his ignorance — not at all. He would ask what seemed to others to be the most foolish questions. Sometimes the graduate students knew the answers, but he would ask anyway. He was always willing to stick his neck out and ask questions in order to get the discussion down to the level where it would be available for the younger students who didn’t know. It was a very interesting technique. I think he was not as ignorant as some of his questions sounded, but he used this method of getting the discussion down to the level where it would help the beginning students.
Was he seeking in his discussions with Oppenheimer, for example, some theoretical clarifications?
Oh, yes. There was much discussion on the meaning of the basic concepts of the nucleus. After all, Cockcroft had the advantage of Gamow’s theory of the penetration of potential barriers by that time. Gamow used quantum mechanics to explain disintegrations. His work was known by Cockcroft, but I don’t think it was known to Lawrence in the early days — this penetration of barriers. Lawrence was aiming at one million volts as a goal which would perhaps disintegrate the nucleus. Cockcroft had the advantage of knowing that disintegrations might be produced with lower energies. So he tried and was successful at 400 kilovolts.
And yet that paper had been out since 1928.
That’s right. And yet a great deal of this was not well known to experimentalists. Now, Oppenheimer brought quantum mechanics that he had learned over in Gottingen to Berkeley. He was very live and active. He was splitting his time — one term at Berkeley, one term at Caltech — in those days, and when he was at Berkeley all the theoretical students in the physics department thronged around him. There are many interesting anecdotes about Oppenheimer in those days when he was a young professor. But he certainly added a great deal, in the Journal Club discussions, to our understanding of this newly developing field. We realized we were on to something interesting and exciting just from the attitudes we could sense in the professors.
During that time was there some assignment of journal articles to the graduate students?
O, yes. I reported on one or two papers and others also did. A particularly interesting paper would be assigned to a student to report and there would be a big discussion following his presentation.
Do you recall if there were any records kept of these discussions?
I doubt it. I don’t recall any minutes being taken.
How about the physics of the machine itself — the work that you were doing? Was there any need to consult with someone with more theoretical background?
There was need, but I don’t think there was very much interest on the part of the theorists. For example, Lawrence did not understand particle focusing in electric and magnetic fields when I started my thesis topic. He conceived that you had to have a field-free region inside the Dee, and that meant a cover plate over the face. And yet the particles must go around, so he wanted that cover plate full of holes. He conceived that the field between faces must be straight and parallel in the direction the particles had to be accelerated. So in one of the first models that I built, I used fine tungsten wires about a millimeter apart stretched tightly across the opening to give an electrical plane across the face of the Dee. I don’t think Lawrence knew even the simplest kind of ion optics at that time. I certainly didn’t. I had had no training in electron optics at all. Lawrence didn’t know how to predict what would happen to ions in the electric and magnetic fields. When I had observed my first 80,000 volts of particles, Lawrence made a trip east and I was on my own. I wanted to increase the current. The first intensities of 10-10, 10-11 amps were observed with galvanometers, and I even used an electrometer for a while. I felt somehow that those wires were in the way. And more or less intuitively — I didn’t have any reason for doing it except that I had an urge to get something out of the way — while he was away for a few weeks I took it apart and stripped out the wires.
When I tried it again I immediately got an enormously greater current. When Lawrence returned he recognized that there was something acting here, something in the way of focusing from the electric fields that he hadn’t been aware of. He sketched out on the blackboard the shapes of the lines that would produce focusing in the electric field. I recall such sketches on the blackboard, which he used to try to explain the higher intensity obtained when the faces of the dees were opened. Similarly, I found that I could increase intensity with shims of iron placed at the edges of the magnetic field. I found certain places where a thin shim of iron about five mills thick would increase the beam intensity. Then we began studying this result. It was Lawrence’s genius for understanding a new phenomenon when he had only a glimpse of it. He saw the significance of the shaped lines of magnetic force around the edge that led to the concept of magnetic focusing. So we knew how to proceed and I used magnetic shims from the very early days. But it was an art in which I’d cut the shims and try them out one after another in the long afternoons in the laboratory. And when I’d get a pattern that would really work I’d talk it over with Lawrence and we’d decide what to do next. I was a pure experimentalist in those days. I did much by cut and try and ingenuity.
You’ve described the involvement of Lawrence in this, and by implication others — Oppenheimer, for example — wouldn’t be involved at all in this.
No, I don’t remember Oppenheimer ever coming to the laboratory until we’d got to one million volts, and then he just stuck his head in.
After 1932 there were another two years at Berkeley where a lot of things were going on. How would you characterize the work itself? Let me just ask this: You mentioned earlier that some financial support was found by tying your work in with the work that Sloan was doing for the hospital. How was the general economic situation at Berkeley? Was there a general tightening up of the department?
I don’t have any memory that the Depression period harmed us. Lawrence always seemed to be able to find enough to keep us going somehow, and I don’t recall it as being a squeeze. I’m sure the Physics department budget was small, but again it was probably pretty stable, and I don’t imagine that it would have been cut very much. Lawrence was always finding extra sources of funds, you see, support from outside, and gifts of pieces of apparatus — transformers from the electric company and the magnet core from the Federal Telegraph Company and things like that.
But it wasn’t a period of expansion, though.
I think he raised more money — probably from the Research Council for the cost of the 27-inch, while I was engaged in building it during most of ‘32. I recall going down to Palo Alto with Lawrence and seeing the old magnet cores that had been given to him, and then going to a machine shop in San Francisco where the pole faces were being machined. I remember quite clearly the contractors that came in to erect the magnet and put it on its foundation in this old lab building which became known as the old radiation lab. I was engaged there in putting the machine together. The coils came in and we had workmen to install the coils. They were formed of copper strips, wound in layers and imbedded in oil tanks; the oil was circulated through a cooler. The top oil tank leaked, and I complained about it so Malcolm Henderson invented a way to fold newspaper into paper hats; we all wore such paper hats to keep our hair from getting oily as we crawled under those coils. In this period of time, during ‘32, I was over in the old Radiation Lab building the new machine for most of the time.
Then what you’re saying is that you were moving onto the next stage of machine design and experimentation and developing new machines, and you weren’t so much concerned with the uses of the machines, although the earlier generation of machines was now being used for experiments.
I literally had no free time. I agree that it was my own willingness to accept Lawrence’s urging that led me into this schedule, but I was working most every night until midnight, all week-ends and holidays. How I found time to get married during those years I’ve never been able to figure out, but I did.
Well, was this a happy time?
Oh, yes, extremely exciting. Lawrence was the most dramatic person I’ve ever known. He was just full of enthusiasm. He was excited about everything that went on. I’d be working in the lab late at night, trying to plug that last leak to get it ready for the next day, and he would pop in after some affair that he’d been to at 11:30 or 12 o’clock and find me there. I can recall a variety of such times when he came in late at night. He didn’t spend very much time himself working in the laboratory — very, very little. I did all the technical work. I was the mechanic, and things worked under my hands that gave him full satisfaction — he just left me to it. I went to the physics shop and used their lathes, I learned how to become a brass mechanic and I learned how to solder; we put the chamber together out of brass, solder and sealing wax. During that winter of 1932 I spent most of that year developing the new machine and making it run. Now, do you have a record of when we got the first beam with the 27-inch machine? I don’t recall the exact date.
Papers 5, 6, 7 and 20 according to this bibliography.
Well, the papers don’t necessarily establish the date when we got the beam. Maybe I wasn’t keeping very good records. I recall keeping some laboratory records, but they must have been lost, because none of my notes were found after I left Berkeley.
This is the 27-inch?
It was July of ‘32 — you had a 1. 24 MeV H2+ beam.
That was at 16 centimeters orbit radius.
Meanwhile, others were working with the 11-inch.
Yes, that’s right.
So you were already
I was already working on the next generation machine. You see, Lawrence just kept us at it. He was so full of energy and vitality, that we had to work as hard as we could to keep up with him. He was really a marvelous person. We had good social times together occasionally. He had an old coupe with a rumble seat; my wife and I went out with him on one trip to Oregon for a week’s vacation; we were sitting in the rumble seat and it rained. That’s a vivid memory.
Then in the medical work that you did in connection with Sloan’s work, was this any real interest on your part in the medical applications or did this come about because…
No. I accepted this assignment as a way of getting salary because I knew my instructorship had run out. I liked Sloan’s ideas. I thought they were wonderful. And I wanted to make them come true. His idea of producing million volt X-rays sounded good. There was no other place where it was being done at that time. So we built it and in less than a year it was running. It was used for 25 years as a tool for medical therapy by Dr. Robert Stone. I learned something of the technique of radiology during this assignment. We built various instruments for measuring the roentgen equivalent of the dose and other properties of X-rays, all at a much higher energy than had ever been used before. We had to devise our own calibration instruments. This was Milt Chaffee and myself; Chaffee stayed on in the field of radiology for many years afterwards. I was there just during that one year to get it built.
That was your last year at Berkeley?
No, I think it was ‘32 - ‘33. The next year Lawrence got me a research assistantship that was financed out of funds granted to him. The last year I was at Berkeley was as a research assistant.
Now the dates are straightened out.
I guess I didn’t give a very connected story but it’s a little vague in my mind what was the source of funds in which years. This wasn’t really important. These were Depression years or just post-Depression; I had a good job; my wife was working in the University; our income was sufficient — in fact, we saved money. We weren’t in any sense embarrassed by the Depression. Lawrence raised the money for the equipment, and we just rolled through the depression without its bothering us in the slightest.
You have recounted an interesting story about the learning of the discovery of artificial radioactivity in 1934 and then reproducing…
Let me go back one step earlier than that and recount the wonderful experience of our first use of deuterons with G. N. Lewis. That came earlier. Now, when was the first deuteron? I think it was early in ‘33.
The theory was discovered in ‘32.
Yes, but G. N. Lewis got battery-acid residues, concentrated them by distillation and prepared for us samples of gas, hydrogen was with — I think it was — 20% deuterium, which we used instead of normal hydrogen for our ion source. The first time we tried it we tuned right to the new resonance field and had a beam. I think the first beam we got was molecular hydrogen, that is, a hydrogen deuteride molecular beam. That would require a different magnetic field to tune for resonance, which was why we were so sure we had observed it. It was a hydrogen molecule of mass 3, in other words, we were tuning up for resonance of a molecular ion of mass 3 instead of mass 2; so that required different magnetic field for resonance. It wasn’t long before we were also able to tune to the deuteron molecular peak and then to the deuteron atomic peak. Ed McMillan gave me a sequence of dates which I think were included in that article of mine, summarizing my talk at the Lawrence memorial meeting of the Physical Society.
That was May 30th, 1933.
Yes. Well, Lewis was an interesting personality and was getting along towards retirement age in the University. He wanted very much to find ways to do good science with simple apparatus. He was a chemist who was appalled by the growing commercialism of the large-scale chemistry developing in those years and was searching for things that chemists and other scientists could do with fairly cheap apparatus. This, he once told us, was his reason for going into deuterium separation. It was something that could be done rather cheaply and easily. So he made some deuterium; obviously he and Lawrence had been talking and planning for a long time. He was right there in the laboratory when we tuned it in — I can recall him sitting on a stool with a cigar clamped in his teeth and weaving back and forth to keep the smoke out of his eyes while we were tuning up the machine — he sat there on many subsequent days watching the disintegration data come out. The interesting thing was that just as soon as we used deuterons we got enormous yields of reactions that had never been seen before — the deuteron reactions. We were the first in the field. We sent in a lot of publications, mostly trivial in content. My name was associated with some of them because I was running the cyclotron. Someone else was running the counters, Lawrence was in and out, and between us we wrote up papers and published them with Lawrence’s name on them too. There were, I think, 15 articles on disintegrations with deuterons.
This is a different trend than the things we’ve been describing. This is actually using a machine…
Oh, yes, we jumped into experimentation as soon as I had the machine running and had a beam. We installed target systems and detection equipment. And then the others joined the group. Quite a crowd collected in ‘33. And, as I recall, the first man who came into the group was Malcolm Henderson. He developed the counters. First there were Geiger point counters, and power supplies for them, and counting registers. He built linear amplifiers for ionization chambers which could detect single particles, like those which had been developed by Wynn-Williams in the Cavendish. So Henderson was the expert on counting equipment and electronics. Livingood arrived about that same time, that same year; he started working with Sloan on the resonance transformer, I think. Whether that came first or not, I don’t remember. Anyway he was involved, and before long he was also with us on the cyclotron, taking data. Livingood found his specialty in the measurement of the lifetimes of induced radioactivities; that came a year later. But meanwhile, here we were with deuterons. We’d been getting long-range alpha particles from targets, some of longer range than any that had been reported in the literature of radioactivity, and so of higher energy. We extrapolated range-energy relations to estimate the energy of these particles. We correlated the type of reactions that were involved. We knew we were observing many new types of disintegrations. We knew we were opening up a whole new field of science. Everybody was busy, excited. There was almost a publication a week; they just came rolling out.
This was in …?
This was in ‘33 and early ‘34. Anyway, this discovery of deuteron reactions was what made the Berkeley Laboratory famous. All of a sudden we were flooding the world with papers on nuclear physics, in a field that no one else could enter because they didn’t have the deuterium and they didn’t have the high energies.
It was about this time that Lewis, I guess, was starting to make it available elsewhere, too, wasn’t he?
Yes, other people did enter the field soon after. Here’s a story, which I think should be told, which is not entirely to the credit of our laboratory. We were observing neutrons at this time. We heard about them from Chadwick’s work in ‘32 and by ‘33 we were searching for neutrons. We had some difficulty getting instruments to measure them for a while. Finally we ran onto the trick of using an ionization chamber with a layer of paraffin in front of it, and observing the recoil protons in the ionization chamber; the pulse heights were pretty constant and we used the linear amplifier to separate neutrons from other particles. So, we could observe neutrons. When we tuned in a deuteron beam in the machine, the neutrons just poured out. We got neutrons from every target we put in the machine. We couldn’t determine their energy very well; we had no good method of measuring it. We couldn’t measure the full energy of the proton recoils, or determine the angle of emission. So we couldn’t tell the neutron energy except to know that they were in the million-volt range. Meanwhile, we were also observing protons from every target, of different and measurable ranges from each element.
One group of elastically scattered protons could be recognized from each target. Then there were alpha particles from each target, and then often other groups of protons of longer range. We found one group common to all targets — the same range of protons. We — Lawrence was probably the primary thinker of the group at that time — decided there was a possibility that these protons were due to the breakup of the deuteron in the nuclear field and that we were observing both the protons and the neutrons. Since the protons were of constant range, we figured that the neutron should also have a constant energy. From this assumption we could calculate the mass of the neutron. This result was reported by Lawrence at the Solvay Congress meeting in Brussels in ‘33. Lawrence both made his reputation with some people and lost it with others at that meeting. Chadwick didn’t believe him. From then on and for years afterwards Chadwick thought all the reports from Berkeley must be literally fabricated, because he just couldn’t believe our result of the very low neutron mass which came out of these calculations. It wasn’t long — I think in ‘34 — when the first work with deuterons was being done by Tuve-Hafstad-Dahl in Washington with their Van de Graaff generator, when they found that our result was due to a d-d reaction, deuterium on deuterium.
What we had been observing came from the contamination of deuterium in the target s. We bombarded each target with deuterons, and it left a contaminant so we had been observing the d-d reaction: One reaction going to He3 gave a neutron; one reaction going to H3 gave a proton, and these were the groups we had observed. Now, this was a mistake and a serious one, and Lawrence was very sober when he reported the conclusion to us. He told us we had allowed our enthusiasm to carry us along too fast and that we should be much more careful in the future in analyzing our results before we published.
Do you think that was any sort of a turning point or that it was absorbed in the learning process?
No, I don’t think it had any great effect. It was part of the learning process. I was only peripherally involved. You see, I was the man who ran the cyclotron and repaired it every night and made it work. I wasn’t doing the detailed analysis or plotting curves. That was someone else. I had relatively little connection with it myself. Yet I think it made quite an impression on some of the others because from then on more individual papers came out, and it seemed with more careful analysis before they were published.
You told me Lewis’s motivation, but he kept on top of it though. He was closely involved, because he wanted to see…
Oh, yes. These were simple enough concepts — these elementary reactions. As a chemist he understood them and knew what was going on.
He was a very brilliant chemist in the first place.
A very clever man, yes.
I wonder now about…
I have one more story, the radioactivity story.
Yes, that’s what I started to ask about. And then I wanted to get from there to ask about the next step.
The radioactivity story -– this was a short-lived sensation. Lawrence came roaring into the lab one morning waving a copy of Comptes Rendus over the head, which had been translated for him, telling us that Curie-Joliot had discovered induced radioactivity with alpha particles on boron and had also predicted in their paper that, if you used deuterons on carbon, you should get the same radioactivity. Well, we had been observing long-range alpha-particles with a counter set to observe heavy-charged particles, with thresholds deliberately set high so we wouldn’t get too high a background. My memory is that we were imbedded in the alpha particle range studies and the counters were tuned to be especially selective for alpha particles. We had a wheel of targets in the cyclotron, including carbon. When Lawrence came in we were running and he immediately says, “Let’s try it out.” Well, we had been using a double-pole switch, an old open knife switch; one pole was on the oscillator for the cyclotron — turned it on and off; and the other pole was connected to the counter. I had a stop-watch, and was timing it for one-minute runs; Malcolm Henderson was counting the data and recording the counts and slipping the chamber back and forth to get ranges. So we immediately disconnected this switch to leave the counter connected, swung the carbon target into place, and re-tuned the amplifier so it would be sensitive to electrons. (These were positrons, in fact. So we must have known about them by that time, in ‘34.) Then we bombarded for 15 minutes, pulled up the switch, turned on the counter, and there it was — click, click, click, click, click, click. It was the induced radioactivity due to radioactive nitrogen. It was there waiting for us. In less than half an hour from the time Lawrence brought the news we were observing it.
Was this because you had to bring in the detection equipment and redesign the machine because it hadn’t been intended for that sort of thing?
Well, we’ve reached essentially the end of my story at Berkeley. In July of ‘34 I left Berkeley to accept a position at Cornell. The only man who still remains at Berkeley who was there at that time was Ed McMillan. He came to the Rad Lab a few months before I left and was there at the time of the radioactivity episode. There was one article with both my name and his on it. He is the only one of the present group at Berkeley who overlapped with my time there.
And how would you describe the transition from Berkeley to Cornell? To start with, how did this move come about?
A year earlier I had an offer of an instructorship at the University of Washington at Seattle at $2500, and I had thought it was time for me to move on and get started in a career. But Lawrence persuaded me to stay on with him for another year. I don’t entirely know my motivations for leaving. I think a big part of it was that I wanted to get out on my own. I had been under the pressure of Lawrence’s dominating personality a long time. I liked the guy enormously and all that, but I hadn’t had a chance to find out what I could do on my own. I wanted to break free somehow. The following year I got an offer from Cornell. The people there who were interested in me were primarily Lloyd Smith and Gibbs, the department chairman. They wanted to start developing nuclear physics at Cornell, and they searched me out because they wanted me to build a cyclotron at Cornell. I went there with that intention. They promised me a certain amount of support for building a cyclotron, but it proved to be small. They didn’t have the contacts or I didn’t have the promotional ability to raise much money. What I built was an 11-incher which operated at 2 million-volt deuterons.
I went to Cornell with the intention of going it alone. I was an instructor, had teaching assignments, etc. And also there was my memory of my embarrassment at my doctor’s oral. I didn’t know anything about nuclear physics. I hadn’t had a chance to read or study anything. I was an ignoramus in the field while working under Lawrence. Because I was so good at mechanics, he couldn’t afford to let me spend my time on anything else. So I immediately started reading, using all available references. After all, Professor Merritt was there, who had organized the Physical Review and the journals in physics and engineering were full and complete, so I had lots of material. I started reading on my own, mostly in the evenings. In the daytime I’d be working designing the 2-MeV machine and teaching courses. After the first year I developed a reference file of three by five cards with every article published in every journal on artificial disintegration and also basic references to natural radioactivity — nearly 2000 cards, I think.
Did you rely much on Rutherford, Chadwick and Ellis?
Well, I went back and studied that again, but I frankly wasn’t very much interested in natural radioactivity. I used it as a background. I needed it.
You had an extensive bibliography?
Yes. I searched the field. Now, I was doing this on the side, educating myself, because I could for the first time control my free time. And that’s when I started to grow up in a sense, to learn what I wanted to do. The first winter Hans Bethe came; the year after that, Bob Bacher arrived. I found Bethe very much interested in my thorough collection of references. I had also started to compile them and collect them into type reactions. My friend, Robley Evans, had gone to MIT the same year I went to Cornell. We knew each other well at Berkeley; he was in natural radioactivity and age of the earth problems and later specialized in medical radiation problems. He started teaching a nuclear physics course at Tech, and I developed the reference and index of artificial disintegrations. Well, Robley Evans and I published a paper or two on the correlations of type reactions, which fitted into my interest in summarizing the new data in the field. When Bethe came, he asked me if I would work with him, develop my correlations further, and join with him on a review paper in the field. Robley Evans went on to write what I think is the most thorough nuclear physics text ever published. As you know, he has been the major nuclear physics man at MIT over many years. Bethe published his trilogy of papers and one of them included my correlative summaries of the reactions of nuclear physics at that time. We published this article jointly. This trilogy of papers made Bethe’s reputation in nuclear physics and it pulled me along with him. Now, I was supposed to be knowledgeable in nuclear physics as well as an accelerator builder.
This was what you set out to be. You were listed as the major author of part C of that three-part article;
Bethe wanted it that way, it was entirely his choice.
Did you play a role in any of the earlier articles?
No, I didn’t.
How did this collaboration work out? You had these files of publications, and yet it wasn’t just a question of compiling them. It was a question of evaluating them and in some cases doing them over.
And there was an enormous amount of analysis needed on ranges and energies. This is where Bethe was very helpful. I told him of my problem, that I couldn’t evaluate the various reports because there was no accepted range-energy relationship to use. He jumped right in and did the theoretical work on the range energy relations that came out for the first time in our paper. That paper was the basic reference for years to come. Even ten years later it was still being used as one of the major references in nuclear physics. I don’t think there was an equivalent summary until about ten years later.
I think there were two books in the late ‘40s or early ‘50s which began to replace it.
Now, getting back to what Bethe really did for me: he gave me a feeling for the fundamentals of physics, and of what was going on in nuclear physics. With him for the first time I sensed how deep the field was, how involved it was, and how much we needed in the way of new information. I learned of many new kinds of concepts like magnetic moments and quantum aspects, that I had never heard of while with Lawrence. It was a different environment. I was now following a scholar and was really impressed. In some of our early work with the small Cornell cyclotron, guided by Bethe, we observed the magnetic moment of the neutron for the first time. This fact isn’t very well known. It was not a thorough study, but Bethe was satisfied that we had demonstrated the existence of the magnetic moment of the neutron.
There’s been some attempt to say that the magnetic fields which you had were not large enough to demonstrate the effect.
Well, we were satisfied at the time that we had demonstrated it. We studied the scattering and absorption of slow neutrons in magnetized iron plates.
Who had done the theory for that?
When was that paper?
It was called “Some Direct Evidence of the Magnetic Moment of the Neutron.” That was December, 1936. And it was done with J. G. Hoffman.
Well, Bethe was the one who suggested the problem, I had the machine going, and Hoffman was my graduate student at the time. By that time I had acquired two or three. Marshal Holloway was one. Charles Baker was another; and Frank Genovese. Holloway went to Los Alamos. Baker has been at Brookhaven for many years. Hoffman went into bio-physics up at the New York State Cancer Research Institute. This was the group of students that helped me build the cyclotron and joined in these first experiments. Now, another problem that Bethe suggested was the need for precise data on the ionization at the end of the range of a proton or an alpha particle. He needed this to figure out the detailed shape of the range energy curve. He again suggested that we study this experimentally, which we did with our deuterons. Marshal Holloway was the student who did this experiment. It was a rather important step forward, I think, in determining the calibrations of range-energy relations. The shape of the extrapolated foot of the range-energy curve was very important to know because we determined energy from range in those days. And this paper with Holloway was a delicately performed experiment with thin ionization chambers which measured the ionization at the extreme end of the range. Well, this was the sort of work that Bethe stimulated me into, this detailed study both of the properties of radiations and of new phenomena like the magnetic moment.
I gather from your comments that the relationship at Cornell was a very personal one rather than coming from a group journal club discussion.
Oh, yes. Our group was very small. There were Lloyd Smith, Bethe, Bacher and myself, who were the group that started Cornell into nuclear physics.
Konopinski came later? Was that it?
Yes. He was a theoretical student of Bethe’s. He was there during my time, but as a graduate student.
Rose was another theoretical student of Bethe’s.
But this group you refer to was…?
Holloway, Genovese, Baker and Hoffman were my students. The professors were Bethe, Lloyd Smith, Bacher and myself. Bacher brought an enormous experience to the staff when he came because of his background in spectroscopy. He and Bethe published the second issue of the trilogy on the internal properties of the nuclei, which was a very important paper. So those four years started Cornell in nuclear physics. Now, that cyclotron was very cheap one. I think I got $800 from the Research Council, the National Research Council.
Do you remember the circumstances of that?
I remember going down to Washington with Gibbs and baiting the NRC in their lair. We asked for funds and left documents behind, and we got the money. I used that to buy the essential parts. We made everything else by hand. We wound the coils for the magnet ourselves in the machine shop — the machine shop staff and myself — out of copper tubing. It was my first attempt at a water-cooled magnet. I water-cooled it by making the coils of copper tubing, which was double-cotton coated on the outside for insulation like the ordinary magnet wire of the day, but was hollow and we ran water through it. We connected up an old generator that Professor Bedell had in the electrical engineering department and used it for power. We made our own radiofrequency power tube, machined it out of brass parts and tungsten filaments, rated at about a 10-kilowatt radio power, and evacuated by a diffusion pump. We built almost everything with our own hands. It was excellent experience for the students.
Would you characterize the atmosphere at Cornell as being different from Berkeley as related to the sense of urgency that you have described at Berkeley?
It was quite different. The urgency at Berkeley resulted from Lawrence’s own personality. But his methods had other results. He prevented me from having time enough to become a scientist. In his view I was an excellent mechanic, and that’s what he wanted me to be. When I got to Cornell, I tried to become a scientist and with Bethe this was possible. I could really feel that I was getting into the field of nuclear physics there. The two places were entirely different. There were two different styles, because they were two different people. Bethe was the leader at Cornell, and he put his imprint on it; he represented careful analysis and detailed thinking about every problem. It was a wonderful experience for me to have such an opportunity to learn the field.
Do you recall the period when he was working on the energy limit of the cyclotron? Do you recall any discussion in that period? Were you involved in any way?
I wasn’t much involved. Rose was doing thesis work, and he got his name connected with the paper. Bethe had asked him to help me out. I guess it must have come up as a request from me to Bethe to help me solve the problem of the shape of the magnetic field; how to shim it more scientifically. Rose came to me and then wrote up and solved the equations for the shapes of the magnetic fields in the gap region. One of the results that came out was the “Rose shim,” which was a set of ring shims around the edges of the pole tips such shims were used for many years after as one of the major features of cyclotron field shaping. It extended the uniform region out a little farther. Then I don’t know whether it was Bethe or Rose who recognized the fact that the increasing mass of the protons would run into relativistic difficulties. But when it was published it did cause a flurry, and I remember some of the repercussions. I heard that Lawrence was very mad at Bethe. I didn’t see him personally, but I heard that he was angry because he was then engaged in promoting money for the 184-inch, which would have gone way up above Bethe’s relativistic limit. It was a little unfortunate that in their publication Rose and Bethe cited too low a number for the maximum radio frequency voltage you could put on the dees. At that moment in time it may have been a reasonable figure, but it has been far exceeded since. Bethe didn’t recognize — and I didn’t put my oar into that either — that the energy limit was flexible and would certainly go up in the years ahead. If you put in modern values of what has been achieved in dee voltage, you find that the Bethe-Rose formulas were quite correct.
I have another question about this. In this four-year period, you were learning nuclear physics and you were learning theoretical approaches to it. Did you become aware of various models of the nucleus that were certainly being discussed by theoreticians?
Oh, yes. There was an evening seminar or colloquium at Cornell, and Bethe was the leader. He was a very inspiring man and brought in all the new ideas. The theoretical models were discussed thoroughly, mostly by his own rather large team of graduate students. So, I heard a great deal of the implications of the theoretical models and of the various proof and disproofs as they developed. Konopinski was doing work on beta ray disintegration at that time. I heard a lot about that. I had a chance to listen in on a lot of high quality theoretical physics.
This was part of your education, but did it have any application at that time in your other work?
No, I wouldn’t say so, except for the specific ideas that Bethe threw at us as experimental possibilities — things to study. Bethe was the source of ideas for many of the experimental theses that were carried on with the 2-million volt cyclotron.
You did an experiment with your graduate students on slow neutron disintegration of lithium 6 in the disintegration mass scale, in which I recall you pointed out how you were able to determine masses using Q-values of nuclear reactions. Could you give us some background as to what the status was at that time — whether the mass spectrograph was felt to be more accurate or the Q-values more accurate?
Well, they were competing techniques. We were thoroughly appreciative of what was going on in the mass spectrograph field, and we were confident that the disintegration measurements were measuring the same masses. But we felt that we had something to contribute, particularly for the rarer isotopes that the spectrograph could not detect and the radioactive isotopes that couldn’t be observed with mass spectra. We were developing the disintegration mass scale parallel to the mass spectrograph and trying to correlate them, to make them fit. Eventually it worked out very well. I think Bainbridge’s work at Harvard and Neher’s work at Minnesota were the two most important studies that clarified some earlier discrepancies that came from Dempster in England. By the time their work was published we were all quite satisfied that they were in basic agreement with our results, and we were searching for explanations for the remaining discrepancies. In one case it might appear as though we had the wrong range energy relation for one particle; so we would go to Bethe to have him think it through and see if he could find an explanation. This kind of analysis was going on continuously while we were developing the values of masses from disintegration data and the use of Q-values. I think, in fact, that it was Rob Evans and myself who first used Q-values for identifying the mass differences in nuclei.
I notice that in Part C of your review article you devoted section 18 to nuclear masses.
Yes. That was very important at that time. We were trying to get the most accurate data we could for all particle masses so we could anticipate and predict reactions. We soon learned which reactions would not occur because the Q-values were negative. This was an important aspect of nuclear physics in those days. It was somewhat simple minded, yes. The field has become much more complicated now. But in those day this problem of masses was in the forefront of the field. Making mass values balance with the Q-values was a tremendously important step. This work, in which Bethe was closely associated with me and doing most of the thinking, was what led Bethe to discover the reactions occurring in the sun, which explained stellar energies. It was published the next year. This was one of Bethe’s major, unique contributions to the field of astronomy and astro-physics — the nuclear reactions in the sun. It was a direct outgrowth of our detailed precision interest in the Q-values and masses.
And he was involved in the way that you explained. You would go to him if you had something and ask him to look at a specific problem when you had something in mind.
What about the development of the time of flight techniques, especially those that Baker was involved in and Bacher? Do you know anything of the background?
No, that came later. I remember hearing some preliminary discussions, but I never got closely involved in it myself.
Let me ask another question. You mentioned that through Bethe you became aware of theoretical problems. How did you keep up on developments in accelerators at other institutions?
Mostly at scientific meetings, exchanging information, and some visits back and forth. I had a few chances to visit other labs. But my Cornell machine was one of the few operating cyclotrons. I was one of the leaders, and I was usually being asked to advise others. During this period the Rochester people were building a machine, also at Columbia and at Michigan. I talked with the people who were designing these machines. You see, I was the first one to leave Berkeley with some experience in cyclotron technology. So, I was able to help most of the others who wanted to start building cyclotrons. Eventually others came from the Berkeley group into other schools and built still other cyclotrons.
How did they avail themselves of your knowledge and advice during this period? Were you called in as a consultant?
No, not as a consultant — just visits.
You were invited — to give a talk, for instance?
Well, sometimes invited to give a colloquium talk, and sometimes I would arrange my summer trip to go by a laboratory and spend a day or two. It was pretty informal, but we kept ourselves informed by such visits.
More so than journals?
Yes, in our field. You could not transmit the kind of technology we were developing by words. It was very difficult to describe in writing. I think I’ve done as much as anyone else in trying to write it down, but even that was not enough.
You said something very interesting. You talked about “our field,” and apparently you mean “our field of physics,” which is accelerator design.
Yes, accelerator design. You see, it’s not nuclear physics. We don’t use quantum mechanics; we use classical mechanics to determine the sham of fields and the orbits of particles. We were a field apart. We didn’t have much in common with people like Oppenheimer in our field because he wasn’t working in classical physics, nor were many of the other theorists. It was a rare situation where I had someone like Bethe or one of his students to help do a job of analysis for us accelerator builders. We were classical physicists and engineers, and we did not utilize the new mathematics. I’ve always had this problem — that my major interest has been the field of classical physics, engineering and electrical phenomena. On the other hand, in order to use my machine, I’ve also become a nuclear physicist. This requires a completely different set of concepts, of mathematics and of people. And for many years we could not persuade qualified, competent theorists to help us out in the design field. One case that did exist was by Thomas at Ohio State, who did give a solution to a classical problem of particle orbits in the cyclotron. But we in the field were too busy with our day-to-day engineering problems to recognize what his analysis meant; it was not really utilized until 20 years later when strong focusing was discovered.
When did you first get this feeling that the accelerator builders constituted a separate group with a need to communicate? In other words, when was it a community that you would know was your particular audience?
I don’t know. It’s a little hard to say. I made a real effort to get into nuclear physics myself. I was trying to be both. I made friends, acquaintances and I learned the language of the nuclear physicists and did my best to become a nuclear physicist. I frankly was never very successful except with a great deal of help like what Bethe could give me. Research in nuclear physics was not my field. I didn’t know enough quantum mechanics. To a large extent I had to go by hunches in this new field where other people were using the new mathematics. I recognized my own limitations and eventually found that I should stick to the one field where I could be competent. I didn’t feel that I had adequate training. You see, quantum mechanics was not being taught when I was graduate student except to a few special students of Oppenheimer’s at Berkeley. It was not yet & course in the curriculum.
In this period you relied a good deal on personal communication. What role did the journals play for those who were interested in accelerators?
They reported accomplishments and the basic facts. We knew what to look for and who was the expert.
But then you had to go to him personally.
And what about correspondence?
Not very much. We exchanged designs and drawings. I’d go someplace, pick up a sheaf of drawings and carry it back with me and study them. But in general it was through personal discussion and copying what other people had done or getting new ideas from theirs and moving on.
How large would you say this group was — I mean the major people in the group?
Well, it’s all a question of time. It was growing exponentially all the time.
I meant, though, in the period, say, of ‘34 to ‘38 when it apparently began really to take shape?
Well, there were the various types of accelerators. There was the electrostatic generator. I got to know Van de Graaff fairly well. I visited him a few times when I was at Cornell. I got to know Tuve and Hafstad and Dahl in Washington, but they were using different techniques. Our common interests were dual. I mean I could talk with them about the nuclear physics results but also about the technology they were using in their generators. I didn’t go out to Berkeley often; that was pretty far away. I didn’t really get back often after I left.
About how many times during that Cornell period? Can you estimate?
No. I must have made a few visits to my family, who were still in the West, and I probably stopped at Berkeley but I don’t recall any specific visits. But I did eventually get to know the next generation of physicists there, mostly at Physical Society meetings. I got to know Thornton, Lofgren, MacKenzie and Salisbury and several of the others at Berkeley quite well.
Now during this period — let’s say it was in the take-off stage of accelerator development already and things were rolling in many different places — had Berkeley changed significantly? I’m asking now from your vantage point at Cornell and later at MIT. Did the Berkeley tradition still remain very much the Lawrence tradition or was it influenced somewhat by developments elsewhere? By the Lawrence tradition, I mean a very personalized approach.
Well, I’m not able to say much. I recognized a few new factors. Don Cooksey, who was Lawrence’s friend and colleague at Yale, had come out after I left. In fact, Lawrence asked him to come out when I left Berkeley, and he took a leading position in the laboratory and on the cyclotron. So a new era developed at Berkeley with people that I didn’t know. It’s hard for me to judge whether or not there was a different flavor. I will say that Cooksey brought one thing into the picture that I have regretted. He brought a certain idolization of Lawrence into the laboratory. I didn’t think he should have focused all credit on Ernest Lawrence as he did. He made a real effort to promote Lawrence’s reputation. He thought Lawrence was a tremendously important man and he just idolized him. The consequence was that Cooksey’s handling of the story of the early days caused the new generation to be unaware of what had been done in those early days, and to think that Lawrence must have done all of it with his own hands.
There’s a tendency I think in all of us to...
Now, I can understand it to a certain extent, but, I think he did harm to history. I think Cooksey’s idolatry — and there’s no better word for it — was the motivation for his distorting history. It is not true that Lawrence did everything with his own hands. We were talking about the Berkeley attitudes following the time when I left and with which I am not very familiar. I’ve only commented on a few feelings I’ve had that there has been some distortion of the early history of the project. By now, I think that the record has been largely cleared of the errors made in that period. I’ve made an effort myself to tell my side of the story and my version of history, which may help to balance it out a little better. Incidentally, it was valuable to me when I was asked to give that talk at the Lawrence memorial session, at which Ed McMillan also spoke. We exchanged manuscripts beforehand and corrected each other. In this way we were in good agreement on the basic facts and dates. Ed and I have at least reached a better understanding, although earlier there had been some divergence of opinion between myself and those at Berkeley as to what had actually gone on in the early days.
I think that a lot of this distortion of history is due to rapid change. Things change so rapidly that it’s very difficult to put yourself back into an earlier situation.
This shows, for example, in what happened immediately after I left. The next big development was the 60-inch cyclotron. By the time he had raised the big money to build the 60-inch there was a much larger group of people with Lawrence. A slide that Ed McMillan showed of the staff — of the physicists and engineers — at the time they were setting up the 60-inch cyclotron, showed a tremendous increase in numbers from the days when I was there. The staff continued to build up after that time. There must have been a major change in the atmosphere in the laboratory as their numbers increased. I was not there to observe so I haven’t much real knowledge of what went on.
I think one of the things that later came out of Berkeley was the team research approach where you had to do it in a very large group. I’m not saying that it originated there, but it was characteristic of Berkeley certainly because of the large staff it had and because it was all centered on a massive instrument.
Lawrence did one important thing. He showed how to organize a very large laboratory and to raise very large supporting funds for a major project for fundamental physics. This was really the first time this had happened in history. His example, the tradition he established, has gone on and has led to the enormously large accelerator laboratories of these days. It also had a definite impact during the war in the big project developments, and in the big laboratories like NASA since the war. Lawrence showed how to promote big funds and support for fundamental research.
This brings me back to Cornell and a question about the cyclotron: Why was only a 1 MeV cyclotron built? Was this a question of funds?
Well, yes. It was a 2 MeV, and was entirely a question of funds. At Cornell they didn’t have a Lawrence to promote it for them, to urge them on. I went there as one individual in a well-established department. All that I could swing by myself was the 2 MeV machine.
Because essentially you were the whole show when you came. You came there with this project in mind, and it then was a question of getting some graduate students to work with you and some funds.
Yes, I have never had the urge that Ernest had to build big groups or promote big operations. I preferred to work with a few people and within my limited scope. It was the difference in personality.
Yes, and training and interests. In 1938 then you went to MIT. I’d like to know how that came about — whether you felt you were ready for a change and therefore were sort of a little restless after this transition period or whether this came out of the blue.
Well, the big reason was that Robley Evans had promoted funds for a fairly large cyclotron for MIT. The money was to come from the Markle Medical Foundation and to be used primarily for medical research studies but also for fundamental nuclear physics. The money to be supplied was enough to build a 42-inch machine at MIT. So Robley Evans arranged for an offer to me as a research associate, to build this much bigger machine. I was ready to move into something bigger by then and was beginning to feel that I could do better in machine building rather than by going on in nuclear physics with a small machine at Cornell. I was not dissatisfied with Cornell; it just was another opportunity. So I came to MIT to build a cyclotron, and the first year that’s all I did. The next year they gave me an instructorship at MIT and a year later an assistant professorship, and later on higher ranks. But my start was to build a machine.
Did you think you’d be staying there for a long time or were you willing to take a chance just on the machine?
Well, I sensed that MIT was a big, powerful place. If you like, I sensed that I would get the support I needed to develop larger machines. With Evans’ glowing reports of the future at MIT and of the staff there — and he was right — it was a marvelous staff to join. You know, Compton, Stratton, Allis, Morse and others were there. They were wonderful people, and I was completely happy with the change. Basically I went to build a cyclotron, to continue to improve it, and to get into a large university environment with a bigger opportunity for support of my field of physics than I had seen at Cornell. I became a member of the department within two years. It only took me two years to build the 42” and get it operating. From then on I was part of the department and was doing my share of teaching and doing research with the cyclotron; had several students at MIT of whose work I’m very proud. One was Keith Boyer, who went to Los Alamos since. He was an excellent experimentalist and gadgeteer. I had quite a sequence of graduate students there.
Were there any moves afoot at Cornell to get a larger facility?
No, none at all at that time.
And it wasn’t your inclination to…
It was not my inclination to be the promoter. Well, perhaps I was reverting to type — finding in Evans a man who would do all the promoting and money raising which I found distasteful.
I needed a patron, all right. By the way, that 11-inch cyclotron at Cornell was used by Bob Wilson for several years after he went to Cornell. But eventually he built a large synchrotron and he sent the small cyclotron to Israel where it’s in its second reincarnation.
Where is it?
I think it’s in the University of Jerusalem, but I am not sure. I’ve never seen it.
In the early period at MIT did you have many contacts with some of the emigres — for example, James Franck?
No, I didn’t get to know him. During the first years my interests were largely in getting that accelerator running. I was associated with Evans and with his rapidly growing staff of what he called the Radioactivity Center; this was the beginnings of nuclear physics at MIT. Van de Graaff came to MIT at the same time, and we had his challenging development of electrostatic generators going on in the same department. Van de Graaff’s team of people were also working on accelerators and nuclear physics, and that made it an exciting place for me. I personally took great pride in the machine I built there. It has now had the longest continuous service as a research tool of any accelerator I know of. It’s been going since 1940 — that’s 27 years — and it’s still in service.
Any have the uses of it changed over time? Originally the Markle Foundation supported it for medical purposes.
It maintained Evans’ interest in providing induced radio-activities for medical research for a long time. It was barely finished before the war; I had it running in 1940. During these years the MIT Radiation Lab was starting; Lawrence, Compton and Conant organized the MIT radar laboratory. I was exempted in a certain sense. Compton didn’t want me to stop the work I was doing on the cyclotron to join in with the Radiation Lab group on radar because at that time there was also a growing desire to use radio-activities for wartime medical research. Before the war Evans started work on the use of radioactive iodine for hyperthyroid treatments; it had been quite successful medically. I became very much interested in such applications and I was beginning to feel that was the kind of physics I wanted to do. So I was willing to keep on with the cyclotron and to get it into shape for production of radioactivity for the medical services. The Office of Medical Research of the OSRD, supported this and many other activities during the war. I developed the cyclotron for 24-hour operation; it ran around the clock during most of the war years, mostly making radioactive phosphorus and radioactive iron isotopes for use as tracers for studies of preservation of whole blood and of blood fractionation. One of the consequences, as I understand it, was a successful development of the technique for treating whole blood so as to stabilize it against going bad, so it could be shipped to the Pacific for the use of the troops. This technique was developed using the radio-activities produced in the MIT machine.
How would the results of the machine group get translated into medical practice?
Robley Evans raised the money and was the leader. He was the man in charge. During the war many of us were searching for something to do to be useful. Now, here was a demand from the medical field for radio-activities, and there was no other source in the country. Well, there were other cyclotrons, but they were mostly being used for work which ended up in the Manhattan District — the ones at Cornell, Indiana and several other places. But this one at MIT was used for medical research and it was the only source of such radio-activities.
Was there a tie-in with a hospital locally as sort of an intermediary?
Yes, there was a lot of interest. Evans had developed contacts with several medical research groups in Boston and the activities from this machine were being used widely as tracers for medical research studies. Radio-activities were the main product of the MIT machine both before and during the war.
Was this a period of just utilization of the machine or was it a period also of improvement?
Well, it was also a period of improvement. I did quite a bit of rebuilding to make it reliable enough to survive a 24-hour production schedule.
Did you have difficulty in recruiting staff?
No, there were only three or four of us. We were there and we stayed on.
You had no tie with the radar laboratory or with the underwater laboratory?
No. During the early war years I stayed at MIT. By 1944 I had it under good control. One of my graduate students, Eric Clarke, was completing his thesis and in a position to take up some wartime job. I took this opportunity to take a wartime job myself, leaving him in charge. He carried through the 24-hour operation of the cyclotron during the war years. And I went to the operations analysis group in the Navy Department, sponsored by the Office of Naval Research; this was Phil Morse’s group. I had two years of a completely different kind of work. My chief interests and my assignments were in the field of radar and radar counter-measures for the anti-U-boat campaign, and in that capacity I was in Washington a good deal of the time. I did get a chance to take a quickie training course in radar at the Radiation Laboratory for a few months before I went down to Washington; so I became their “radar expert” after a few months and brought this knowledge of radar practices, techniques and capabilities into the counter-measure studies against U-boats.
You lived down there, too, didn’t you?
Yes, I was on assignment. I also had an assignment abroad at the end of the war. I was in London for six months on a liaison job with the British anti-submarine groups.
This period, as far as I know from your life history, constitutes the longest time away from accelerators per se — two years plus this six months.
Yes, I guess it is.
Well, let’s get back now to the cyclotron. In your paper on it you indicated that (I’m referring to the same paper) you wanted higher energies for deuterons. Do you remember what paper, Neil —?
Yes, this was the two-part paper published in 1944.
Yes, on the cyclotron.
On the cyclotron at MIT.
Yes, that was a technical paper on techniques of the cyclotron. I felt it was needed to transmit information abroad. I think it was useful; it was used widely in Europe and Russia as the source paper for technology in the cyclotron field.
Why did you feel that you wanted to go up to much higher energies at the time? What was the motivation there?
Much higher energy? No, that was not the purpose. We achieved 16-MeV deuterons at MIT and that was an adequate energy for most nuclear physics studies.
There was some mention in the article that you would like to have seen 20 MeV deuterons instead of being limited down to 15 MeV deuterons.
No, I don’t know why I made that statement at that time except for the general attitude of “Let’s build something bigger.” It probably had something to do with the fact that we were doing some deuteron stripping reactions. Out students were doing good work on deuteron surface interactions. The results led to some revised theoretical developments.
I have a few other questions. This paper, even though it’s entitled “The Cyclotron”, shows a lot of experimental results in the second part of it. There’s a whole series of results that you’ve gotten from it. Now, were these results and techniques that you describe here a carry-over of your Cornell work or was this a new endeavor?
No. This shows my continuing interest in nuclear physics again. At MIT, after the machine was completed, I started directing student research projects using the cyclotron, and publishing the results. We had quite a bit of success in the area I mentioned, of the deuteron stripping reactions which required that we develop some very special instruments. Keith Boyer did much of it. These were instruments to separate and identify the output protons, deuterons and tritons and measure their energies at the same time. This was a productive period with graduate students using the machine as a scientific tool.
This was during the wartime period then.
Yes, it was going along parallel.
You were still trying then to use the machine for nuclear physics research as well as…
These were in the years between ‘40 and ‘44 before I left MIT, when we were using the cyclotron primarily for research.
Well, then, I’m not clear on something. I thought that it was also used for the medical work through OSRD.
It was. But there was time for everything. We would spend a long night run making radioactivity and the next day we would return to a research program.
Was this the prelude then to the type of activity that was done after the war of having accelerators running around the clock? I notice that in the Brookhaven reports they then continue their runs almost all day.
Well, whenever you1re making a long-lived radioactivity, you run long hours. It’s a natural thing to operate around the clock.
In the reports you mentioned that the machine ran a large amount of hours each week and you had two shifts...
Yes, I know. Art Roberts memorialized this era with a song called “The Cyclotron Song”. I don’t know whether you’ve run into that or not: “Round and round and round go the deuterons” was its sub-title. I don’t know whether it was published with the major issue or recordings of Robert’s songs that came out of Brookhaven or not. Marietta Kuper at Brookhaven handled the distribution and a large number of copies were circulated.
We have a set of that, but I don’t remember all of them.
The first song that he wrote of this category was “The Cyclotron Song”. It contained an interesting bit of social comment as well. It described the problems of a director who was patterned after Ernest Lawrence, and was written when Robley Evans was urging the students and staff in his laboratory to make oodles of radioactivity for science. Well, this song of Roberts was composed for and first sung at a birthday party for Robley Evans in his home sometime in 1943 or 1944. During the war Roberts also wrote several musical operettas for the Radiation Lab group at MIT. After the war he wrote others, including one about Rabi’s Nobel Prize and “Take away your billion dollars” and some others. I think those songs of Roberts were about as sharp a commentary on the social implications of accelerators as anything you can find.
Do you think his poetry, if you can call it that, reflected a feeling that was in the air then?
I was also interested in the sources of the theory that you were following doing these experiments that the graduate students were following. Were you able to get information about developing theories during that period?
Oh, sure, yes. When did Weisskopf come to MIT?
He was in Rochester in ‘38.
In ‘38. I knew he was there before the war. But when did he come to MIT?
I don’t remember. I thought maybe it was after Los Alamos. I’m not quite sure. [Weisskopf came to MIT in 1945.]
Well, theoretical support was available during this time from the theoretical physics group at MIT. In any event, following the war Weisskopf and his group of students — Herman Feshbach and others — were always on the ball with new theories and were interested in the experimental results from the machine. There was a great deal of mutual discussion with theorists of the significance of the results.
How would you characterize the effects of the war, first on nuclear physics, and second on accelerator design?
Well, first, practically all cyclotron people except myself were enlisted by Lawrence for the MIT Radiation Laboratory, the radar lab; later on he was instrumental in pulling them out and assigning them to Los Alamos. So there were very few cyclotron people left except in a few places where they stayed behind to do a specific job — such as, where some of the Midwestern cyclotrons were used to make the earliest samples of separated uranium and plutonium for chemical studies before Los Alamos really got going and in our laboratory at MIT where the cyclotron was used for medical research. Aside from that, accelerator work and research essentially stopped during the war. Everyone went to one or another of the war-time laboratories.
What effect did the development of certain radar techniques, for example, during the war have on subsequent designs?
On, an enormous effect. The accumulated experience in radar and high frequencies that had been developed and the new skills that had been learned and used by the scientists when they were in these war-time laboratories were brought back to their university labs and promptly put to use. A major example is the way Luis Alvarez got surplus Army radar equipment to build the first proton linac at Berkeley. For that matter, the first electron linacs at Stanford were pretty much a direct outgrowth of Hansen’s work on klystrons and cavity resonators; they used many radar techniques in their electron linac developments. And McMillan brought his experience back to Berkeley, including the idea of synchronous acceleration. McMillan built the first electron synchrotron at Berkeley at the end of the war, and there was also prompt use of his ideas for proton acceleration. Veksler had the same idea. Their two papers were independent, almost simultaneous. For example, at MIT Ivan Getting and a group built a 300 million volt electron synchrotron within a few years. And at Harvard they built a synchrocyclotron instead of bringing the old 42-inch cyclotron back from Los Alamos. At Rochester they built a synchrocyclotron and at Columbia, Chicago and Pittsburgh; and elsewhere electron synchrotrons. There were about a dozen or more of these new machines built, mostly by people coming back from their wartime laboratories. The new ideas of the synchronous principle of acceleration were ripe to be exploited.
Let me ask you a question about this group. Were they nuclear physicists in the sense that we talked about before or were they the accelerator designers? I don’t think they’re mutually exclusive, but…
They were basically nuclear physicist some of them more competent at accelerator design than I and some of them perhaps not as competent. But they were also accelerator designers. McMillan was a more than ordinarily competent nuclear physicist as well.
And so these dozen places got into this that hadn’t been into it or at least hadn’t been into it on that scale before the war.
That’s right. The Office of Naval Research made funds available for about ten synchrocyclotrons and synchrotrons, all started within the first few years after the end of the war and almost all of them in universities.
When did you first become aware of McMillan’s work that led to the synchrocyclotron?
I think it was when I read his Physical Review letter that described the principle in ‘45; it was quite simple to understand the principle and what the possibilities were. And I talked with Ivan Getting at MIT at the time he was building his synchrotron. I was still involved in the cyclotron and didn’t start a new project immediately. But I became involved in something else after the war. I had been back at MIT for less than a year when the plans for Brookhaven Laboratory started. I was in fact making my own design studies for bigger machines on the side. Phil Morse and others — Zacharias at Columbia and Ramsey at Harvard — were organizing plans for the Brookhaven Laboratory. One of the things they asked me to do for them was to survey the possibilities of a large synchrocyclotron. The 184-inch at Berkeley had been completed and was running at 200 MeV a year after the war. It went to higher energies later, but it was already operating during ‘46. I was asked to recommend what was the highest energy accelerator of this new type that could be built. I made a trip to Berkeley and studied plans at other labs, and came back and made a quickie design study. I concluded that we could build one for 700 million volts. I gave them some sketches and also gave a colloquium talk at MIT. Incidentally, I am convinced that my talk at the MIT colloquium was the instigation for Arthur Roberts’ song “Take Away Your Billion Dollars”.
You mentioned that at our conference. I thought it was very interesting.
Well, so I was involved with Brookhaven plans right from the beginning, and joined the Brookhaven staff in ‘46. It’s interesting to note that 700 MeV is about the highest energy that’s ever been achieved with a synchrocyclotron.
You just didn’t come up with a figure. That type of considerations entered in?
I studied the range of frequency modulation and the size of magnet; a variety of considerations made me feel that 700 MeV was a reasonable goal for a big machine without making it too costly.
Had you any precedent to go on in this type of analysis? You had one, the Bethe-Rose precedent, but I don’t mean this.
The synchrocyclotron was the answer to the Bethe-Rose limit, of course; with synchronous acceleration we could beat that limit and go to higher energies.
Did you use your own plans?
Yes, but I discussed them with other people in the lab. I had become a fairly competent engineer and had learned how to estimate the limitations and sizes. My report to the Brookhaven planners was taken as their goal; then they asked me to come to Brookhaven as the chairman of their accelerator department in order to start building it, which I did in the end of ‘46. It wasn’t long before Rabi persuaded us to add another design study to what we were doing on the big synchrocyclotron, which proved to be the cosmotron. In other words, it was a proton synchrotron which used a ring-magnet instead of the solid-core magnet of a synchrocyclotron. Rabi had talked with the people at Berkeley — Lawrence and McMillan and Brobeck, who were thinking of a ring-magnet machine at that time. It was the natural next step in the development of McMillan’s and Veksler’s idea of synchronous acceleration into the next range: protons and a ring magnet. So Rabi came to Brookhaven and persuaded Morse and myself that we should start a design for a ring-magnet proton accelerator. I took that on, and before long we began to realize it was the one to build rather than the big solid-core synchro. So we dropped the synchro design study and concentrated on the cosmotron. Before I left Brookhaven we had completed the basic design; my name (with others) is on the paper reporting the design study for the cosmotron before it was built.
I read in one of the Brookhaven reports that Columbia got an award for a cyclotron during this period.
Yes. In fact, that might have been another of Rabi’s motivations. They got funds from the Office of Naval Research, ONR, for a synchrocyclotron at Columbia, which was built at the Nevis Lab. They eventually built a 400 million volt machine. Rabi, I guess, felt that a 700 volt machine at Brookhaven was not sufficient; he wanted much higher goals. He wanted to see us go to a higher energy range at Brookhaven. And, as I say, one of his motivations may have been that the 700 MeV would have competed strongly with the Columbia machine.
You also mentioned that you made a trip to London towards the end of the war. I was wondering, during your stay over in England, did you happen to know anything about the accelerator work that was under discussion there?
Not on the wartime assignment. No, I was in London doing my assigned job and I did not get to any of the laboratories except for a brief visit to Cambridge, where I had a chance to meet and talk with Chadwick for the first time. They didn’t have anything visible in the way of accelerators in England during the war years.
In your book, wasn’t it in ‘43 that you mentioned Oliphant in England?
That came in this later period, in ‘46. While we were developing the cosmotron at Brookhaven, I found that there was a similar development for a 1 billion-volt ring-magnet machine at the University of Birmingham. So in ‘46 I made a trip over to see Oliphant’s machine.
I see. You (Goldman) were confusing two trips.
You see, I was on a wartime assignment during the winter of ‘43 - ‘44 when I made my first trip to England; then I went over again in ‘46 when I was at Brookhaven. The trip when I went from Brookhaven was for the specific purpose of finding out what Oliphant was doing. I found that he had conceived of a ring magnet machine during the war but without knowing about the synchronous principle of acceleration. Their publications including synchronous operation came after McMillan’s. Oliphant had made a proposal to the British Directorate of Atomic Energy, for a big machine, but did not include anything to indicate that he knew about the synchronous principle of acceleration. So I have always given McMillan and Veksler credit for the invention of this principle. Oliphant’s people picked up this idea and applied it to their plans. They were already starting to build the machine in ‘46. It was completed and they did publish later — in ‘47 — their version of theory about the operation of their machine.
I don’t think he would advance this as a claim. We just picked it up from your reference.
What is interesting historically is that Oliphant had the concept of a circular ring-magnet proton machine before McMillan’s paper. He had the concept. But he apparently hadn’t thought through the orbit dynamics.
You see, Pm trying to find out how information is transferred between accelerator groups. Now, I know about the trip you made out to Berkeley, and now you’ve mentioned that you made a trip to England. Were there any other trips you made during this period of surveying the field?
You mean in ‘46?
This is the ‘46 period.
You mean during the Brookhaven design study?
No, I think those were the only places where there was anything going on.
Anything that you didn’t already know?
Because you were involved at Cornell prior to the war and at MIT.
There were a lot of synchrocyclotron laboratories, and I had visited several of them while they were being developed. I saw the Rochester synchrocyclotron in an early stage before it was finished. That must have been about the same period. So probably I made some other trips to the smaller synchrocyclotrons while I was developing the 700 million-volt plans for Brookhaven.
So therefore there was an interplay between you and these other parties at these other laboratories.
Particularly Berkeley, which was the major center. They were the ones who knew what was going on. Everyone else took their guidance from Berkeley in those years.
During the Brookhaven period, how would you characterize the atmosphere there? First of all, it was the first national laboratory so there was no precedent. It was a conglomeration of people from various universities, some of them there only on a transient basis. You’ve indicated that you were there practically as an individual, at first anyway, in accelerator design. Then there are people we know with various personalities. There’s Rabi and Zacharias and Morse and so forth. I’m very interested in your impression of the general atmosphere and of how this group worked together, what the expectations were, what the problems were.
Well, there were two levels. There was the level of the planners, which included Zacharias and Rabi and Ramsey and Morse and others from other universities that formed the Associated Universities. They were the ones who conceived the laboratory, set the goals, and selected the people to do the jobs. Morse was the first Director. They picked me for the accelerator field, Lyle Borst for the reactor, Ramsey for Physics, etc. Then we, as the working team, began to collect our staff and moved in on our jobs, which were to build the things that the planners asked for.
And what types of interplay would there be between the planners and the doers?
Oh, we were all good friends. We all talked together, argued together. I would talk all these things over with Morse. Haworth soon came as Assistant Director. I’d talk with Ramsey and anyone I could find. They were all interested in my designs and they were particularly interested in the ring-magnet (cosmotron) concept. So I had full support and lots of communication with others at Brookhaven all through the planning stage. I might report as an aside, Ramsey’s story of the setting up of Brookhaven. He claims that the total elapsed time was seven months from the conception of the idea by the planning group, organizing of university people, the approach to the AEC for money, the choice of site, to the moving in on the site. Just think of the speed. And Ramsey explains this speed as being due to the experience with crash programs that many of us had just gone through in the wartime laboratories. We were familiar with crash programs and applied the technique to Brookhaven. There was no holdup anywhere.
This also implies a certain minimum of bureaucratic roadblocks so someone else outside of the physics group must have been convinced…
Well, there had been considerable experience in reactor building during the war by commercial firms, and there were quite a few people who thought of themselves as experts in that field. So Lyle Borst was not given a free hand at Brookhaven. They put an architect-engineering firm over him to do the detailed designing; he was just supposed to be the physicist outlining basic goals. But there was no experienced commercial firm for building big accelerators. I was fortunate in not having anybody looking over my shoulder. I was given full authority to go ahead. I had to check with my laboratory director and see that my designs were in order in terms of budgets and staff, then went ahead and made my own decisions. I claim that one reason why our cosmotron succeeded so rapidly, was that we had a free hand.
And because there was no real precedent.
There was no precedent for commercial organizations to design accelerators.
At the same time were you aided or hindered by the availability or lack of availability of commercially available components in this period?
Well, there was a time when we were held up waiting for deliveries. But it was really not very long.
Did you find that the American industrial firms at that time were geared to respond to the current types of needs?
Oh, yes. This was the end of the war and they were anxious to get new orders. For example, one of the things we did was to introduce ferrite as loading material for radio-frequency transformers, which became the basic element of the tuned frequency r. f. system for the cosmotron. And the material had been developed abroad in the Philips Laboratories but we found the local Philips branch here was anxious to work with us; they provided materials and let us use them for model tests. There was plenty of commercial support for the new products we needed.
And you weren’t concerned about the funds. You had authorization.
The funds came through the AEC, and were largely handled by the planner group of the Associated Universities plus the laboratory management. Of course, I had to prepare budgets, but I never had the feeling that there was any limitation.
What was the goal? What did you have in mind as the potential use of the accelerator you were designing?
Already by this time, pi-meson production had been observed with the Berkeley machine. We knew that machines of 400 or 500 million volts could produce p-mesons. And they were just beginning to observe the first of the meson resonances. We could see a new field of physics ahead. To be sure, most people described it as meson physics in those years. And yet, as we were planning this machine, we knew of still other possibilities. We knew about anti-protons and anti-matter. Those were in the background of everyone’s mind. There is a story to tell here about the selection of the cosmotron and bevatron energy ranges. You see, the Atomic Energy Commission had two proposals before them — ours from Brookhaven (and we proposed two sizes; a 2. 5 BeV machine and a 10 BeV machine) — and also a proposal from the Berkeley Radiation Lab for 5 BeV and a 10 BeV machine of the ring magnet type. Our design matured at about the same time, not matured but reached the state where we could make a proposal and cost estimate to the AEC for construction.
About what year was that?
Let’s see: That was 1947.
The design study, and this was one of the results.
This was a design result, and we were requesting authorization to construct. Now, the AEC informed us both that they had a fixed amount they could allocate — I don’t remember the exact numbers at the moment — but it could essentially build one big and one small machine. They suggested that both Berkeley and Brookhaven should be supported. So there was a time — and I can’t remember the exact date — when Haworth, Morse and myself went to Berkeley and met with the head of the AEC Research Division at that time. We met there with Lawrence and a few of his people, like Cooksey, Brobeck and McMillan and Alvarez, I think. The purpose was to divide up the AEC money and decide who was to get the big one and who was going to get a small one. After a half day’s discussion it became very clear that it was going to be possible to build two but there would have to be a choice. We couldn’t build two of the same size; one had to be smaller and could probably be completed sooner, and the other could be a larger one. We each had our design studies for both sizes. We had sensed it long before — politically it was running this way. So we at Brookhaven had a design study for a 2.5 BeV machine and for a 10 BeV machine. Berkeley had design studies for a 3 BeV and 10 BeV machine. They didn’t want to accept the lower one. That’s where we stood.
The man from the AEC said, “Well, now, it’s very clear. One of you people has to accept the small one and the other one gets the larger one. Now, who’s going to be it?” And we said, “Well, we had better break up into our two groups and talk it over.” So I met with Phil Morse and Lee Haworth. I remember my views were very positive, and the others agreed, which was that I didn’t want to challenge the great Berkeley Laboratory by demanding the lion’s share for our new, untried place at Brookhaven where I was the only experienced man. It was too much for me to take on. I wasn’t that sure of myself. I said, “If we take the small one, we can build it quicker. We’ll finish it before the Berkeley people can complete the larger one, and we’ll have a chance at the next size beyond that.” I remember making this statement at that time. And Morse and Haworth agreed that we would take the smaller one, the so-called 2-1/2 Bev; it became 3 BeV. Berkeley also bumped theirs from 5 to 6 BeV during design planning — you always do a little overdesigning. So that’s how the division was made; we accepted the small one and made the Berkeley people happy. But it gave Brookhaven the opportunity to start on a project which was not too big an assignment for our inexperienced and small staff in a new laboratory. And we did finish it first and got it into operation in 1952.
The first injection of protons was in March of 1952.
The design study was completed by November of ‘49; at least there was a publication with my name on it. Actually, what happened was that I came back to MIT. I had used up my two years’ leave of absence. That’s all MIT would give; otherwise I would have had to resign.
Did you stay…?
I moved down there and bought a house in Long Island for the two years I was down there. But I couldn’t stay away from MIT any longer without losing my tenure position. I chose to come back rather than to stay on at Brookhaven. So I was back at MIT for the years from ‘48 to ‘52. I was back and forth to Brookhaven a lot, but I was based at Tech. To finish this part of the story, I believe it was an excellent opportunity we had at Brookhaven, to build the first of the multi-BeV accelerators... We were the first in the field. We had a wonderful period of productivity with the discovery of associated production and “heavy” mesons, the particles of more than nucleonic mass. Now, to go back a bit: the reason for the 5 BeV figure (which went up to 6 BeV) at Berkeley, was to have enough energy to make a pair of protons. Matter-anti-matter was known to be a possibility. The goal of 5 BeV which crept up to 6 BeV to be safe, was to be able to make matter-anti-matter pairs. As you know, they did do this. The Nobel Prize went to Berkeley people for the discovery of anti- protons and anti-neutrons. This was what we gave up when we chose the small machine. But my other prediction came true, with a different twist because strong focusing came along to help. Brookhaven did get the chance at the next big one, and Brookhaven’s 32-GeV AGS came because we had taken the small one and had built our reputation sufficiently to earn the right to the next big one.
The interesting thing about it is that you had the expectations that there would be a bigger one.
How do you account for your confidence that it would be technically feasible?
We always knew these machines would grow bigger and bigger. The only question was: How big a step to make each time? A factor of 10 was the largest that anyone dared to try. That’s what we accomplished with our cosmotron. We were a factor of 10 above the highest-energy protons at Berkeley when we started our design; and the AGS was a factor of 10 higher than the cosmotron; and so it went. We jumped by factors which were sometime five, sometimes ten.
But at the same time this implies an expectation that the funds would be there, that all you had to do was to make the proposals.
Oh, we had every expectation. Remember, after the war physicists were in a very strong political position. Every large university had a group of accelerator physicists or others who would ask the Office of Naval Research for money; and most of them got it. We were expecting to be supported.
Of course, you were getting money already from AEC.
That came a little later. ONR gave the first round of support following the war, and the AEC gave the big money for Brookhaven and Berkeley and soon took over from the ONR the support of new accelerators.
In the choice then of the smaller machine, these reasons certainly were valid as was demonstrated by later developments. What physics work did you have in mind at that time?
Oh, we wanted to make heavy mesons. We wanted to produce the spectrum of particles that we now know. At that time we only had glimpses of them, but scientists were fully expecting to be able to make particles heavier than protons as well as lighter than protons.
And this was used as one of the reasons for the design study for setting that particular goal?
I hate to have to backtrack but I think it’s necessary. Your original study paper — it was actually a talk given at the APS meeting in January of 1948 — had the plans for a 10 BeV synchrotron and in that particular report you mentioned the need for at least 5.6 BeV.
That was the threshold for proton-anti-proton production.
And I went back and researched it and it was due to the letter by Feshbach and Schiff. And it seems in that letter they refer to a discussion they had with you before writing the letter.
Well, you see... (laughs)
And I’d like to get a little more background. Obviously, now you’ve had some fairly intimate connection with some theorists, and therefore I’d like to get some feel for the situation.
Well, I’m not a theorist, but I’ve always enjoyed the chance to discuss accelerator plans with them and to have them respond with guesses as to what can be done with higher energies. I did not invent anti-matter. I heard about it from the theorists, but it was a goal we all became aware of. So we accelerator builders were aiming at this goal. We didn’t consider ourselves different from other physicists, you know. We thought we were physicists. (laughs) The separation between builders and users, which has unfortunately developed in these later years, didn’t really exist at that time.
All right. So the primary driving purpose you then mentioned for these machines was for heavier mesons, pair production of nucleons...
Yet when one reads the report at that time, the purpose listed is for understanding nuclear forces better.
That’s the caution of the nuclear theorist showing up there.
And another primary reason listed for the Brookhaven 3 BeV machine was proton-proton scattering...
Well, that is basically the study of nuclear forces.
So was it felt at that time then that it was necessary to bring in nuclear forces as a means of making the proposal more acceptable to the government, or was it still the idea that mesons and this work being done of these machines was related to nuclear physics? In other words, was the split actually taking place now between nuclear physics and high-energy physics?
I don’t know where you draw that line. I don’t really remember when we began calling ourselves particle physicists rather than nuclear physicists. I think it was a smooth transition during this period when mesons were considered a part of nuclear physics and had been identified by the theorists as being associated with nuclear forces. Nuclear physics, which means studying nuclear forces, would certainly involve mesons, which meant very high energies, which meant accelerators which went way above the disintegration energies. We always considered this as a part of nuclear physics. It was years later when we began to note the separation between low-energy nuclear physicists, who just disintegrated nuclei, and those who studied basic particles and forces.
Would you say the separation was the result of those who had available to them machines of a certain energy limit and therefore they were nuclear physicists, not by any conscious design or choice, but that they found themselves with that machine?
And so that became their specialty.
This is an interesting way to look at it. It hasn’t been brought out in this way before. When would you say that this became apparent, that you could put people in column A or in column B?
I don’t really know any date or any event that would characterize this. I suppose it was during the same years when Brookhaven was starting and when we were making nucleonic weight particles for the first time in addition to light mesons; when we began to realize that there was a more intimate structure to nature in the form of more particles. It was not the same thing as the structure of protons themselves.
So it was the results themselves in a sense that determined this. It wasn’t the availability of the energies per se.
No, I think that the results themselves led into studies in which the dominating interest became the study of the new particles themselves, rather than the study of nuclear forces through lower energy interactions of disintegrations and scattering. This is a hard distinction to make because particle physics is still a part of nuclear physics in the sense that the ultimate goal, which is finding out about the nuclear force, is still a nuclear physics goal. Although by now it pretty clear that the answer will probably come by studying particles rather than by studying nuclear interactions. There must have been a time when the theorists and others began to sense that these new approaches by way of studies of the properties of particles were going to be more productive in terms of understanding nuclear forces than the study of nuclear interactions themselves.
Wouldn’t you say that coupled with that it was the decreasing flexibility of the instruments themselves? In other words, in order to act on this proposition that you’ve just stated, on this recognition that they had, you had to get into higher energies; and once you had a machine that goes to higher energies, it was good for only those purposes. It had to be built specially for those.
It had to be built specially for particle physics — that’s right.
So, in other words, you left nuclear physics in the old sense?
I can’t identify a date when this happened. It was a gradual separation.
It was post-war certainly.
Right. But, for example, at MIT it occurred when Ivan Getting and some of his associates like Frisch and Osborne separated their interests from the low-energy physics going on with the cyclotron and the Van de Graaffs there and began to study mesons; that occurred back in about ‘46, I guess, when they began their first studies of mesons. This separation into people interested in special areas of energy occurred within the department.
Were you at the Rochester meetings, I mean the early Rochester meetings…?
I was there at the first one held in Rochester, yes.
Was it pretty much established then what the situation would be, that this division already existed?
Yes, this was a special conference for high energies only. Marshak would be the man to quiz on this matter, as to what his reason was for pulling together this conference on high-energy physics.
I’ve talked with him informally on a half dozen occasions, and we’re going to sit down sometime within the next six months. Unless you have something pressing on the Brookhaven thing, I wanted to get on to strong focusing — you know, the later Brookhaven thing. Are we due for that now according to your notes?
Well, there’s just the period in between strong focusing and the work at MIT. And there’s just one experiment I’m interested in, and that’s the beta ray experiment done at Los Alamos. I went out there one summer, in 1950, and they asked me to do a study of the lifetimes of beta decay from uranium fission. I couldn’t find anything shorter than about half a second.
It was mentioned in the article that it was a very important experiment.
In the article — well. It was only a confirmation of the fact that, in a nucleus, energy levels can only be so high because the barriers are limited; this prevents the nucleus from being excited higher than a certain amount. If you associate decay lifetimes with energy through the uncertainty principle, and the lifetimes are limited by the energy, you come out with the result that the beta rays should not have lifetimes shorter than a few tenths of a second. So, I was assigned the job, and we did it, and we got this expected result. It was a quickie experiment one summer, but it made a point. I don’t think now it was a very important point. It was already known. I think it was just an experimental check of a known fact of nature.
The reason I brought this question up is that in the Conference it was pointed out that information about uranium and uranium levels was not easily disseminated even after the war until about the Atoms for Peace Conference, and your group was going out to Los Alamos…
I went out there personally, on a summer job. I often took such an appointment rather than a vacation, partly to earn money. Whenever I could get an opportunity to be in an interesting environment as well as a chance to earn some extra summer money, I’d do it.
Did this ever involve consulting with industry, for example?
Occasionally. Yes, I’ve done some consulting but not very large jobs.
Getting back then to the strong focusing, actually I think it would be good if you could tell, as a case history in your own recollection, how it came about, what the considerations were, and anything that you think is relevant to it. It would be a lot better than us intruding with questions.
All right. I will start with coming back to MIT from Brookhaven while the cosmotron was building. In ‘49 and ‘50 I was back at MIT. Very soon I found my urge to design accelerators again getting the best of me. One of my reasons for coming back was that I felt strongly that it was important to get the tools for research into the universities rather than only in the national laboratories. Although I’d helped build a synchrotron at Brookhaven, I felt there must also be facilities in the universities. We have heard this argument from abroad — it is coming to us now from CERN — about the need for strong backup within the member countries if their people are to utilize CERN properly. Well, in those days I felt that we needed an accelerator facility in Cambridge, Massachusetts to give our local staff and students a better chance to get research experience before they went to Brookhaven. My records show that in the early part of 1952 I presented a memorandum to President Stratton suggesting an accelerator design study. I wanted to design a 10 BeV accelerator. Berkeley was running at 6 BeV; Brookhaven was running at 3 BeV. I knew that someday there would be larger ones in national labs, but I felt a 10 BeV machine could be used in Cambridge.
Just like that, 10 billion volts.
Well, it was a goal. I mean it was a round number. And I had been doing some designing. I wanted to get some others to join me, particularly some theorists. I had approached and talked with Hartland Snyder and Ernie Courant at Brookhaven. They weren’t opposed to it at all, they thought it was a good idea. So I wrote this memorandum to Stratton suggesting it and requesting permission from him to approach various people and organizations to get supporting funds. I thought of it as a summer study, a brief one. I don’t have a record of an answer from Stratton. But I do remember that Haworth couldn’t release his people in that critical summer when the cosmotron was just coming into operation. He made a counter proposal to me, which was to come to Brookhaven and do the study down there. I agreed and went to Brookhaven that summer.
Did MIT sponsor you to Brookhaven?
No, I got a salary from Brookhaven for the summer; I had to request permission at MIT.
Any yet your intent was to design a machine for them?
Well, by then I also knew that the Europeans were also aiming at a big machine. This was the group that eventually became CERN. I had heard about it earlier, and it was included in my letter to Stratton –- this plan in Europe for a larger machine –- and we knew they were talking about 10 BeV. Well, I went to Brookhaven in ‘52, backed up with a graduate student and some instruments we developed at MIT for meson detection. I had an idea for a differential counter with which I thought I could measure the ranges of mesons; and through that work back to their energies. I wanted to take this instrument down and try it out. But the Brookhaven cosmotron didn’t work that summer; they had engineering problems. So my student didn’t get much out of the summer. But I had full time for the design study.
I started out with the question: How would I build a 10 BeV machine now that the cosmotron was completed and quite sure to work? How would I build a bigger one and better one? I started with the magnet and said, “How would I build a better magnet?” Well, I was dissatisfied with the cosmotron magnet in one sense. I had myself conceived of the “C”-shaped core, so the outside would be free for beams to emerge, in order to simplify the handling of the beams. It was the first “C”-core that had been used in a proton machine as far as I know. And yet I knew that as it approached the iron saturation limit, the fields went bad; the region of uniformity between the pole faces to narrower. And this weakness in the basic properties of this C-shaped core magnet bothered me. I wanted to correct it, and I started thinking about alternate designs and sketching and calculating. I thought: “Wouldn’t it be nice if we could put the back legs alternately on both sides of the orbit and cancel out the saturation effect? Maybe we could still retain the major usefulness of the C core but improve its magnetic properties.” In the process, I tried to calculate what would happen to the gradients of the fields as excitation energy is increased, and couldn’t solve the problem myself. So I talked with Ernie Courant and asked him to think about it, and he did. He took it home one evening and the next day he came back with a quizzical expression and said: “I think it’s even stronger. There’s more focusing with the gradients alternating.” Well, this was when we used small values of gradient trying to average them to n = 0.6. This symbol “n” is the exponent of the radial decrease of field. In the cosmotron it had to be in the range between 0 and 1. When Courant informed me that the alternating gradients seemed to be better for focusing, I didn’t even know what mathematics he’d used on it at home that evening.
On my suggestion he tried gradients: one with a value of +1.2 and another with a value of -.2, so they average just what we wanted, which was +.6. That’s what he had worked on the first evening. It led to better focusing. We talked it over that day with Hartland Snyder, and we all agreed to carry it further. So, the next evening Courant calculated for “n” values of +10 and -10. That was even better. The next calculation was for an “n” value of 100. By this time it was clear that it wasn’t the +.6 that was significant — it was a new kind of focusing principle due to the alternation. Hartland rather quickly recognized what the general principle was. He saw it as an example of dynamic stability. He described several other examples of dynamic stability. I’ve even used a few of them to demonstrate experimentally. One is an inverted pendulum: If you stand a pendulum on its end and just give it just a slight tip, it will fall over. But if you oscillate the base up and down with a rather high frequency, it will stand upright. This is a kind of dynamic stability. If the forces on the pivot are greater than gravity, and you oscillate them, you can make the inverted pendulum stand up. There’s another analogy in optics of the use of lenses in which a converging lens and diverging lens of equal strength are set a certain distance apart and you observe focusing as a result.
Did you have this kind of physical intuition?
We knew we were dealing with particle orbits and that the alternating magnetic gradient produced a type of focusing similar to the dynamic focusing in mechanics. This development took only two weeks. Every day we used bigger and bigger “n” values, of 100, 1000 and then 10,000. Meanwhile, I was designing and sketching the magnets to make these high gradient fields. By the time Courant calculated for 10,000, the magnet I designed had practically a point for a pole tip. There was no room for a vacuum chamber, and I complained: “We can’t do this. We can’t use a vacuum chamber that small and pump it out. It’s just too small.” But Courant’s calculations showed that the higher the gradient the tighter the focusing became and the smaller the beam. So we were convinced that we had discovered something important and useful. During this time Hartland developed the concept of the scalloped orbit fixed-field (FFAG) machine. It was later reinvented elsewhere, including the MURA group. But we discarded it because it didn’t lead to the simple, cheap, high-energy machine we were after.
It was only a blackboard sketch and calculation and was soon erased. Meanwhile we kept going with alternating gradients using pulsed magnetic fields, and in these two weeks we settled on a fairly definite design. John Blewett joined with us; before long he came back with calculations showing that alternating gradients work for electric fields, also. He showed that electric field gradients have the same focusing properties; only electric field focusing is about one three-hundredth as strong as magnetic focusing. That factor of 1/300 comes into the basic relations between electric and magnetic fields. But Blewett showed that you could also focus with alternating electric field gradients. Since then it has been used in a variety of strong focusing systems using electric fields. Lee Haworth was also at Brookhaven and he talked with us. He was a very active person. Although he was assistant director, he was a very good physicist and he got involved with our discussions. The next week, we found, was the date when a group from Europe was coming over, the organizing committee of scientists for the laboratory that became CERN — to see the cosmotron and then to go to Berkeley to see the bevatron and to make their decision on what to build in Europe for their international accelerator. Rabi had sparked and sponsored the idea of an international accelerator laboratory and they were moving in that direction.
So that group was to be there the next week, and the question was: Can we tell them about this? We asked Haworth, and he said we could, because all accelerator technology had been declassified by the AEC. Haworth said: “If they’re going to Berkeley, it would be unfortunate if they carry this story with them and the Berkeley people haven’t heard about it.” So Lee Haworth called up McMillan and described our new concept to him over the phone before the European delegation arrived. But meanwhile the CERN group came, and they listened very intently and seemed to appreciate it. They went on to Berkeley and then went back to Europe. The first thing we knew they began AG calculations in England and Europe. Soon they selected AG focusing as the technique to use in their CERN accelerator, and for the same funds were able to increase their planned energy from 10 to 25 BeV.
Who was in that group — do you know?
They were Dahl from Norway, Goward from England and Wideroe from Switzerland. Well, one of the first reports from abroad was that some British scientists found what looked like a major flaw in the theory, which was the effect of orbital resonances. They showed that a single deviation in magnetic field in the orbit would give the particles a kink each time they hit it, and at the same phase of their motion; in other words, if you have an integral betatron frequency, then the motion will build rapidly due to this one anomaly and it will throw the beam out. This is the integral resonance. That seemed like quite a blockade, but we realized that we could tune frequencies between integral resonances and even in between half integrals. The British were the ones who first analyzed that particular feature. So the CERN group went on with their design study and at Brookhaven we went on with ours.
Had you done anything? Had you published?
We signed papers for a patent application assigned to the AEC and collected our one dollar apiece, and we wrote up a paper which was published in the Physical Review that fall, in August, I believe.
It was received August 21, 1952.
Right. We prepared it during the later part of the summer.
You worked on it for two weeks and then the following week you were expecting the CERN group.
Yes. But when they left we continued with our designs. Now, this paper gives a schematic design of a machine for 30 billion volts. Instead of 10-billion, here was a machine in basically the same price range that could produce 30 billion. That was the machine we reported in the first paper; also we described quadrupole lenses in that paper.
How soon after you had this two weeks of discussion did you decide to write it up?
Oh, immediately. In fact, we wrote the first paper before I left that summer. As I recall, I wrote most of the paper myself.
Just as a point of curiosity, if the paper was received August 2 1st, how many people had you discussed it with prior to the time the paper was sent out?
With this group of Europeans, but not many more. We hadn’t been out of Brookhaven.
But the Berkeley people knew about it.
The Berkeley people knew about it by telephone. But others had the same idea. Six months or a year later Christofilos came to this country. It seems that he had essentially the same idea. When he read our paper, he came over to this country and went to the Atomic Energy Commission in Washington to ask them why we were stealing his patent. He had patented it while in Greece. He came to Brookhaven to talk with us, and although Hartland Snyder found him a little difficult because his mathematics was somewhat unique — individualistic — it was clear that he had the same basic idea of alternating gradient focusing for a ring magnet as a part of some private studies on accelerators two years earlier. He had also written up a report and sent it out to Berkeley. To them it sounded like a patent application and had been filed with the crackpot letters at Berkeley.
When Haworth had passed the word along to Berkeley about what you were doing, there was no reaction from them?
There was no reaction at that time.
They didn’t relate it to the earlier letter.
I found out later that during this time the Berkeley people were still working on classified wartime projects, and one of these was a technique for getting higher energy in the cyclotron and avoiding the relativistic limit by using Thomas’s method of special pole face shaping. They found it in the literature and were developing it. They had some models and were building sector-focused cyclotrons at Berkeley, but they couldn’t talk about it. Well, when Christofilos came and persuaded us at Brookhaven that he did have a right to a credit for his earlier work, we actually published a brief note to that effect.
You and the group met with him?
We met with him at Brookhaven.
You came down.
I came down from MIT. Meanwhile, at Berkeley they were not able to talk about what they had been doing on the Thomas cyclotron because it was classified. Christofilos went out there and I guess persuaded them that his claims were valid. He came back to Brookhaven, and the AEC bought his patent. They did this by employing him as of the date in 1950 when he had invented it; so he signed away his patent rights to the AEC and was employed at Brookhaven as an engineer. And for a year or more he was at Brookhaven as one of the development engineers working on the AGS project. Then he got some classified ideas that really were hot, so they transferred him to Livermore where they could handle classified projects.
That’s part of the history of Brookhaven — the question of the kind of laboratory it was.
It was mostly open. We didn’t do much classified work there. Certain elements of reactor technology were classified, but that was a small proportion of the laboratory. The reactor was classified, but the rest of it was open, including all accelerator work.
Does that essentially cover the strong focusing story? You certainly have told us the details of the work on it. You told us about the article and about subsequent effects of these discussions — the British discussions and the use of it in CERN and so forth. How did it become implemented?
Well, Ramsey came down later that summer. The two of us had been working together on plans for a Cambridge accelerator. We decided to adopt the AG technique, and I made some preliminary designs. We even approached Tom Johnson of the AEC that summer in Brookhaven and started the ball rolling. That was the origin of the CEA machine. When I returned, the first thing I did was to search for support funds for a design study I would do at MIT for a strong focusing machine. I started a group and got support through a sub-contract from Brookhaven, and published a report. I have it here: “MIT Nuclear Science Lab Publication: A Design Study for a 15-BeV Accelerator.” The date: June, 1953. This was published in August, ‘53. Meanwhile, Brookhaven was going ahead with their own design study.
Based on the same principle.
The same principle. They were hot on it and at first they picked 50 BeV as a goal.
Was that a proton-synchrotron?
Yes. These were all proton machines.
But you weren’t involved in the Brookhaven designs?
No, except that I made several visits. We kept in touch. Then the CERN group began to get more active; they collaborated closely with Brookhaven. Eventually Brookhaven dropped their goal from 50 down to 25, which grew to 30 BeV. Both Brookhaven and CERN ended up designing machines of about the same energy; they kept in very close touch during the design period. Well, my MIT design study did not continue. When we found out that Brookhaven was going to be supported by the AEC for the AGS, we changed our plans at Cambridge. We didn’t want a lower-energy proton machine. So we changed to electrons, and out of that grew the Cambridge electron accelerator. It used the same alternating gradient principle. The next several years we spent in designing and promoting until finally we got authorization and money in ‘56, for the Cambridge accelerator.
Do you think that this problem that you had anticipated — and that is making sure that there was national support but on a local level at the universities rather than exclusively national laboratories — has been solved? Did you have great difficulty in making this point, that this should be supported?
No, We got our requested funds. We were stymied for a year by an administrative ball-up in AEC. Someone decided that this university accelerator opportunity should be opened up to more than just Harvard and MIT and Princeton and Penn, who had made proposals for machines. They asked for proposals for design studies which wasted a year of our time before we could get our proposal accepted. This explains one of the years between ‘53 and ‘56. During the rest of that time I was engaged on detailed design. From about ‘54 on, I had a group working on the designing and planning of the electron machine. I think it’s fair to say that Ramsey and myself, representing the two schools, were the ones primarily responsible for promoting and pushing through this Cambridge accelerator. As you know, we held the energy record for electrons for several years before SLAC at Stanford got going. And Brookhaven held the energy record for protons until this fall (1967) when Serpukhov [Institute of Theoretical and Experimental Physics at Serpukhov, USSR – 70 BeV] will get going.
With no end in sight. Did you have any other specific questions on this period?
Yes. In the design for the electron synchrotron did you realize beforehand the problems you might have with the energy loss and radiation damping?
Oh, yes. Schwinger had published a thorough study of radiation loss, an excellent study, all quantum mechanical. I also got Ken Robinson on my staff; he is a good theoretically trained man who has done an excellent job on our own calculations of radiation loss. No, we knew that radiation loss was the one fundamental limit from the beginning. We knew there would be a problem with radiation loss if we tried to go to very high energies, and we just had to solve it.
I’d like to introduce some concluding questions. One of them relates to activities in the ‘50s, professional activities that are not directly concerned with research — for example, you worked with the Federation of American Scientists and made public statements in that connection. And I do think that relates to research, by the way, so I’d like to know your views on that and how you characterize that period. Also how physics itself fared in the post-war period on the political scene. That’s one thing. And then there might be a general question on trends that you can see in the field of accelerator design and how things are different today perhaps than before.
Well, let’s take them one at a time.
I just wanted to find out if you were game.
All right, yes. I think my period of fairly concentrated activity on the social problems and responsibilities of scientists originated when I went to Brookhaven in ‘46; I talked with others who had been at Los Alamos and elsewhere. Willy Higginbotham came to Brookhaven; he had been one of the leaders of the group in Los Alamos that developed a feeling of responsibility for the misuse of atomic energy and weapons. I agreed with their purposes, and I helped to organize the Brookhaven Chapter of the Federation of American Scientists. I was chairman of that Chapter for a year. Then I got into the national group as delegate and eventually I was chairman of the national Federation for two annual periods. I can’t recall the actual years; one was about ‘54. I was chairman of the Federation two separate times.
‘54-‘55 is one listing we have.
There was another year later — around ‘59-‘60, I think. In any event, I spent quite a bit of time on it. This was in a period when the Federation was really useful. We felt that we were being listened to; we felt that we were having a beneficial effect; we tackled problems such as the classification of scientific papers, the undue classification of knowledge, trying to get material declassified that wasn’t of military importance, so scientists could use it freely. We entered the defense of certain scientists who had been persecuted because of former Communist associations, and we went to bat for a group of scientists and engineers at the Signal Corps laboratory in Fort Monmouth, New Jersey, which was attacked by Senator McCarthy. We did our best to stand up against McCarthy’s attacks on scientists whenever it was possible. There was a lot of activity trying to persuade Congress of the importance of international control of atomic energy. I testified twice before Congressional committees when I was chairman for the Federation. We had many day-long sessions of our executive committee or of the council of the Federation at which we argued these things out and tried to draft resolutions and statements. I felt it was a time when we were having an impact. The world needed to know what scientists felt, and I felt that they were listening to us. To a certain extent progress was visible. There was some improvement. Some years later I began to lose my feeling of confidence that this particular channel was being listened to; it seemed to be getting less important, less valuable as a means of communication. The prominence of scientists at the end of the war and the interest of the Congress in hearing their views declined in later years; eventually, it seemed, people got tired of them. So for a later period back here in Cambridge, I became associated with the SANE Nuclear Policy group and was put on their national committee and went to several meetings in New York and Washington with Norman Cousins and others. I helped to organize the local chapter of SANE, thinking that maybe this was the time to put my interests and efforts into appealing directly to the public. This was when the problem of bomb tests and fall-out was a public issue.
In the late ‘50’s?
The late ‘50s, yes. So I worked with SANE for several years and finally got discouraged with the local chapter because a group took over the leadership who represented what I can best describe as the “housewife fringe”: housewives who are so concerned about their children’s health (their children and others) that they were willing to stop all tests to stop fallout regardless of what harm it might do to our national security or the balance of international power or any other aspect. They were extremists who wanted SANE to put posters all over the city: “Stop the tests!” Well, that wasn’t my view. My view was: “Let’s control the tests. Let’s work for an international agreement.” I did not want unilateral stopping of tests but hoped to use this issue for international agreement to stop the tests. So I couldn’t go with them and I dropped out; I sent them a letter of resignation and said why. But I have continued to maintain my support for Cousins and the national committee of SANE. I believe they’ve done a good job, although, again, I think their impact has been fading. They may have had some influence on helping to get the bomb test moratorium agreement — I don’t know.
History will be able to determine that. I think it might have had an effect. It did have an impact, although it’s very hard to pinpoint just how these things come about.
Yes. Well, I have lost my confidence that such a civilian group can do very much more. They had their day. I think something else is need now.
You say that nuclear physicists as a group in the post-war period were creatures with social responsibility or was it just the particular group represented by the FAS?
Well, the FAS had a membership roll of about 2000 in their heyday.
But this group was all American scientists.
But over half of them were physicists. And they represented a selection of people who had a feeling of responsibility — out of a total membership of 40,000 or so physicists possibly a thousand physicists were interested in FAS. No, this was by no means a majority. Usually only a few felt they could do anything through this kind of a scientists’ organization. Now, as I see it, the problems which we had at that time were specifically important to scientists: the questions of bomb effects, fall-out, radiation and so on — where scientists had a reason for speaking with some authority — those problems are no longer the major social problems. I have dropped my interest in the FAS, because I think there are other social problems that are more important today.
Getting back to this other more difficult question: Could you in some general way review the basic trends in accelerator design and use? You’ve made some recent statements at the celebration of Bethe’s 60th birthday. For example, you talked about the energy limit and that now the size limit for accelerators is not an energy limit but is a fiscal limit — it is the amount of funds society wants to provide, which does represent, I think, quite a change from 35 years ago. I can’t even phrase a proper question on it, but I wonder if it brings any comments to your mind?
I worked hard to phrase my statement in that chapter in the Bethe volume. You can find it there. My feeling is roughly that accelerators are so expensive that the support of this field has become a social problem; for society as a whole to judge. No longer does the high energy scientist have the right to be supported regardless of cost. If it is important to society to develop basic research in this direction, to learn more about the fundamental structure of matter, I think our society will support it. I believe it’s a valid goal. But I’m not very sanguine about the possibility of continuously increasing support. Frankly, I’m somewhat surprised that our government has been willing to go so far as with the 200 BeV with its very high price tag.
But you’re in on the ground floor.
Yes. I’m pleased in a sense, but I’m somewhat surprised. I hope the motivation is not just political, that the Russians had taken the energy record away from us. There should be a more significant reason than that for supporting the 200 BeV. I hope it will not result in decreasing support for other necessary research fields. I don’t think that that should be allowed to happen. If it is possible for our society to afford these investments in the equipment for basic research, then it’s wonderful, because this generation of scientists will have a chance to come closer to the solution of this basic problem. If they do solve the problem of the origin of nuclear forces, I think it will be one of the most impressive milestones in the history of humanity. Scientists have this as a goal and it certainly is worth supporting as far as possible in the face of other competitive needs in our society.
That’s a very concise answer. I’d like to ask a final question in two parts. The first part is: In looking back over your own work now, what do you consider the most satisfying work you’ve done.
My career has been a sequence of fast-moving periods with excitement, interest and productivity, spaced by plateaus of consolidation. The time with Lawrence was enormously important to me. And the experience with Bethe was of tremendous value. The building of the cyclotron at Tech was an important step, especially working it into the university as a tool for research for the students. I’m a teacher, and I still like to see research activities materialize as a direct aid to students. Then of course the Brookhaven experience was wonderful, with the development of strong focusing. I have had a sequence of fortunate breaks and opportunities. I don’t think I can distinguish between them.
But you found, in other words, a lot of satisfaction in different ways.
How about if I ask the second part of the question now: If you consider the impact of certain things that you’ve done — in the short term or the long term depending on how you want to look at it — which pieces of your work would you say were the most important?
I think the one that will have the biggest total impact is strong focusing, because I think it has lifted accelerators into a higher energy range where they can really attack the problem of nuclear forces. I think that problem is going to be solved some day with future machines.
And it’s also something that has given you personal satisfaction, too.
Well, I think that really covers a lot of ground. I’m sure we’ll think of a thousand questions we wanted to ask as soon as we leave the room, but the tape is coming to an end. And I’d like to say we’ve done very well with the tape. It’s pretty good, and we haven’t touched a number of things. We haven’t talked about detectors, for example, but I don’t want to start that now. I think that if there are some specific things, we’ll have a chance on the transcript to indicate them. So I want to say thank you very much.
Fine. It has been a pleasure.