The Manhattan Project

Alexander Langsdorf's Interview

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Dr. Alexander Langsdorf was an American physicist who worked under Enrico Fermi at the University of Chicago. He helped design the nuclear reactor Chicago Pile-2, following the success of Chicago Pile-1. After the war, Langsdorf become an outspoken opponent of the proliferation of nuclear weapons and helped found the Bulletin of the Atomic Scientists. In this conversation with author Stephane Groueff, Langsdorf describes how he became involved in the Manhattan Project, his decision to stay in Chicago rather than go to Los Alamos, the genius of Enrico Fermi, and the process of designing and building a heavy water nuclear reactor. He discusses the personalities of many of his superiors, including Walter Zinn, Arthur Compton, Norman Hilberry, Samuel Allison, and Fermi.
Manhattan Project Location(s): 
Date of Interview: 
April 20, 1965
Location of the Interview: 

Stephane Groueff: Now it is recording Dr. Langsdorf. If you can tell me in a few words how you got connected with the project and where you came from.

Alexander Langsdorf: Oh, in the first place, as soon as I got my PhD at MIT, I went out to Berkeley as a national research fellow and started to work in Ernest Lawrence’s lab doing nuclear physics, which was a brand new field then, just opening up in 1938.

Groueff: ’38.

Langsdorf: I spent my first year there trying to further perfect a diffusion cloud chamber that I invented. Then I spent a year working with Emilio Segre on fission products. This was just after the discovery of fission. The news of that came out in January 1939, so we measured a lot of fission products.

In the fall of ’39, back in St. Louis, where I came from, I had been an undergraduate at Washington U, where my father was Dean of the engineering school.

Groueff: In St. Louis.

Langsdorf: Yeah, in St. Louis. The medical school, they had a Mallinckrodt Institute of Radiology and they had some research funds that were available. I decided to get into neutron therapy experiments, which up until then had only been done in Berkeley, in this big cyclotron. John Lawrence, and I remember Joe Hamilton, who was a young MD working with John Lawrence.

Ernest Lawrence knew that they wanted to build a cyclotron, and arranged for Bob Thornton to go there in charge of building it and taking care of his young men. I figured it would be nice if I went back there. I came from St. Louis, it would be nice if I went back there. So on my first job with Bob Thornton.

Groueff: Yeah, I met him about—

Langsdorf: You did?

Groueff: Yeah, he is still there at the Radiation Laboratory.

Langsdorf: Yeah, he was an Associate Director there a long time now, and in charge of the big cyclotron at one time. I do not know if he still does that. But so I worked with Bob Thornton beginning in the fall of ’39 to build a cyclotron.

Groueff: At Berkeley?  

Langsdorf: No, at the Physics Department at Washington U. It could not be built by medical people then; you could not get physicists to just give up physics and go be employees in a medical school. So the way it was done was to have the Physics Department build it and get the use of it in addition to the medical work that they hoped to do, but never did. Because in the fall of ’41, things were happening I did not know about, except that the war was imminent. Of course we really began mobilizing in the fall of ’41, before Pearl Harbor, really.

Rumors came back to St. Louis. Bob Thornton was told by Lawrence and other people from Berkeley that there were things afoot, they wanted us, had plans for us in St. Louis. And in fact, in the month before Pearl Harbor, Bob Thornton left St. Louis and went back to Berkeley and got into the work, whatever it was. I knew that there was something, and I actually suspected it had something to do with uranium fission. Because the idea that you could get power out of it somehow was in the air. Although the exact method I did not know, in spite of the fact that I had read [Frederic] Joliot-Curie’s articles and letters describing how he was looking for the new trends from fission and thought he had seen them.

I had read that, but it did not soak into me that this was important. It did not. But still somehow, I knew it was uranium that was involved pretty early. I do not know just when I became aware of that. But at any rate, I was left with this brand new cyclotron, which had already shown it was going to be very good. We succeeded in having it working very well just shortly before Pearl Harbor, so the people in Berkeley were pretty sure they knew what they wanted us to do with it. Indeed, in about March of ’42, we were in touch with people in Chicago. I knew [Glenn] Seaborg and I knew he was involved. He was in Chicago along about then because I had known him in Berkeley, and he was a contemporary of mine.

So we were ready and waiting for whatever they were going to ship us to do with their cyclotron. Actually, there were several months delay. Finally, some group of people came down with about 600 pounds of uranyl nitrate to be stacked up around the machine and irradiated with all the neutrons we could make.

Groueff: All of this with the assembly?

Langsdorf: Yeah.  I stayed to be in charge of the cyclotron and we had a very small group. Never was many people working on it. But we could run a steady 300 micro ampere beam, and we could have run more except that some of the interior parts would have melted down. They melted down too fast. We had to hold it down, so we did not damage it by overloading it. There were not any other cyclotrons. No other cyclotron could run for days and days at 300 microamperes. This was a phenomenon.

Groueff: Your job, who was giving you the assignments? Lawrence? Or from Chicago?

Langsdorf: When they made the legal arrangements and financial ones, it was from Chicago, and I think [Norman] Hilberry and [Richard] Doan were most involved in making the arrangements with Arthur Hughes, who was head of the Physics Department at Washington U.

So for a whole year, we ran and ran the machine with uranyl nitrate. During this year, occasionally, people would come down to St. Louis to stick some samples of theirs into the neutron flux. [Frank] Spedding sent a man down from Iowa with some little chunks of uranium, and people from Chicago had sent little chunks down. Occasionally, people would come down, so there was a little trickle of information.

Groueff: Did you work with the Mallinckrodt people?

Langsdorf: No, not at all. Not at all. I did not even know that Mallinckrodt was involved at that time, though. See, the very first uranyl nitrate they purified right in the labs in Chicago. In fact, the technique of it was worked out, as far as I know, by [Enrico] Fermi and then Herb Anderson extracting with ether and all that sort of thing. Mallinckrodt did become involved, but there were time delays.

All I know is, they brought us the uranyl nitrate from Chicago and we irradiated it. Then I picked up what it was they were after in there, because someone who thought I already knew mentioned the element 94. I felt stupid that I had not thought of it already, because I was acquainted with the field. I knew about the Bohr-Wheeler theory, the importance of D2/A, and I knew that – well, it was obvious that element 93, which I already knew about, decayed into 94. That would behave like uranium-235 was known to do.

Groueff: It was already discovered by the Seaborg team, no?

Langsdorf: Well, they had already found it, but I did not know that they had found it or that they wanted to separate it. But as soon as I got the idea of what they were after in all this stuff we were irradiating was element 94, it was obvious why.

But then, this work clearly was becoming routine and tedious to a physicist who wants to be in research. So I came up and visited in Chicago and I talked to Seaborg and [John] Manley, who I had already known, too, from the University of Illinois.

Groueff: He was at Los Alamos.

Langsdorf: Yeah, not now. Well, Manley was a professor at the University of Illinois and doing neutron studies before the war, too. So I was looking for things to do and I decided I had to move from St. Louis. I wanted to go where the work was most interesting. I knew there was a lab out west, and Los Alamos was being formed, and I knew there was Berkeley, and I knew there was something down in Tennessee. But Fermi was in Chicago and I knew that, so I thought that made it more attractive than the other places.

I gambled on that and decided in November of 1942 that I wanted to move. But Arthur Hughes – Arthur Llewellyn Hughes, the head of the physics department at Washington U – had the responsibility and did not want me to leave, because he wanted to be sure that machine was running. I had reasons why I wanted to leave, anyway. There was really no point in staying. But I did stay in spite of him for a while.

I came up in the early spring in February or something to go into it further. And finally, in April of ’43, I actually arrived here and was assigned to work out at Site A, the place where the first pile was. It had just been picked up and moved from the West Stands [of Stagg Field].

Groueff: So you were not involved with the CP-1?

Langsdorf: No. CP-2, not 1. CP-2 was the same pile turned upside down and remounted. It had just been stacked up and there were the holes in the ceiling were still open. We had to run out in the backyard and build wood fires under an iron pot, and melted tons of lead and cast it in crude molds. The whole gang of us—Walter Zinn and myself and Leona Woods, who married John Marshall in June of that year, and John Marshall and a few other people—would take wood chisels and chisel the bumps off the lead bricks and take them in and stuff them in the holes, close it up, so we could run it with some power.

Then I began to take part in the cross section experiments, learned a little of the theory of the pile. Herb Anderson gave us some lectures on it. He had learned it already. He had been with Fermi, you know. Did you talk—?

Groueff: Not yet, no.

Langsdorf:  Yeah. Well, you will. Of course, he was important, too. Very young, a couple of years younger than I am.

Groueff: Zinn and Anderson were the sort of assistants of Fermi?

Langsdorf: Yeah, they were the assistants. Zinn was the chief executive assistant for the whole lab and Herb Anderson was independent. He had his own group, essentially. As equal as you can be under a situation like that. But Zinn was the hard-driving executive type, so it worked out pretty well. The two of them fought but they kept it within bounds [laugh].

Groueff: And Anderson was a much younger man than Zinn?

Langsdorf: Oh, yeah, Zinn was older. Not a whole lot, but he was older.

Groueff: And very different temperaments?

Langsdorf: Oh, entirely.

Groueff: Zinn was the—

Langsdorf: As I said, he was the hard-driving executive type. Herb Anderson is not that. He is more of a pure scientist and friendly. Zinn was never noted for his warmth to people, in general. He had more warmth in him than most people under him knew about. Most people were scared to death of him. But if they would face up to him, he was quite reasonable. I always got along with him very well.

Groueff: But he had the reputation of being strict and severe?

Langsdorf: Oh, yeah. And somebody could be buffaloed, or was stupid and buffaloed, well, that was terrible for them. But if he respected a person, or if they could stand up to him and give a good argument, he would end up being reasonable. Personally, I mean, he always treated me with great – very well. I got along just fine.

I worked essentially independently and I got a project and I did it. The first important thing was, Fermi told me what he wanted. He wanted a decent measurement of the cross section for a neutron capture of deuterium. He was never planning to have any water processing. He had already gone ahead with the plans and the heavy water, gradually. It was on order and we were waiting for it.

Groueff: But they did not know the cross section?

Langsdorf: But they had not a good value of the cross section, and this was important. They knew it was small, but they did not know what it was.

Another friend of mine from before the war, Martin Kamen, had published a project report, which he had a measurement which, astonishingly enough, was pretty near right, though it was based on a fantastically small amount of activation of deuterium captures in neutron midstream. He had irradiated some in the cyclotron in Berkeley and found a cross section of about a millibar. It was a tremendous error, but considering the uncertainties, he was right because I found it was six-tenths of a millibar and that is essentially the values that have been assigned ever since.

At any rate, it took four months. And the conditions for working were fantastic.

Groueff: Where did you work? Here?

Langsdorf: Well, at Site A. We moved into that building at Argonne, the one that is in the park that this lab was named after, four miles east of here.

Groueff: Yeah, [inaudible] said—

Langsdorf: Yeah, yeah. Well, that building, I moved into a bare room. It had a plug in the wall and that is about all. It had to have gas put in and a sink and water. We had the carpenters knock together some tables and they had a tiny little stockroom. I ordered some glassblowing equipment, set to work. I thought I would never get done. It seemed to take so long to do anything.

Then when I look back, you lived in this town – we had an apartment in town. As a matter of fact, when we moved here, I looked for a place to live. Edward Teller was going to move out and we arranged to get his apartment when he moved. In fact, I came here in April and my wife could not come until June, because it was June when Edward Teller’s wife left to go to Los Alamos.

Groueff: So you were commuting every day?

Langsdorf: Yeah, everybody commuted.

Groueff: Nobody lived here?

Langsdorf: Everybody commuted out from the city, because the headquarters of the project was right around the University. My apartment was on Kimbark [Avenue] near 57th Street. It was quite a nice apartment. We lived there five years.  

The first bus ran shortly after I got here. At first, we just had some station wagons that belonged to the Project and we took turns driving. Somebody just drove, it was all informal. Just shuttled a carload of people back and forth in these lab cars that were bought, some station wagons that were [inaudible], many different people driving them and they had good care.

So then they got a bus. It was a little school bus. It was painted blue, so we called it the Blue Flash. And then later when there were more people, they got a bigger one, which was painted brown, so we called it the Brown Bomber.

Groueff: How many people, more or less, worked here at that time?

Langsdorf: It gradually grew. It varied from about twenty-five to fifty scientists, and almost all young.

Groueff: The building was big enough? You had enough rooms?

Langsdorf: Yeah, well, they gradually built more space anyway. At first, it was really very small. Just this one brick building that had the pile, and had been designed as if they were going to assemble methyl uranium oxide blocks by pressing them right there. They designed it as if there was a commercial chemical engineering flow. The rooms were ridiculous, because they were designed for this special purpose, but the builder was too slow. They got that all done in the West Stands. By the time they set it up out there, the building was obsolete, because they were just too damn slow.

Well, anyway, we used what was there and it was extremely informal. Up on the second floor, there was a dormitory, two big rooms for a dormitory of about equal size. Leona Marshall used the one all by herself, the only woman, and all the men used the other. There were about thirty cots in it. When you worked at night, you would just stay there, and often Bernie [Bernard] Feld came out sometimes.

Groueff: And the head of that was Zinn?

Langsdorf: Yeah. Philip Morrison would come out, all sorts of people.

Groueff: Fermi?

Langsdorf: Well, Fermi never stayed all night.

Groueff: And he would come to work here, too?

Langsdorf: Oh, yes, he was there regularly, very regular. Fermi was a very regular nine to five man.

Groueff: He did not work at Chicago University at that time?

Langsdorf: Oh, yeah, well, he worked at various places, but he preferred, he spent more of his time in the earliest days of his work with the pile, at Site A. A lot. He was there a lot. When he got into it, he liked to do some of the fundamental experiments with his own hands. When he did it with his own hands, then if he needed a little metal part that needed to be turned on a lathe, he went in the shop and did it himself. This would upset the machinists, who thought they had to do it for him. But he wanted to do it. When he wanted to, he did it.

Groueff: Was he good with his hands?

Langsdorf: Oh, yes.

Groueff: Excellent, huh?

Langsdorf: Oh, yes. He did not undertake things that were elaborate or would take days of machining, but it was a few hours of work. He actually liked to do it and did it by preference, not because he had to. So he was a man on the move. When he wanted to waste his time doing a menial thing, he just did it and nobody could stop him.

Groueff: So he was doing everything from the theoretical side and the experimental?

Langsdorf: Yeah, yeah.

Groueff: And physically—

Langsdorf: Yeah, he considered himself always – this was a bit of his ego showing up in a left-handed way. He said, “I am an experimental physicist.” Well, he was, really. But he was also an excellent theoretician of a kind who simplifies things. Only he was so smart and knew so much that what was simple for him, might be beyond a lot of other people’s comprehension. But still, he was an experimentalist, he really was, and he remained such, though he understood an awful lot of theory. I mean, he hated complexity. He said so, and it was true. A lot of things that are simple for him were not simple for me.

Groueff: But you would say that Fermi was really in the category of a genius?

Langsdorf: Oh, of course, yeah, no question.

Groueff: He was the greatest among the scientists of the Project?

Langsdorf: Yes. Of those that I knew personally, there is no question of that. But I mean, probably [Eugene] Wigner has just as great a mind. I did not know him as well and you might say a more pure theoretical man. But he started out as an engineer and he was responsible for the design of Hanford, which shows he was just as flexible.

Groueff: Yeah, from theoretical work to engineering, huh?

Langsdorf: Yeah. I mean, he covered the whole gamut, and so did Fermi.

Groueff: But you would put those two men are in a special category as mind—

Langsdorf: Of those that I knew, yeah.

Groueff: [Leo] Szilard? You would put him—

Langsdorf: Well, Szilard was an entirely different sort of man. He never carried through anything to a practical conclusion. He was an idea man, and some of his ideas were good and some were bad.

As an example, when I started to measure this cross section of deuterium, there was a question. When I irradiated some heavy water, would the radioactive solution be in the water, or would it be in the gas phase in the bubble above the water in a little glass ampule? Well, this was a question of the Szilard-Chalmers reaction. Szilard and [T.A.] Chalmers said Szilard thought of this idea and Chalmers did the experiment. I knew about this from before the war. I knew the technique. In other words, when something becomes radioactive by capturing a neutron, the radioactive atom gets knocked out of this molecule and you can leech it out. But this was Szilard’s idea and the technique of extracting rich radioactivity out of a material, concentrating it, because it was knocked out of the original molecule.

It is an important technique, or was then. It is still of some consequence. I knew that process would go on, and so I asked Szilard. I went especially in to see him in his office in Eckhart Hall one day. He told me he thought it would be in the water phase. I saw him the next day, by chance. He said, “Oh, I thought about it last night. I think it will be in the gas phase.” So I did not know where it would be, so I did some experiments to find out where it was, and some of it was in each place.[Laugh] So he was wrong both times, you might say.

Groueff: So he had great ideas, but sort of erratic.

Langsdorf: He was erratic, no question. Having great ideas, but he was not a doer himself. He would engineer getting other people to do things. The general pattern would be, when he thought it was a good idea and somebody accepted it, if they were going to get anywhere, they had to stop listening to Szilard because he would have a new idea every day. They would never get anything done because they would be changing their project all the time. They say that is why Szilard had to be relieved of being an administrator of a group, because the group went crazy. Because every day they had to change their project and never did anything.

Groueff: Wigner was not like that? Wigner was steady?

Langsdorf: Well, Wigner never had a good – I do not know. Wigner, of course, was steady. But he had this big project of getting Hanford designed and built, and I never had much personal connection with him in those days.

Groueff: It was a different group.

Langsdorf: He stayed in the city and had offices in Eckhart Hall and worked with Marvin Goldberger and Al Weinberg.

Groueff: It was a special group?

Langsdorf: A special group, and Gale Young and a whole group of people who were involved in very important things about Hanford. I was compartmentalized out at Site A, although I knew what was going on. Once or twice a week, we had meetings at night, and people from various parts of the Project talked about their work to all the scientists who wanted to come. I went to a lot of those meetings.

Groueff: But it was not your direct work?

Langsdorf: It was not my direct work. My direct work was first, to capture cross section of deuterium. That took four months. When I think back, I realize I did it very quickly considering I started from scratch in an empty room.

Then at the end of that four months – so May, June, July, August – we were getting set to start building the heavy water pile. Well, actually, we did not start quite that soon. I think we started really seriously in October that year, ’43. And as I look back, I am still astonished because that thing, starting with having to dig a hole in the ground and put in the footings and everything, that whole thing, it was running in eight months. Nobody has ever done anything like that since.

Groueff: How long did it take you to build the heavy water reactor?

Langsdorf: That is what I said, eight months.

Groueff: Eight months from scratch.

Langsdorf: Yeah. And my role in that was as one of the traditional branches of physics – plumbing, quite literally. I laid out the actual piping for the heavy water and the gas circulation. Made the drawings. They gave me a draftsman, and he was such an awful dub that I had to do everything myself. Anything I let him do came out wrong. So I essentially designed all the details of the piping myself. Then we got it made in some little – they got the stainless steel and it is all stainless steel pipe. Then it was most urgent that it not leak, so I devoted close attention to sturdy phalanges and gaskets and we bought the best kind we could get.

The phalanges, I had to machine in the shop. The shop was too slow so they were cast with – oh, we could not get the very best. We had to take what could be got, which were stainless steel castings were phalanges that were rough and we had to machine them. To hurry up the machining, I learned how to machine stainless steel phalanges myself. The shop only had six or eight machinists and a couple of machinists machined phalanges and I machined phalanges, too. Down in what we called the Jerk Shop, the scientists could work out there while the good machines had to be reserved for the professional machinists. But all the scientists worked out in the Jerk Shop. But the lathes were all okay, and so I machined a lot of phalanges.

Groueff: That worked? They did not leak?

Langsdorf: No, we never lost any appreciable amount of heavy water.

One of the amusing things was, we were so worried about that precious heavy water, Walter Zinn thought about it and had, under every phalange, he put a catcher to catch a drip if it dripped, with some wire netting or screen in it, so that if water dripped, it would make an electric connection and ring a bell. That night, when everybody quit at midnight – when I worked at night, and I did frequently, and sleep in the dormitory they had built just outside the fence by that time, a new building was built.

Several times I was waked up in the middle of the night by a guard who came over. That bell was ringing. Maybe there is a water leak. I had better go find out what it was. And then every time it turned out to be a cockroach that crawled down to that screen and short circuited [laughter]. We never lost the water. So it was good piping and it was used for many years.

Groueff: How big is a heavy water reactor?

Langsdorf: The aluminum tank that held the uranium rods in the water was about six feet down in diameter and seven feet high, the fundamental part, the heart of it. The biggest delay in getting that thing finally together for serious experiments was that when we first put the heavy water in, it turned out they had – and Fermi had leaned over backwards to be sure it would be big enough, and it was a little bit too good. They could only get it about a little more than half full of heavy water before it went chain reacting. It had to be filled full. So they had to stop, open up the top, pull out rods, fix up dummies, and make changes like that so that they could get it full without running [00:57:00] away. That caused several weeks’ delay. It was essentially complete about May of ’44. And right away, I started doing some experiments.

Groueff: Where did the heavy water come from?

Langsdorf: I never knew, except that DuPont made it and that they set up an enormous distillation plant that made it by simply distilling water. The story I heard was that they used more coal than any other one thing in the whole country. To boil water. It was very inefficient. It must have been fantastically expensive.

I stood out on the dock the day the first delivery was to come. They backed up a truck and brought out an aluminum drum, a fifty-gallon drum full of heavy water. Yeah, I was really impressed because I knew how expensive it was. We bought lots of it before the war for a cyclotron at quite a few dollars per gram.

Groueff: You had never seen so much heavy water?

Langsdorf: Nobody had seen that much, until they made it for that project.

Groueff: What did it look like? Like water?

Langsdorf: Just looks like water. Cannot tell any difference by looking. It is ten percent heavier. It is just water.

Groueff: Water.

Langsdorf: But it weighs ten percent more. You cannot tell any difference by looking.

Unidentified Male: Not even the consistency.

Langsdorf: Qualitatively, you would never notice. Oh, a ten percent difference in weight. If you hefted a vessel, you could notice it, but I have never paid attention.

Groueff: You could drink it, you will notice it?

Langsdorf: Well, if you drink too much, it would kill you. But one glassful probably would not.

Groueff: It is not poisonous?

Langsdorf: Well, if you want to learn about that, you talk to Joe Katz over here, who has done experiments. They can grow algae and fish and everything else in heavy water now by gradually adapting them. You know about that.

Katz: This is mostly [inaudible].

Langsdorf: Oh, but this is years and years later. In those days, nothing like that was—

Groueff: But this heavy water reactor, was it built only for experimental purposes? Or you still had the idea of—

Langsdorf: Well, in the original planning, of course, they took a broadside approach. Supposing if Hanford would not work?

Groueff: The graphite.

Langsdorf: Suppose something is wrong with the graphite method? They knew that the heavy water method would work even better, and so they undertook not to—

Groueff: To wait for the last moment, yeah.

Langsdorf: Not take any chances of not building it and it was a very useful reactor, but Hanford did work. So as soon as they were pretty sure that Hanford was going to work, they ended any plans for any more piles of that kind here and let the Canadians go ahead with what became their NRX several years after the war. That was an international plan, that they would work on heavy water and we did not. And then, well, we did not until quite a while later when they built Savannah River Plant.

Groueff: I see. But during the war, you did not produce any plutonium from heavy water?

Langsdorf: No, it was an experimental pile. Now one interesting thing that intervened before I began devoting myself towards experiments, cross sections with that pile, with that heavy water pile which we called CP-3, that Walter Zinn told me that they were going to get a small sample of uranium-233 and wanted to measure its important properties. And then it was so valuable, I remember when finally it was delivered, they sent me into town to pick it up. They had some Army couriers bring it to Chicago and some young lieutenant drove the car. I had a little box with a tiny little bit in and brought it out to the lab.

Meantime, for a month before that and doing experiments aimed at being able to measure such a small sample with the graphite pile – the heavy water pile was not yet going. This was in – I guess this was in the – no, heavy water pile, this must have been in the early spring of 1945. I cannot remember exactly.

Groueff: A long time ago.

Langsdorf: At any rate, we had this sample of uranium-233 to come, and then I said I got it. But backtracking, I set out to find the way to measure such a small sample in that graphite pile. I knew about the idea of putting a sample in a valve repeatedly to make the pile bounce up and down and oscillate in intensity. And measuring these oscillations, in order to separate out the effect of this tiny sample from the nasty perturbations due to the change in the air pressure – see, the barometric pressure normally goes bouncing up and down quite rapidly, and this perturbs a pile like that old graphite pile quite badly. As the nitrogen in the air leaks in and out, it changes the neutron absorption and the pile responds to this. Sam Allison, I think it was his quote, quoted from him, that the graphite pile is the most expensive barometer ever built.

At any rate, I studied these barometric effects. I studied them and set out to modulate the pile. I developed a method, which by test was several times as accurate as the previous method, which was called a danger coefficient method because it measured the danger that a material might stop the pile from working, which used a rod of cadmium that was running in and out of the pile.

Well, this method was better but it was difficult. I got it all worked out and I had a vacation coming up and we went on it. Walter Zinn himself did the experiment using a method I had developed of moving the sample in and out. We did not have time to build a machine to pump the sample in and out, so we had one person stand on each end of the pile and a long aluminum rod with the sample in the middle. Had a clock on each end and every ten seconds, the men would push – he pushes his end in and that pushed the sample into the pile. And then after ten seconds, the man on the other end pushed it back. He had a couple of slaves doing it. It gave them the measurement they were after.

As a matter of fact, I developed this method, which was the pile oscillator. Fermi already knew about the idea, of course, so he never did it. I knew he knew and thought of it because John Marshall was his direct personal assistant and John had talked to me about the idea, which he picked up from Fermi long before I actually did it. I was the first person who did it and made it work. Walter Zinn felt it was such a good idea that we ought to perfect it. Since the barometer was such a nasty perturbation of the graphite pile, we now had the heavy water pile.

So in the spring of ’45 or thereabouts, I set out shortly after the critical experiment had been done by Zinn using my method to adapt the pile oscillator method to the heavy water pile. One of the major parts of my experimental program from then until summer of 1948 after the war was over with, with that pile oscillator, I measured some cross sections that have never been remeasured any better since.

Groueff: But you did not go to Los Alamos?

Langsdorf: No.

Groueff: Or to Hanford?

Langsdorf: In the summer of 1944, there was a big to-do about the expansion of Los Alamos. It was coming into the final stages of its work, and we knew that is where the bomb was being made. There was a big meeting and they told everybody that everybody that wanted to go to Los Alamos could volunteer. Only certain people had been specifically requested to go, and others had a choice. I chose to stay here because I had feelings that if you went out there in the latter stages, you would be starting all over again, and I was doing things that I was interested in where I was. But at that time, Allison himself, who had been officially the Director in the lab here, went out to Los Alamos, too, and so did Herb Anderson. Both of them are good friends to this day. And Fermi stopped coming to our lab. He stayed out in Los Alamos for that final period, too.

So that was summer of 1944. But all those people who went to Los Alamos found they were sort of on the tag end of things and did not get any of the excitement that they had kind of hoped. Because the other people were in it first, you know? I had heard complaints about that, so I do not think I made a mistake in staying. I did keep right on with the programming work I liked and in fact, I have been here ever since.

Shortly after the war was over, I was put in charge of getting speakers for physics seminars. We started having seminars as a regular thing, as any physics department should do, have visitors come and talk about all kinds of physics. Amongst the people I wanted to get, I heard Vicky Weisskopf was coming through, would be in town or on his way or something. At any rate, he would have been in Los Alamos; he was going east. So I wrote to him and wanted him to come. That came through. Everybody had to be cleared for a visit. I put in an application, and we never got the clearance. Time passed and summer was over, and it was all over. They did not clear him to come because he had been to Los Alamos. From that day to this, he has never visited the Argonne Lab. It is a shame.

Groueff: The people at Los Alamos couldn’t visit here?

Langsdorf: They tried to prevent it. Walter Zinn was on top, of course. I should have come, pressed him to do something about it, because he would have blasted those stupid people into getting him here. I did not tell Walter Zinn soon enough, so he didn’t have a chance.

Groueff: During the war, did you have must to do with the military people? General [Leslie] Groves?

Langsdorf: No. I never even saw General Groves. I never happened to be around when he visited. He did visit Site A a few times, but I did never happen to see him, at least to notice. Zinn would not disturb people in the lab just because he had to show some brass around anyway.

I frequently rode into town with Zinn after work. He had a lab car he would drive, and I rode with him if it was convenient. He told me one of his stories. It was either General Groves or Colonel [Kenneth] Nichols, one of the two visited the lab, and they wanted to see how things were. Being a military man, he had people actually open the closet doors and look in and that sort of thing. He opened a particular closet door, and there was a janitor, a particularly eccentric one, shaving in the closet.

Groueff: In the closet?

Langsdorf: Yeah. This janitor was a character with an impossible Polish name who always called himself Murphy. He said, “Poor Murphy all the time work.”

Well, Walter Zinn said, “There is no question of it, that that ‘Poor Murphy all that time work’ was the smartest man in the whole place, because he was more artful at dodging work than anybody else. He would hide in a closet and shave. When there were graphite blocks that had to be stacked or lead bricks had to be moved, they would get these guys to come and do the picking up, they were laborers. He always disappeared just in time to avoid it.”

Unidentified Male: Sounds like the Army.

Langsdorf: Exactly. So it fitted exactly with his being in the closet shaving when a General came around, but I never actually was around when—

Groueff: Actually, Groves’ contacts were mostly on the level of [Arthur] Compton, probably.

Langsdorf: Our lab was thoroughly insulated from the military.

Groueff: Your superiors were Fermi, at one time?

Langsdorf: And Zinn. Zinn was a lieutenant and he was the chief of lab directory.

Groueff: What kind of a man was Zinn? Do you know where he started, where he came from?

Langsdorf: Well, he is Canadian.

Groueff: He is Canadian.

Langsdorf: Yeah. He was born in – I forget just what town. Maybe you should talk to Zinn.

Groueff: He is somewhere in Connecticut, I understand.

Langsdorf: That is right; you can get his address there easy enough. I got it somewhere.

Groueff: He is a physicist?

Langsdorf: Well, he gave up physics for business. He directed this lab and got it started, but after ten years—

Groueff: But in the beginning, he studied physics?

Langsdorf: At Columbia University and got his PhD at Columbia University. Before that, he was raised in Canada. Jean, his wife, was from the same town in Canada, I think. She just died last year of cancer.

Groueff: What was his main talent?

Langsdorf: He was a very competent physicist who always knew what he was about in physics. He was practical about the engineering, and he could administer and drive people, get them to work. If red tape was going to tie something up, he would cut that red tape with a battle-axe.

It was typical that the man in the stockroom locked the stockroom when he went home at night. We were working at night. We had to get something out of the stockroom. Nobody had made arrangements to have a key. So Zinn would get the door taken down, and if you could not take it down, he would chop it down. Actually, it was such a crude building you could always take it down. There were exposed screws or pins that you could pull out or something to get the door off the hinges.

He would always do whatever was necessary to get the work done in the shortest possible time, and get it done, by God. He was a pusher and a driver. He did whatever Fermi knew ought to be done next, Zinn did it.

Groueff: So it was a good team?

Langsdorf: Oh, yes.

Groueff: He was a disciplinarian?

Langsdorf: In an American way, not in a German way, not in a Prussian way. He had a temper and he had the drive. He would boil and say, “Right now!” when there as a block due to red tape or inefficiency, and he would boil up quick. He would argue. But I think it is really true that in an argument, though his temper was on top notch, if the other person could stand up and talk to him, that if the other person’s point was reasonable, by the next day he would come around to the sensible in-between. It is too bad a lot of people did not understand this well enough.

Groueff: He was getting angry and sort of bullying people?

Langsdorf: He would push people if they were pushable, but he never used that method on me to ask me to do some kind of research. I would do it on my own. He was interested more in what was going on. He left me alone. He knew whatever it was I had been asked to do, I would do it my own way, but I would do it. So he did not tell me how to do it.

Groueff: And he got along with Fermi?

Langsdorf: Of course. He was his right hand, his chief lieutenant. Everybody got along with Fermi. I mean, what Fermi wanted was the thing you knew you ought to do. You were lucky to have the chance to do it.

Groueff: Because all of you, the fact that you were in this field and successful physicists, supposed that you were all at a certain level intellectually, as far as knowledge goes. What makes people like Fermi and Wigner genius?

Langsdorf: What makes them that way? Well, that is another subject. I do not have a good answer. They were. They were respected for their abilities, and they did not make mistakes very often. They knew a lot.

Groueff: They read a lot?

Langsdorf: Sure, they had to.

Groueff: But it is not enough on its own.

Langsdorf: They had already demonstrated their gifts ahead of time. Fermi already had the Nobel Prize, and he had made his mistakes. Even Fermi made mistakes. He mistook, when he irradiated uranium, he mistook all those radioactivities for being transuranic elements when they were fission products. He slipped up badly. Actually, you might almost say he got, to some extent, he got the Nobel Prize for a mistake, but he deserved it anyway. He was not immune from making mistakes, but he made less mistakes than other people.

Groueff: Than other people. He had this ability of comprehending and grasping a new problem.

Langsdorf: And simplifying it.

Groueff: Simplifying.

Langsdorf: In a manner that was sufficiently justifiable by the fact that it would work. This was a gift of his, and he was very proud of that ability to simplify.

Groueff: Who were the other top people here? Was [Samuel] Allison important at that time as director?

Langsdorf: Well, [Arthur] Compton was the big boss, and Allison was the next, under. Compton ran the whole Met Lab business in a sort of general way and as it developed, and Allison was the director of the lab in Chicago for a period before he went to Los Alamos.

Groueff: What was his manner of working? Was he like Zinn?

Langsdorf: In those days, I did not know Allison particularly. I know him very well since then.

Groueff: I am going to see him tomorrow morning.

Langsdorf: He was never a man who was obtrusive. He is practical and does what needs to be done quietly. He is the antithesis of a prima donna and tends to belittle himself, if anything.

Groueff: He is not one of those?

Langsdorf: No, far from it.

Groueff: He is not like Zinn?

Langsdorf: Oh, heavens no. He is not. I have never seen Sam Allison display that temper in all the years I have known him, ever. Always very even-tempered, very wonderful person with a very good sense of humor. He is not talkative in conversational situations, but if he has to get up and give a speech, he always does an excellent job. He has a gift for speaking very well, but when he is not actually speaking formally, he tends to be quiet.

Groueff: No small talk?

Langsdorf: He does not like small talk. He is bored with it.

Groueff: But very likable?

Langsdorf: He is quite bored with talking about the project days, I can tell you. You may have trouble with extracting anything from him unless he feels like it and takes to you, because he complains bitterly about having these big dos every year. Every anniversary of the chain reaction, he is always dragged in to those.

Groueff: To make speeches?

Langsdorf: And to go to Washington and shake hands with the President or something. It goes on every year. The University, of course, makes a big thing out of it for publicity. He always likes to make private jokes about how tedious it gets. Well, it is tedious unless you just love publicity, and he doesn’t. He is a wonderful man.

Groueff: Did you work with [Norman] Hilberry in those days?

Langsdorf: Yeah, I have. Not with him. He was sort of associate director at—

Groueff: With Compton and Allison?

Langsdorf: With Compton and Allison. I first met him, he came down to St. Louis to see what we were doing with that uranium. He and Doan once came. When they came down to take the first shipment back, they came down and brought a truck to put it on and came and looked at it.

My next experience with Hilberry was an embarrassing one for Hilberry. When I decided I wanted to come to Chicago, I wanted to come up and actually talk to Fermi. I actually made a date. Hilberry made the arrangement. I would come on a certain day, and I would see Fermi. So I came to Chicago, and Hilberry had forgotten to tell Fermi. So I saw Hilberry, and he apologized. Fermi was out of town for the day. I found out later he was out at Site A, of course. He was working. They were setting the pile up out there, where I later went. But I did not know out of town, so I went back to St. Louis quite unhappy. The whole thing was up in the air.

It was all Hilberry’s fault. He could have at least told me to stay over long enough to see Fermi when he came home, followed up or something, but he did not. He goofed completely. I will never forget the day, because then I smoked a cigarette and went out on the street. There was a strong wind and my suit coat caught on fire, and I had to yank it off and stomp on it. I ended up with a whole about four inches in diameter. I went back to St. Louis and was quite unhappy about the shemozzle.

I am much indebted to Charles Coryell. He is another person you might talk to if you want to hear somebody who was [inaudible] . He never got along with [Glenn] Seaborg at all; he worked under him. Anyway, he came down to irradiate something in a cyclotron. We became very friendly immediately, and I told him what had happened. He thought this was dreadful and went right back to Chicago and told Fermi, and Fermi called me up that evening and invited me to come up and work with him. I did, right away.

Groueff: But Hilberry also seems to be the kind of quiet, easygoing man?

Langsdorf: Easygoing, not so quiet. I mean, he is great on small talk. He is a chatterer, outgoing, friendly, not a working scientist, really.

Groueff: Administrative, more?

Langsdorf: I was always astonished – I mean, when he became director of the lab sort of by default because they could not get some big shot when Zinn quit, he took over and ran it. It ran quite well. Some things ran better. Considering that scientists like myself could hardly respect Hilberry technically, I think he did very well as an administrator. The fact is, he seemed to do better than I ever expected.

Groueff: I understand that during the Manhattan Project days, he did very well in sort of rounding the angles, troubleshooting for Compton. 

Langsdorf: Because he was easygoing, friendly, and I guess he could talk with anybody in his colloquial way. I always liked him, quite well personally. Easy man to talk to, very. Zinn was not so easy to talk to, except in a purely social situation, then yes, Zinn would be.

Hilberry didn’t do any lab work. I do not know what he did. I had nothing to do with him, I never saw him. The time I saw the most of him was after we moved over here. For several years, he would go get a cup of coffee at five o’clock before he went home. If I worked in the evening, I would go over and eat supper and see him in the old cafeteria and sit and have my supper while he drank that cup of coffee before he went home. He was lab director then, and stayed just as informal as he had ever been.

Unidentified Male: He comes in the office; he talks just like anybody else.

Langsdorf: Well, Zinn, as far as the difficulty with him as lab director was that he did not want to stop building piles and running the reactor development.

Groueff: He wanted to continue—

Langsdorf: And he did continue. He devoted himself to two things: running the lab and the reactor development. He was a hard worker, but with two responsibilities, the administration may have suffered some from making quick snap judgments on things that maybe deserved more attention.

He was so sure he was right offhand, that probably his was not exactly the way to do it. Anyway, when he had an opinion, he was very strong about it. That is the way it would be, unless somebody was an awfully strong fighter indeed. Very few people could fight adequately, especially when he was the main administrator. Now, Don Hughes was quite unhappy, trying to be head of the experimental physics division after the war, because Sam left. You cannot talk to him; he died about five years ago.

Another fact that might be of interest, isn’t so well known – the day that the news came back here from Los Alamos that Louis Slotin was going to die from the accident out there, the scientists all told each other, we knew about it. It just happened that we had a party that night, my wife and I. My wife is an artist, and a well-known one. We decided we wanted to try to mix up some scientists and artists and other people, not just one-sided. That party absolutely did not work at all. I did not know until later when it came out publicly, all the scientists went in one room and stood around in a circle mumbling to each other, talking about Louis Slotin.

Groueff: They could not say to anyone?

Langsdorf: They could not say it. All the artists and other people were in one place, and all the scientists went off by themselves. She wondered why in the world the party was such a failure, even worse than normal. Scientists and artists frequently do not mix too well, but that was the worst failure to mix that ever happened.