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Oral History Transcript — Dr. Lee DuBridge

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Interview with Dr. Lee DuBridge
By Charles Weiner
At California Institute of Technology
June 9, 1972

Listen to Lee DuBridge talk about Ernest and John Lawrence and their experiments on the biological effects of various types of radiation.

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Lee DuBridge; June 9, 1972

ABSTRACT: This session covers only DuBridge’s career at the University of Rochester (1934-40, 1946) with emphasis on the Rochester cyclotron. The cyclotron’s funding is covered in particular detail, with the aid of documents from the E. O. Lawrence Papers (Bancroft Library, Berkeley, California). DuBridge also comments on the Rochester Physics Dept. and its relations with other institutions, and on biophysical and medical research.

Transcript

Weiner:

I think, because of the limited time, I’d like to start with the period at Washington University, after your National Research Fellowship at Cal Tech. You left Washington University in 1934 to take the position at Rochester, I’d like to know how that change came about, whether you were ready to move on and had an offer or whether you were looking for new opportunities, And if so, what your hopes were at this new institute.

DuBridge:

Well, as far as I was concerned, I suddenly got a wire from the then president of the University of Rochester, Dr. Rush Rees, asking if I could come to Rochester for a visit to discuss accepting a position there. I found out later that Robert Millikan had visited Rochester a few weeks before; the president asked him for a nomination for the position of professor of physics to succeed the man who was retiring, and he had recommended me, among others possibly. So I simply got this wire, I think I suggested that I stop in when I was going East to a meeting, but I got a wire back saying, “No, that’s too late, please come at once at our expense.” So I went directly to Rochester from St. Louis, just to talk with them about the position.

Weiner:

This would have been late winter or spring of ‘34?

DuBridge:

It would have been spring of ‘34.

Weiner:

The meeting would have been the Washington (American Physical Society) meeting.

DuBridge:

That was probably the Washington meeting that I’d planned to go to. So I immediately went, I looked up something about Rochester in the meantime and found they had recently inherited a very large sum of money from George Eastman which put Rochester among the then well-to-do institutions of the country. Washington University at that time was not particularly well-to-do. During the Depression they were hard hit. Salaries had been reduced. Research funds were rather meager. So when I visited Rochester and talked to them, I found a very handsome salary increase, a position as professor (I was associate professor at Washington University) with quite nice laboratories and promise of a quite adequate research budget. It was, for me personally, extremely attractive; an almost new physics building and very good equipment, obviously a moderately well-to-do university, which was a contrast to Washington University as of that time. I had no difficulty making the decision to go, and went the following fall.

Weiner:

Was there any discussion of the direction of research or any field for you to get into?

DuBridge:

No. They didn’t seem to be concerned about which field of research I wanted to do. It was up to me. At that time there was no work going on there in the physical electronics field, thermionic and photoelectric emission, so I said that’s what I wanted to continue work on. At this time, I had just completed a series of papers and a small book on the photo-electric effect, following the new R. H. Fowler theories, which opened up great new possibilities for understanding surface photoelectric and thermionic emission. I wanted to pursue that. I immediately started that work, when I got there, with a couple of students.

Weiner:

Was there anyone at all in that field?

DuBridge:

No. There’d been nobody working in anything close to that at all. In their new physics building, there was quite adequate space for setting up the necessary laboratory facilities, and there were funds to buy the necessary equipment. Of course, it was not expensive, except I needed two or three quartz monochromaters to isolate spectral lines for measuring the photoelectric effect of various wavelengths. I was able to get two or three of those, which would have been out of the question at Washington University. I did have one (there). And one or two graduate students were interested in starting to work with me, so we began.

Weiner:

You came there then in October or September of ‘34.

DuBridge:

Yes — in fact I think I got there late in August. I spent the summer at Ann Arbor at the physics symposium which they used to have every summer there, just getting caught up on recent developments in physics. My wife spent part of the summer at her home in Iowa, then joined me at Ann Arbor. We spent a couple of weeks out at a cabin on the lake near Ann Arbor, and then went to Rochester. So, that was quite simple — what seemed to me like a wonderful personal opportunity. At the time, the question had not come up as to whether I’d be chairman of the department, because Professor H. Russell Wilkins who, while I was visiting there in the spring, was on leave, studying in England —

Weiner:

— didn’t he work on emulsions?

DuBridge:

He did some of the pioneering work on alpha particle tracks in emulsions. At that time, the photographic plates were not very effective. He got most of his plates from England, and they were better than anything available in this country at the time; but even then the alpha particle tracks from most radioactive materials were quite short with rather a small number of developable particles along each track. Wilkins was led a little astray by the statistics of these very short tracks with the small number of individual gains. He thought he had a spectrum of alpha particles of different velocities, but it turned out it was just fluctuation. But still he established the technique and improved it a great deal. It was years later that it became a standard technique as photographic plates improved.

Weiner:

He was away when you arrived, though…

DuBridge:

But then in the fall when he returned the dean and the president apparently discussed the question of the chairmanship. The man who had retired had been chairman, and it had been assumed that Professor Wilkins would become chairman, but the dean persuaded the president that I should be appointed chairman. So that’s the way it turned out. Wilkins was very agreeable.

Weiner:

As chairman then you had to consider the entire research program of the department, not just your own.

DuBridge:

Yes.

Weiner:

Could you mention some of the other people there?

DuBridge:

Well, of course Wilkins was really the only other research member of the department — outside of the Institute of Optics. (It was in the same building with the department of physics and closely tied in, but a separate department.) There was a good deal of research in optics going on there. But in physics proper, the only research program that was going on was Wilkins’ work on alpha particle tracks. I made it clear to him that he was free to go ahead and do whatever he wished to do, and I would start up this new line of work. So it was a small department then. The man who had retired had not been a research man, and the other senior man in the department also was a teacher, not a research scholar. Wilkins and I were the only ones in the department with research experience. We began to change that, and brought in almost immediately two theoretical physicists. Fred Seitz was one, Plesset was the other. Two years later Fred Seitz left to go to GE (General Electric Co.), and I asked Niels Bohr (who was visiting Rochester) whether there were any theoretical physicists he could recommend to take Fred Seitz’s place. He suggested Victor Weisskopf (then at Copenhagen) who came then. That must have been 1937. I should say there was one other thing that came up, about the time I was moving to Rochester. There was a Radiation Committee, I think it was called, of the National Research Council, that had secured some funds to look into the question of the reality of the so-called mytogenetic radiation. Scientists in Germany, and one at Cornell had reported that radiation was emitted by growing plants of various kinds, and that radiation could have effects on other plants. There were some strange things about this effect, and many physicists and biologists did not believe it. So the National Research Council set up this committee. I guess it became the Committee on Mytogenetic Radiation. With their funds they started two or three projects to look at this question, and since I was just going to Rochester, I was asked if I would undertake a project there using photo-electric detectors to try to test the physical reality of this mytogenetic radiation. With the funds provided by the Research Council I invited Sidney Barnes, who was then at Cornell, to come and work on the detection by physical means of the so-called mytogenetic rays. Now, it happened that his wife, Margaret was a bacteriologist. She had been working with Professor Rahn at Cornell, who claimed to have identified the mytogenetic radiation from bacteria, so she believed in it. We said, “That’s fine, you come here, we’ll set up a different line of approach.” So we persuaded George Berry in the Medical School to supervise her research on biological effects of the mytogenetic radiation. Sid Barnes and I worked with Geiger counters and photoelectric cells to see if we could detect physically the mytogenetic radiation. We worked on that for a couple of years. There were two or three other projects around the country too.

Weiner:

Are there reports on this by the way, if I want to look into it?

DuBridge:

Yes. We ended up, all of us, being quite unable to find any real mytogenetic effect, and we traced some of the reported biological effects to side-effects of some sort that hadn’t been properly screened out. Sid and I and Margaret Barnes with George Berry — who became later Dean of the Harvard Medical School — worked on that. So this was a second line of research that I carried on for a couple of years.

Weiner:

It started just shortly after you went there.

DuBridge:

Yes. I think it was during the summer, while I was in the process of getting ready to move, that this question came up — would I start this work at Rochester — and I agreed to do it.

Weiner:

Do you remember who at NRC was the contact, just for my —?

DuBridge:

The chairman of the committee was a great botanist from the University of Wisconsin, a wonderful guy. He was the chairman of the committee and coordinated it and overlooked the work. We got together with him and his committee to discuss it, He was the one.

Weiner:

It wasn’t a physicist.

DuBridge:

No. It was really a phenomenon thing that had been worked on by botanists mostly, because it was mostly plant radiation, although radiation from bacteria was also reported at Cornell by Dr. Rahn. That’s really what Mrs. Barnes worked on; and George Berry was a bacteriologist, so he undertook to supervise her work to see if mytogenetic ration from bacteria was a reality.

Weiner:

We find though that by April, within about six months after your arrival, you’re announcing to Ernest Lawrence that you just received a grant for a cyclotron — April 2, 1935. You may be interested in the last paragraph of the letter. (Pause while DuBridge examines letter.) It leads me to believe that it was in the works a little while before that.

DuBridge:

Six months? I’d forgotten it was that soon. I think this must have been stimulated by Stafford Warren (a radiologist in the medical school). As soon as I got acquainted with him there, he started talking about medical studies with a cyclotron, and I think he got me interested. We got together with some local industrial people in Rochester, and we both discussed it with them. A rather curious sidelight to it — there was a little self-appointed committee called the Rochester Fall Meeting Committee and they sponsored every year a fall meeting at Rochester of the electrical engineers.

Weiner:

Nationally?

DuBridge:

It was essentially a national meeting, but it was kind of an unofficial one. It was just a Rochester enterprise. This group of mostly electrical engineers got together and said, “We ought to get together some people and have a fall meeting in the electrical engineering field”, and this grew and grew until it became quite a sizeable thing. I think not until much later was it actually incorporated as an official meeting of the Institute of Electrical Engineers.

Weiner:

Sounds like that Rochester (Particle physics conference, postwar) —

DuBridge:

— yes, yes, that sort of thing. This little Rochester Fall Meeting Committee invited me to become a member of it. It was a lively group, mostly — I guess all except myself — industrialists, from the Rochester Gas and Electric Co., the Telephone Co., the — what’s the big electronics company there?

Weiner:

How about Kodak? Atwater-Kent.

DuBridge:

I don’t think there was anybody from Kodak on that, at least at first. But there was a big radio and electronics company in Rochester, Atwater—Kent; one of their people (was there). I guess Staff Warren and I talked with them and said, “Do you suppose we could dig up a motor generator set and get some steel and get some local people to do the machining? The university in the meantime gave, I think, at first, only a few hundred dollars, maybe a couple of thousand. So we got interested. It’s interesting that it happened that fast.

Weiner:

That was April 2nd you wrote, you said you’d just received the grant. So you’re saying that this came through your biological-medical (mytogenetic) cooperation. That had already started, was Staff Warren involved?

DuBridge:

— no, he was not involved. It was a wholly separate thing.

Weiner:

I see. How did you meet him?

DuBridge:

I got acquainted with a number of people over in the Medical School, through various faculty affairs and so on. I don’t recall just how. I guess Staff Warren, being a radiologist, called on me when I first arrived and said, “Come on over and see what we’re doing in the X-ray radiation field”. So we just got acquainted through the normal friendliness of the Rochester faculty people, including the Medical School, which was only two or three blocks away from the physics building. Then I think he began promoting the idea of a nuclear machine. Ernest Lawrence and I had known each other for some time, and I’d followed his work, as all physicists did in those days, with considerable interest. The idea finally came that we might try to build a small one, and the medical interest would help underwrite the support for it. Actually we did very little medical work with it, although some.

Weiner:

What about Dr. George Whipple? Wasn’t he involved in a major way later?

DuBridge:

Not in a direct way. I knew Whipple. I think he encouraged Staff Warren, but I don’t recollect any direct conversations or meetings I had with Whipple on the cyclotron. But I’m sure Staff Warren discussed it with him and no doubt got his approval to collaborate with the physics department. There may have been an official exchange of letters that the Medical School and the Department of Physics would collaborate on that.

Weiner:

His name came up, maybe it was in an official capacity. Your letter to Lawrence was April 2, then he replied a week later, and of course it was a pretty beautiful Lawrence statement, “Nuclear physics will be a lot more interesting to all of us when there are more laboratories active in the field.”

DuBridge:

Yes. He was very anxious to promote cyclotrons around the country. Some people were surprised at that, expecting that he thought that he ought to have a monopoly, but that wasn’t his idea at all.

Weiner:

No, his strategy was to help others get started.

DuBridge:

Exactly. A lot of people didn’t know that, but it was true. He helped with all the early cyclotrons. And Don Cooksey was especially helpful. Don came to Rochester with Ernest and we talked about it. By the time of their visit we’d already located a basement storeroom which wasn’t much used and we went down there, looked around, and Ernest said, “This is ideal”. It was in the basement, a good solid foundation, and there was room nearby for motor generator sets, a control room and all the rest of it.

Weiner:

He came in May. It was really fast, because he was coming East. But meanwhile had you obtained the necessary financing — this memorandum is apparently June, and I’m really amazed at it, because it was —

DuBridge:

Well, I probably got most of this from Ernest.

Weiner:

It certainly was after his visit. The problems to be studied — now, this is interesting — artificial radioactivity — that’s the physics, certainly — biological effects, photographic effects —

DuBridge:

(Looking at the memorandum) Well, I welcomed the opportunity, you see, to study nuclear ... Any physicist in those days would have said the same thing, I’m sure.

Weiner:

mp3But what’s unique I think is the plan for specific cooperation here with people in the medical-biological field, sort of a specific university program. I’m trying to think of —

DuBridge:

Well, Ernest and his brother, John Lawrence and some of the other people at Berkeley, had begun experiments on the biological effects of various radiations. So this certainly was not an original idea. Ernest was very enthusiastic about the possibilities of biological and medical uses of neutrons, and maybe high-energy protons and deuterons. Certainly the artificially induced radioactive materials were of special interest. I remember seeing Ernest give a paper at a National Academy meeting, probably it was in 1934, where he had a Geiger counter and he had some radioactive sodium which he had shipped in by air from Berkeley. He drank a solution of radioactive sodium, and then showed how quickly it got to his fingers and various parts of his body. It was a very exciting demonstration.

Weiner:

I have on file, didn’t bring it with me, a clipping of the newspaper story of that. Interestingly enough they called Lawrence a Nobel Prize winner in 1934. I’m not sure of the date but if you say it’s ‘34 — it was interesting how they gave him the title —

DuBridge:

— before he got it. (Lawrence’s Nobel Prize came in 1939.)

Weiner:

This (memorandum) — I’m assuming it’s yours, it comes from the physics department — made the point that it benefits the Medical School as well, and the point that they were willing also to make a push in this direction, to get support for their own efforts. This would support what you said about Warren’s —

DuBridge:

Yes, he was quite anxious to do it, to do what he could with it.

Weiner:

I notice, as far as getting the support, you went to local companies.

DuBridge:

Yes. Through this Rochester Fall Meeting Committee, the Rochester Gas and Electric Co. agreed to donate an obsolete motor generator set, AC-DC, to provide the DC for the magnet (and that was a great thing) together with the control equipment, the switches and voltage regulators and all the rest of it. So that was a big gift. If we’d had to buy that new it would have cost us quite a lot of money. I knew some people at the Bell Telephone Laboratories and inquired of them about used or obsolete power oscillator tubes usable at these frequencies. They gave us a couple of water-cooled high power vacuum tubes, which again was, in our minds, a magnificent gift. I think at that time the Berkeley people were still building their own, or ordering them on design from the local company — it was the original Litton Co. I think, Charlie Litton.

Weiner:

Was it the same one?

DuBridge:

I think so. Litton had a little shop of his own; he was a very good glass blower and technician, and built some of their vacuum tubes. But the Bell Labs gave us ours. Then we did buy the steel beams to make the magnet, the two uprights and the cross pieces. A local machine shop machined them up for us at a very modest cost, due to the influence of one of these people on the committee.

Weiner:

GE wound the coils, I guess.

DuBridge:

That’s right. We got the water-cooled coils through GE. I’ve forgotten the exact arrangements there, but we must have got a very good price on it.

Weiner:

Then I guess Kodak, Dr. Hickman, built two large diffusion pumps.

DuBridge:

That’s right. His own design —

Weiner:

— this was really September, ‘35, describing everything in progress, a report on what’s going on — the radio station apparently gave you something too.

DuBridge:

That’s right, we went through the local station to the Bell Labs, and they were able to arrange, the Bell Labs shipped us these. Oh no, these are the rectifier tubes.

Weiner:

Bell Labs isn’t mentioned here in this letter, I don’t think. (Pause while looking at letter.) That was the period when all the contracts were out, everything was being done. This was September, so it may mean that the money was already in by that time.

DuBridge:

I guess it was, yes.

Weiner:

— a rather whirlwind campaign.

DuBridge:

Yes. By that time Sid Barnes, who was still working on the mytogenic project, expressed a great interest in the cyclotron. I don’t know what I’ve have done without him, because I finally asked him if he would not work out the design of the accelerating chamber. I’d made a few sketches, following what I knew of the Berkeley designs; but Sid was a great fellow at designing things, and boy, he whipped the design of that vacuum chamber into shape. He went out to Berkeley. We sent him out to get some firsthand information from the people there.

Weiner:

Would it have been that summer, ‘35?

DuBridge:

Must have been, I guess. So Sid was really the engineer for the project. After he got the vacuum chamber worked out, then we worked together. He did the engineering, and was invaluable. He was, in a sense, my Don Cooksey.

Weiner:

Then you had some contact with Hans Bethe, who was over at —

DuBridge:

— Yes, he was at Cornell and they were building their cyclotron at the same time. Stan Livingston was there then, building a small cyclotron. The Cornell and Rochester people were continually having joint seminars and meetings and parties, and so we were close friends with Livingston.

Weiner:

— Smith. He had his own kind of accelerator which was on a completely different line.

DuBridge:

Yes, he was on a different line. But we were good friends, and the Bethes. We used to have an annual Cornell-Rochester Sunday physics dinner at a great restaurant in Skaneateles, New York which had easy access to both Ithaca and Rochester. So, yes, we talked a great deal with Hans and Stan about this. Robert Bacher was at Cornell then, too.

Weiner:

Yes, that’s when (he and Bethe) were working on the review articles (in Reviews of Modern Physics).

DuBridge:

Yes, that’s right.

Weiner:

You mentioned specifically, to Lawrence, Bethe’s theoretical work —

DuBridge:

At that time Bethe was worried about the focusing of proton and deuteron beams in the cyclotron, as related to the shape of the magnetic field. He actually published a paper which made Ernest Lawrence very mad, in which he said that the limit of energies probably would be — I’ve forgotten what figure he gave.

Weiner:

The upper limit would be about 8MeV for deuterons.

DuBridge:

Yes, that’s right. And it made Ernest mad because even at that time they’d found focusing techniques to get above that energy. But Bethe made a very important contribution in pointing out the problem of the focusing (because of relativity effects) and how critical the shape of the magnetic field was to it. His point was that you had to have the magnetic field tapered toward the edges to get the focusing effect, but if you tapered it too much, you’d get out of resonance, and the beam would blow up. But we weren’t planning to go that high anyway. I don’t know how we finally decided, instead of using deuterons, we would use protons. I guess we found out that Berkeley was largely on deuteron work and they were going to have higher energies than we were. I think Cornell was going with deuterons. And we quickly figured out that with our size we could get six or seven million volts of protons, and that was higher than anybody was then working with.

Weiner:

It was also higher than the limit that he (Bethe) predicted. He predicted 5.5MeV.

DuBridge:

For the protons? We didn’t get to six or seven right away. But we still, I think even at five, had the highest-energy proton beam. So we decided to concentrate on proton reactions; that was a lucky thing because out of it came the (p,n) reaction. And it turned out that you needed at least two million — we needed to get up to two and a half or three million (volt) protons to detect the (p,n) reactions. Rather early, as we were just exposing a lot of different substances to see what radioactivities emerged. We assumed that we would find either proton capture reactions, or (p, alpha) reactions, and nobody had thought much about the (p,n) reaction, but here we found some radioactivities that could only be identified with a (p,n) type of reaction. Right away Bethe then started working on the theory of the (p,n) reaction, and sent us his paper on it, in which he worked out what the threshold should be and the relation of the beta ray energies to the threshold. We were able to check out his theory eventually, and there was a direct relation between the threshold and the beta ray energy emitted by the product nucleus.

Weiner:

This was, of course, when it was in full operation. When did the cyclotron first go into operation?

DuBridge:

Well, I don’t know, did you find any papers there? My memory on dates is obviously faulty.

Weiner:

I don’t have it here —

DuBridge:

It certainly took a year from this time. I would guess in the fall of ‘36 (looking at papers).

Weiner:

You said, “What we hoped to obtain in our new chamber”. You said new chamber, this is ‘37. You were already in business then.

DuBridge:

Yes, I’m sure we had a beam then, but it was maybe only four or five million at that time, and we hoped to be able to push it up later.

Weiner:

Here’s when Whipple came in, by the way.

DuBridge:

I see (looking at papers). Well, I’d forgotten that. So Whipple did get into this. I had assumed that he’d talked to Staff but I’d forgotten that we’d had this conference. Whipple was a wonderful guy.

Weiner:

He was already quite well established by then.

DuBridge:

Oh, yes. He was the most distinguished member of the Rochester faculty by far, the only member of the National Academy, and his Nobel Prize came along in there some time (in 1934, in fact).

Weiner:

I do have the dates but, I’m sorry, I don’t have them here; but let’s say it was surprisingly early, compared to other cyclotron laboratories. Since there was local support for it, it seems there’d be a great deal of pride in the project, in that kind of community especially — was there much publicity on this locally?

DuBridge:

Yes, quite a lot.

Weiner:

How did they approach it? Did they focus on the medical-biological application primarily?

DuBridge:

That was always prominent in the stories, the potentialities of the biological use of induced radioactivity especially, because at that time we didn’t think much about neutron irradiation. Our neutron beams were pretty weak, and as a matter of fact, we didn’t think in the early days about the (p,n) reaction and therefore didn’t expect we’d have any neutrons at all. That came later. I remember, I gave speeches to various organizations around town. They had an organization called Town Hall. And Staff and I, I remember, each gave a talk at a Town Hall meeting. There was a big crowd, several hundred people. I talked about the cyclotron and nuclear physics generally, and Staff talked about the biological-medical aspects of it. It drew fascinated attention. And there were others — I spoke to various local groups. That was the beginning of my speech making, I guess. I started talking to various groups around town. I think I talked to the Rochester Fall Meeting when it assembled, about the engineering aspects, mechanisms of acceleration, and the nuclear physics results and hopes. I gave a paper at the Washington meeting of the APS. That must have been in the spring of ‘36. The title of it was “The Rochester Cyclotron”, and I just talked about the design. That was before it was operating. Incidentally, I made one blunder (among others). We wanted to get a very uniform magnetic field (the focusing effect of the field gradient was not too clearly understood at that time) — In order to get a uniform field across the whole diameter of the magnet, the obvious way was to shape the poles so that the air gap was smaller at the edges than at the center. So we calculated out what the shape of the poles ought to be, to take care of the fringing flux. With flat pole faces, you had a fringing effect and the field tapers off at the edge, and it wasn’t realized at that time that this was important. So we made these shaped poles, machined them to a specific curve, and tested it, and found out indeed that the field was extremely uniform right up close to the edge. But we tested it with the magnet operating at very low power, with just a very small field. Only later, when we tried to get the thing operating, it wouldn’t work — So we took it down again, and then tested the magnetic field at full magnet power. And we found, of course, due to the saturation in the magnetic material, that the behavior at high fields was very different from that at low fields, and that we’d much overcompensated for the low fields. At the high fields it was better to have a flat face, so we flattened out the pole faces and used flat pole faces. That worked.

Weiner:

This took a good deal of time?

DuBridge:

It took some time, you know, and we were very puzzled because we couldn’t get a beam. We measured the magnetic field at low fields, where the saturation effects were not important; I don’t know how the idea finally came to us, “Let’s go up to the full operating field and measure it there”. Then we discovered that the field rose at the edge instead of staying flat, and so obviously that just completely unfocussed the beam. And by that time I think we’d talked enough with Bethe to realize the importance of the field gradient, so we went back to the flat pole faces — and it worked fine.

Weiner:

It seems there are three things involved here. Once is the problem of developing the cyclotron itself. Another is the two uses of it, one for physics another for the biological-medical applications. In my experience with digging into the history of other institutions, it turns out that the cyclotron is a much more difficult instrument than people think it is to get rolling as you indicated, and yet the biological-medical people expect some results pretty soon. After all, that’s their reason for building it. Did you get into that situation, where there was pressure, where these guys said, “Well, where’s your beam? Where’s the results? We need to do our work”.

DuBridge:

No, I don’t recall much of that. Staff was a very understanding guy and he knew that building this thing and getting it going wasn’t a very easy job. He followed it but he never said, “What the hell are you twiddling your thumbs about, why don’t you get busy?” No, he was very understanding and cooperative, and we worked together. I think as soon as we were able to produce any radioactive materials, we let him have what he wanted. I don’t recall just when and to what extent we were supplying radioactive materials to him.

Weiner:

I think Berkeley helped too, until you got rolling.

DuBridge:

Oh, yes.

Weiner:

On supplying radioactive material — they were better able to produce then, so that probably took the pressure off of you.

DuBridge:

That could be, yes.

Weiner:

Berkeley was doing this with everyone.

DuBridge:

Yes, that’s right. So that enabled Staff to get his laboratory set up and instrumented and some experiments undertaken with mice or whatever he was using. I think things went along fairly smoothly. We weren’t able to produce the large quantities of radioactive materials, partly because with the proton beam you just didn’t get the large cross-sections that you did with deuterons, and therefore the large quantities of radioactive materials were not produced with the proton beam. But enough were produced for them to do tracer experiments of various sorts, especially measuring blood volume, I think.

Weiner:

Doing some radiophosphorus work —

DuBridge:

Yes.

Weiner:

If you had to think back about the breakdown of the time of cyclotron was used, say between physics and the biological-medical uses, is it fair to say it was used mostly for physics?

DuBridge:

It was mostly physics, yes. The production of radioactive materials for the Medical School was kind of a by-product, because we were interested in finding out what radioactivities were produced anyway. Giving them samples really did not put on a large additional load, so that we were able to keep on with a large share of time doing physics, and not much diversion of effort to the medical things. Because if they wanted some radioactive phosphorous, for example, we’d produce some, give it to them, and we would keep a sample of it and do our own analysis, measure the periods produced and try to work out what the reactions were and so on.

Weiner:

How did this relate to the educational role of the physics department?

DuBridge:

Of course, the graduate students got involved in this right from the start. Even during the building phase, we had graduate students helping with the design and construction, tuning up, magnetic field measurements, electronic circuits and all the rest of it. So if you look over the papers we published, essentially every one had the name of one or more graduate students on it. Some of the papers were just DuBridge and Barnes. Some involved Jack Buck and Charles Strain; _______ Hill and George Valley. It was not Al Hill, now at MIT, he was there at the time but he was absorbed in photoelectric effects. I still get kidded by some people who remember one of the earlier papers was signed, “DuBridge, Barnes, Buck and Strain.” And “DuBridge, Hill and Valley”. So Valley, Hill, Strain (who’s now at the Naval Research Lab), and Buck (who’s out here some place now — he worked with the Radiation Lab at MIT during the war with us, and went into industrial work and he’s just within the last year or so come to a company out here). We wouldn’t have been able to work without the graduate students. Because there was just Sid and myself and the machine shop man who did the machine work for the whole department, including the Institute of Optics; a very good and very clever machinist. We had no full time hired technicians. We did all the work ourselves, except what had to be farmed out — to be done in the shop or farmed out to a local company. (During the war, the thing went into larger, more intensive operations. We worked with the Manhattan District people and did quite a lot of work with them during the war. Then they had several full time employed technicians.) But I don’t recall that we had a full time technician. There was a kind of laboratory handyman who did a lot of technical work for us. His principal job was setting up lecture experiments for freshman lectures, but he helped on apparatus and so on also, kind of a part-time technician. Also, several undergraduate students did senior thesis work on the cyclotron.

Weiner:

Nobody really was added to the staff, especially until Weisskopf came in, you mentioned others — Plesset and so forth —

DuBridge:

They were part of the professorial staff, yes, even before we started the cyclotron. Just to round out the department when I arrived. I felt strongly we needed two theoretical physicists. Everybody said, “Don’t try to get one, he’s too lonesome,” so we always tried to have two. Seitz and Plesset were the first two, and Seitz left and we got Vicky and then Plesset left; I’ve forgotten who came in then.

Weiner:

Didn’t Marshak come just before the war?

DuBridge:

Yes, that’s right, Marshak came after Plesset left, I think.

Weiner:

The grants that you had — they weren’t really grants, they were sort of contributions for the cyclotron — did they in any way cover the graduate student work?

DuBridge:

No. These graduate students were all teaching assistants. They were supported by their teaching duties, all the graduate students.

Weiner:

Did you have any problem of university administration? I can understand the two departments which had something directly to gain wanted to cooperate. Was there anything you had to buck in the larger administration to get this program rolling?

DuBridge:

No, I don’t remember anything.

Weiner:

You had their support — the reason I ask, at Ithaca they had difficulty. When Lewisohn wanted more money for a better cyclotron, there was resistance on the part of the university as far as independent fund-raising.

DuBridge:

No. As I recall, the president who hired me in 1934, Rush Rees, retired the following June, and Alan Valentine succeeded him as president. Now, I will hesitate a minute as to whether Alan Valentine came in in ‘35 or ‘36; I’m not sure, but I think it was ‘35. He was quite a young fellow. We quickly hit it off pretty well. The then treasurer of the University of Rochester was pretty hardboiled but a very understanding and helpful fellow, and when we needed funds I would go directly to him. I remember the first year I was there, when I was getting photoelectric equipment set up. I needed two more quartz monochromaters and I went over to Ray Thompson, treasurer, explained to him and he said, “Let’s go see the president”, Rush Rees. So we went in and he asked me to explain it to him again and Dr. Rees turned to Thompson and said, “I think we’d better get Lee his monochromaters, don’t you?” (They cost about $950 each.) Ray Thompson, as I say, was in a sense a tight-fisted treasurer, as he was supposed to be; nevertheless, he was always very cooperative, and if we presented the case, he would find the money. At that time Rochester was not hard up.

Weiner:

But you did get outside grants after a while. You did get at least something from Research Corporation, because I know in 1939, I think, you wrote to Ernest Lawrence what a disappointment, their not renewing your grant. This apparently was something you had not expected. Can you recall?

DuBridge:

I remember we got a small grant from the Research Corporation but it was only $500 or something like that.

Weiner:

Oh, that small?

DuBridge:

I think so. We never got large grants. Did you check the amount, the outside grants, was there any correspondence out there?

Weiner:

Didn’t find that, no.

DuBridge:

I think I inquired informally of the Rockefeller Foundation. They turned us down. Research Corporation stalled a long while and finally gave a grant of $500, which helped us for a year or so. I think at that time the attitude was, “Well, University of Rochester just got $20 million from Mr. Eastman, you don’t need any outside help.” In a sense for the whole university, that was true, so after this $4,000 construction fund was gone, the operating funds just came under our regular research budget each year. I would request a research budget each year from the university and it was always given, at least almost always. But it was not a large research budget. We did not have, as I say, employed technicians. Graduate students were either on regular university fellowships or teaching assistantships, and I don’t think we hired any more out of our research funds. I have no idea what the research budget was in those days.

Weiner:

Were there any plans, before you left for Cambridge (Mass.) to develop larger cyclotrons?

DuBridge:

No.

Weiner:

So this is the program and it was working effectively.

DuBridge:

Yes, and they kept on with it after I left. Of course, Barnes eventually left to go to Oak Ridge and Vicki Weisskopf left to go to Los Alamos. Marshak went up to Canada on a nuclear physics project. So it looked as though the thing would kind of fall into disuse. I wasn’t there and I’m not quite sure just what happened; the Manhattan District through Staff Warren probably, got funds for getting some better oscillators and better equipment and so on, more adequate control system, so that the cyclotron was quite handsomely rebuilt during the war, the beam increased and energy increased and so on, and they used it during the war.

Weiner:

For biological purposes?

DuBridge:

I think so.

Weiner:

Livingston did the same at MIT.

DuBridge:

Yes, I think that was largely for biological work. Maybe for some of the (p,n) reactions. They became important in some of the Los Alamos work. So by the time I came back after the Radiation Lab the cyclotron was going well, had new vacuum tubes, new oscillator system, new tank and a new electronic control system, so it was greatly improved. Then I left for Pasadena. But before I left, the ONR (Office of Naval Research) people came to Rochester and said, “You’ve had a good experience with your present cyclotron; isn’t it time that you thought about a bigger one?” That’s before the Cal Tech offer came up and we were just deciding what to do at Rochester after the war. I didn’t enthusiastically jump up and down at the idea of undertaking a great big cyclotron construction. But Sid Barnes came around one day and said, “Look, are we just going to sit with this little cyclotron and let the rest of the world go by, in the field of nuclear physics?” I began to think, well, it isn’t really fair to the department not to take the opportunity. ONR was offering funds, and so about the time I was leaving, ONR agreed to provide the money for the large cyclotron.

Weiner:

They initiated it?

DuBridge:

They initiated it.

Weiner:

The whole setting up of the ONR, Charlie Lauritsen’s role as a matter of fact, is a fascinating thing, a separate story, I want to keep you to your plan —

DuBridge:

— which is getting on, isn’t it —

Weiner:

— We’ve really just squeezed this in and there are lots of other things I would like some other time at your convenience, with some advance notice, to get together for another, much longer session, if you’re agreeable. This covers very nicely this little sort of interlude, but it’s part of a larger story.

DuBridge:

You’ve taught me more than I’ve taught you. You recalled a lot of things that I’d forgotten.

Weiner:

No, but the two together, the documents plus the recollections. I wouldn’t have known to ask certain things without documents. At the same time there are things that you tell me that are in no way documented, as far as I know.

DuBridge:

Probably.

Weiner:

What I’ll do on this: I’ll have it transcribed, add to it whatever other information I have, send it to you, and maybe then we can discuss about filling in some gaps here and continuing. I don’t know when I’ll get to the West Coast, with my travel budget.