Nuclear Museum Logo
Nuclear Museum Logo

National Museum of Nuclear Science & History

Joseph Katz’s Interview

Manhattan Project Locations:

Dr. Joseph Katz was a chemist at the Metallurgical Lab at the University of Chicago. Katz was a part of a team that studied ways to separate plutonium from irradiated uranium. In this interview, Katz elaborates on the technicalities of the process to produce microgram amounts of plutonium. He explains how scientists had to use speculation to determine the chemical structure of plutonium for its use. He also discusses his background, the safety hazards associated with plutonium work, as well as his time in Chicago and experience working there. He recalls the tight security, and how scientists feared the Germans might beat them to developing the bomb.

Date of Interview:
April 21, 1965
Location of the Interview:


Joseph Katz: Now it was recognized that plutonium would have a chemistry that would be quite similar to that of uranium. And developing procedures for the separation of plutonium from irradiated uranium. The assumption that was most commonly made was that the chemistry of plutonium would be similar, if not identical to that of uranium and this, of course was an entirely reasonable assumption to make.

So all of the vast amount of semi-empirical research that was carried out was generally founded on the notion that one of the reason from the behavior of uranium. And in fact, one was able to devise procedures for the separation of plutonium. Nevertheless, it turns out in retrospect that the chemistry of uranium is a far less satisfactory guide to the chemistry of plutonium then what might have inferred. That the differences between uranium, neptunium, and plutonium are really quite dramatic in that if one had known about the complexities one would have been much more diffident—

Stephane Groueff: It never intimidated you?

Katz: It’s always easy in the situation to generate problems and the more you know the easier it is to imagine contingencies and you may have to guard against. If one had known all of the complexities of plutonium, the fact that it has— exhibits a greater variety of chemical behavior then does uranium, that it is displaced relative to uranium.

That even the chemistry of neptunium, which is intermediate between uranium and plutonium is already significantly different then one would have not proceeded was quite the same expedition.

But it turned out in retrospect that those aspects, that were considered important, were the important ones, and that even though it turned out later that one didn’t know exactly what one was doing, one did the right thing in some cases for not quite the right reasons.

Groueff: Was that by sheer luck or—?

Katz: It was up to the perversity of nature. You can’t always count on it to be hostile.

Groueff: It could have worked in the other direction?

Katz: It could have worked in the other direction.

Groueff: And then you would be—

Katz: And then you would be in terrible trouble.

Groueff: But in that particular fields that I applied, for instance, you mentioned that oxidation of plutonium. How did that affect the work and how would that have affected how knew it?

Katz: Well if you had set out to say we must know these important parameters in great detail, then would have been a tremendously difficult research to undertake given the very small amount of material that were available and the difficulty of interpretation of experiments carried out on the Tracer scale.

Groueff: So that would have taken a lot of time?

Katz: It not only would have taken a lot of time, but it would have generated controversies that could never have been resolved.

Groueff: So you just proceed without the basis—?

Katz: So you proceed on the basis of similarity with uranium and say there is an upper and a lower. It turns out that there are two uppers and two lowers and that some of the confusion [telephone ringing] in the early results, really as a result of this multiplicity behavior—

Groueff: In a way we’re lucky that you didn’t know enough about this?

Katz: Ignorance isn’t always a disadvantage. And sometimes it is helpful. No one was inhibited by knowing too much. Actually some of the chemical details are still in the process of our study because of all of the elements in the periodic table, plutonium probably has the most complex chemistry of all of the elements in the periodic table.

Groueff: And before your group started putting the chemical part of this plutonium there was no knowledge?

Katz: It was essentially zero.

Groueff: Zero. It was just being discovered by [Lawrence] Berkeley [National Lab]?  

Katz: And a few of the salient properties had been observed. You see, in the very earliest work, only vanishingly small amounts of material were produced, prior to little to treat as a substance. Now in a situation through which a chemist proceeds, if he has a solution containing this unknown species he infers its behavior by adding something common, an element about whom he knows a great deal.

Then he will add another substance which causes a precipitate to form. Then you observe the solution to see if the new substance follows the old or did it remain behind. If it follows the old, then you say in this respect its chemical behavior is the same as the norm element. If it doesn’t then you say it’s different.

And so you use this sort of sideway approach, this oblique approach, to learn about this new substance, this new species, in terms of old. In this sense one knew that there was a form in which plutonium could exist, which resembled a certain class of uranium compounds, and another form in which it resembled another class of uranium compound. This is really all that turned out to be necessary in order to devise procedures which work very well.

I think one of the interesting things about the whole business is that to a good first approximation of everything worked in terms of the separation of the uranium isotopes. All of the methods, which were discussed, turned out to work. Now they differed in economics, they differed in technological problems, but there’s no question that one could have succeeded by any one of these procedures. I think it’s also fair to say that with respect to the plutonium and the problem of producing it and separating it, that all of the procedures which were contemplated have been made to work.

Groueff: On a very approximative basis?

Katz: By intuition. By similarity, and, oddly enough, even in those cases where one’s intuition was well grounded, it was still sufficiently well grounded so that one was correct about the essence if not about all of the stuff.

Groueff: But the other element of you said you usually compared to something that you know pretty well. If you compared to uranium that was also rather unknown—

Katz: Yes, but uranium wasn’t old and had discovered during the early part of the 19th century.

Groueff: So the chemistry was well known?

Katz: Well as well-known as many other compounds.

Groueff: Because the metallurgy is completely different, that was completely new here.

Katz: Probably the metallurgy of plutonium differs more from the metallurgy of uranium than does the solution chemistry. Plutonium was really a very unique element.

Groueff: The metallurgy was done at Los Alamos like later—?

Katz: Mostly later.

Groueff: But the first study of plutonium was done at [Lawrence] Berkeley [National Lab] and here [At the University of Chicago], no?

Katz: Yes, mostly here.

Groueff: Here, and that was the group that you told me, the Seabrook group and it was in the years ‘40 to—?

Katz: ‘42 to ‘44.

Groueff: To ‘44.

Katz: Middle of ’44. At that time the experimental plant at Oak Ridge came to produce milligram amounts.

Groueff: Not before ‘44?

Katz: Well sometime around then it began to produce plutonium.

Groueff: Only then you could have it materially?

Katz: Only then you could begin to work with it in terms of visible amounts of material.

Groueff: And then when it became in the grams that was— from Hanford and in the grams, let’s say?

Katz: Well they still do. People will still very often work with grams.

Groueff: But when this material came in very large quantities, they did the work out at Los Alamos?

Katz: Most of the chemistry. Well the problems associated with producing it in a form in which you could use it, many of these aspects were carried out ourselves.

Groueff: That’s mostly metallurgy and—?

Katz: The preferative metallurgy and—

Groueff: Purification; they had a tremendous problem there. But could you give me some more details on what it was like to work with infinitesimal quantities of an unknown metal in the first years? I mean before Oak Ridge produced the first samples? Was it microscopic?

Katz: There were microscopic amounts of material that were isolated before the Oak Ridge Pile produced it; it was made by cyclotron bombardment. On the one hand we work out hundreds of pounds of uranium in order to get—

Groueff: Microscopic—

Katz: Microgram amounts of plutonium, visible amounts. I think the first visible amount of plutonium came from a cyclotron bombardment. It was worked up by Arthur Jaffey who was in helium. But the chemistry was really an art that had not been intensively practiced in the United States. Much of the very word for Tracer methodology, had been carried out by the Russians.

Groueff: Okay.

Katz: In the uranium institutes. They were perhaps the first to lineate the various types of ways in which tracer behavior can be cataloged.

Groueff: Was that known to you or to the general public?

Katz: So one read this and there was a great deal of discussion about what one learned from tracer experiments and how one should do them so that one could interpret them. But it was the sort of chemistry by consensus in that one experiment is never definitive that one does lots of experiments and gradually—

Groueff: Modifies the conditions—

Katz: In various ways, and after awhile one develops a feeling of what, what it must be. You can never point at one particular experiment, except in retrospect, and say that’s the one that answered the question.

Groueff: But when you had the microscopic quantities then you could confirm or cancel—

Katz: Then you did conventional chemistry and many of the details became immediately obvious. You could see a color with the naked eye. You could see blue and you could see red.

Groueff: But under microscope of course?

Katz: Even when they’ve got milligram amounts then you’ve got enough so that you can—

Groueff: But before that, you did it only by the trace they leave on the—

Katz: First you did tracer chemistry in which you never see it. You know where it is only in terms of counters and electronic instruments. And then you get to do ordinary chemistry and the concentrations that one normally works with, but in very small amounts so that one has to use the microscope to see it. And then in the third stage one works with ordinary concentrations and with volumes sufficiently large to be handled by hand.

Groueff: For the first stage these very small quantities, where were they produced? Here?

Katz: They were produced mostly, I think, by cyclotron bombardment in St. Louis. The uranium would then be brought here and people would then—

Groueff: What did it look like to the eye? I mean in what form you get the trace of uranium?

Katz: It’s the emperor’s clothes. It’s nothing to the eye.

Groueff: Nothing. But you received what physically? A solution? A liquid?

Katz: A liquid which is mostly nitric acid. If you used very ordinary chemical procedures, it would be very pure nitric acid. If you put it on a counter, only then you would discover that there’s alpha activities?

Groueff: Nitric acid, which only under the—?

Katz: You ended up with a solution.

Groueff: But that is exactly the same?

Katz: Well the amounts are weightless. When one is doing tracer work, one is working with weightless amounts in the sense that even the most sensitive balance couldn’t weigh it. So you generally specify the composition of a solution in terms of the formula weigh; how many formula weights are dissolved in a liter of water?

Well, ordinarily one would work with solutions in which there is one formula weight per liter. And the dilute solution would be one in which there is a thousandth formula weight per liter. A very dilute solution would be a millionth of a formula weight per liter. These were of the order of a millionth of a millionth.

Groueff: That would be—

Katz: Ten to the minus eighteenth moles, which would be undetectable by any sort of measurement other than the detection and the radiation.

Groueff: So the radiation could be detected even in such small amounts?

Katz: The style of Madam Curie, in exactly the way that she discovered polonium. The detection of a radiation—

Groueff: But what did it look like, the solution, what color?

Katz: At these concentrations it would be whatever color of the solution. If it’s a colorless solution it would be colorless.

Groueff: And that’s, from that solution you started the original work?

Katz: Then you begin to find out from what precipitates would the radioactivity be carried; under what conditions could precipitates be formed in which the radioactivity remained in the solution. The work I did was, if you take uranium oxide and pass Fluorine gas over it, then uranium was converted to hexafluoride and it goes from here to somewhere else.

We did experiments in which you evaporated solutions containing perhaps 1,000 or 2,000 alpha pounds per minute of plutonium on a nickel disk, and invisible, except in terms of alpha particles. Then we would put in an apparatus and pass a stream of fluoride over it under conditions where you know that uranium would be converted to hexafluoride. And these conditions, the alpha pounds characteristic of plutonium still remained.

Then you found if you heat it to higher temperature, you could get the plutonium pounds to disappear from the nickel disk and the question then was: where was it? When working with these very small amounts, any surface is enormous and surface phenomenon that we ordinarily ignore become very large when the amount of material you are working with is less than enough to form a layer one atom thick. You have less than a mono molecular film and under those conditions it’s easy to get things lost. They come in at one end of the pipe and they never come out of the other. And this work is very difficult—

Groueff: You are working for nothing, you are just—

Katz: Well yes, it’s like this Vaudeville act where they thread a needle—

Groueff: There is no needle—

Katz: And how can you end up with a suit?

Groueff: But it is so small. How don’t you lose it in a room, in a laboratory?

Katz: You didn’t lose it.

Groueff: You trace it over it?

Katz: You trace it all the time; you never pour. You transfer it with syringes and you do— it’s a technique. It’s very similar really to the techniques that were used by the Curie’s to isolate radium to show the presence of a new radioactive substance. You had to isolate it from uranium more.

Groueff: How did you learn the technique or what are the elements previously that were treated in this way?

Katz: Practice.

Groueff: So you had some practice—?

Katz: There was literature and one learned.

Groueff: And literature was Russia?

Katz: Russian, French, German, not as much English.

Groueff: Not much American, no?

Katz: Well there was some work that had been done by the American investigators in the early days—

Groueff: But the main thing was the Russian and French sources and Madam Curie —

Katz: French and German.

Groueff: And German. And that stage of the game were you supposed to give an answer even to questions like, “What’s the critical mass would be”?

Katz: That was a physicist.

Groueff: And probably they had similar problems too because—?

Katz: Well they had to assume a density. They had to assume that plutonium would indeed be a metal.

Groueff: Nobody could guarantee that?

Katz: No, nobody could guarantee anything. It was highly unlikely that it wouldn’t be considered a rare earth but in the early days, one of the important decisions that had to be made had to be made relative to where plutonium was going to be placed in the periodic table. I don’t have a periodic table now. But, you see, if you had continued to fill up the periodic table by continuing— I sometimes have a periodic table.

Groueff: In your wallet?

Katz: Sometimes. But I don’t think I have my periodic table. I have one in here somewhere. But the point is if one continued to fill up the lower portion of the periodic table, one would have decided that neptunium, uranium is in group five. Then you would have decided that neptunium was in group six and that plutonium was in group seven.

That would have made plutonium an element similar to fluorine. It would have been a halogen and so one of the first things that had to be recognized or decided was whether one would continue to fill in the vacant spaces in the bottom of the periodic table, or one would decide that at uranium, one had a group of elements related to each other the way the rare earths were. In the rare earths, there are 14 elements which are in one pigeon hole. And so the first decision that had to be taken was is plutonium going to be a member of a closely related group of elements?

Groueff: Isn’t that a little bit cheating the table?

Katz: No it’s actually correct. If you hadn’t decided this, then you’d never been able to do anything.

Groueff: But I thought the periodic table was completely prove that every element follows the other one, no?

Katz: In the exception of the rare earth. In the case of the rare earth the thing, the fact that it even gives rise to periodicity the successive. The addition of successive electrons does not take place in the outer shell. Whenever an electron is added in the outer most shell, then successive pigeon hole of the periodic table is filled up.

But in the case of the rare earths, these incremental electrons are added deep in the electron clock; so the outer shell is the same. So you keep it in the same box; and it turns out that this is also the case.

Groueff: But you had to arbitrarily guess?

Katz: We speculated about this many years ago. Harold Urey and Maria Mayer had speculated about whether there might not be another heavy rare earth like series of elements and had predicted it as occurring from energetics or physical principles that it ought to be somewhere in this part of the period table.

Groueff: Every element after uranium would be the same?

Katz: It turns out that the box isn’t the uranium box, it’s the actinium box. That’s why it came out to be the actinide element.

Groueff: Actinium also goes in the same box.

Katz: Actinium, protactinium, lutharium, uranium and all the others in the same box.

Groueff: But at that time you could only speculate about those things and hope they will be right?

Katz: Hope that they will be right otherwise—

Groueff: And they were right?

Katz: They were right. It turned out that originally people thought that all of these elements would be urinide series in which they— how the transuranium elements would fit with uranium in the same box. [Glenn T.] Seaborg’s contribution was to show that they ought to really fit in with actinium.

Groueff: Was there any possibility in the theoretical that, after working for months and months, you realize that it was not a metal, it was a different kind of element?

Katz: No.

Groueff: Yeah.

Katz: It is a metal. It could have— well it turns out now it couldn’t have turned out to be anything else but it could conceivably been something else.

Groueff: And then all this work would have been for nothing. So you started an assumption and luckily—

Katz: The early experiments were carried out at [Lawrence] Berkeley [National Lab] to find out whether this was actually a metal.

Groueff: So actually it was an assumption, not a speculation, but a very well informed one? Not again, blind guessing.

Katz: That’s right.

Groueff: So all this work you carried in ’42, ’43, ’44 here in the chemistry building, this was the group with Seaborg and a few other people.

Katz: One of the tools that was extremely powerful which was very useful when microgram amounts of material were available was x-ray crystallography. [Fredrik] Zachariasen was a member of the physics department at the University of Chicago and really one of the world’s outstanding x-ray crystallographers, refined methods for taking x-ray crystal data so that one could do this with a few micrograms of material. And if one could get an x-ray pattern, Zachariasen turned out to have quite an unusual facility for interpreting these patterns and so the structure of many of the solid compounds of plutonium and neptunium were established by these x-ray methods.

Groueff: You used his methods?

Katz: Well, the chemistry people made the samples—

Groueff: And he continued to—

Katz: And he photographed them and then he would look at the picture and he would tell you what the substance was.

Groueff: What was your standard equipment instrument; how did you trace the radiation?

Katz: With counters.

Groueff: Counters, which looked like Geiger counter or—?

Katz: The alpha counters, there were a variety, but a lead container in which one introduces a plate.

Groueff: I would like, if you can, in a few words give me some elements of your career. You said that you came from New York, from the group of [John R.] Dunning, no?

Katz: No we did our work here.

Groueff: But you were connected with the Columbia people?

Katz: The work that [James R.] Schlesinger did at the University of Chicago was done for the Columbia—

Groueff: I got that.

Katz: Our problem was to see if we could find volatile organic compounds. Volatile compounds of uranium which would be suitable for use in a diffusion plant or in a mass spectrometric separation. Substance which would be volatile and would not have the problems associated with handling UF6. So we actually found volatile uranium compounds but they were far less usable than UF6. It turned out turned out to be simpler to devise the engineering techniques for handling UF6 then it did to find a substitute for it.

Groueff: But you worked here in Chicago? Are you originally from Chicago?

Katz: No, I’m from Michigan.

Groueff: From Michigan; yes. And you studied there, your high school and—?

Katz: College.

Groueff: And college and then university—

Katz: Came to graduate school.

Groueff: In Chicago. And did you study under one of the people who later played roles in the project? There were not many chemists?

Katz: Not particular, no.

Groueff: [Harold] Urey was in Columbia. He was outstanding, I mean in the sense of Nobel Prize and all this. The others were mostly physicists; [Ernest] Lawrence was Nobel Prize and [Enrico] Fermi and [Arthur] Compton.

Katz: But, I’m sorry.

Groueff: You studied here at the University of Chicago chemistry and then you got involved with the chemistry division of the Manhattan Project—

Katz: Metallurgical laboratory.

Groueff: In 1942?

Katz: Early in 1942.

Groueff: ’43. How old were you at that time?

Katz: Thirty-one.

Groueff: Thirty-one. And you had this curriculum with [Hans] Bethe to get—

Katz: Yeah.

Groueff: But anything particular about the human interest side about your, outside of this curriculum, do you have any hobby or I don’t know, were you involved in some other activity, music, sports, game?

Katz: Not that I can think of.

Groueff: You were mostly interested in chemistry?

Katz: I must have done something interesting in the interim, but it escapes me.

Groueff: It’s a very difficult question asked point blank. But your main interests were and are in science, especially in—?

Katz: Of course the science I do now is quite different then the science I did then. It’s sort of a large evolution.

Groueff: But also in chemistry.

Katz: Oh yes.

Groueff: And you were a very studious young man reading a lot. You were good in school and good in university.

Katz: Now isn’t everyone? [Laughing].

Groueff: Can you give me some other example of these assumptions, wrong assumptions, which people made? We talked about the oxidation of plutonium.

Katz: This strikes me—well there may be many others as far as I know— and I’m sure that in any organized scientific activity one starts sometimes, one has misconceptions. There may have been many of these but—

Groueff: The difference in this case —

Katz: This case I think strikes me as having more than ordinary.

Groueff: And also the whole purpose was of such a nature that any mistake could have been fatal to the project.

Katz: Yeah.

Groueff: Something else could have come in the meantime and would have delayed the project very much?

Katz: Possibly.

Groueff: So the main difficulty that you saw in your particular work personally was the fact that you had to work with invisible elements with completely unknown characteristics?

Katz: I, and many others.

Groueff: Yeah.

Katz: It’s hard work. It was hard work and, to a certain extent, dangerous work.

Groueff: Dangerous in what sense? Of radiation?

Katz: Yes. Also, ingestion.

Groueff: Did you know at that time—you didn’t know that the danger of radiation or you knew enough?

Katz: Knew enough.

Groueff: How did you work, very protected, some gloves or special—?

Katz: Very primitive.

Groueff: Primitive; so you handled those things with—?

Katz: You worked fast.

Groueff: Now you were exposed with those substances?

Katz: With plutonium it’s not a radiation hazard, it’s an ingestion hazard. If as little as a microgram of plutonium was affixed to the skeleton, then the probability of developing bone tumor was very high.

Groueff: That’s if you inhaled it?

Katz: If you inhaled dust.

Groueff: Yes, containing plutonium.

Katz: Any plutonium that enters the lung is removed quantitatively and deposited in the bone. Even a microgram is high. I think present standards are much less than micrograms. So that in working with plutonium, you always faced the hazard of somehow atomizing and breathing, or running it into a finger or—

Groueff: Into the blood stream.

Katz: So that accidents which ordinarily would be very trivial, could become very dangerous.

Groueff: But how did you protect yourself? For instance about inhaling, did you wear some mask?

Katz: Yes, but they were primitive compared to, you know chemists ventilated areas in which air was pulled through. One tried to be careful.

Groueff: But were there any significant accidents? You never know, so you know later, one year later.

Katz: I think the record— it’s over 20 years and one would have thought that if there had been a sizeable accident it would be known, but I would think on a whole the people who did this, had to be careful.

Groueff: Radiation is not very dangerous especially in such small—

Katz: Internal radiation.

Groueff: But later when you had bigger samples, then the radiation became also—?

Katz: No, the radiation, alpha particles are stopped by a sheet of paper. So in terms of the kind of radiation that’s associated with beta or gamma, then there you need shielding. With plutonium you don’t worry—and if it’s ordinary plutonium— you don’t worry about radiation. You do have to worry about ingestion, spreading it around so that it can be inhaled. When that happens the results are bad. I don’t know if this conveys the flavor. After all it was much more like being in the Army than climbing the mounting. I mean many, many people were involved at all levels, at all various phases of action.

Groueff: Each one doing his particular—?

Katz: Some particular aspect of it. Some more important than others, some less important. Everyone feeling though as if what he was doing as far as the critical—

Groueff: So they were very few cases of one verse or spectacular achievements?

Katz: Well if you were working in a given area and part of your problem was to make a new compound and if you made it, that’s very glamorous achievement.

Groueff: I see, but most of the work was just working on just one project—?

Katz: It would be right to say an anti because that implies a certain kind of instinctual response. But it seems to me in retrospect the characteristic flavor of it which made it different then the way people ordinarily did research then, and even now, was the fact that one was actively and consciously engaged in a very large enterprise, which had a well-defined goal and lots of well-defined small goals.

Groueff: Would that give you a feeling of urgency or emergency, and an atmosphere of pressure?

Katz: I think on the whole it tended to the fact that everybody was moving tended to drag along everybody. It requires a certain momentum.

Groueff: Were you pushed by leaders getting impatient like, let’s say, [Leslie] Groves used to push people—?

Katz: Everybody was a pusher—

Groueff: Or Lawrence was driving his men, [James] Herbert not so much, no?

Katz: No it wasn’t relaxed.

Groueff: [Walter] Zinn was pushing his people; no?

Katz: Everybody worked very long hours and six, seven days a week.

Groueff: Six, seven days a week.  Yeah you would come early in the morning and stay—?

Katz: Stay till late at night.

Groueff: At night. It really was a hard, hard work and constant— not just for a few weeks and then you relax. This plutonium chemistry group, how many people were more or less in the same—

Katz: Oh I don’t know.

Groueff: The same laboratory?

Katz: Well, forty to fifty people.

Groueff: Forty to fifty people.

Katz: And there was a turnover because it was sort of training. People would come and work for a few weeks or a few months and then go off to Hanford or go off to Oak Ridge.

Groueff: And the secrecy add some of this flavor, the fact that you have guards everywhere or—?

Katz: One doesn’t have guards in the lab.

Groueff: It’s more or less what you have here in some buildings, no?

Katz: The way it used to be here.

Groueff: Wearing badges and things like that and have to be careful to lock your doors?

Katz: Yeah, people weren’t used to working in that setting. As is often the case, even though the people who made the rules were well intentioned, they weren’t always well informed. You had people making the rules about science who didn’t know anything about science. The scientists were the ones really maintaining the security and the secrecy and were the ones who made the rules.

Groueff: This was on a voluntary basis, yes?

Katz: Oh, sure.

Groueff: Actually Z-lab originated the system even much before the Manhattan Project began voluntarily withholding information.

Katz: But people would take a document to mail on, you know, the German standard work on inorganic chemistry, the volume on uranium, and stamp it secret. Well that used to annoy and irritate. One of the things that [Glenn T.] Seaborg did very, very well was to protect his people from security invasions of privacy and excessive regulation and regimentation. His judgment as to who he told what didn’t interfere with the internal flow of information that people needed to have.

Groueff: There was no important break of security here in Chicago, no? Some of the famous spy cases—

Katz: I don’t think a scientist has ever been involved in one; as far as I know no American scientist—

Groueff: But there were the—  

Katz: Klaus Fuchs.

Groueff: And Alan May—

Katz: May—

Groueff: They were two of them foreigners, no?

Katz: But as far as I know—

Groueff: No scientists?

Katz: As far as I know. There were many scientists who had the usual background during the 30’s—

Groueff: Oppenheimer.

Katz: Like Oppenheimer. I think it’s hard to remind oneself of the terror that was associated with the Nazis and how invincible they seemed for such a long time. You know the prestige and the awe in which German science was looked up to made it—that was the factor that applied the pressure and the pressure really came from the fear.

Groueff: People, like the refugees, were the constant reminders, like [Leo] Slizard—?

Katz: But you’ve got to remember, not as much as you might think because there’s always been foreigners, seriously. Even before Hitler there were always foreigners coming to the United States.

Groueff: Those were more or less—

Katz: But one knew them as refugees.

Groueff: Yeah they came for security. Also for the fear that the Germans may be doing better than you in atomic—

Katz: I knew of no one who assumed that the Germans were not doing work in this area. The fact that they weren’t and they did it so poorly came as a real surprise. Have you read this book by [Samuel] Goudsmit, “Alsos”?

Groueff: Yeah, it’s extraordinary, no?

Katz: I would have wagered, I would have sworn that it could not be that way. That they would have— that even Heisenberg would miss by— he thought he really had something he was going to negotiate with at the conference, at the peace conference.

Groueff: It’s a form he needed, no? I think Heisenberg said once about the Hiroshima bomb when they were all interned at a villa, that all this was a propaganda.

Katz: There were many Americans who thought about them in the same way.

Groueff: Which was good in a way because it was a good stimulus, no?

Katz: Because nobody took the attitude that the Chinese would never do it and there were many people who thought that the Russians would take—

Groueff: Yeah, twenty years.

Katz: Twenty years.

Groueff: But the Germans everybody—

Katz: Everybody assumed—

Groueff: Also it was normal to assume it because after all it came from Hans [Bethe] and [Eugene] Wigner.

Katz: They were, up to World War II, in chemistry, preeminent.

Groueff: And you beat them in about five years. Did they explain after that when new scientists at international conferences need similar German people like [Werner] Heisenberg or [Joseph F.] Leisek or those people? Were they asked why?

Katz: If they have, it’s not public.

Groueff: And they wouldn’t say exactly—

Katz: Well there were some interesting practical situations and it was internal rivalry between Hitler’s—you know the Post Office had its own laboratory. They had half the uranium.

Groueff: The Post Office?

Katz: Yeah and somebody else had the other half; neither one of them had it all. But they could never agree how to share it and—

Groueff: It was a little bit like this rivalry before here between Air Force and Navy and Army about intelligence or about rocketry?

Katz: One even had the impression that, even though scientists who were confirmed Nazi’s by conviction, were not the best ones. The ones that were tolerated were never able apparently to really commit themselves—

Groueff: You don’t think there was a real form of sabotage?

Katz: You see, one of the advantages or one of the consequences of a great number of people working is that no one individual ends up in a position—

Groueff: Where they are highly responsible.

Katz: If there are only a few people involved, then I suppose one individual—

Groueff: Could stop—

Katz: Could stop it. But if you’ve got hundreds of people involved in every aspect of it—

Groueff: People like [Otto] Hahn or [Fritz] Strassman continue?

Katz: As far as I know they were never involved. 

Copyright 1965 Stephane Groueff. From the Stephane Groueff Collection, Howard Gotlieb Archival Research Center at Boston University. Exclusive rights granted to the Atomic Heritage Foundation.