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Interview of Frederick Seitz by Lillian Hoddeson and Paul Henriksen on 1982 March 16, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/4877-4
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Family background and early education, motivation and funding for college; math program at Stanford University, from 1928; physics studies at California Institute of Technology; graduate study at Princeton University, beginning 1932, atmosphere of the department, faculty (Lou Turner, Eugene Wigner, John Von Neumann); colloquia, Edward Condon. Development of applications of group theory, work in solid state with Linus Pauling, Hillard B. Huntington, Albert Sherman, William Hansen, William Shockley, Robert R. Brattain, R. Bowling Barnes. Betty Seitz; work with her on the text Modern Theory of Solids. Sodium band theory work with Wigner. To University of Rochester with Lee DuBridge. Centers for solid state work including University of Michigan, University of Wisconsin, Harvard University (John Van Vleck). Work at General Electric, 1935-1936, studies of luminescence; atmosphere in industrial labs following Depression, contacts with other industrial labs; association with DuPont. State of physics in 1930s, trends at solid state centers. Work on crystal defects, pigments, leading to work on germanium and, particularly, silicon; history of study of semiconductors and influences on its development such as World War II; work on dislocations and creep; work at Westinghouse Company. World War II work with Frankford Arsenal, Dahlgren Proving Ground, and Massachusetts Institute of Technology Radiation Laboratory; University of Pennsylvania, 1938; Carnegie-Mellon University, 1942, on dark trace tubes, leading to color center papers; University of Chicago work on reactors and neutron diffraction, 1943; Oak Ridge National Laboratory with Wigner; Argonne National Laboratory, solid state group. With Field Intelligence Agency Technical (FIAT), visit to Gottingen, 1945; state of solid state physics in international centers and U.S. Return to Carnegie- Mellon; diffusion theory. Pugwash Conferences; trips to Japan, 1953 and 1962, conditions and theoretical solid state work in postwar Japan. To University of Illinois, 1949 (Wheeler Loomis); John Bardeen's work, visits by Nevill Mott and Heinz Pick; McCarthyism. Development of Seitz's bibliography, changes in the study of solid state during the 1950s.
This is Paul Henriksen talking with Dr. Seitz at Rockefeller University on March 16, 1982. I'd like to ask some more specific questions on certain things and general questions on other things, mainly starting with your work at the Frankford Arsenal in '39. I have a couple of questions on that, and then running through to the end of '45, when you were at Argonne and University of Chicago. Now, at the Frankford Arsenal, you were working on brass shell casings, right, and fatigue cracks?
That was one of the problems. I was brought in by a group at the Research laboratories which were headed by a man named Herschel Smith, who had taken the job there as Director of Research, a very experienced physicist. They had a number of problems. Initially the big problem was to get back and try to understand armor penetration. Frankford was responsible for armor piercing bullets. They were doing tests and developing bullets.
Now, did you go at that from a theoretical standpoint, or mainly to see —
A combination. They were doing experimental work, and I was interested in plastic flow, in metals, and so forth. Incidentally, one of the things they did at one point was, commission a paper from Hans Bethe, who went to the ENCYCLOPEDIA BRITANNICA and found a lot of stuff on armor plate that had been written by some British ordnance people, and presented them with a paper which described some of the basics. They classified it. Then at that time Bethe didn't have any clearance so he never could get a copy. He was awfully amused by that.
Even though it was based on the ENCYCLOPEDIA BRITANNICA.
What happened is that about once every week, I'd go over and spend a day with the people . . . (omit chatter) Then one thing led to another there. They were developing what was called a 60 caliber, that's 6/10 of an inch, armor piercing bullet for aircraft use, because aircraft had got armed with armor, and we spent a lot of time on that. Season cracking was one of the problems that came up. The cartridge case was made of brass. It developed cracks. That was an old problem. And George Sachs, who was then at Case as a metallurgist, he'd been a German refugee, helped me with that. We had a variety of problems related to ordnance going on. One of the things they got into was, to study steel cartridge cases. Brass is a very expensive metal. They used huge quantities of it. The Germans had long since given up brass and had learned how to make steel cartridge cases, and some of the work at Frankford was tied up with that.
This all started when the war started?
It started in the fall of 1939. United States was not yet in the war.
They figured they were going to be, so —
Well, it was what was called "Preparedness." I had been at the University of Pennsylvania, I guess something on the order of just under a year.
You worked on it mainly from the theoretical side?
That's right, but I talked to the experimentalists. I learned a lot of practical metallurgy which was interesting.
Was any of that beneficial to you later?
Only in a very general way. Sort of, contact with the real world of metallurgy. I gave a night school course in metal physics at Penn, and had, oh, I guess about 30 of the metallurgists in the city, mainly with industry, who came to it.
Let's move on then to your work with DuPont. Did that start in 1940, when you talked to them about producing the high purity silicon?
It started in 1939. The DuPont Co. has a plant in Newark, New Jersey that makes colored pigments, things for automobiles and so forth. Still going. They still have a small laboratory. They were one of the principal manufacturers of a pigment known as chrome yellow. It's lead chromate. It was widely used for signs and also for street markers, yellow street stripes, and it darkened. They had noticed, while I was at the General Electric laboratories, I'd written a paper on the darkening of pigments by light, so they asked if I could be of any help, and we did some research.
They gave us some money to work at Penn. A couple of our students got theses out of that, in which we demonstrated pretty well that the darkening was very much part of the fact that the pigment, at room temperature, was photolytic, a little bit like silver salt, and while you could slow it down, by coatings, the material in the presence of light liked to give up oxygen, which changed the valence state of the chromate radical. It convinced them that while they could do a lot, they couldn't go all the way. And because of that work and its success, the people in Wilmington who were interested in white pigments asked if I'd work with them.
They had a very strong position in titanium dioxide, which was now the very high grade, high quality white paint. Before 1932, most white paints were made out of lead compounds, which were poisonous, so called painter's colic, and they were outlawed. So DuPont, as I recall, had bought some patents from Europeans manufacturers of titanium dioxide, and got a very strong position in the United States, wanted to be sure that there was no competitor going to come in.
So we got to look at other pigments that might be white and cheap, and competitive. That led them into a very interesting study of other compounds. The only thing we ever found that would have come close was silicon carbide, and one couldn't make it white in quantity. In stoichiometric form it would be white, but it turns out, at the temperatures that you make silicon carbide, it isn't. But in any case, they got so much experience in making unusual compounds that when the silicon problem came along, I thought of them as a source of pure silicon.
You'd started working on silicon at Penn, then, before you went to — ?
That's right. The Radiation Lab, I forget who it was — it may have been Lee DuBridge, or someone else — gave me a call one day and said that they had this problem with the silicon diodes, and wondered if we could help. So they put us under contract. I had Andy Lawson and a little team. At that time, I suggested the DuPont people try to make pure silicon, which they did.
So it was the Rad Lab that actually asked you to start the work?
Was it easy to convince DuPont to make the silicon?
Yes. They got a contract with the Radiation Lab or NDRC through the Rad Lab, and were glad to, you know, the people of the lab felt they were out of any contribution to the war effort and were glad to get into something that was down the mainstream.
Did they see silicon as having any use after the war?
Well, after World War I, DuPont had been called a Merchant of Death because they had manufactured explosives, and as a result, as soon as the war ended, they had a policy — they pulled out of everything. They had put up the first nuclear reactors at Hanford. They dropped it. They dropped the silicon program and went back completely to commercial things. Then about 1948, '49, the Bell Labs came to them and said, "We need the kind of silicon you were making during the war, and wonder if you'd get back into business." This is for commercial, not military purposes. So they did get back in.
They were mainly the supplier, then. Did they do any research on silicon themselves?
They did some. Judged by present standards, it was pretty modest. They had an opportunity to have a big market, but they didn't know how far things would develop, and they never put the effort in. Eventually the semiconductor manufacturers demanded material of higher quality than DuPont was manufacturing, and DuPont wasn't willing to put in the research effort. I imagine that if they had been able to guess what was on the way, they would have been happy to have that market. In the main, Texas Instruments went out on its own and started making its own materials. Very soon that took over the market.
Did they have their own methods for purifying it, or was that something that you contributed?
It came out of our other work. They started with titanium chloride and reduced it with zinc, reducing agent, used zinc chloride. It looks at present like an infinitely crude method, but infinitely superior to anything else at the time.
Did they do anything with doping?
We did doping experiments at Penn, in testing. Discovered a lot of the rudiments which appeared in reports that we sent to the Radiation Laboratory. Incidentally, a number of laboratories became interested in these things. Of course the group under Lark-Horovitz at Purdue, and then, some of the laboratories, Sylvania, Bell Labs, and so forth. We used to have bi-monthly meetings that lasted a day or so, in which everyone would review their work.
I think I've got a couple of questions about those meetings. Did you go to many of them yourself?
Yes, I went to all I could. Once I got involved in the Met Lab at Chicago, I had to taper off.
In your biographical notes that you wrote for the London meeting in '79, you mentioned in one place that "the pressure to do military research became all-consuming." How much of this was internally generated and how much of it was external?
It was both. You found that, you know, people would ask for help, and it was very hard not to give it. Then in addition you've got to remember that practically the whole scientific community became involved, one way or another, in defense research, as it was called. That's the way it was.
How did you get started with the silicon work at Penn?
Request from the Radiation Laboratory.
Were you, I guess you'd say the staff theorist then on it?
I was what was called the principal investigator. The contracts were with the university, but the research was under my direction.
Had Penn done anything with silicon or semiconductors before the Rad Lab request?
Well, we had the solid state group that was much interested in semiconductors. In a sense, the lead chromate material I mentioned earlier was a modest semiconductor, a very poor one compared to silicon. We were interested in these imperfect crystals.
Was the motivation for the Rad Lab request the fact that there was a group there that could do something for them?
There weren't many people in the country who were interested in solids at that time. You know, it wasn't as yet anything like as prominent a field as it is now. There were, you know, throughout the country, you might have found half a dozen people taking solids seriously.
Who was with the group before the request from the Rad Lab? Park Miller?
Park Miller, Andy Lawson — Hill Huntington was there. He went to the Rad Lab, after a period with me.
Did many other people go from Penn, from your group, to the Rad Lab?
Well, Andy Lawson. I left Penn to go to Carnegie, I guess the beginning of '43, and soon after that Andy Lawson went up to the Rad Lab, spent the rest of the war there.
Did he still work on the silicon then while based at the Rad Lab or did he go into more of the components?
He worked on other things.
Let's talk a little bit about some of these solid state groups. In the late thirties, about the time we just mentioned, there was the group at Penn and the, well, the group at Purdue hadn't really done much until the war.
There's a group at Princeton, I believe.
Small group under Wigner.
And then a group under Slater?
Then Van Vleck at Harvard, I think?
Magnetic properties of solids.
Rochester also, that was under Lee DuBridge?
Yes, photoelectric work and so forth.
Did that keep going after DuBridge went to the Rad Lab?
There was some work. Also Brian O'Brien who was head of the Institute of Optics did some work on fluorescent compounds, which was of interest to radar work.
I see, for the PPI's?
Yes. But I think in the main the work at Rochester died down.
Was there much interaction between the people working on solids?
Yes, we were all —
Would you call it a community?
We were all good pals. You could get all of them in this room.
Were you friends mainly because you were interested in solids, or had you met at other things before?
Mainly professional links. We'd meet at the (American) Physical Society meetings, and then retained a sort of companionship.
Did the work that was done at GE and Westinghouse and Bell on copper oxide materials have connections with any of the university groups?
Well, we did some work on copper oxide at Penn, and one of our students got a thesis measuring the properties of copper oxide, doing a kind of basic study, Steven Angelo. He eventually took a job at Westinghouse, became their expert.
He did some work on, I think it was, silicon perhaps germanium too.
Yes. Westinghouse had a small group, where GE had quite a good group under Harper North.
At GE they did mainly germanium, then.
That's right. Harper felt that germanium was the material of the future, because it was so much easier to handle. But eventually, in the 1950's, people learned how to handle silicon. It's much more stable.
Was silicon more expensive to produce than germanium at that time?
Yes, germanium can be reduced very easily with high purity. And many of the early transistors were made out of germanium. But once methods of purification, growing single crystals and the like developed, silicon took over the market.
It seems to me it's harder to make germanium single crystals than silicon single crystals.
I don't think so.
Not too much difference?
It's much more temperature sensitive and hence not as rugged.
Were you ever asked to go to the Rad Lab itself to work?
Who would be the most knowledgeable about Penn's war work all the way through to the end?
I don't think there's a trace of it. When I left, Leonard Schiff, who later went to Stanford and became head of the physics department, took over the project, but Leonard died about ten years ago. Andy is gone. Park Miller stayed through the war, and he might be able to give you some picture. He works in the San Diego area, I think for General Atomics.
I'll see if I can contact him.
Yes. He ought to be a member of the American Physical Society, Park H. Miller. I think he stayed at Penn through the whole war, and left after the war to go to San Diego.
We mentioned before, the bimonthly meetings of the Rad Lab and its satellite groups. Did that lead to . . . I'm trying to compare that to communication possibilities before the war. Was there less communication between the groups during the war or about the same?
During the war, we met more frequently. Before the war, there were the Physical Society meetings, about two a year, that you went to, and then people were invited to give a colloquium talk, here or there, perhaps, you know, during the course of the year, I'd go to five places to give a talk. Another place we tended to meet was University of Michigan, during the summer. That was a crossroads.
Then during the war that, those types of —
— died down —
So they substituted these meetings.
And these bimonthly meetings were very concentrated. They were on the properties of solids specifically, as rectifiers, whatever.
I've been able to find a few programs and sets of abstracts from those. There were several in Lark-Horovitz's papers at AIP that I was looking at yesterday.
That would be a good source.
So at these meetings, these specific topics that each group was working on currently were discussed, and
— argued about. Were they violent arguments, or?
No. No. They were a very friendly group. You know —
I mean, was there much disagreement over methods or anything?
Were any of these groups more active than other groups, or were they of about the same size and level of activity?
The Bell Labs had a very big group. I suspect that much of their work was done, financed by the company, and they always had in mind the fact that patents were important to them. So they, I don't want to use the word secretive because in this matter they were fairly open, but one always had the feeling that they would bring in things which they thought were relevant to the discussion, but then back home, they were doing other things. I think someone probably realized that, if you could make diodes, perhaps some day you could make triodes. So —
So there was a glimmering there that, they might be working on —
Bell Labs has always had very far seeing leadership. Mervin Kelly was the head then.
Was Penn's research on silicon, here for the rectifiers, based mainly on producing a rectifier for the military or was there also a theoretical component, looking at the basic properties?
We were much interested in the basic properties. The first materials used were doped with aluminum. I think either the Germans or the British discovered that they got a reasonably good rectifier if they doped the crude commercial material with aluminum, and we were interested in knowing what other elements would give remarkable properties.
Were you left pretty much to your own devices in the group itself? They just said "Look at silicon and see how it works"?
Yes. It was characteristic of the whole Radiation Lab that the people in it had a lot of freedom.
In a paper that I have, written by Lark-Horovitz on the history of germanium development at Purdue, he mentions a part, in August of '42, where, at one of these meetings, I'm not sure which one it was but, he made the announcement that germanium and silicon were intrinsic semiconductors. Was this unexpected at all? How much did Penn contribute to that?
There were results available, in the literature, on germanium, measurements that were made at Cornell in the twenties —
You mentioned those at the meeting. Was the man's name Bidwell by any chance?
I found a PHYS REV article of his on basic germanium.
There's a publication which still exists in libraries, International Critical Tables. One looks under germanium there. You'll find reference to the Cornell work. I took that, it was not plotted in the log kind conductivity vs. 1 over e basis, and reached a conclusion that we were in the intrinsic range in pure germanium. Then, there was immediate follow-up from that doing temperature-dependent studies, with silicon, also in the intrinsic range. We got the gap and so forth.
So the Lark-Horovitz contribution then was mainly a sort of a summarizing?
I suspect. From the standpoint of basics, we were way ahead of the Lark-Horovitz group, but they did some very fine experimental work. They were dedicated and careful.
People have mentioned that before, that Purdue didn't really have the experienced theoretician —
To really pull everything together. They started from the purification, then worked up to the devices.
Lark-Horovitz was a remarkable man. He had much of the artist about him, and also haunted the literature. Came up with all kinds of obscure papers published in obscure journals. So he was always interesting to have around. But Bob Sachs was there briefly. I don't know how long Bob stayed.
I think it was less than a year. When we talked to him, he was there right about when they began in '41, and then I don't think he got along with Lark-Horovitz too well. Two bulls in the same ring, I think.
And left soon after that, went out to the West Coast. California.
Yes. I remember, I met Bob there. He had done a thesis, I think with Edward Teller, on some problem, perhaps breakdown or some such thing. We became good friends. Then he left the circle. But our group at Penn and some others, Esther Conwell, were on top of the theory, whereas the group at Purdue were not, in that sense. I was often amazed that they did so much general fussing around with their materials, and continued it well beyond the end of the war. In a way it's amazing that they never, they — never just stumbled on the transistor in some form.
It seems like they had two halves of it. They had the high back voltage one that Benzer worked on, and they had the forward one that Bray was working on. Although Sachs claims that he had one actually put together but said, "Well, we'll work on that after the war," and they never got back to it.
Never got back to it. See, with the Bell Labs, it was a very dedicated effort. Trying to push ahead and see what they could get.
And also probably just the university setting, they were not really looking for a device.
Then at Carnegie, this is late 1942 now, you started working on the dark trace tubes? Did the Rad Lab ask you to investigate the —
Yes. I had good connections up there, and when I moved to Pittsburgh, since the group at Penn was well established, we didn't want to upset that. As I say, Leonard Schiff took over the business of being principal investigator, and he had Park Miller and Andy Lawson working with him, and Bob Maruen came with me. So I went up to the Rad Lab and looked around and found that they were much interested in these dark trace tubes and were glad to have us work on them. They had two very good people there, Estermann and Stern, who wanted to do something. Marvin Goldberger, who is now president of Cal Tech, was an undergraduate, and we put him to work in the laboratory.
Did he work with you at Argonne also?
Yes. What happened is, he got drafted, once he finished his degree. In the meantime I'd got tied up with the Met Lab, and found that the Engineering Corps could pull anyone out of the — Army — in uniform. They had a special name for it. And assign them to people. So we had Marvin assigned to our theoretical group. His wife was the girl who did all the computations for the crowd. It's often been said that he married a computer. It had a slightly different connotation then.
Was the Rad Lab's interest in these dark trace tubes, again this is a question of theory versus basic devices, they were interested in it mainly for getting a position indicator that they could — ?
— the Navy wanted something they could use in broad daylight. They didn't like the tubes that you could only see in a darkened room, phosphorescent things. They liked to be able to look at the ocean at the same time. The dark trace tubes you can have out in the open.
So then, were you able to extract some theoretical?
Oh yes. We had a lot of, did a lot of basic work. One of the problems was that the signals tended to burn in and persist, and it was a problem of discovering how to alleviate that. Shipboard, since they were moving slowly, it wasn't infinitely serious, but it was a serious problem. It impeded their use. I don't know what's ever become of the dark trace tubes. I think they probably are gone by this time. They never got perfected sufficiently.
You never overcame that problem of the persistance, or decreased it?
The Navy got used to working in a darkened room.
Made do with what they had.
Who first suggested that alkali halides screens be used for the radar display?
I think that someone got some captured German documents, in which they were working on it. They called it blau schrift which means, the blue writing. And the English may have taken it over, skyatron. By the time we got it in the United States it was sort of third hand.
Was the name Rosenthal connected with that in any way?
It rings a bell, but I forget in what connection. Do you know — was he English?
I'm not sure. Krzyzstof Szymborski who is working with our group wrote down some questions for me to ask; he thought Rosenthal might be —
It rings a bell, but I can't quite pick up where.
What fundamental questions arose from the dark trace work? Was the problem of f-center mobility discussed at all with Huntington?
That's right. I saw a good deal of Huntington because while I was at Carnegie, I still went to these bimonthly meetings and we talked about these dark trace — and Hill proposed that something called a double vacancy was the mobile agent. It turned out, it wasn't. But he had done calculations on mobilities in the alkali halides. There was some agent which would aggregate at room temperature, when the system was irradiated by light, and I don't think to this day we know what it was.
What was the relation between the dark trace tube program and Estermann and Stern's research on the density of colored crystals?
Well, Stern got interested in the source of darkening. And carried out some gravnomentric experiments, density of rock salt or potassium chloride, of both the dark and light. The — at first he was skeptical of the notion, which had developed even before the war, that the F centers were tied to electrons in vacant lattice sites. He thought that was very unlikely. But then proved that it was right, by making density measurements.
Are you familiar at all with the work done at MIT on F centers during the war?
Well, only with the work at the Radiation Laboratory. Nottingham was in on it, and as a matter of fact, Lee Haworth was coordinator of all of the work at the Radiation Lab. But I didn't know of any work being done in the department of physics or electrical engineering.
Chris was wondering if, he says that two PhD's were done at MIT on the color centers, one, J.P. Molnar and Henry Ivy. He was wondering if you knew who they worked with.
Yes. Bob Maurer knew Molnar very well, and I think that he worked with von Hippel. Von Hippel had come out of Göttingen where a lot of work was done on color centers by Pohl, and I think, you might mention this, Molnar went to the Bell Labs and started moving up into top management and then I think died of cancer a decade ago, died very young.
Do you know if he was primarily interested in color centers or in the experimental optical techniques?
I think he was interested in color centers and how they behaved. I know we referred a lot to his work. Ivy is a name that I know, but I don't think I knew him personally, or if I did it was not as intimately as Molnar. As I say, Molnar was a good friend of Bob's.
OK, then let's talk a little bit about University of Chicago and the work at Argonne. You went at the request of Arthur Compton?
Well, that was formally. Eugene Wigner asked John Bardeen and I if we would consider coming, and John was working in Washington on torpedoes, at one of the Navy labs, and felt he was too deeply committed there. While I had this work going on at Pittsburgh, it was relatively easy for me to go to Chicago with the understanding that I'd commute back to Pittsburgh periodically.
So you kept up with both programs.
Yes. But most of my time was spent in Chicago.
Was it the radiation effects on the reactor materials that enticed you to go?
The story goes as follows. After the West Ends reactor work, they started planning for big reactors. There was one at Oak Ridge, and then the really big ones out at Hanford, and Wigner got worried about what would happen to the graphite and asked if I would come and try to track the issues. And also set up under James Frank and Milton Burton an experimental group over in the chemistry division of the Met Lab, and Burton had quite an active group. They used a cyclotron — I wonder if it was Indiana, University of Indiana? Some outfit had a cyclotron and they did a lot of irradiation of graphite there.
I know they had one at Purdue.
It could have been Purdue. I know that during the whole period, until Hanford came into operation, they had about the equivalent of one Hanford day or irradiation, so you were extrapolating a very long way. They did basic experiments with graphite. We learned an awful lot about graphite. Then I realized, another thing that became of interest was whether or not you'd get bubbling in the water that would increase the thermal resistance. But then in the middle of it all, I realized that the really big worry was with the uranium itself, because it was easy to see that the fission fragments were going to do far more damage than the neutrons. Almost everything we predicted turned out about the way it was — it was partly luck, but also, the results of the experiments could be extrapolated linearly for quite a way. The engineers thought we were pests, you know — getting in the way of construction.
Worrying about what actually might go wrong, rather than —
— worrying about what might go wrong. Right. We wanted to put test equipment in, but they so to speak forbade it, said it would interfere with the operation of the reactor.
Even though the operation might be an explosion. How did the neutron diffraction work begin, at Argonne?
Well, Wally Zinn and Fermi designed a one megawatt heavy water reactor for experimental purposes. It was at Chicago, I think in the West Stands. No, no, it was out in Argonne Forest. That was how the Argonne Laboratory got started. They wanted a reactor there. We began commuting back and forth. And after it started, Fermi did some very rudimentary experiments with neutron diffraction. Side 2
Fermi did some rudimentary experiments, and then as I recall, he got pulled away to Los Alamos, and spent time there. Wally Zinn had been an X-ray diffraction person, and got interested in carrying on those experiments, and I worked with him on the theoretical side. Zachariassen had written a very beautiful book on the theory of X-ray diffraction, pulling together more than just the routine things. There are effects where you get multiple diffraction, back and forth, within the crystal if the diffraction distances are short compared to the dimension of the specimen, and we pulled all of that stuff together, from the neutron language.
So it was sort of taking what had been done for electrons and saying, let's try it for neutrons, and now we have the source of the neutrons.
Then ultimately Schull, who's now at MIT, started work of that kind at Oak Ridge, and the person who helped him get started had been a student of Compton's in X-ray diffraction. I'm sorry I can't remember his name, but Schull soon became the expert.
So that mainly started from the fact that there was a reactor there, rather than from the radiation damage?
That's right. One had a neutron beam, and could do systematic work.
Who were the principal researchers then besides, say after Fermi left, and besides Zinn?
You mean? Wigner stayed until the end of the war, with Weinberg and so forth, and Gail. Then there was a group, Seaborg and so forth, James Frank stayed with his group of chemists. They continued pretty much. O.C. Simpson was part of the chemistry group and did some very fine work on the chemistry of uranium and plutonium and so forth.
I see, that's how he got started with solid state and everything.
I'd known Simpson at Carnegie Tech.
He was trained as a chemist, then?
Yes. Well, yes. He was a physical chemist, worked under Phipps, got over into the physics department, starting as a kind of assistant to Stern and Esterman, got into molecular beams and then Phipps asked if he would come to Argonne, about 1943, and he moved there and then stayed on after the war.
Was he really responsible then for building up the solid state group at Argonne?
I came across one letter in your files in the U of I archives from, a letter from and he mentioned Simpson and the Argonne directors. It was a letter to George Beedle from F.C. Brown, in 1963, and it mentioned that the group was very good and high quality.
Was there anybody specific with the administration at Argonne, or was it just that they supported Simpson?
They supported Simpson. Simpson pulled together a very fine group, Delbecq and Yuster, and then there was the German whose name I will remember, he spent the war years in England, had been a good friend of James Frank's, and he joined the group and became quite an inspiration to them.
I was able to find one paper from that time with Goldberger.
That's right. That was the paper that Murph and I wrote. It was written during the war, and then dressed up for publication after the war.
Did that cover most of your work on the neutron diffraction, is that fairly comprehensive?
It's a digest. The original paper probably sits in some warehouse, and is much bigger and went into more detail about this. Pringzheim was the German who joined the group. This is what was published in PHYS REV. There was much more speculation about other materials that could be used for — Incidentally, the person who got the work at Oak Ridge started was Wollan. I see his name here. Wollan.
How did you get started specifically on the neutron diffraction? You started with the radiation damage in the uranium fuel rods?
That's right. One always had time for exciting things, and Wally Zinn was doing this work, and we sort of worked together on it.
Wally had good physicist's intuition about what kinds of experiments to do, and he had taken his degree, I think, in crystal X-ray diffraction at Columbia with some of the people there in the twenties.
What were the important areas of solid state research at Argonne after the thing got started? Who were some of the principal researchers? I guess we're talking early fifties on into the 60's.
Well, the person to talk to there would be Simpson. But they did a great deal of very careful work on the alkali halides, color centers and so forth.
Were you familiar with any energy band work they did there on solids?
I'm not. You know, I can't remember — but I wouldn't be surprised if they did. They brought in a lot of summer visitors who would spend a couple of months working with them. Some of the best people from Rochester and so forth.
Were they looking at solid state as sort of an end in itself, then, to keep the program going, or was this still kind of in conjunction with their reactor work?
They had a responsibility for the behavior of materials in the reactor, and you did other things just to broaden your experience.
So it just got its start in that, then they knew that there were other things there.
And there were crises that occurred. I remember, the British built reactors without paying due heed to all these radiation effects, and got into some serious problems.
Have you been connected with Argonne since that time?
I used to go there fairly regularly to give talks and what not, but once I left to go to the Academy, that died down.
I've got a question on color center research. The color center group there was Pringsheim, Delbecq, and Yuster.
How did they get started? We just talked about them working on the neutron diffraction. Then did they branch off from that to the color centers?
I think Pringsheim probably brought the lore with him. But Delbecq and Yuster were young, very capable people, and they were able to get, introduce what might be called a modern viewpoint. They read all the papers and so forth. But Pringsheim was quite a famous physicist in his day. I'm trying to think, there were a series of books published in the twenties called the Yellow Peril series. One of them was written by Pringsheim. It may have been on infra-red properties of compounds.
What was Simpson's role in the color center work? Was it just mainly from his leadership of the solid state group?
Yes, he was a person who made sure that people had what they wanted. He was interested. He was a good scientist in his own right, had all this experience with molecular beams.
What interaction was there with Clyde Hutchinson working on electron spin resonance of the f-centers?
He may have set up a laboratory at Argonne, but I didn't know a great deal about it. He was one of the pioneers in spin resonance.
Just a question or two on your work after the war. When you were a consultant to Secretary and worked in the FIAT project. In your work with that, what were you able to learn about German solid state work during the war? Did they really have much of an active program along the lines of rectifiers or radar development?
Well, they had done a good deal with radar, but at longer wavelengths. Of course they had radar at the start of the war. Most of their work was of a practical engineering kind, didn't parallel ours at all, where you had all the basic people. The universities pretty much sagged.
Was anything ever printed from your work with FIAT? Did they ever write up the findings?
I don't know whether there are reports. I wrote some things, and there was a physicist who followed me, who, I had a feeling, wrote some stuff. By the time I left FIAT the war was over and I pretty well dropped all such activities. This person had been at Princeton during the war, and then he went over and stayed on, for a period of the order of a year, and I think wrote stuff that must have appeared in either PHYSICS TODAY or the equivalent. By that time, my interest had waned. We got into other things.
Did you have any connection at all with the Alsos mission, bringing back the German documents?
We had this office in Frankfurt. H.P. Robertson was the American head of it. There was also a British head, but Robertson was the key person. There were obviously military people involved. And Sam Goudsmit and Colonel Pasch decided to use it as their headquarters, so they became, you know, they cohabited with us and used it, for their trips around. By that time, they had been following the Army right at the front, to look for anything that suggested the Germans might be close to having an atomic bomb, and concluded that they didn't. One dramatic thing was when Pasch was ordered to try to find the French uranium standard, which the Germans had taken. He thought he'd located it somewhere in what was to become the Russian zone, and certainly found a radium source, which he put in his hip pocket, taking it out of a lead case, and drove all the way, arrived at our office and said, "Here's the French uranium standard," and Robertson and I tried to see who could get out of the door fastest. Here was several Curies of radium, sitting on the desk! I don't know what's happened to Pasch, but I know he got a military disability from that exposure. I went over to see some German group that worked in medical radiation, and got a lead case. We put the radium to rest.
As quickly as possible. I might ask the question anyway, our people in Germany, Jürgen Teichmann and rest, were wondering about some papers of Heisenberg and Welker that the United States brought over from Germany, that never found their way back. Would you know anything in general about that?
No. What were they on?
I'm not sure if they ever said.
Welker ought to know.
They asked us to try to find out what ever happened but I don't think the chances are too good.
That stuff would get bailed up, but on a truck, and God knows what would happen to it. There was absolute pandemonium. Our office was supposed to regulate that, but it was like trying to catch Niagara Falls in a tin cup. We saw a lot of the people — every branch of the service — you know, it was sort of like the early days in archeology, when you went around with sledge hammers and busted off pieces of monuments.
I'd like to get your opinion on some of the groups that were working on color centers, in to the fifties. For example, how would you rank the groups in importance, the ones you had direct contact with, some examples would be like Argonne or the Naval Research Lab.
They were both very good. The Germans got back into the business. Mainly under Pick, and did some very fine work.
How about Oregon State College?
There was one person there who did some good work.
But that was more limited in scope?
And then Kittel groups at Berkeley?
Very good. Well, they got into resonance. They were leaders in that. We have some good people at Illinois, too. Frauenfelder got interested in some of the resonance, had some of his Swiss friends working on it.
Were there any other major ones I didn't mention?
No, I think you got them.
I'll just finish up with a couple of general questions. I'm getting people's reactions on this. How do you think World War II affected solid state physics on the whole?
Well, it came out of the closet. Obviously, aspects of solids had been long of interest at the engineering level, materials, copper oxide, but the basic science was regarded as abstruse, interesting but a sideline, and the thing that happened is that it became a major part of physics, and now again of applied physics. It would have happened anyway, but not as fast. It speeded it up by 10 or 15 years.
Did the study of semiconductors specifically start with the rectifier motivation, beginning of the war? Or is that another case of where it was in existence beforehand?
It was well in existence. There's this book written about 1910 by a German physicist, Baedecker, on semiconductors, what was known about them. He worked with copper iodide, I think. He discovered a lot of fundamentals.
But they were working with very dirty, crude, polycrystalline materials, and it really took the purification and perhaps —
— but he understood the deviations from stoichiometry were important. Very beautiful piece of work. He's one of those people like Mosely that was killed in the war, but was intrinsically a very outstanding person.
OK, that takes care of most of my questions for this time. One other question first, would it be possible for you to release or give us permission, all our — all the people in our group at Illinois to look at your files there in the archives?
Yes. I thought our secretary called that person?
Yes, she did, but I wasn't sure whether that would extend to everybody or was just for —
— yes, go ahead. I don't have any secrets.