Lew Kowarski – Session II

Weiner:

This is Charles Weiner. We’re sitting in my living room, and this is a resumption of the tape-recorded interview with Dr. Lew Kowarski. We had just indicated that we had covered the period in the ‘30s pretty well, with some gaps, up to the time when Joliot and you went to the College de France in 1936 or 1937 — I’m not clear exactly when that came about or whether it was a gradual transition. There are a couple of things I want to know about: how Joliot got the appointment, what your duties were in connection with him there, what the plans for the lab were, what the purpose of it was. So wherever you think it is appropriate to start in…

Kowarski:

Right. Let’s take a time point: end of September, 1937. Joliot’s gradual move from Radium Institute to Col1ge de France has been by that time completed. He is no longer in the Radium Institute. He is full time in College de France. Why? Joliot was intensely French; and although in the French scientific Establishment, he was a complete outsider, resting only on the basis of his genius — which for any Establishment is a very flimsy basis — but by that time he’s been universally recognized: a Nobel Prize, which already in those days was a very rare thing in France; a world celebrity, rather more so than in France; and on his way up to something quite dizzy. For a man of that size and of that sort of ambition, it was normal to aspire not just to be a professor at the Sorbonne but a professor in the College de France, which was at that time — and I think still is — the most prestigious chair an academic can have in France. He got it. He got it, by the way, not through physics, but through chemistry because his Nobel Prize was for chemistry — nuclear chemistry. He got the chair which was occupied before him by an organic chemist, and he transformed it into a chair of nuclear chemistry. So it was a bit of skullduggery — how a physicist became holder of the chemistry chair; however, Joliot was not only a physicist — he was also a chemist. That was an important part of him, but he was primarily a physicist. So he moved in. He had very vast ideas.

He considered himself the discoverer, and therefore probably the most important person in his own eyes in artificial radioactivity. He thinks of isotopes, of making isotopes, of preparing the way of using isotopes in biology, in engineering (at that time he was more interested in biology as the immediate point of application). He wants to have machinery to make isotopes. He doesn’t quite know how to go about it. We already talked about the cyclotron. He was never very good in selecting people. Essentially, in his most important things, he was a lone wolf. He had a few devoted pupils, who were nice people but not quite at the level which should be surrounding the master at that time, and he also was full of all sorts of humanitarian ideas, which in France meant at that time he was less xenophobic than the others. So he brought two outstanding young men with him to his new laboratory. One was Pontecorvo — I don’t have to explain who he is…

Weiner:

We might want to talk about him later.

Kowarski:

Yes. And the other was Halban. As for myself, I can say that I came into that crowd mostly as his personal secretary – “la petite dactylo” — and a bit on the background of the early reasons why he took me at all. He knew that I had some kind of queerly inventive mind, although he realized that at that time it was dormant, but he thought it might come in handy later on. It turned out he was right. So I had this dual capacity, but primarily in the capacity of his personal secretary. He was able not only to pay me a small stipend for the secretarial duties, but by that time he also obtained for me a kind of scholarship or fellowship, which was, as I think I’ve already stated, 4O of what was considered minimum for a young man. This of a minimum was for me a very important sum, because it enabled me at last, after over eight years, to stop my activities in the steel tubes.

So at the end of September, for the first time in my life, I began to spend all my working days in a scientific laboratory — partly as a secretary, but this left me at least half a day in which I could do what I wanted. It turned out that probably the secretary part was more important for me than the research part, simply because — since I was involved in helping intimately this great man in a great phase of his career in founding a new center, which was started modestly but which had very high ambitions of becoming one of the most important, if not the most important, center in the world for isotope applications — that was my first, very first hand contact with organizing new scientific ventures. And this later on became my main profession in life. As to research, my aims were modest. I wanted to produce something which would convince people that I was still worth keeping in a lab and paying modestly for the lab work. I showed it in crystal growth before. I showed that I was probably worthy of giving something to, but nobody would give it to me. So I had to start again in nuclear physics, not even because nuclear physics was my special interest, but obviously nuclear physics was attracting the most attention and later on money — and yet I did have some vague ideas that nuclear physics had an interest of its own. I just yesterday looked in Szilard’s memoirs. Szilard read for the first time H.G. Wells’ novel, The World Set Free, in 1932. I read it in 1917. I had this 15 years’ jump ahead on Szilard. But in those days I could hardly consider that this would have any practical consequences in my life or in that of anybody else then living although there was a prophetic episode a year later in 1938 to which we must return.

Weiner:

I’ll make a note of that. But let me ask you: on this question of nuclear physics, it seems to me that since Joliot himself worked full-time in nuclear chemistry and nuclear physics, that it was clear that without any other influence, this would have to be what you would be doing. The apparatus and everything else was there.

Kowarski:

But now consider that at that time point which I am describing now, I was slightly over 30 and a half. My knowledge of nuclear physics was rather small. I had to start again in a new branch of science. It’s amazing how late it is in life when one is over 30 to do this sort of thing. And I was never good at just sitting down and learning a thing. I preferred to absorb things by osmosis. And although I was quite ready to apply my inventive faculties, whatever they are, there had to be something to apply them to; and that was missing. And here I found myself again in this position in life, which recurs again and again, that I was quite ready to work on the highest level of something but the basis was lacking. I have the same problem in music. I have the same problem in languages. For example, my wife is always surprised by my very, as she says, fine understanding of fine shades of meaning in German words; yet I am incapable of ordering a meal in German. It’s always the same pattern. I was also acutely conscious of the fact that I was here up against my fundamental problem — whether I am a scientist at all — because I’m not a scholar; I definitely am not a scholar. And any scientific activity, especially today, more so than in the 1930s, must have a very solid basis of scholarship. I think the question of whether I am a scientist at all has arisen many times since, for reasons which have not always been purely disinterested on the part of those who raised the question. I probably could compare myself — perhaps as a somewhat exaggerated example — to Aston. You know the story of Aston?

Weiner:

No, I’m not sure I know his full background. This is the one from the Cavendish lab?

Kowarski:

Yes. Aston was a lab assistant, a technician of rather low standing. He helped J. J. Thomson with original investigation on isotopes, mass spectrography. And he obviously had some peculiar kind of genius. J. J. Thomson, being a very great man and not interested in status symbols, accepted Aston’s genius for what it was; and Aston got a Nobel Prize, and he became one of the foremost authorities of his time on isotopes — on isotope concepts and mass spectrography — and yet he had no basis whatsoever. Well, on the one hand, I’m not a genius like Aston; I even lack the manual ability he had; on the other hand, my basis is not as reduced as Aston’s was. But it’s a bit of the same contradiction. I chose deliberately as an excessive example — in both directions.

Weiner:

Did this self-questioning of whether you were a scientist and if not, what were you, occur at that time, in the 30s?

Kowarski:

Oh, yes.

Weiner:

When did this first occur to you?

Kowarski:

Well, here I was in these surroundings with a recognized and quite obvious genius of a great stature, with whom I was in everyday contact, surrounded by pupils, some of whom were very accomplished. I would single out especially Pontecorvo, who was one of Fermi’s original group of six, which was an exceptionally brilliant group. I knew things the others didn’t know. I knew, for instance, far more chemistry than they knew then. But they knew things in nuclear physics itself, where 1 was supposed to work. They had an enormously greater store of knowledge and experience than mine. So I had to ask myself what the hell I was doing there. That’s why the question arose, in a very practical way. For the first time in my life I had a few hours every day for which I was paid — modestly, but I was paid — and I was expected to produce results. What results? On what basis? There was no question of being directed to do something definite. This is not the tradition in France in general and especially it was not a tradition of Joliot’s. Joliot, if I may say so, simply was not able to direct anybody. It was not one of his abilities.

Weiner:

When did Pontecorvo come to the lab? Halban came as early as 1935.

Kowarski:

Pontecorvo came, I think, in 1936.

Weiner:

That was before September of 1937 where our story picks up. But by that time they were in the group, as you were?

Kowarski:

Yes. I think these two, Pontecorvo and Halban, were the most outstanding personalities in the lab, after Joliot. I had started before by trying to make a coincidence amplifier for a definite experiment which Joliot had vaguely suggested on gamma rays. Now, Joliot and his surroundings at that time were almost incredibly weak in electronics compared to what went on later on and what was already going on in other labs. The principle of the coincidence amplifier, which was invented, by the way, by Bothe, and later on simplified and made in a more elegant way by Bruno Rossi, for anybody who knew anything about the use of radio tubes was a very simple affair. I knew very little. There were scientists, without much imagination, who would learn with considerable trepidation about how to use radio tubes. They at the same time wanted to have the knowledge and despised it a little as mere engineering and would design amplifiers far too complicated, unnecessarily so, and would putter for years over some fine aspect of resolution or something. I was more or less working in the same way but without even any knowledge of fundamentals of how a radio vacuum tube works. Again, I had some interesting ideas of what I would do once I could force a vacuum tube to obey my commands. I knew perfectly well what I wanted it to do and had a few original concepts, but I still again lacked this fundamental basis.

Weiner:

You had to learn the grammar.

Kowarski:

Yes. I was able at that time to secure the help of a colleague of mine of Polish origin who knew far more about radio tubes than I did, and using his advice, I finally was able for the first time to produce a coincidence amplifier, which Joliot decided was a workable contraption. By that time he lost completely all interest in the problem for which he had originally launched me on it, and I was left more or less with my clumsy amplifier without knowing what to do with it. Then I had an idea, typical of my ideas. Let me now spend a few minutes on a few technicalities. Geiger counters in those times were giving typically between 50 and 100 pulses randomly spaced per minute. More than that would overload their mechanical recording device. And, of course, much less than that would give very poor statistics. So usually one tried to work them (at least in our lab — I am not sure about what was done elsewhere) in approximately that range.

We heard about the scale of two, the scalar, which was a binary device developed at the Cavendish by Wynn-Williams. It looked to us like a fairly complicated arrangement of vacuum tubes and gas-filled tubes which enabled to transmit to the final mechanical counter. Because of the confusion between the word counter (in the sense of producing a visible count in reading figures) and the Geiger counter, I myself introduced the word “numerator,” which came into use around us. So these mechanical numerators, being mechanical, had inertia and could not follow more than a little over 100 per minute. With Wynn-Williams’ arrangement one could extend the range. If necessary, one could count 200 or 10 or 800 by selecting every second or fourth or eighth pulse. He usually had it in eighths. That’s why his machine was called “Scale of 8” at that time. We knew it existed, but it seemed to us something terribly sophisticated. It’s rather amusing to remember it. So I had a completely different idea — to render the circuits insensitive for most of the time so that if, for instance, I had incoming 20 pulses a second randomly, if I rendered the machine sensitive for only 1/20th part of a second, then I would count 20 times less. And therefore I could expand the range. My machine would be able to cope with activities which went instead of 100 per minute up to 2000 per minute.

There was one very fundamental difference between this contraption and Wynn-Williams’ which, by the way, Joliot first pointed out to me. Wynn-Williams’ machine was precise. When he counted 100 pulses, it meant that the counter had received exactly 800 — it was proportional. Mine was random. It had a statistical element in it, which therefore made it less precise than Wynn-Williams’. As I say, Joliot explained it to me. I didn’t understand it all by myself. Still in this random way I was able to extend upwards the ability of the numerator to cope with activities, and so I was able to demonstrate, for instance, a long decay curve of radioactivity from a level of, shall we say, 2000 per minute to the level of 2 per minute — which was a nice demonstration, a nice gadget, and still with the same numerator which couldn’t count more than slightly over 100 per minute. That convinced Joliot that there was something in these earlier intimations he had about my inventiveness.

Weiner:

This was about 1935?

Kowarski:

No, I started developing this gadget immediately when I had my free time.

Weiner:

That was ‘37.

Kowarski:

‘37. By the spring of ‘38, here was my gadget working; so I showed it to Joliot and to the world and to myself that I could still invent things like that. But what to do with it? There were obviously two people from whom I could learn a lot if only they wanted to teach me. One was Pontecorvo, the other was Halban. Pontecorvo had no use for me. He saw my quandary. He may have had ideas in his mind that perhaps I was aspiring to something which I couldn’t deliver anyhow. He wasn’t precisely discouraging, but I could understand from his tone: “After all, why should I be interested in your struggles? Besides they don’t look promising, and you are too old anyhow.” Halban was different. Halban was expanding; he could use all sorts of assistants and helpers and colleagues in his ever-expanding schemes. There was something which appealed to me in Halban’s temperament, in his extremely concrete approach. He could envisage any situation, including scientific situations, in terms of what is to be done, which is fundamentally my own approach. His motivations were perhaps of a kind which I couldn’t entirely serve, and as our collaboration developed this disagreement about motivations became more and more pronounced, and I will have to return to that, because it became a very important factor in my life and in his life. He believed in showing his strength when he was dealing with strong people in strong positions, and he believed also in showing his strength when he was dealing with people in weak positions. I don’t know whether I make myself understood.

Weiner:

You mean showing it in a different way?

Kowarski:

Well, there was an element of a Prussian officer in him very strongly or of that somewhat caricatural version of a Prussian officer which was an Austrian officer. In some ways one can say that in the Viennese character there are some elements of caricature of the German character. Halban’s whole life was marked by his origin suspended between Germany and Austria. He was actually born in Germany, not in Austria, and there was far more German in him than in an average Austrian. And to be quite blunt about it, he tended to be brutal with the weak. In 1935, when I first met him, he explained to me quite frankly that in his opinion I was in the wrong place. Whatever my possibilities were, I had no possibilities where I was; that in fact I was making a fool of myself. That was in ‘35, at the time when Joliot was beginning to lose interest in me after the episode which I described last time. He said, “Don’t think that Joliot will be ever different to you unless you are useful to him in some way.” This I don’t think was an accurate analysis of Joliot’s character in its entirety, but maybe it was accurate as to one facet of Joliot’s character. And because of Halban’s own character he tended to exaggerate the importance of that particular facet. But I learned my lesson. And that’s how I became la petite dactylo, because that was at that moment the way I could be useful to Joliot.

So I had already tasted this attitude of Halban’s, which was intensely unpleasant (not only for me; he produced this kind of impression on many people), but since I had learned from him in this way one useful lesson, I made my decision: “He will be the medicine I will have to take again.” Pontecorvo told me that Halban could make some use of me, and Pontecorvo even offered to talk to Halban about it. So somewhat to my surprise one day, in the spring of ‘38, Halban told me, “Well, I have an interesting problem. I could do with some help. Come and help me.” So we started working together for the first time. The problem was the interaction of various elements with medium energetic neutrons. These neutrons were obtained by action of one of the thorium products on heavy water. They were monochromatic more or less, in an interesting region, which was neither fast neutrons nor slow neutrons — 200 kilovolt — and he had some ideas, which he had learned from Placzek on how they should react with various kinds of matter. In particular, (on the basis of the Bohr theory of the compound nucleus, as it was understood in those years; that was before the shell model and magic numbers and all that) there should be no individual phenomena like resonances, which elements show for slower neutrons.

There should be a steady variation of the cross section with the atomic number, and the way this variation goes in various domains of the z-series of elements would give some insight about the interaction of neutrons with nuclei. So we started irradiating various elements and observing their activities. I learned from Halban all the techniques (I knew nothing about these techniques before) of using sources. One source I already used with Joliot on that experiment in ‘35, but here I had to handle more closely a new kind of source for a new series of irradiation. Then there was the use of detectors, how to use Geiger counters for measuring the activity of neutron detectors and so on. When we started measuring radioactivity of a series of elements in the middle range — shall we say somewhere between silver and barium — Halban expected a certain value characteristic for the middle range, which would be different from the very light elements or from the very heavy elements. Instead of which we began to observe enormous individual variations from element to element. This was a typical situation: when one starts taking measurements to satisfy a theory and one finds results which contradict the theory. I’m always amused how even a brilliant mind like Halban’s feels a kind of dismay at that situation. I felt an elation. And that was our first disagreement. Halban considered these enormous variations between neighboring elements a nuisance. I considered we had discovered something.

Weiner:

Of course, he was more committed to the theory than you were.

Kowarski:

Halban was in no way a theoretician. He knew more of theory than I did, but he considered that theory was something a little bit on a higher level — higher than him even — and all he could aspire was to learn something. When he was in Copenhagen around that time he took formal lessons in theory from Weisskopf. He always said, “Oh, you won’t know anything about that. That is far too high.” His knowledge of some theory and my ignorance of it put him in a position of advantage — not that he needed it with me; I was a benevolent helper, who practically begged to work with him to learn something. But he always had this attitude of seeking for positions of strength in life, and probably I was a kind of exercise: he did not need anything of this kind when dealing with me, but he still exercised these techniques of positions of strength. So when it turned out that the theory was hopeless, and all we needed was to observe the phenomenon and realize that it was a new phenomenon and adapt ourselves to it, perhaps my more chemical kind of mind — especially when differences between various elements were involved — was at some advantage over his in that position. And so a cloud arose between us. The experiments gave the results which were going too far my way and not enough his way. This was a typical situation which occurred in the next few years when we would work in a sincere collaboration. I have to insist on that. He had a considerable dedication to the scientific phenomenon, and so had I; we were both advocates of the scientific phenomenon, and this was quite sincere. And yet there was this interplay of characters. Events played in this way for me and against him. We published it.

Weiner:

Was that the captured cross-sections paper?

Kowarski:

Yes.

Weiner:

For 200 key neutrons?

Kowarski:

Yes. At that time my English, which was mostly known by reading (I had tried my hand at writing, but I was not very sure, and he still wrote the paper) … I don’t think I’m slandering him by saying that I’m a better writer than he was. Later on I took over the writing function, but at that time I wasn’t ready. There were certain mistakes in the numerical evaluation of the results. I will not go into that in detail. I had to leave him considerably the responsibility for that. And this peculiar lack of attention of his to a proper numerical evaluation of the results occurred later on, and I will have to return to that. It was for him a kind of drudgery he was not interested in. He wanted to make one brilliant point, and he neglected a little the linking up of the numerical results. Usually when one makes a few small mistakes, Nature is kind to you and they compensate each other. In this case we lost out in the sense that perhaps as many as three small mistakes were made, and they were all in the same direction. Therefore, the cross-sections we actually quoted in the paper were about ten times too weak.

Since this contradicted the results obtained elsewhere, this discredited to some extent the value of the paper, and although we were really the first to mention the phenomenon of difference between neighboring elements in the absorption of these “non-slow” neutrons — we really were the first to notice it—and that was the important result of the paper, and that was later on completely explained by the shell model. But the paper did not leave a great trace because probably people dismissed it since the figures were wrong by a factor of 10. I don’t know whether I am giving the impression here that somehow Halban was wrong and I was right. I don’t want to give that impression. The experiment was his, not mine. The conception of the experiment was his; all the techniques were his. All the interpretation (somewhat unfortunately) was his. What I did was the purely material work — just making the detectors and making the arrangements and measuring with Geiger counters, and then somewhat naively saying, “Look, here it is. The neighboring elements are very different. What shall we do about it?” I insisted on that. Joliot later on was apt to say that ideas, some fundamental ideas and interpretations, came from me, not from Halban. But I think ideas are cheap. What is important is the conjunction of ideas with a solid basis of technique, observation and fact. And it was in this solid part of the work that my contribution was very small, it’s easy to have an idea and claim: “I thought of everything.” But a scientific experiment has to be made on a strongly solid basis, and that did not come from me. Well, that brings us to about the late summer of ‘38. External events began to impinge quite seriously on our life.

The Munich crisis arrived, it was quite obvious that the clouds were gathering very very fast on the horizon. Halban told me that our collaboration would not go on indefinitely, and perhaps if I have an idea of an experiment, I perhaps could develop it on my own. I began to have some ideas. I read at that time one paper by two people in Oxford — Booth and Hurst — who used a certain method invented by Szilard (it became known later on as the manganese bath) which was very chemical and it appealed to me. I decided that I would work in that domain, on the fringes between nuclear physics and radio-chemistry. Szilard, whom I met once in 1935 at the Radium Institute (at that time I was one of the innumerable young men at the Radium Institute and by no means remarkable, and I don’t think Szilard ever remembered that first meeting, although he might), Szilard’s ways of approaching the problem, his ways of using chemical methods, appealed to me very much. I had ideas of some investigations on beta radioactivity, some specific ideas. I remember that Pontecorvo commented very favorably on my idea. Curiously, I can’t remember exactly what it was. It had something to do with using the Szilard-Chalmers effect on radioactive bodies which had two successive beta radioactivities. It was never done. But I was preparing for doing it, using all the little tricks of trade with detectors and counters and so on which learned from Halban. From my point of view, the collaboration with Halban during the summer of ‘38 was completely successful. Then came a slightly comic interlude. We used the Szilard-Chalmers method to measure the neutron effects in the atmosphere.

Weiner:

Cosmic radiation?

Kowarski:

Yes. It was a typically Halban experiment, very spectacular, sending things up on high-flying planes. We did it. We published it. It was our last publication in common which did not deal with uranium. Actually, when it appeared fission was already on. It was after that piece of work that we definitely prepared to separate. That was an afterthought — this experiment with cosmic rays — but in the lab it established us (it was the second bit of work we did together) as specialists of measurement of slow neutrons in complicated conditions. Well, here comes the fission. How shall we tackle that question?

Weiner:

Well, it doesn’t come right away, but it sets the stage for it.

Kowarski:

I might say another thing. In the fall of 1938, my scholarship had to be renewed.

Weiner:

This is a CNRS scholarship.

Kowarski:

Yes. In ‘37-‘38 I had this 40% of a minimum. My scholarship was not quite doubled. Now I had something like two-thirds on the strength of our success with the 220 kilovolt neutrons. Joliot was very quick not only to notice himself, but also to explain to those who gave scholarships: “Well, you see, you gave him credit. You gave him this 1i0. And he did a nice piece of work during this year.” So by the fall of ‘38 I began to be established as a professional scientist.

Weiner:

Was the fellowship given for a specific research project or just to support you in the laboratory?

Kowarski:

No, it was a definite kind of salary.

Weiner:

There was no research program specified?

Kowarski:

It was considered that it was entirely the responsibility of the head of the laboratory. Perhaps in other laboratories there would be some control, but with Joliot nobody ever dared. If Joliot says it — well … Joliot had some resistance in giving me my first little bit, because they would say, “Well, he is your secretary, isn’t he? Why should we start giving scholarships to secretaries?” So he was able to return and say, “Well, you see, he made good.” I suppose it gave him some pleasure to be able to tell the same people, “I told you so.” And so I was established by that time. But by that time I was already over 31 1/2, pushing 32. It was a rather late time to be established — in no way as a celebrity or an outstanding man but at least as a professional. So fission — what do we do?

Weiner:

Well, before we get into it. Let me ask just one question on the background. What about Irene Curie Joliot in that period? Did she have anything to do with the new institution, or was that considered Joliot’s own laboratory?

Kowarski:

We are touching here on a very delicate subject. I think I shall be compelled to treat Joliot as a human being and say things about him in the description of his personality which are not usually said of very revered figures. I don’t think I can show better my reverence of him than by treating him as a human being, although fundamentally of enormous value. If I ever do write about Joliot myself, which probably will be if I ever write an autobiography, he will play a very big role in it. I do not think I will do him a service by treating him as a sort of exalted statue. He was an intensely human being. So I could as well start now. Joliot was a complete outsider in the scientific establishment, which was very closely linked by family ties and so on. He was selected more or less by Irene as her husband — a kind of prince consort to the princess. And the establishment treated him at first with contempt. He was known as Irene’s gigolo. He had a kind of slightly coarse good looks which suited him for that role.

For several years he was the member of this peculiar community which had its summer quarters in Brittany near Paimpol essentially as Irene’s gigolo — well, Irene’s husband. That was supposed to be his defining function. Now, Joliot had always a very objective and healthy respect for his own abilities, but he was in no way a megalomaniac. He knew a very able man when he saw one, and the fact that the man happened to be himself made no change. He knew that he was more able than all people surrounding him who sneered at him, and it left him with a bitterness, which probably you will not find any trace of in any literature about Joliot, but about which I can testify firsthand. And then, in 1930, when he was already 30 years old, he published his first important scientific work, which was “An Investigation of the Electrochemistry of Polonium,” which had all the hallmarks of his genius, but the subject was not very interesting in itself. And polonium, of course, was always the special love of Madame Curie. This was not remarked at all in any way. He was still in his purely matrimonial basis in this work.

In ‘32, working with Irene, they made their brilliant discovery of the properties of the neutron, which at that time everybody misunderstood — that a neutron can transfer momentum to protons, create recoiled protons, which are essentially the meat of Chadwick’s discovery of the neutron. It was the fundamental fact about the neutron which enabled Chadwick … Chadwick, by the way, although he considers himself to be the discoverer of the neutron … Well, there is no question about the facts. Chadwick knows the facts, and Chadwick had always a very high reverence for Joliot — always. Whether Chadwick considered himself the discoverer of the neutron is his philosophical conception of what a discovery means. On the whole, I probably would agree with Chadwick’s view. I also consider that Chadwick is the discoverer of the neutron, and for exactly the same reason I consider Frisch to be the discoverer of fission — Frisch and not Hahn. But that’s a personal opinion. After that and after a couple of other works on the same level, Joliot suddenly became to be known abroad as a kind of miracle maker, and people in France began to sort of take notice: “This prince consort of Irene’s seems to have got something.” But it really took the artificial radioactivity and the complete recognition given by Rutherford to Joliot to launch Joliot, and Joliot always had a tremendous gratitude to Rutherford — and to Chadwick. Before I met Chadwick for the first time, there was a certain halo around Chadwick’s personality for me.

Weiner:

Because of the impression you got through Joliot.

Kowarski:

Yes. But Joliot’s position in these crucial years when he was already making brilliant work and before the recognition came around him in the French establishment, when it was still considered to be the work done by Irene Curie and Frederic Joliot, made him a little impatient of that position. And although his personal link to Irene was always on a very high level and very deep, I can sense that he was glad to work for a while without Irene. Also, he was more of a physicist; Irene was more of a chemist. That meant that they could have collaborated, but it also meant that their specialties were somewhat different. So they drifted apart in their work. The fact that Irene stayed at the Radium Institute and he went to the College de France made the drift stronger. So there was this kind of, I would say, workaday estrangement, which was not at all a family estrangement — it was an estrangement in work — which went on between ‘34 and ‘39, and on which Irene remarked later on. I will have to repeat the remark in its proper place. I think that was in answer to your question, whether he was working with Irene.

Weiner:

That’s right. When you say this period, ‘34 to ‘39, it wasn’t until ‘37 that he began to work separately physically that is, to spend the days in a different place?

Kowarski:

In very late ‘34 and ‘35, when I had my first period of work with him, he already worked apart from Irene. Halban, curiously, started with Irene, and then went over to Frederic.

Weiner:

The question was partially to establish the background. You indicated when you started this account that in late September ‘37, he was a celebrity, was known abroad, had influence in France, had his own research program. Now, at this time he was also interested in what I would call more of the extra-scientific activities, too. He started perhaps in the mid ‘30s with some of the political issues — the Committee of Vigilance of Intellectual Anti-Fascists? That was somewhere in the mid-30s.

Kowarski:

Late ‘30s.

Weiner:

I see. How does that tie into the story in terms of his own position and his perception of his role as a scientist?

Kowarski:

It’s precisely that. It was a tenet of belief among the intellectuals that they had to play a role in politics, to an extent which I consider now and I considered then as somewhat naive. The fact that a man is good in devising an experiment on neutrons doesn’t mean that he is any good in telling the government how to run a country. It may be embodied in the same person, but not necessarily. And the Committee, which called itself the Committee of Vigilance of Anti-Fascist Intellectuals — the word “intellectual” always appeared to me slightly comic. And the fact that people went about calling themselves “intellectuals” also appeared to me slightly comic. On the other hand, there was nothing comic in the wave of sympathy for the Spanish Loyalists, which started in the summer of ‘36. It was a generous feeling. One felt somehow a feeling of guilt that people who had the same beliefs as you were massacred over the border, because the French Socialist government decided on the policy of nonintervention. It was Leon Blum who created the policy of nonintervention.

There were some older figures like Langevin or the ethnographer, Paul Rivet; and one of the pupils of Paul Rivet — a very brilliant man called Jacques Soustelle — was very active, and that was the beginning of his somewhat checkered political career. You probably know about what happened to Soustelle later on. It was quite normal for a prominent intellectual, especially like Joliot, who came in a way from sort of a… I think I told you before about his peculiar family origins. He came from a family which on the one hand was well—to-do and on the other hand considered itself as the people, anti-bourgeois. There were some crude revolutionary and populist tendencies in the family, so it was quite natural for him. I might say again (probably it will surprise most of his biographers) at that time he was anti-Communist, rather violently anti-Communist. He told me at that time many times that “Communists are Jesuits; they have no sincerity. They are a clique of power-grabbers.” I could more or less agree with him. On the other hand, I consider myself that in politics power-grabbing is the normal phenomenon and should not be taken as a stricture on a party. And what I was afraid of was that his violently leftist leanings and total divorce from any ideology, such as Marxist ideology, could have made him easy prey for any Fascist lure. I remember many discussions when he would be expressing his sympathy for this or that figure on the non-Communist left.

I would tell him, “Yes, but look, this man looks to me very ambitious and unscrupulous. Be careful.” There were a lot of these little groups in France, as in other countries, which considered themselves very leftist and which were in fact budding Fascists. Fascism always comes from the left, always. Mussolini was orthodox Socialist in the beginning. Hitler was one of the first members of the German Workers’ Party. I could continue. Joe McCarthy came from the left. Don’t you know the early history of Joe McCarthy? In America the populist movement of Wisconsin and Minnesota always was sort of half Socialist, half Fascist in some of its leanings.

Weiner:

Getting back to Joliot, was there anything in the style of these individuals which he might have been attracted to that was more important to him than their ideology? You were talking about his own style.

Kowarski:

Joliot was a very nonideological person really. Whatever he himself might have thought of that, he had, in a way, a very naive, warm and generous idea about the good that was in the people. I suspect that fundamentally he sucked this with his father’s milk, if I may say so, because his father was at a very early age a radical under Napoleon III — when French radicals were really radical. It was this fundamentally mid-19th century tradition which persisted in Joliot, I should say, to the end of his life. The 19th century had its good points, you know. Again I would not be surprised if whatever I’m saying now, comes later on as something quite unexpected as someone who knows Joliot only from his hagiographic biographies. And I’m saying that, politically, Joliot was a throwback to a hundred years before. If his father had started being active in the late l860s, the tradition was really 1848 — practically the year of the Communist Manifesto.

Weiner:

So was it this period that we’re talking about now — of the Spanish Loyalists — when Joliot began to get involved in the political movement?

Kowarski:

Yes, this action group — I think Soustelle was one of the youngest and most prominent men of action in that group — needed great names to put on their notepaper, on their letterhead, and Joliot was beginning to have a great name. Jean Perrin was active in that, too, and Langevin, of course.

Weiner:

This was sort of an extra-curricular thing.

Kowarski:

It was almost not extra-curricular. It was a part of life of a prominent intellectual. So I wouldn’t call it extra-curricular. Besides, he didn’t devote much time to it.

Weiner:

How did it affect his position within the French scientific community? It would endear him to Langevin, but what about the other circles in French science?

Kowarski:

Well, you know, no Nobel Prizeman in France could be sneezed at. There were precious few of them. And his was a real authentic Nobel Prize. It was not a fluke. He was considered a very brilliant outsider, definitely not a member of the establishment, but someone who married into the establishment — let’s face it. And the establishment was somewhat reluctantly ready to take him to their bosom. Here I don’t mention at all the other thing which is characteristic of French society: the eternal division of France into the two halves — the reds versus whites, the Freemasons versus Catholics, the socialists versus traditionalists. Before that it was the tri-color flag versus the royal flag with lilies and so on. There is this traditional dichotomy which is still going strong today. There was in the French scientific establishment the same dichotomy. I think probably the best hallmark would be their religion. They were Catholics and non-Catholics. Le-prince-Ringuet, who was almost exactly the same age as Joliot, was sort of a budding glory of the Catholic part of the scientific establishment. But in these years — the 1930s — they were lying very very low. They had no discoveries to their credit. All the discoveries were on the left side. That changed after the war, but they were very much the underdog. I mention that because it played some role later on.

Weiner:

I think it’s very significant that that existed.

Kowarski:

It’s a peculiarly French phenomenon. Always, in every walk of life, there’s this dichotomy.

Weiner:

Did it affect the jockeying for positions of influence, like editorships of journals and positions in faculties?

Kowarski:

It did. And, as I say, the Rightists were very much the underdogs. Of course, their greatest glory at that time was Louis de Broglie. One can say that Louis de Broglie, roughly speaking, played the same role on the underdog side as Perrin, Langevin and a few others played on the upperdog side.

Weiner:

How about the editorship of journals? Was there any real problem that interfered with scientific work, in terms of whether something got published or was looked upon with favor?

Kowarski:

I don’t think that any work of value went unpublished because of that. After all, you know, we shouldn’t dwell too much on the negative side of human nature. Human nature has also a positive side, and most of these people had a very genuine regard for real scientific values. So there’s no question that Louis de Broglie was considered as a great genius by the whole scientific left. It’s always difficult to keep balance between being realistic about human nature and not forgetting that human nature has its best side.

Weiner:

It’s hard to put them together, but it must be done to talk about it in its full dimensions. So with that as background, then it was no surprise or shock that Joliot came out with positions that were identified with the left.

Kowarski:

Oh, Joliot was not particularly prominent as a pronounced leftist. Joliot was never a Marxist, for instance, and there were many scientists in all walks of science who also would be Marxist scholars. So Joliot was not particularly remarkable in that way. The political tinge of Joliot — or rather of Joliot-Curie, as he began to call himself at that time — that came later on. There was no hint of that sort of scandalous attention to his politics that came later on.

Weiner:

By later, do you mean in the 1940s?

Kowarski:

After the war.

Weiner:

When did the Joliot-Curie name become desirable for him?

Kowarski:

Joliot began to be called Joliot-Curie by the press a few years before the war, and he lent himself to it with what I considered somewhat excessive complacency, which I interpret essentially as a lack of self-confidence. I tried to explain to him (at that time I still called him “Monsieur” and “vous” and all that — the more informal forms of our relationship came after the War): “Look, if one is a Joliot, one doesn’t need to be a Curie.” To my astonishment he didn’t quite get the point. And he would say, “Funny, you have a bee in your bonnet about it. You’re like my daughter.” His daughter was 11 or 12 at the time. “She always tell me, ‘Father, don’t call yourself Curie.’”

Weiner:

How about Irene? What did she call herself?

Kowarski:

Irene quite properly called herself Irene Curie in her publications, because that was the name she had completely established herself under, as a young scientist; and I think she called herself very often Irene Curie-Joliot, which was again in keeping with the French usage. In France the assumption of the name of the husband is slightly less pronounced than in some other countries. In all official documents she would be called “Irene Curie, femme Joliot.” In the minutes of a court proceeding of any sort she would be called that way. So for her it was quite natural for her to call herself Curie or Curie-Joliot or Joliot-Curie. For him to call himself Joliot-Curie was a kind of weakness. I considered it a weakness, although an understandable one.

Weiner:

This gives me, I think, the background I wanted for this period. We were in the fall of ‘38 when you and Halban had established yourselves as a team with a particularly good ability to measure slow neutrons under special circumstances. You published two papers on it together.

Kowarski:

The second paper was published only in January, I think, of ‘39. The work was done partly in the very last months of ‘38 and possibly even in early ‘39.

Weiner:

Anyway, at the same time this collaboration continued, were you doing anything independently in the latter part of ‘38?

Kowarski:

Well, I started thinking about the experiments on the Szilard-Chalmers effect, but since these experiments never saw the light of day, we needn’t talk much about it. It’s perhaps interesting to mention again that by that time people like Pontecorvo began to know that Kowarski had some ideas because of this. That’s why I mention it.

Weiner:

How many people were in the lab in the latter part of 1938? You mentioned that Pontecorvo and Halban were the most prominent personalities, but there’s no indication to me of how many other bodies were there and in what capacity.

Kowarski:

Well, you know how it is. It’s very difficult. People come. There is a whole spectrum, from the people who drop in for only a day or a month, to the person who stays there all the time. There are in this spectrum people who come for three months and people who come for three years. Also, in the peculiar circumstances of Joliot’s set-up, he inherited a chemistry lab; and there were in the same lab many pure chemists still doing their chemical work. There were increasingly guests from abroad. Hugh Paxton, for instance, a man who is now of some prominence in Los Alamos (he also played some role, I think, during the war), stayed there for a year at least. It was, I think, my first long-term contact with a living American. There was a brilliant biologist, Charles LeBlond, who after the war went to Montreal, to McGill. There is a peculiar episode concerning his arrival in Montreal about which I will have to tell you. LeBlond, by the way, was a Catholic, and his presence in Joliot’s lab created a little bit of tension.

Weiner:

Was there any kind of formal or informal screening mechanism that would determine the kind of people who would come in?

Kowarski:

Simply the Catholics would be afraid to go to a non-Catholic lab because that might be detrimental to their faith or possibly even count against them in God’s eyes. On the other hand, a non-Catholic would hardly be accepted in a Catholic lab. This was substantially relaxed after the war.

Weiner:

So there was some self-selection but also some institutional barriers.

Kowarski:

They were not institutional.

Weiner:

Well, you said “would not be accepted.”

Kowarski:

Not because there was any formal barrier, but it would be felt he was incongenial. There were exceptions, of course — all sorts of exceptions.

Weiner:

I don’t know if it’s appropriate to explore it now, but it would be interesting to see if the types of problems the so-called Catholic labs would tackle would be different than the type of problems that the non-Catholic labs would be attracted to. Or did this depend on the personality, more than anything else, of the leader of the lab?

Kowarski:

Well, who said that the difference between talent and genius is that talent does what it can and genius does what it must? Let’s put it this way: there was no attempt on the side of the Catholics to prove by their discoveries about nature something about God’s existence or providence. The other side is not quite that simple. I think there definitely always were ideological attempts on the leftish side to use science as an argument against God. In fact, I would say that the atheists or agnostics were more dogmatic than the Catholics.

Weiner:

You talked of the difficulty of saying how many were in the lab. So I still have no feeling of whether we’re talking about six, eight or 30.

Kowarski:

Well, if we take the number of people … First of all, if we eliminate the chemists proper and we take only what one calls today nuclear physicists as opposed to nuclear chemists — in those days the difference was not all that clear, and I could perhaps describe myself more as a nuclear chemist than a nuclear physicist (Joliot was both always—a bit like Fermi) — and if we take them, shall we say, on what might be called in this country the assistant and associate professor level, then starting with assistant professor level, there would be at any given time something between five and 10, not more than 10. And after the summer of ‘38 I definitely was among them, not before the summer of ‘38. I think it’s only after this first work with Halban that I acquired a certain status.

Weiner:

Did the laboratory have any educational role in terms of being a place where people worked for their degree and qualified there?

Kowarski:

Yes. First of all, the lab was attached to the chair of what was called nuclear chemistry. Joliot lectured once a week. And they were very conscientious and very good lectures; and I was always surprised whenever I happened to be at one of these lectures that Joliot could handle quantum mechanics on the blackboard with complete ease as a lecturer since I knew perfectly well that he never handled it outside the lecture room.

Weiner:

He never used it in his work and never had to think about it?

Kowarski:

No. He was somewhat like Rutherford in this respect. He understood enough of it to be able to take conclusions from a paper by Bethe, shall we say, and when he was lecturing about it you never had the impression that he never used it in his life — but he never did. Quantum mechanics in those days was something new in France. Compared to other countries it was definitely less developed — for exactly the same reasons as calculus was less developed in England, because of Newton during the whole 18th century. Newton’s heavy hand slowed down the development of mathematical life in England. In exactly the same way Louis de Broglie slowed down the development of quantum mechanics in France. It’s a terrible paradox, but you’re more familiar with this sort of thing than I am and could give some other examples. Incidentally, that was the historical role of Leon Brillouin. Leon Brillouin had, so far as I can judge, a complete understanding of quantum mechanics. And he was probably the only one who did — I am exaggerating, of course. Incidentally, quantum mechanics was not called quantum mechanics in France. It was wave mechanics — mechanique ondulatoire.

Weiner:

That’s out of an old tradition in France.

Kowarski:

Well, it was simply because Louis de Broglie didn’t want it any other way — that’s all.

Weiner:

Getting back to the students, Joliot would have these lectures once a week — was there any change either in the numbers of students or their backgrounds or motivations or in the subjects they studied that you were aware of? I know that you don’t have statistics, but I mean what you could sense at the time.

Kowarski:

I don’t quite remember now — I would really have to make an effort of memory — how many young men were present in the lab who were definitely younger than shall we say an assistant professor would be here. I don’t think many. Don’t forget that College de France never gave any degrees. That’s an important part of the picture. People who went to lectures at the College de France would have to have at the end of the year some kind of attendance certificate at most, which would enable them to say, “I also attended the lectures of so-and-so during such-and-such semester.” But there were never any degrees. So therefore the bulk of the young men were not interested. But there were young men around. Still the main function was definitely research, not teaching.

Weiner:

What about any special colloquia or sessions where the new results would be recorded and discussed?

Kowarski:

That existed and was important — I think once a week. I think I said something about it in the first part of the interview.

Weiner:

I know you did in reference to Jean Perrin, but…

Kowarski:

No, no, no. In Joliot’s lab. I was asked whether I wouldn’t like to prepare a paper to discuss and I prepared a paper about beryllium 8. I think I mentioned it. That was some time in ‘38. I was sort of acquiring the trappings of a young scientist, except that I was not so young then.

Weiner:

How about when visitors would come in, though? Would there be an opportunity to hear them?

Kowarski:

Yes.

Weiner:

Do you recall who some of the people were in those two, three years?

Kowarski:

I don’t much remember. There would be all sorts of illustrious persons, but I don’t much remember them. The fact is they would be more likely to go to Jean Perrin’s place. It had already been established. This was a new struggling place. We were more among ourselves, but certainly there were some. They mostly were people who were not just passing through Paris and going to the newest colloquium, but more people who were staying in Paris for a time. Gamow was in those days in Paris for a time, but I don’t think he ever appeared at Joliot’s colloquium. He appeared at Perrin’s. Guido Beck, a physicist — I don’t remember if he’s still…

Weiner:

He’s in Argentina now.

Kowarski:

That’s where I saw him last. He, I remember, made an appearance. I think if I delve a little more in my mind, I could think of some. Characteristically, when I first heard of Weisskopf, for instance, it was a paper given about some Weisskopf theories, but the paper was given by Halban — not by Weisskopf himself. In fact, I never met Weisskopf until 1948.

Weiner:

Well, I wanted to get this background as a general picture at this time, as a sort of interlude before we got back to your own work.

Kowarski:

I might add one important part of the picture. I will venture it. The scientific establishment — not French but the world scientific establishment — was at that time very much central Europe, which was Germany, Austria, Hungary, Scandinavia, Holland, Belgium, Switzerland. Their mecca was Gottingen. If you look at Jungk’s book, Brighter Than a Thousand Suns, there is, in the beginning, a passage on the role of Gottingen. This world establishment was self-contained, arrogant, full of conviction of its worth — with very good reasons, I must say — and in those years it was, of course, completely disrupted by the expulsion of the Jews. People like Wigner and Gregory Breit and a few others in this country were then much a part of it … Placzek. Placzek’s name is familiar to you?

Weiner:

Yes. We have just found that we have some of his papers.

Kowarski:

Placzek himself bodily was at that time (if we are now considering the end of ‘38 — that was after Munich) in Paris and very much a crony of Halban’s.

Weiner:

They probably met in Copenhagen originally.

Kowarski:

Yes. The somewhat closer connection which came by Mrs. Halban becoming Mrs. Placzek –- I have no reason to believe that, at that time, there was any inkling of what would happen in the future.

Weiner:

When did it happen?

Kowarski:

Els married Placzek, I think, in ‘43.

Weiner:

So he was one of the people then. This was due not to a sudden prominence of France on the world scene but due to the disruption of the existing framework.

Kowarski:

It was simply like taking shelter in a certain building, because it happens to be a tall building, in a flood. All the animals which are chased by a flood have to climb on something.

Weiner:

Which is called a refuge.

Kowarski:

Yes, exactly; and they were refugees.

Weiner:

Well, this is pretty clear.

Kowarski:

I was starting to say that France was very definitely outside of this establishment, and French results were disbelieved by the establishment. And as we know — it’s quite historical now — when Irene Curie and Paul Savitch discovered this 3 1/2 hour lanthanum, which they didn’t realize was lanthanum, Otto Hahn heard the report of Irene in the spring of ‘38 in a Rome meeting and was heard to say: “This damned woman. Now I will have to go home and waste six months in proving that she was wrong!” That’s not a piece of gossip. It’s now historical. That was the initial incentive which Hahn had for his work of 1938.

Weiner:

And he got a result which surprised him.

Kowarski:

Yes. That’s an understatement. Joliot was acutely aware that his position was in some ways shaky in France but it was very quickly stopping being shaky — he was being established — but that somehow the arrogant “Mittel-Europa” establishment were looking down on him. Now, England was in the same position. England was outside of the establishment, but England was of course so sure of herself that the English hardly noticed it. Heisenberg or Manfred von Ardenne or any of these people who became prominent later on in the early days of atomic energy in Germany might possibly have the idea that nothing is good which comes from France or from England. But England would not understand this.

Weiner:

I can understand the attitude toward France, but not toward England, because, after all, the Cavendish — Rutherford was still alive, prior to ‘37 anyway — was still known as the home of nuclear physics.

Kowarski:

Yes, but you know the German attitude to England; that it was a decaying, decadent country; and they obviously had some old glories, which cannot be disputed. And it must be said that in this particular science which we are considering now, England began to fall behind-there was no doubt about it.

Weiner:

You mean in the radioactivity questions?

Kowarski:

Yes. They were supreme in some older brand of nuclear physics but not in that one which began to flourish on the Continent, and in France and in Rome.

Weiner:

But at the same time the high-energy artificial disintegrations were flourishing in England and not in any other place.

Kowarski:

No, they are flourishing chiefly in America.

Weiner:

I was talking in terms of Europe.

Kowarski:

England was the first to split the atom by artificial means — Cockcroft and Walton — which was perhaps somewhat forgotten in Europe. When I say Europe, I never include England. It’s my old British-induced habit. The British never considered themselves as Europeans. As you probably realize, the British influence in everything is very strong in me.

Weiner:

We’ll get to the reason for that.

Kowarski:

Quite personal reasons for that. Well, this peculiar situation — what else could I add? You know, a French extreme right politician, Le Pen, said in, about, the l950s: “It’s time that France should stop being a brothel and a museum.” I’m at ease quoting this because he said it publicly. And there certainly was something of this appreciation of France and things French in many facets of scientific, technical, military, economic life in Central Europe. It’s somehow “the garden of pleasures,” you know. “Of course, we are really uncouth. If we want to be really and truly civilized, we must learn to be refined in our pleasures as the French are.” But refined pleasures — they always are a bit off-color or something. Oh, yes, the French, of course, are geniuses. They are geniuses at everything they put their hands to. Look at the 20th century French music. Look at their movies. Look at Le Corbusier; look at Joliot. Tremendously talented, frivolous, unreliable. Which, of course, is the exact opposite of what French nature really is.

Weiner:

This was the image which prevailed, you feel, in the scientific community as well as the rest of the world.

Kowarski:

A prominent French writer (Jean Dutourd) said recently: “We are a sad and puritan people.” And I think he is right.

Weiner:

A counteraction to this other image.

Kowarski:

I think that the image was deliberately fostered by the French during the whole 19th century for purely commercial reasons.

Weiner:

So they could sell perfume and lace handkerchiefs, you mean?

Kowarski:

Exactly. It brought in money. After the 18th century, after the French aristocratic establishment was beheaded, all the innumerable craftsmen and trades people and so on were left without a market. So during the 19th century this image was fostered throughout the world.

Weiner:

So there was no longer a craft tradition. It was an industry.

Kowarski:

Yes, but this particular industry of the garden of pleasures was carried in a very accomplished, craftsman and crafts-womanlike way.

Weiner:

In a French way.

Kowarski:

In a French way, yes.

Weiner:

Let me ask another part of this same question. What was your conception and perhaps Joliot’s conception of what world science was like? For example, last night when we were talking you mentioned this statement that he had made to you and Halban where Alvarez’s name came up. I’d like you to go into that. This implies to me a certain view that he had an awareness of what was going on elsewhere.

Kowarski:

Joliot was above all a dedicated scientist with a considerable perception of values in science. He could see a scientist of genius wherever he saw him. And for him, after all, it was the most important thing. He knew that Fermi was a genius, and he knew that Alvarez was a younger and somewhat different type of genius and so on. He might be a little bit peevish when he saw what veneration I had for Fermi, for instance. And much as I think of Joliot, I think that Fermi was definitely of a higher class than Joliot. By the way, you asked if any famous people came. Fermi once came. That was the first time I saw him. At that time he had no reason to cast a look on me. Later on my relations with Fermi were very good.

Weiner:

During the war period, you mean?

Kowarski:

After the war. I never met him during the war, because when I came to Chicago the first time, he already had left for Los Alamos. I met him very soon after the war. The relations were always very easy.

Weiner:

Well, I think, unless you feel you want to go on with this, that we’re ready for the beginning of the fission story; but I think we should take a break. [pause in recording.] We’re resuming now after our break of two and a half hours, and we’ve just decided we would return to the allusion of a prophetic episode.

Kowarski:

It was in the summer of 1938 at about the time when I was working with Halban on the semi-fast neutrons. And it was still less than a year since I had left le Tube d’Acier. And red tape being what it is, I needed some documents. I still wasn’t naturalized then; I was a foreigner living in Paris. There were dossiers, files concerned with my naturalization. I needed some documentation about what I did in preceding years, and I went back to le Tube d’Acier and talked to my ex-boss, who was my boss between 1929 and 1937, about some kind of certificate for my past efforts. And he started writing: “Kowarski worked full time one year and then half time the remainder of the time in the function of technical secretary.” I said, “Well, couldn’t you put what really was my function in the last few years?” I was a design engineer, ingenieur d’etudes. That immediately was blocked. The word “ingenieur” in France is more honorable than “engineer” in the English-speaking countries, and I was obviously in a rank of personnel which was below those entitled to be considered an ingenieur — even if I did it in reality. He was a firm man, kind-hearted. He had suffered for years the hardship of having to be in contact with my eccentric ways, and now he finally asked, “But why is it so important to you?” So I said, “Well, you never know where life brings you.” In those days, you see I was 31, so there were still some future years stretching before me. So “I imagine,” I said in a somewhat dreamy voice: “I imagine in some situation, let’s say five years from now, somewhere — let’s say in Central America –- I am suddenly asked to deal with some new kind of power station.

At that moment to show on paper my experience as design engineer, using those words, might be useful.” He looked at me with infinite compassion and said: “You see, Kowarski, that was always what was wrong with you here in this house. Instead of making a reasonable career in which we would have helped you, you always had some strange dreams and some preposterous ideas like the one you just told me now.” Finally I did not get my certificate as I wanted it, and I never saw this man again. He was a very patriotic Frenchman, extreme right of course, rigidly fulfilled his duty during the war, was taken prisoner and died in captivity; so I never saw him again. Now, consider that, exactly six years after that conversation, I was not in Central America but in Canada. So the place was slightly wrong and I was one year wrong. But then, after all, I did get the commission of building a new kind of power station, in fact I did use some of my engineering experience. I think it was not a bad instance of second sight. I have only one other one. I have no proof for it. It’s like all the stores of parapsychological and supernatural phenomena — you have never any proof.

Weiner:

Is that something you’d like to go into now, the other?

Kowarski:

The other one was purely literary. That was much earlier. I wrote some piece of literature inspired, I think, more or less by Edgar Allan Poe. I had this bit of paper and then I lost it unfortunately, so there is no proof. There was something about some lofty-minded youths discussing their future careers and one of them advising the other to become an experimental scientist, and he said that perhaps by studying the growth of a crystal or the bursting of a bubble, you will discover the new insights which — and so on and so forth. I wrote that page probably in 1927 or so. About four years later I entered Jean Perrin’s laboratory and there I was given a problem of studying the growth of crystals, using the methods which Perrin developed by observing the bursting of soap bubbles. So these two examples are the only two I think of of real prophetic second sight. Let’s consider they were coincidences.

Weiner:

They are interesting in themselves. Well, let’s see, that does take us into the period of late ‘38, when you had completed the work with Halban and established your special abilities as a team working on slow-neutron measurements. Now, how did the whole new episode begin to shape up? The new work of the laboratory?

Kowarski:

You mean fission?

Weiner:

That was the only new thing.

Kowarski:

This story has been told many times — I can only tell my own side of it. I was still “la petite dactylo,” and I used to hand Joliot his morning mail, and I would see him reading it. It was on the 16th of January, and I told him that Naturwissenschaften, the famous number, arrived in the morning mail. Joliot probably had his first glimpse of the Hahn and Strassmann article in my presence, and it was of course a bombshell. Immediately everything was understood about the strange findings of Irene and Savitch on the lanthanum. For the next few days nobody talked of anything else. Irene made her famous remark to her husband: “What fools we have been.” She used a somewhat stronger word.

Weiner:

I think you described that part of it.

Kowarski:

She said that if they had worked together, Joliot would have discovered fission from her lanthanum findings immediately. I think she was right. Joliot immediately had the ideas about the splitting of the uranium atom in two, which of course because of the curve of mass defects would give excess neutrons. He quite correctly predicted that excess neutrons would manifest themselves in two ways: one that fission fragments would be strongly radioactive, and the other that there might be free neutrons floating around. So he devised a very naive experiment to detect these free neutrons. He wanted to detect them not for their own sake but as a proof of fission. It didn’t work. It didn’t work for a very simple reason. In order to provoke fission of uranium, one had to put a source of neutrons in the system; and the source of neutrons would provide a continuous stream of neutrons through the system. And in this stream of neutrons, a few resulting from a few fissions observed in the system would be completely drowned. Joliot possibly did not see it in the beginning. He saw that he couldn’t detect anything, talked to Halban (this is hearsay; I was not present in these conversations), and Halban told him slightly patronizingly but at the same time very respectfully: “Well, anyone who has worked with neutrons sees immediately that you cannot do it this way.” Halban was never to pass a position of strength, and Joliot was rather touchy — that a man his junior in his lab would be in a position of strength — so the conversation possibly was a little delicate. Here was another circumstance which has to be taken again on faith when I say it.

It turned out from the conversation that Halban knew about Hahn and Strassmann’s finding before the Naturwissenschaften came out. And Halban knew it from Placzek, and Placzek knew it from Frisch, because Placzek saw Frisch around January 10th or so in Copenhagen. So Placzek brought this exciting piece of gossip to Halban, but neither Placzek nor Halban said a word about it to Joliot; and they considered it quite natural: “Well, this is not yet published. It will be published in a few days. If we spread this gossip, it’s unfair to Hahn and Strassmann.” They probably, completely unconsciously, considered themselves as members of an in-circle comprising Hahn and Strassmann and, again unconsciously, felt that Joliot was out. So according to their lights, they were quite correct. According to Joliot’s lights, their conduct was monstrous, because they had a red-hot piece of scientific information, and they were in Joliot’s lab, and they deliberately withheld it from their host. I say again I don’t blame them. It’s just a clash of two completely different ideas of what was the proper behavior in the circumstances. So Joliot was rudely reminded again that there was this Central European enchanted circle, of which he was not a part. They all were among themselves, and he was considered as an extremely respectable outsider but an outsider.

All this was in the background of these conversations with Halban which took place around January 20th or so. Halban went on a skiing holiday, which turned out for him probably far more expensive, in terms of its ultimate consequences, than he realized. He left around January 20th. I stayed behind. I was meeting Joliot, of course, every day in my secretarial duties, and Joliot had no reason to conceal from me either his abortive experiment with neutrons or the fact that he had decided: “Well, if neutrons don’t work, the other manifestation will work — the beta radioactivity.” And then he designed his famous experiment, which is I think one of the most elegant experiments I know of in the history of science, and which he performed before my eyes. It was that simple. It took a few days. The first observation was the radioactivity due to projected fission fragments, and one had also to prove that in the absence of uranium there would be no such radioactivity, which he showed — I was present at the split second when it was quite clear that in the absence of uranium the control was blank. So here it was. Fission was proved as physical reality. In those days we still didn’t know that Frisch had already observed it two weeks before, in a different way. So I congratulated Joliot. “Well, here is a typical discovery of the kind you have done in the past. So you’ve done it again.” I added under my breath: “At last.” Joliot accepted my compliments with becoming modesty and said: “You know, one shouldn’t have any illusions. Just at that moment the experimental proof of the same phenomenon is, no doubt, being obtained in other places.” It was on the 26th of January towards noon, and the equivalent experiment was performed in America at several places on the 26th of January — I think rather in the afternoon and also, of course, New York time — in various American cities. So Joliot was wrong by a few hours, although he didn’t know of Frisch’s earlier experiment. And then he told me about the neutron problem.

He also told me that he discussed with Halban the idea that I would work with Halban on the neutron side of the experiment. He may have devised an experiment which was too naive, but Halban was undoubtedly in possession of all relevant techniques. Here is something about which I don’t know exactly what happened. It seems that Halban said: “Why can’t we have Kowarski to help us?” And Joliot said, “But you realize that if there are results, anybody who works on it will acquire great renown. Do you think that Kowarski would be entitled to it?” Halban said, “Well, he knows a thing or two. I think it’s all right. We can take him in.” That again I don’t know. That is hearsay.

Weiner:

But who could the source of it have been? Either Halban or Joliot could have been the only ones.

Kowarski:

According to Halban’s account, Joliot was rather dubious and Halban was rather in favor of my being taken in.

Weiner:

Did Halban tell this to you?

Kowarski:

Yes.

Weiner:

I see. That’s what I meant.

Kowarski:

Well, then Joliot explained to me what the problem was. New neutrons would appear in the midst of far more numerous old neutrons — how to distinguish them? He put it as a question mark. I went home for lunch. And here is one of those practical cases when scientists describe how they got ideas. I perfectly remember which place on what street it was that I had the idea. The idea seemed so stupidly simple. Well, how do you distinguish them? Obviously, if they are in no way different, you cannot actually distinguish them; you can do this only if they are different in any way. It’s logical. Now, how can they be different? What does characterize neutrons? You can characterize a given stream of neutrons by the energy, by the place of birth, by the time of birth, and possibly there are some finer properties — I don’t know; magnetic orientations or something, about which I didn’t know much then and at present I don’t know much either; I’ve forgotten what I knew about it. Clearly, the energy was the most obvious characteristic, and I was perfectly familiar with how to distinguish fast neutrons from slow neutrons and so on. I had worked with Halban the year before or six months before on monochromatic neutrons of a certain energy. Now, these fission neutrons — I knew enough about general nuclear phenomena to think that if neutrons do come out of a splitting nucleus, the chances are there are several million volts of energy. So here was the answer. You take your primary neutrons, the ones which will have to act on uranium, below that threshold — that is precisely the neutrons which we have used, of 200 kilovolts or so, or 100 with another similar source — and use a detector which is insensitive to neutrons of that energy; it’s sensitive only to neutrons of higher energies. If you observe any neutrons of higher energy, that proves it. It’s rather elementary. It’s purely a logical chain of reasoning.

There is, I would say, no extra flash of insight in it. So I came back from lunch and told Joliot that that’s how you have to do it. You have to have a primary source of relatively low energy and put in detectors for neutrons of relatively high energy. Then by that token they will be the secondary neutrons from uranium. They can’t come from anywhere else. “Well,” Joliot said, “That’s very nice. Can you tell me what neutron source, what detectors?” “Yes, of course, I can. You take neutrons from thorium and beryllium or radium acting on beryllium, not by alphas but by gammas. Then you are sure there will not be more than a few hundred kilovolts, and you take a reaction which would go only with fast neutrons above a million, and here you are.” “Aha,” said Joliot. And then came a letter from Halban from his skiing retreat. Halban proposed a completely different method. He also in that letter wrote something about the possibility of a chain reaction. Joliot also had the idea of a chain reaction almost immediately. A few days later, in early February, Halban came back, and this time there was no question whatsoever whether I should be a member or not. Joliot said, “Kowarski will be in, of course.” We discussed first whether there would be a Joliot-Halban experiment and a Joliot-Kowarski experiment. And then we decided — perhaps it was not quite high-minded reasoning — that we’d better have a counter-insurance. “Let’s do all the experiments, all three of us. One may fail; the other may be successful. We don’t know yet which.”

Weiner:

And were you thinking when you were talking about that, about the credit for it should it succeed?

Kowarski:

Well, if you like. Let’s not think exclusively in terms of credit. We decided to make a pool of our problems, ideas and methods — make a pool and to share and share alike more or less the results of the pool. So we immediately started on both experiments. Halban, of course, streamlined my proposal. He proposed exactly which reaction to take and how to dispose the source and the detector and so on. He was still more knowledgeable about such concrete aspects. On the other hand, since Halban’s methods included a water bath, which was close enough to the Szilard ideas I had been thinking about before, I proposed the exact details of chemistry — what chemicals to use, what solubility values had to be kept in mind and so on

Weiner:

You were talking about how the knowledge of water solutions came into the situation, because of your experience with Szilard’s work.

Kowarski:

Yes, not so much the experience of workings but rather of thinking in these terms. So our very feverish work started in early February. I don’t need to dwell on the political atmosphere outside of the walls of our lab. That was when a peaceful Europe was really on its last legs. As I was telling some of my friends who were asking my opinion whether they shouldn’t go to America if they had a possibility, I said, “Clear out as soon as you can — immediately.” They said, “Well, what about yourself?” I said, “Well, first of all, I have no possibility.” My economic situation was still very very low. I was still living now more or less full time on this 2/3 of a minimum scholarship for a young man plus a few hundred francs at that time per month, which Joliot gave me for my dactylographic services.

Weiner:

Did you have any responsibilities other than maintaining yourself?

Kowarski:

A wife and child. My wife earned a bit on the side.

Weiner:

Somehow we haven’t introduced them into this.

Kowarski:

Well, my private life so far we haven’t touched on at all.

Weiner:

We’ll fill in.

Kowarski:

The cooperation between Halban and myself was absolute and complete. We knew perfectly well that we were in the same boat and we had to row with all our strength. Yet there was an interesting difference between our motivations. Here I will talk about very human and sordid considerations of why scientists work very hard. My overwhelming motive was to establish myself at last as a working scientist who makes discoveries. I didn’t care whether I was getting the credit alone or sharing it with Halban. Halban was a very respected name in this branch of neutron physics, and it was quite all right by me to be a successful collaborator of Halban’s. Therefore, my selfish motivation did not prevent me from collaborating sincerely. But Halban’s case was different. He was in a group of three, and he was obviously the hub of the whole experimental set-up. He was the man with the techniques. Joliot co-discovered the neutron, but the handling of neutrons was already sort of past his age a little. So Joliot was the lofty teacher, administrator, protector, dispenser of general ideas; but in Halban’s mind Halban was the real source of the real handling of things in an experiment.

Kowarski was considered to be an assistant, a bit clumsy, with a lot of funny ideas about his own worth or prospects, obviously with not much future because at that time I was already 32. And so Halban was in a very convenient position in the trinity — between the protector above and the assistant below. And in those days he had no reason to doubt that he was the central and the most important part. Besides he was the only Central European in the group, therefore the only one in the enchanted circle. Also, alphabetically he was the first. It was Halban, Joliot, Kowarski. And so many people referred automatically to Halban et al. And he never lost that opportunity. It’s amusing today to read, like in these Szilard memoirs, the description of the experiments of Joliot and his co-workers or Joliot’s experiments. That’s not how Halban saw it. And I might also say that’s not how I saw it, because it was obvious that Joliot’s role was that of a spiritual guide — on a very high level. Joliot, after all, was the originator of the whole problem. It was not that Halban came to the problem all by himself: Joliot asked him how to do it. And this is very important.

Also, Joliot had an immensely greater knowledge of physics as a whole, and at any unexpected aspect he would intervene. But Halban’s problem — how to present these experiments of Halban et al in such a way that they would be seen as Halban’s experiments, was already present in his unconscious mind (I’m completely sure that it was completely unconscious). The “Halban-originated” experiment and the “Kowarski-originated” experiment were carried out in parallel. Both were long-term experiments, relatively — several weeks — on the Halban side because there were innumerable measurements to be done; on the Kowarski side the measurements were very few, but the irradiations were long. Because of the formation of radioactive phosphorus, a 15-day period was involved. A few weeks after the second experiment started, Halban suddenly decided to scrap the results that were done so far, because he remembered that the room, in which we put the sulphur-containing liquid to be irradiated out of which the phosphorus was to be extracted, was too close to a place where we kept a radium source and there might be contaminating neutrons of higher energy, finding their way to the sulphur, which would not be from uranium. I knew nothing about this position of the rooms for some reason, so I took it for granted that the experiments had to be scrapped and begun again.

This delayed the “Kowarski” experiment results for two weeks following the completion of the “Halban” experiment. I feel by now, with my very gloomy view of human nature, reasonably certain that it was a piece of unconscious but brilliant sabotage — I insist again unconscious. Something had to be done that the “Halban” side would give the results first. One unexpected feature of “Halban’s experiment” was that he at first thought that he would distinguish the extra neutrons simply by counting and observing that there were more neutrons than there “should” be. He, in fact, committed the same mistake on a higher level that Joliot had. He did not realize that precision was not enough for that exact count. But in “his” experiment it turned out finally that the secondary neutrons could be distinguished not by their number but by their place of birth. So his experiment in a way was a bit changed in character. Incidentally, Fermi and Szilard at the same time were in exactly the same kind of opposition — Fermi proposing ideas like Halban’s and Szilard proposing ideas like mine. Of course, it’s the other way around: I was proposing ideas like Szilard’s, because I was under his influence. And Fermi also had to change his horses in midstream — for a somewhat different reason, but we will not go into that technicality. It’s very curious — this parallelism.

Weiner:

You weren’t in touch with them at all during this period?

Kowarski:

No. In fact, in those days we didn’t know at all that they were working on it. In the early stages of that came the famous Szilard letter to Joliot.

Weiner:

That was February 2nd 1939.

Kowarski:

Yes. It came by sea mail, and sea mail in those days took about eight days. Since then, there has been progress, of course: sea mail today takes at best two weeks, sometimes three weeks, sometimes four. In those days it took just over one week. And so we received it sometime around February 10th or 12th. And here comes the fact, the very simple and human fact, that when Joliot read the letter he said to himself and possibly even to me: “Well, here they go again.” Obviously, again it’s a Central European ramp. They want to keep it again in the enchanted circle and ask me to be quiet.”

Weiner:

And there was a rejection of the argument on the grounds of the political situation. This was not viewed by Joliot as a legitimate argument?

Kowarski:

Joliot disregarded Szilard’s letter for a very simple reason. People who wrote about Szilard’s letters in subsequent books never quoted the exact wording of it. I have the letter photostated in my home, so I know the exact words.

Weiner:

I’d like to see that some time.

Kowarski:

The exact wording was — Szilard, being a Hungarian, wrote with this exquisite courtesy for which Wigner is so famous — literally this: “Dear Joliot: The only purpose of this letter is to prepare you for the remote possibility of a cable, which we might send you in some weeks. We hope that this letter is an unnecessary precaution.” There was no cable, and Joliot disregarded the letter. It’s that simple. The cable came at the end of March. In fact, it came on the 1st of April.

Weiner:

That’s two months then from the receipt of the letter.

Kowarski:

Well, we received the letter a little before mid-February, and we faithfully waited for the sequel, for “some weeks,” four or five from the date of the letter. There was nothing. So we disregarded the letter, as it said in the letter. But there was a cable at the end of March. I’ll anticipate a little. That was not from Szilard but from Weisskopf, and it was not addressed to Joliot but addressed to Halban. It was a typically, I would say, Weisskopfian way of doing things. He should have thought of addressing it to Joliot, not to Halban. Also, it was sent on the 31st of March as a letter telegram and came on the 1st of April, and that didn’t help things. Well, we knew that it was a coincidence, and yet it did sound like an April joke, I must say.

Weiner:

Oh, I see. I didn’t realize that you were saying April Fool.

Kowarski:

Yes, because what was proposed in this letter was: for political reasons to forgo publication and henceforth to communicate, for the preservation of secrecy, only through private channels between “friendly laboratories” in the United States, Britain, Denmark and France. To propose withdrawal of publication and communication by private letters between four countries, Europe being at that time what it was, was such a damn fool proposal, if I may say so — as a way to preserve secrecy. It looked like a piece of self-delusion — by sort of sacrificing one’s personal glory on the altar of resistance to the prospect of furthering Nazi science. Joliot was realistic enough politically to realize that any way of communication of that kind would be completely open to all leakages into the Nazi domain; and the fact that it would be not published would only draw their attention to it. So as a practical proposal, it was just nowhere. By that time, of course, Joliot’s, my and Halban’s first paper was already published, and the whole thing came too late.

Weiner:

By the time the Weisskopf telegram was received, you mean?

Kowarski:

Yes.

Weiner:

When was the first fission paper that came out of the lab?

Kowarski:

Fission or chain reaction?

Weiner:

Fission. I’m just backtracking to make sure I have the time sequence correct.

Kowarski:

In France there was at that time, and I think still there is, this mechanism of letters read at the meetings of the Academy of Science on Monday afternoons, and then they are published extremely quickly. It’s a very good mechanism for claiming priority. Usually for a letter that was given on Monday, at that time one could go and correct proofs on Wednesday or Thursday. Joliot’s first letter about his experiment on fission was presented on the 30th of January. It was the first mention in print, I think (I mean the scientific press), of the possibility of secondary neutrons. We know now from various accounts that Fermi had this idea a few days before. Hahn himself had this idea at about the same time, the last days of January. And at least one German had this idea around the 20th of January — von Droste. So the idea was in the air, but Joliot was really the first who published the idea of fission neutrons, and that was because the publication mechanism was so extremely quick.

Weiner:

This was the Comptes Rendus appearance.

Kowarski:

That’s right.

Weiner:

And then the next paper was the paper with the three of you, which was also on secondary neutrons, wasn’t it?

Kowarski:

Yes, the Joliot paper only mentioned their possibility in principle, whereas our paper — also with Joliot, of course — showed them experimentally.

Weiner:

And when did that come out?

Kowarski:

That paper appeared in Nature the 10th or 11th of March, something like that, and it bore the postmark 8th of March. At that time I was sent to Le Bourget to put it in the air mail. This was duly noted later on by expressing to what depth of iniquity had the scientist sunk by that time, that he dashed to the airport to seek a priority. It’s I think the only mention of me in the Jungk book, Brighter Than a Thousand Suns. Well, there is something in it.

Weiner:

What was the sense of urgency?

Kowarski:

The sense of urgency was in the sense that we knew that the whole scientific world was boiling over these things. We did not realize how much we were in advance of the others. We didn’t realize that there were only Fermi and Szilard working on exactly that. We thought there were far more numerous attempts in progress; so why not secure priority? Hell, as I always say, it’s not vanity — it’s bread and butter. So I went myself to LeBourget, and it was dated 8th of March. The Szilard and Fermi papers were dated 16th of March.

Weiner:

That was Physical Review.

Kowarski:

Yes.

Weiner:

Now, the second paper was Nature also.

Kowarski:

No, the second paper was in Comptes Rendus. It was what I called before. “my experiment,” which was delayed by this little episode. It appeared in the Comptes Rendus of the 26th of March.

Weiner:

Now, the paper that you were referring to, which had been published prior to receiving the Weisskopf cable, was yet another one.

Kowarski:

No, it’s these two —the one dated 8th of March and the 26th of March. The next Nature was, I think, dated something like 8th of April.

Weiner:

This was the one where you gave the average number of secondary neutrons per fission.

Kowarski:

Yes. That was the paper which had a tremendous influence, as I learned much later on, in three countries. It started things immediately in Germany, in England and in Russia. Here we knew already that we were publishing it really against the wishes of this little community in America. Fermi, by the way, was never a member of that. It was strictly a group of Central European Germanic refugees — essentially Weisskopf, Szilard, Wigner, and I don’t know who else.

Weiner:

Teller?

Kowarski:

Teller, yes.

Weiner:

And Einstein in terms of lending his support?

Kowarski:

Not to the secrecy business, not at all.

Weiner:

That was prior to it. Then I don’t know if Teller was involved either with that, because I’m thinking of him in connection with the later Einstein letter.

Kowarski:

I can think of these names I named, but not of others.

Weiner:

This further publication then, where you gave the number of neutrons per fission, was after the Weisskopf thing and was picked up, as you learned later, in three different places. The chain reaction one, where you specifically reported on experiments on the possibility of producing a chain reaction with water as a moderator, was already…

Kowarski:

That was already contained in these two Nature notes, all the principles.

Weiner:

I was thinking of a much later one, September 19th. But that was obviously jumping the gun. We’re back in the sequence of events that you were describing in February and March.

Kowarski:

Well, from March on, the story’s in parallel really of our work and the very fast deterioration of things in Europe politically. The war was quite obviously on the doorstep. In May we began to formulate exactly the principles of the chain reaction, which were well known knowledge — the famous contradiction between resonance absorption in uranium and thermal absorption in the moderator and so on. Perhaps it is at this juncture that I should try to do a very unethical thing and give my idea of our relatives roles in the team.

Weiner:

It’s perfectly appropriate.

Kowarski:

You see, at that time and much later we held onto a very rigid principle — to appear always as a monolithic unit. For me this attitude was profitable because my colleagues were giving me a complete share of the credit for everything, and at the same time in a more subtle way it was unprofitable because no outsider knew what went on inside the team — if they had the idea that Kowarski, after all, was a minor assistant who was graciously admitted to the benefits, there was nothing to disprove this idea. So, conceivably, on the whole I suffered more from it than gained from it. Anyhow there it was, and I must say that Halban, in spite of many of his human weaknesses, held rigidly to his idea of a gentleman and never infringed that rule of behavior in any public way. He may have contrived, without open infringement, to give sometimes a glimpse of his real ideas — I know what his real ideas were; that’s quite possible — but nothing formal, never. He was completely correct formally to the end. So it was never said, “This was Joliot and not the others” or “This was Halban and not the others.” As far as my share is concerned, the final infringement came from two sources. Joliot after the war gave once a lecture in College de France about the psychology of discovery, and he described to his audience in detail the story of what I have called here “my” experiment, giving me full credit for the idea and how I arrived at it and so on. I didn’t really know he was going to do it. So he infringed; he indicated one definite piece of the thing which he imputed definitely to me. The other very fleeting infringement was done by Francis Perrin in one popular article where he mentioned first the lattice arrangement for chain-reacting media and very briefly put in brackets “Kowarski.” This is perfectly true. In our group the idea was first proposed by me. Incidentally, I’ve noticed many times that in America it’s attributed to Szilard, and I was surprised when I saw the correspondence between Szilard and Fermi. In America, it was quite definitely Fermi, not Szilard.

Weiner:

Which correspondence are you referring to?

Kowarski:

Oh, about July 1939 between Fermi and Szilard. I have some facsimiles of letters. I was the second man to have this idea independently. The first man — I only have his word for it, but I don’t doubt that his word is accurate — to have the idea of a lattice was a physicist called Adler, who published with Halban a paper, not on that subject, on another subject, and who happens to be a cousin of Halban’s.

Weiner:

Was he in France at the time?

Kowarski:

Yes. And he told me that he had this idea in late March. I had my idea in May. Since I seem prone to dramatizing myself, I can even remember that I had this idea sitting in the bath like Archimedes, which was definitely conducive to the idea of neutrons spreading in a liquid medium. So, with this idea I had in May, I think I was the second. Fermi had an equivalent idea in June or July, Frisch a little bit later. Harteck in Germany had the same idea in the fall of the same year. And so on, which makes me number two in a distinguished company.

Weiner:

A chain.

Kowarski:

A chain, all links independent from each other.

Weiner:

When did the word “chain reaction” come into use? Did you use it at the time?

Kowarski:

Immediately.

Weiner:

It was used in your papers?

Kowarski:

Yes, absolutely immediately. I think Halban used it first in his famous letter from his skiing resort. But it was obvious. It was known in chemistry.

Weiner:

While we’re talking about his letter and the Weisskopf telegram and so forth, are those two things preserved?

Kowarski:

Halban’s letter, no.

Weiner:

Halban’s letter is not. Why not?

Kowarski:

There were several dangerous periods for documents. Most of our documents were taken out together with heavy water in the summer of 1940. Some of them remained at Joliot’s. Joliot had his own archives. Actually I am convinced that they are still somewhere. But neither Biquard nor Joliot’s daughter seem to be able to put their hands on anything of this sort. Various people tried to get access to Joliot’s papers and these sources, and nobody has succeeded yet. I think quite a few documents will be discovered that way.

Weiner:

Some were deliberately destroyed, weren’t they, when the Germans were coming in?

Kowarski:

I don’t think so. What could be destroyed at that time was mainly comprised in the things which we took to England.

Weiner:

Well, Biquard^[1] I think mentioned that some effort had been put into destroying materials which might be useful only to find out that the Germans through other channels had a complete copy of the same thing.

Kowarski:

Where does he mention that?

Weiner:

In the biography. I’ll dig it up later. We won’t interrupt. I have it downstairs.

Kowarski:

Incidentally, always was surprised at the thoroughness with which the Germans knew what we were doing. I also know that Halban conducted quite a correspondence … Halban was always a bit apart from the rest of the group … in particular with Adler, who at that time was no longer in Paris. Adler told me about it. I even have some letters exchanged between Halban and him in about September ‘39 or so, about which knew nothing at that time. Halban also published this article with Adler in May — I think primarily to show that he was not entirely dependent on his two collaborators.

Weiner:

Was Adler a refugee as well?

Kowarski:

Yes. I say, yes — not quite. The family was a refugee of far longer standing in Switzerland. And at that time Switzerland was no country from which to flee except if one was exceedingly nervous. So in ‘39 Adler was back in Switzerland. In May we began to have general ideas, more or less, about how to show the optimum proportion of uranium in water and whether this optimum proportion is good enough to make the chain reaction work. Like many other people at about the same time, we had some doubts whether it would be, because ordinary water absorbs too many neutrons and so on. I had the idea of a lattice arrangement at about the same time. I was saying about the characterization of the three: Joliot was the great formulator of the problem, the man who situated the problem in nuclear physics as a whole, the man always ready to intervene with some unexpected angle (well, we knew all about neutron techniques, but what if there was something about gamma rays? Then Joliot would come in, because he knew; we didn’t), Halban was the man who had at his fingertips the slow neutron techniques, which were of course all-important in this work, and orders of magnitude and so on. As regards myself, I was still the man without a proper basis, but with ideas. And my ideas were of a chemical kind. And there was also another curious advantage I had.

Physicists always thought of everything nuclear as radiations. A radiation is something which starts in a source of radiation and goes through screens. The whole approach is two-dimensional, in terms of two-dimensional screens. In our baths and mixtures, there was diffusion of neutrons. Slow neutrons are not really radiations; they’re a gas, a gas which diffuses in a three-dimensional medium. So while a trained physicist instinctively always talked in two dimensions, I — a gas engineer — talked in terms of three dimensions. My thinking was more appropriate to the problem than either of my colleagues’. That’s how I was the first to originate the idea of the lattice and its justification. And generally speaking, I lacked fundamental knowledge — that was supplied by Halban — so I was more free to indulge in fringe ideas. Now, Halban also had many of them. He was quite ingenious. But here comes an interesting point. On the terrain of fringe ideas and cute ideas and unexpected gimmicks and angles, let’s say in the first approximation we were about equal. On the terrain of knowledge and complete mastery of what had gone before in the previous five or six years of slow neutrons, Halban was infinitely my superior.

Since Halban always had in the back of his mind the idea that sooner or later he will be recognized as the really important member of the team, this automatically led him to exaggerate the importance of the previously acquired knowledge where he had an advantage and to discount somewhat the relative value of new gimmicks on which he was not in a position of overriding strength. And therefore, in spite of all his own ingenuity and adaptability, he was prone to adopt a more conservative attitude than mine. It’s a paradox. Because he had no lack of ideas. But because of his other considerations, he relied less on his ideas and more on his established knowledge.

Weiner:

He was restrained by his own traditions.

Kowarski:

By the extra value he put, again unconsciously, on his own traditions. Therefore, we arrived at a situation when finally there were more new ideas coming from me than from him, and that in spite of his very, very definite gifts in that direction. A strange situation. At one moment Joliot, for some reason exasperated with Halban, began already to talk about patents and the way of sharing their benefits, and Halban considered that “of course Kowarski shouldn’t have the same rights as we two.” I discussed this once with Joliot in Halban’s absence, and I said, “Well, I think the division of 40-40-20 would be about adequate.” Joliot looked at me with blank astonishment and said, “Are you crazy? All the new ideas seem to come from you.” This was completely untrue. It was because of this greater reliance of Halban on tradition that it seemed that the new aspects came more often from me. But such was the impression that began to come out. Once to a journalist in French, I talked about Halban’s immensely greater fundamental knowledge of things, to which I added “my more chemical and more roving ideas.” I think that’s about it.

Weiner:

That’s much the way you’ve described it. What about the day-to-day working relationships? Was it a question of independent work and then coming together in a group effort?

Kowarski:

No, we were doing things together.

Weiner:

You spent the time physically together, where the two or three of you were working together.

Kowarski:

Very often, yes. Two chiefly — Halban and I. Joliot was a bit apart. The war was starting. He had immense administrative duties.

Weiner:

Beyond the laboratory you mean?

Kowarski:

In the laboratory. Science was mobilized. He was the chief of the group of laboratories under such number and such letter. There was a bit of red tape. Of course, I was still his dactylo also. But by that time the emphasis began to shift.

Weiner:

Was there any secrecy within the lab?

Kowarski:

Wartime secrecy? Yes. Complete.

Weiner:

When did that go into effect?

Kowarski:

About the 1st of October. Our article in the Journal de Physique et le Radium appeared late in September. But the next paper, Joliot wrote himself; well, we all three wrote it, but Joliot was the main writer, it was a note to Comptes Rendus and that was deposited, as a secret communication, in October ‘39. It was not published. I insisted ten years later that it should be published to establish the time of some of our findings. It was finally printed in October ‘49.

Weiner:

That raises a question. It was a sealed document which was deposited October 30, 1939 at the Academy. Weren’t you afraid later after you left of the Nazis finding it?

Kowarski:

I think first of all the secrets were pretty well kept, and second, we never believed in those days that the Nazis would overrun France. You know, one always fights the previous war. We thought of a front line, and some bloody fights somewhere in the north and Paris, of course, living the feverish life of a capital city in time of war, and so on. The idea that the Germans would occupy all of France never occurred to us.

Weiner:

This document stayed in its original resting place. Is that where you found it ten years later?

Kowarski:

That I don’t know.

Weiner:

You just requested that it be published? Well, apparently then it was still intact.

Kowarski:

Oh, yes.

Weiner:

But prior to that time the three of you worked in the laboratory and discussed this?

Kowarski:

Prior to what time?

Weiner:

Prior to the end of October 1939.

Kowarski:

Yes.

Weiner:

Were you in any private correspondence with other people, like Bohr, for example, Fermi or Szilard? The only letters we’ve mentioned are those requesting secrecy.

Kowarski:

We were never in any personal correspondence with Fermi or Szilard. Halban was very much in correspondence with Placzek.

Weiner:

Where was he at the time?

Kowarski:

Placzek came to America some time in ‘39, and Halban considered this correspondence as his private affair. Sometimes he showed us some letters and sometimes he didn’t. Placzek in fact made many suggestions to Halban, I learned later on, which Halban didn’t quite understand. Some of them I have myself discovered later on. Incidentally, by 1939 I was definitely established in the group in three functions. I was the electronic technician. After all, I struggled with radio tubes for years, and I knew about them a little more than my two colleagues. I was responsible for the maintenance of our amplifiers, for Geiger counters and so on. I was also a sort of theoretician. Heaven help me. But I derived, for instance, entirely on my own, some of the fundamental formulae. And finally I became more and more the writer of the team. Crude jokes were made about whether we will get the Nobel Prize for physics or for peace first because we made a war impossible by discovering nuclear explosives, which obviously would make war impossible. But it was invariably Kowarski who was in line for the Nobel Prize in literature.

Weiner:

What was your feeling about the relation of your work to war?

Kowarski:

If I take ‘39, we knew that in some future there would be separated isotopes, but the idea of preparing a few kilograms of separated uranium 235 in the near future seemed fantastic. People in those days thought in terms of micrograms, not kilograms, of separated isotopes. We knew that sooner or later it would become possible. We considered that much before that our uranium reactor would be established, because that looked far easier, especially when the assistance would come from heavy water. We did know that at some moment there would be explosives. We even began to have a very vague idea, which we put on our patent applications, that there a reader might produce some new nucleus with properties similar to that of uranium 235 for fission. I think we were one of the earliest people on record to mention that possibility. But it remained for us very vague. There is another interesting illustration of our relative ways of thinking — Halban and me essentially — in the autumn of ‘39. It was again characteristic of Halban that he stated the problem: “Well, if water doesn’t work, let’s get away from water. What else? Well, helium, beryllium, carbon. Helium, a gas — nothing doing. Beryllium? Who can get the necessary tons of it? Carbon? Yes.” (We knew now that Placzek was toying with these ideas sometime in mid-1939, and I knew then that Placzek corresponded with Halban. Any connection? We shall never know.) Than Halban tried to get a quantitative idea of how these other elements would interact with neutrons. So he derived a certain number of formulae which were wrong. I found they were wrong and I proposed the formula which turned out to be just about right — there was a slight mistake but it was very very close in order of magnitude. And so it would be easy for me to say, well, Halban’s ideas were all wrong; my ideas were all right. But here again came the same thing. My ideas were based on Halban’s proposal. Without Halban I would be nowhere. But when Halban provided the basis, I arrived at the right conclusion, to which he did not arrive. So, again, am I boasting? I don’t think so. It’s very easy to say Halban was wrong; Kowarski was right. Yes, but Kowarski incorporated Halban in order to be right.

Weiner:

On your thoughts in relation to war, the reason picked that up is because you…

Kowarski:

Would you let me go on with an anecdote out of these days?

Weiner:

Yes, fine.

Kowarski:

It’s an amusing anecdote. We had a young lab technician called Delattre, and he had a rather remarkable sense of humor. He made fun of both of us in various ways. He had nicknames. He called me “the great scientist,” and Halban “the great master.” At one moment — I will not go into details — there was a certain very simple experiment which would show whether Halban’s ideas of the workings of carbon were right or mine. Let’s say it figured that if Halban was right, a certain result would be 3; and if I was right, it would be 6 — numerically. By that time — Halban had been naturalized French just before the war in the spring of ‘39. Because I was working on one of the most secret things, my naturalization was pushed through by Joliot and Jean Perrin, but it came only in November ‘39, already during the war. We once went to town — the actual experiment was being done in the suburb of Ivry near Paris — we went for some reason to town to get some supplies or something, and on the way we bought a copy of Journal Officiel — I was expecting my naturalization decree at any time, and there it was. So we came back to the lab and announced to Delattre: Congratulate us. Delattre, we said, “we have news for you. We are all compatriots now.” Delattre duly offered his congratulations and then dramatically said, “I have also news for you.” We suddenly realized that he’d got the crucial number in the measurements he had performed while we were away. He reopened his mouth and said, “Five and a half.” Halban and I looked at each other, and then Delattre superbly dropped a headline: “Amazing Confirmation of a French Scientist’s Theory.”

Weiner:

Very good. When did the shift from the College de France to the Ivry place come about? Was it because of the secrecy of the work?

Kowarski:

No. I told you that in the later ‘30s just before the war, Joliot was expanding his plans for becoming a world hub of isotope research. Not much came out of it finally. But at one moment he used an electric laboratory for the testing of insulators or something in Ivry and started putting there some of the rather primitive accelerators for about one mev particles. It was an industrial place with halls and water supplies and so on. Since by that time we began to operate with hundreds of kilograms of uranium, it was obvious that there was the place to do it.

Weiner:

I’m just trying to distinguish. Where was the Van de Graaff?

Kowarski:

It was there, at Ivry. The cyclotron was the College de France, but it was not yet working.

Weiner:

And where was the impulse generator?

Kowarski:

It was at Ivry. Joliot was not very lucky with all these machines. The impulse generator did work for a certain time, and Pontecorvo did a very elegant piece of work with it.

Weiner:

Who paid for all these new expensive machines?

Kowarski:

Well, first of all, they were not as expensive as you might think. In some ways they were pieces of junk. And second, by that time, Joliot began to have various subsidies from this and that fund, and from some industrialists, and some extra grants from the government — abundant correspondence, which mostly I had to type. Joliot taught me at that time — you know the elaborate, flowery endings…

Weiner:

“Let me assure you with all of the kindness…”

Kowarski:

Yes. His formula was always, “Please accept, I beg you, the expression of my devoted feelings.” “Agreez, je vous prie, l’expression de mes sentiments devoues.” And then he would say, “Sometimes you have to strengthen your feelings by making them “respectueusement devoues.” You do it in two cases when you write to your superior in hierarchy or when you write to somebody who give you money.” He did it quite in a good nature. He gave me many, many lessons about the ways of human things.

Weiner:

In connection with this, this is probably the explanation for the 1937 display of the Van de Graaff at the Palace of Discovery.

Kowarski:

Yes.

Weiner:

Was it a special occasion? Was it to bring attention to the lab or to raise money?

Kowarski:

No. The Palace of Discovery was the creation of Jean Perrin, and Jean Perrin asked all the people around him for exhibits. It was very definitely a Jean Perrin show, and Joliot was one of Jean Perrin’s favorites, especially from the moment when he really began to make tremendous discoveries. Jean Perrin was at a high enough level not to be dismayed by that, His admiration of Joliot was totally unmixed by any inappropriate feeling of the kind. “Why does this upstart get all these beautiful ideas?” Jean Perrin was above that. So he could admire Joliot quite wholeheartedly.

Weiner:

This public display in 1937 suggests that there was the beginning of public awareness of nuclear physics, it’s possible biological implications or its possible energy implications.

Kowarski:

No, nobody thought of nuclear energy at that time, but isotopes, yes.

Weiner:

I see. I’m trying to relate this in my own mind to Joliot’s interest and his relation of science to the state, his feeling that the coming thing was the use of isotopes for biological problems, and the public interest. And I was wondering if all these things fed on one another.

Kowarski:

Nuclear physics in those days was not the overwhelming miracle it became after Hiroshima. But the public was already quite aware of the wonderful things going on in splitting the atom and penetrating the infinitely small — the idea of tracers had been explained in many articles. I wrote a couple at the same time. But the Palais de la decouverte was a part of the universal exhibition, which was held in France in 1937. In ‘36 the Popular Front came to power under Leon Blum, who then became the first Jewish prime minister in France, and this was in itself considered by many as a scandal. The split of France into whites and reds which I mentioned before was terribly active in those days. Actually in my own personal opinion, one can say that in 1937 the Establishment went on strike and began to sabotage everything the Government was trying to promote. Production in France fell tremendously. It was, of course, attributed to the lazy workers. And the exhibition was considered as Blum’s exhibition, of that Jew. But the scientific Left, which was, as I said before, the upper dog in those days, was totally involved in it. The idea was that the French state in those days was Socialism and Socialism was progress and progress was connected with science — Leon Blum put for the first time a few women in his administration, and Madame Joliot was asked to be the minister of scientific research. These things went together in a kind of mixed ideology.

Curiously, they also went together at the same time in Britain. It was the time of the Encyclopedists in Britain, who very effectively prepared Britain for the war effort, and this played an enormous role in winning the war. But in Britain it worked. In France it remained a little bit on the terrain of pure ideology, although to my mind there was quite unmistakably in those last few years before the war a sudden flare-up of French culture, a phenomenon which I think has been very little noticed by historians. Suddenly there was a flare-up in science, not only in nuclear physics, but also other sciences; in some artistic manifestations. Suddenly a very talented playwright was appointed the director of Comedie Francaise, a few things like that. It was a sudden rise of the cultural tonus of the country, which was cut short brutally by the war; and even before the war by the backlash after the Popular Front.

Weiner:

Well, this is further background.

Kowarski:

They were exciting years in a way. There was this feeling of intellectual intensification in the country and at the same time this gathering doom.

Weiner:

But at the same time the relative isolation of France continued in the French scientific community.

Kowarski:

Yes and no. These things are not instantaneous. Joliot got his Nobel Prize in October ‘35. So France suddenly came officially again to the forefront of nuclear physics. Joliot began to attract foreigners to his lab. Joliot was a phenomenon somewhat similar to the dazzling brilliance of Fermi and his school in Rome, which also was unexpected. I think it’s idle to speculate in this way, but if France had had another ten years of that flowering, its situation on the scientific map of the world would have changed completely.

Weiner:

Yes, there are so many other factors that might enter into it, such as the ability of the educational system to bring more people into science and so forth.

Kowarski:

Yes. It would be perhaps a little foolhardy to say that in these ten years the educational system would be changed. But I want to say that the innate French brilliance and the talent with which they do things would probably be able to assert itself even in spite of the educational system.

Weiner:

I see, given a period of relative peace.

Kowarski:

Peace and a period of intellectual intensification, which was well underway in the years ‘36, ‘37, ‘38. By ‘39 it was obviously crushed again.

Weiner:

I noticed in a letter that Joliot wrote to Bohr in March ‘40 that there had been plans for some kind of international scientific congress in New York, and he referred to the 1937 conference or congress in Paris, and I wonder if this was in connection with this universal exposition.

Kowarski:

Was it in ‘37 or ‘38?

Weiner:

He refers to this in a letter of ‘37. He talked of Tomarkin playing a role.

Kowarski:

Tomarkin’s conference took place in ‘38, not in ‘37.

Weiner:

What was that? I have no real knowledge of that.

Kowarski:

Tomarkin was a curious operator, a fringe businessman who also had an immense hankering after culture and things of the spirit. He was an operator of the sort we discussed yesterday, but far more honest, a sort of honest charlatan. I had something to do with this organization and I remember very well how he wrote innumerable letters begging for funds from various rich people and heads of state and so on. There was a lot of haste in his offices, and a letter would be typed with five carbons, with a blank space on top. You would see a fourth or fifth carbon, not very legible, with a much clearer “Dear Sir” or “Gentlemen” or something, typed-in separately. I saw once a very faded carbon starting with a freshly typed-in “Majesty!” It was to be sent to King Farouk. That was a fairly typical manifestation of Tomarkin’s ways.

Weiner:

What was the conference? I still don’t know what it was.

Kowarski:

The conference was hazily meant to deal with applications of X-rays and artificial radioactivity to medicine and related fields. It was the first conference in whose organization I was involved — strictly as Joliot’s secretary.

Weiner:

Was the purpose to be technical papers?

Kowarski:

Oh, you know what conferences are. People are invited to give papers on a subject of their choice, and then they hastily organize sessions. “On Thursday afternoon we will have a parallel session, one on bio-chemistry and another on electrical engineering.” People read a few papers and then there will be a discussion. A panel or two may mark the end of the conference. And finally they will publish a volume of “Proceedings of the 1938 Conference on Applications of X-rays and Artificial Radioactivity to Medicine and Related Fields.” Something like that.

Weiner:

But what I meant was that the technical papers were presented by people who were active in the field.

Kowarski:

Oh, yes.

Weiner:

It was a scientific conference.

Kowarski:

Yes, totally scientific but organized in a very unscientific way.

Weiner:

But with the aim of being international, which would have been Joliot’s desire anyway if he was involved in it.

Kowarski:

Yes.

Weiner:

Do you recall whether the Proceedings did come out?

Kowarski:

They probably did. They probably were published by Hermann.

Weiner:

I’d like to dig into this another time.

Kowarski:

I can tell you more about Tomarkin another time.

Weiner:

Do you know if the conference in New York ever came off in March 1940?

Kowarski:

It never took place.

Weiner:

I assume it didn’t because of the war.

Kowarski:

Joliot had to be a star in it, and by that time not only Halban, who anyhow was a somewhat younger star, but even I would have to play a certain role in it.

Weiner:

And you couldn’t.

Kowarski:

Well, in March ‘40 it was impossible. In March ‘40 Halban and I were on our respective desert islands. I don’t know whether you want to hear about that story.

Weiner:

We’re going to get into that. Well, it probably was planned for later than March, but the letter was written in March ‘40.

Kowarski:

I think it was for September ‘40.

Weiner:

I had no notice of it even ever having been thought of or planned except in these letters between Bohr and Joliot. I started to ask — getting back to fission — who you were in touch with. You said you had no direct contact with Fermi or Szilard, but Placzek had contact with Halban. Bohr, I noticed in that letter to Joliot on the scientific congress, did talk about some of his work with Wheeler on the mechanism of fission. By that time it was published, too. And so there was this kind of…

Kowarski:

Of course, as regards theory, Francis Perrin was our contact all the time in Paris.

Weiner:

He was in contact with who else?

Kowarski:

With us. He was definitely not a member of the group, but he knew all about our results and he contributed to our thinking about them. And when I proposed the lattice, he put it on a more accurate basis. That’s why he remembered that the idea originally came from me. I think he once mentioned to Halban: “Have you ever thought of whether there would be any difference between mixing homogenously or arranging the ingredients in a lattice?” He didn’t have himself any idea of what it would do. “But have you thought of that?” And Halban said, “Oh, yes, Kowarski mentioned something similar to me two months ago.” And that was that.

Weiner:

Now, the work proceeded mostly at Ivry and not at the original lab through October when the secrecy started?

Kowarski:

Yes. And then it went on; it was in November that Delattre’s story with the number 5 1/2 took place. And that immediately put forward the virtues of heavy water as compared to carbon. According to Halban’s ideas, heavy water had a slight advantage. According to my ideas, it had an enormous advantage. We were very dubious about carbon, therefore from that moment we began to concentrate on heavy water. Here comes another fundamental methodological remark. I don’t know how to put it. None of us had the mentality of a pure scientist as it is understood today — that our task is to study the phenomenon for its own sake. We were dazzled by the prospect of opening a new force of nature. And rightly or wrongly, we decided that it was very important — to achieve what Fermi finally achieved in December ‘42 — to actually have somewhere a chain reaction going on in a concrete way. Now, we knew that for that we needed a lot of pure materials. We needed tons of uranium, and we needed dozens of tons of moderator. We even knew that the moderator had to be exceedingly pure, and the uranium had to be reasonably pure.

Incidentally, there is a mistake that even physicists make very often when they talk of these things. It’s not very important that uranium should be exceedingly pure. Uranium absorption of neutrons is so strong that admixtures of absorbing substances are harmful but not crucially harmful. But then you consider, for example, carbon. Carbon’s absorption of neutrons is very slight. Therefore, any admixture — parts per million of absorbing substances — unbalances things completely. So uranium must be reasonably pure; the moderator must be extremely pure. It’s a practical difference. Well, we already had some idea that very slightly enriched uranium — not natural uranium but what the French call supernatural uranium — would work almost immediately with water. We were about the first to arrive at the conclusion, that you don’t need fully separated isotopes. You need only a slight shift in their natural balance. All this meant that there had to be strong government support. All this meant expenditures on a scale a hundred times larger than what we were used to — at least a hundred times if not more. Now, governments can be convinced only if you present them with some evidence in support of your expectations.

And therefore, our aim was to achieve a definite material demonstration, which was already somewhat unscientific, somewhat unsporting. It’s like the desire to reach the North Pole rather than to know about the North Pole, or the desire to step on the moon instead of sending an unmanned device for collecting scientific data. But it’s all right. We were in good company. Fermi had the same ideas. But where we went completely beyond Fermi, was in our conviction that our immediate job was public relations more than scientific information. We had to aim at demonstrations rather than at scientifically impeccable proofs. We had to neglect the painstaking details of a truly scientific study and produce a convincing enough demonstration in the shortest possible way. And henceforth, from about the summer of ‘39, our methods began to be different from those of Fermi who, of course, continued to be completely scientific. The result was that we began to lay our hands on heavy water in conditions which for Fermi were still completely unthinkable. The unkind word has been pronounced that we had “cornered” the world’s supply of heavy water. So we had, but certainly not in order to keep the others out. We simply wanted as much heavy water as we could get; it would still fall short of what we really would like to have for our experiment.

So we began to deviate from the ideal of pure scientist. And that’s why in this Szilard memoir there is a mention of his talk with Fermi about our last publication (autumn 1939). He reports his question: “What do you think of this paper by Joliot?” and Fermi said, “Not much.” Fermi was quite right. Scientifically the paper was not very impressive. As a demonstration it was so impressive that Time magazine, at the time when it still had the pure Time magazine style, put Joliot’s picture in an article with the caption: “Paris did not quiver.” ^[2] What they meant and explained in the text was that the chain reaction was not critical yet. It couldn’t create any earthquake in Paris.

Weiner:

I must get a copy of that, too.

Kowarski:

Well, that must have been somewhere in the fall of 1939. This was the only time, by the way, that Time magazine has ever mentioned my name.

Weiner:

Now, this urgency for a demonstration in order to get the needed sum for a chain reaction goal was still independent of a military application?

Kowarski:

Not quite. There is in France a certain tradition of high military thinking allied to the advanced sciences. The beginnings of France’s very powerful contribution to practical electronics were military during World War I. It was quite comprehensible to the high military minds that there will be some day an atomic explosive, that the way of achieving this explosive was to study the natural phenomena of the chain reaction, and therefore anything which produces a chain reaction someday will contribute to going toward the explosive. I think it’s on the whole a reasonable way to think. Plutonium, in those days, was, as I say, a very very vague idea in our minds. Uranium 235 we knew would work more or less, but the idea of separating kilograms was utopian. We reasoned that what we could do, was to study the phenomenon of the chain reaction itself, in its slow-neutron mode, which we knew would be not explosive. And the Ministry of Supply, which was headed by Dautry, himself a very remarkable man, was all for giving us all support; and that meant some quite fantastic sums on the order of $10-, $20,000. At that time, and in those dollars, it sounded fantastic even in America; it was only in the Fall of 1941 that, for the first time, Fermi received more than $10,000.

Weiner:

Admittedly a long-range possibility arising from this work was a military application. Meanwhile, the country was at war. Were there no other priorities that were more easily realizable?

Kowarski:

There was no competition. I mean these few thousand dollars which could be given to us — they didn’t take them off from magnetic mines or searchlights. So I don’t think a priority in this respect arises.

Weiner:

I’m not talking about the funds. I’m talking about priorities in terms of the three good minds working on this.

Kowarski:

I think Dautry, who was our ministerial boss, reasoned that it’s better for these three minds to work on something on which they work with obvious and unique chances of success.

Weiner:

There was no other large-scale project…

Kowarski:

Oh, there were plenty, but there were other people for them, but there was nobody else already well engaged in this project.

Weiner:

Maybe you can comment briefly about how else science was being used, in a mobilization sense, in France at that time.

Kowarski:

Well, everybody was mobilized. Francis Perrin was mobilized in some provincial center, I think, for gas warfare or something — or defense anti-gas, I don’t know. I suspect that there was not much going on. You see, the national spirit was very low. This upsurge which happened a few years before by ‘39 was already faded. The war was not popular. The whole establishment was against it and, like in England, reasoned better Hitler than Stalin.

Weiner:

Do you think Ilya Ehrenburg’s characterization of France and the fall of Paris was accurate?

Kowarski:

It was a bit crude. Do you know this novel?

Weiner:

It was one of the things I read in the same period when I read Weidman.

Kowarski:

You probably didn’t notice that in this novel there was a shady character, some sort of a blackmailer, who is called Joliot. It’s a pure coincidence.

Weiner:

No, I didn’t, and I wouldn’t have noticed then when I read it.

Kowarski:

He heard of Joliot probably and decided it was a nice name, very French. It’s an amusing detail. No, Ehrenburg in those days, you see, was a Communist public relations man, and Communists in his novel were absolutely ideal — every Communist — and everybody else was completely corrupt. I think this was not at all true. The general tonus of the country was certainly low. But then the Communists, who at that time became more and more obviously a Fifth Column of a foreign power, were also not in a very exalted mood. I think they participated in this loss of morale.

Weiner:

The reason I mentioned it is that the vague recollection I have of it was of this dissolution of spirit.

Kowarski:

That was completely true. Then there was the question of the Maginot Line. The Maginot Line was a joke: as you know, it went all along the German border but not on the Belgian border. I don’t know how many people were aware of the fact the Maginot Line did not go all the way to the sea, that it left the whole Belgian border open. There is an interesting passage in a novel by Joyce Cary which depicts these days and discussions in an English pub before the fall of France, and someone says, “The Maginot Line was a joke. The whole Belgian border is open.” They say, “What?” They never heard of that. This is impossible. What sort of a hoax is that? They preferred to believe that the man in the pub was a defeatist. And yet it was true.

Weiner:

In this background, you had gotten to the point in your story that there was an urgency to demonstrate results so that the needed rare materials could be obtained. This accounted for the shift in your whole research program which started in the summer of ‘39.

Kowarski:

Well, it was not really a shift in the program itself, which was still going towards a chain reaction. It was a shift of the spirit. We began to worry more about our relations with the government than our relations with our fellow scientists. If, in evaluating some experiment, there were some corrections to be taken into consideration, we preferred to go quickly and estimate the corrections on plausible reasoning rather than to find by further experimentation whether it was 2% or 5% and in which direction. In fact, our experiments began to be definitely slap-dash from the scientific point of view. We knew it. And here comes the fundamental difference between Halban and me. Halban never accepted the accusations of being slap-dash. He tried to hold his own not only when talking to the government, but also in talking to the colleagues; and I knew perfectly well that much as we were gaining on the government side, we began to lose on the scientific side. And therefore I was thinking of some compromise.

On the whole, both Halban and I were, so to speak, far to the charlatanesque side as compared to Fermi — perhaps a little less obviously so, when compared to Szilard; but there was nothing to restrain Halban from going further and further in that direction, while there was something to restrain me. And unavoidably a moment came when I began to say, “No, that’s too much, we’re straying too far.” And so disagreements began to arise very seriously on whether we shouldn’t spend an additional month on tying up this or that loose end to some extent. It was then that my disagreements with Halban started in earnest. Later on various historians told about our differences of character and temperament and so on, and on this my comment always has been: “That always existed, but we managed to live with it and be productive with it.” This was a continuous effort on my side, and of course I must also hand it to Halban that was a no less continuous effort on his side — perhaps even bigger than mine. It was not convenient for me to work with Halban all the time, but I freely admit that it was not always convenient for Halban to work with me. We were both sufficiently devoted to our aim or, if you like, dazzled by the prospect of our possible success — one can put this in various ways. If I wanted to appear noble I could say we were devoted to our scientific achievement. If I wanted to throw suspicion on our motives, I would say we were attempting to run off with a lot of loot. It’s the same thing in The Double Helix. Some people accuse Jim Watson of having been completely unscrupulous, selfish and so on. I don’t: I was in more or less the same position. It’s a mixed motive like everything human.

Weiner:

Were you going to say before you were running after a prize, a particular solution to a puzzle?

Kowarski:

Well, to be the first to achieve the chain reaction was like achieving the philosopher’s stone. It’s far more than a Nobel Prize. We were perfectly aware of that. Whether it was disinterested glow of scientific curiosity or sordid interest of self-exaltation, I don’t know — mixed motives, human nature. But the fact is … Well, as I sometimes say, the two fundamental emotions of a working scientist are greed and fear — greed for recognized achievement, fear that his imperfections will be found out. I don’t say that Halban was more greedy than I was, but he certainly was more fearless. That more or less sums up the difference between us. In 1943 there was the famous Fermi-Urey conference called by the U. S. government to discuss the British claim — that is, Halban-Kowarski claims — and Fermi, who was rather hostile to this whole series of experiments, showed their faults, which I knew anyhow. And then he said, “In a paper, such and such number, some attempt is made to evaluate experimentally these corrections.” He even said something like: “Some attempt at least is made.” Now, this work was done after my separation with Halban, and the paper came from me; and so I took it that Fermi had paid me a personal compliment, which probably was true: Fermi perfectly well was aware that the spirit in that particular paper was somehow different.

Weiner:

That was a paper that was published or unpublished?

Kowarski:

No, it wasn’t published. It was one of the British series of reports. It is now declassified, of course. But Fermi did have access to it. And I was, I must say, very flattered by the fact that my attempt to do things a little more scientifically was immediately spotted by him. Oh, he didn’t attach any decisive value to it, he just took some notice.

Weiner:

This raises another question and brings us back to a point you made earlier about the first batch of patents. You were talking about dividing up percentages and so forth. When did the issue of patents first come up? I have the date noted somewhere, the first famous date of when the first one was taken out. I remember questions about that.

Kowarski:

You have some of the relevant evidence in my affidavit. ^[3] It can be summed up approximately as follows: Francis Perrin was developing the ideas of critical mass and of a reflector, using the diffusion concept and so on during the month of March. He had no doubt that we would prove that there was more than one neutron per fission, which was the main essential point. When we finally obtained this result about April 8th or so … You see, Halban was far more a part of the Establishment than I was, and Halban saw socially the Perrins and the Joliots far more than I did. In fact, I was for the first time of my life invited to lunch at Joliot’s home immediately after I announced the success of our second experiment. It turned out that I was the man to do the final measurement of a blank which proved the validity of this whole piece of work. It was on a Sunday, which was perhaps one of the reasons for my fortunate assumption of this role. I telephoned to Joliot. He said, “Oh, that’s nice,” and then added, “Come to lunch tomorrow.”

Weiner:

Your ticket of admission.

Kowarski:

Exactly. It shows that one can be admitted, at the right price. So I don’t know much of these first conversations about the patents. Now here we plunge into some very deep waters. Towards 1910, 1920, a concept began to emerge of a new elite — the intellectual elite, which would replace the older ones based on, noble birth or money. The intellectual elite’s locus in France was L’Ecole Normale Superieure and Jean Perrin and Francis Perrin and Auger were alumni of that school. They took a great interest in this coming elite, and this, of course, included themselves, but I am quite ready to grant that their interest was not personally selfish — it was the interest of their class and of their in-group, to which all of them owed everything. Francis Perrin, who is a high-quality mind, a very fine brain, does not owe his career to his fine brain. He owes it to the fact that he’s a deserving member of this in-group, a meritorious hereditary member. He knows this and is very loyal to it — even now. Among other things, they claimed that they would play a role in higher councils of state, in high economic affairs — that it’s not true that scientists are impractical eggheads who never met a payroll, you know. And during the First War some of them (Francis Perrin was then still too young but his father) and some others were involved in the first acoustic detection of submarines and things like that, and patents were taken. They claimed that this was proof enough of their ability to handle also the practical affairs.

So in Francis Perrin the interest in patents was, I think, another manifestation of belonging to this hopefully coming elite. It’s an H. G. Wellsian idea to a considerable extent. So I think it was Francis Perrin who first talked about patents. He said, “Now you have the proof that a chain reaction is possible. I supplied the fundamental concepts of critical mass and so on. Let’s now think that very soon there will be practical industrial applications on an enormous scale, and we must remain at the source.” Nothing could please Halban more. Halban was steeped in the German tradition of scientists mixing up with high industry and other seats of practical power. Joliot was against it. But then they said: “If you don’t take the patent, somebody else will.” Joliot was sufficiently ignorant of patent law to believe this. Of course it’s nonsense. If you publish it, nobody can take a patent. There was another argument which had more force: “If you publish everything, then you will still be hamstrung by the future industrialists who will take all the secondary patents on various details, whereas if you hold the patent on the basic thing, you will be able to combat them.” This is socialist ideology, anti-capitalist ideology.

Weiner:

And the elitist ideology in the middle of it.

Kowarski:

So Joliot was convinced. I never was. My reasoning was completely different. I said, “If we do take patents, then according to the prevailing ideas of the time, we are soiling our hands.” Madame Curie was always glorified because she and her husband never patented anything concerning radium. I am rather inclined to think it was damned foolish, but this certainly was the climate, and it was still prevailing at that time. So I said, “All right, if I can have untold riches, I’m quite ready to soil my hands. But I don’t think we will get a penny for it. Either our patents, which is quite probable, will not be valid because we will not have complete enough ideas to describe a really patentable invention. Or if there is a valid claim, then its importance will be so great that it will completely transcend the patent law. So I don’t think we will get rich that way. To besmirch my innocence and not to get a penny for that, that’s too much for me. I’m against it.” My opposition was voiced quite rabidly, which moved Halban to remark — somewhat scornfully — that I was free not to put my name on anything I did not like. But that didn’t suit me either. My position in that exalted circle to which I had come so freshly was, let’s say, a little precarious, and if I singled myself out by not accepting to sign the patents, then I would definitely consign myself as an assistant who is not quite admitted. Obviously I had to stay in the same boat, so I accepted. And yet I was fighting it all the time. Originally Francis Perrin wrote most of the applications, and then later on, since I was the writer, I had to write them — all the time being against them. So much about the patents.

Weiner:

One of the statements that was made in the patents was that certain rights were signed over to CNRS, and the argument that you gave at the time was that they had supported the work in the past and maybe would in the future — also it turned out that they were paying the patent fees. How was that decision taken? Because what you just described was on a personal basis, and yet in a sense to me it fits in with Francis Perrin’s view of the elite and the relationship to the government. But it seems to me that there are two separate themes here—personal reward and yet responsibility to the state.

Kowarski:

Well, it was so — that we turned over our so-called inventions to the French state — and a convention was concluded between the French state and the inventors in which it was agreed that a certain percentage (I don’t remember the formula) would be put at the disposal of a certain, shall we say, foundation, in which the inventors would be heavily represented on the board of directors and which foundation would essentially serve to provide funds for research, future research of some or any kind. This looked as if there was never any question of our filling our pockets with tainted gold. But obviously if the proceeds were on that easy-to-anticipate level, practically like Gulbenkian’s 5% in the Iraq oil deal, you know — even if none of the gold went into our pockets, we would still be quite influential persons if we were at the head of the foundation. So although it looked very disinterested and all that, it still provided us with important positions in the future — if it came through. Only I myself was convinced that it would never come through.

Weiner:

You mentioned in the patents the idea of atomic energy and so forth. And at the time when you had to get to the point of writing these things up and thinking about the implications, was that the departure point for discussions of atomic energy in the long range?

Kowarski:

Oh, we were steeped in that all the time.

Weiner:

Well, you talked of the immediate ideas within those years.

Kowarski:

Oh, we were talking about our changing the face of the world map, you know — diverting the Mediterranean into the Sahara, things like that. That we were talking about all the time. Especially I was always aware of science fiction; Francis Perrin, too. Francis Perrin knows everything and has read everything. Joliot and Halban were a little less familiar with science fiction, but there was enough imagination at work.

Weiner:

These were private discussions.

Kowarski:

Yes.

Weiner:

And did this tie in with Joliot’s views — I guess in general — about the role of science and the state? It must have fit in rather easily.

Kowarski:

They were not very original, I would say — Joliot’s views. It was rather the current ideas, not quite those of “the clique” in the sense of Perrin-Auger, but more generally among this leftish upper dog of the dog-fight: that science means enlightenment, means progress, means social welfare, means great works and so on. It was all considered identical. Joliot in those days was much less politically minded than after the war. He shared these general diffuse ideas of progress, you know.

Weiner:

There was a group established at the time. I don’t know if his biographer mentioned it or where I got it — I think I got it from the biography — a Franco-British group of scientists set up before 1939 to develop scientific cooperation. And this is the Encyclopedists in England you mentioned. There were Bernal and Blackett and Zuckerman and Lord Suffolk, who he had contact with later, that were in on it from the English side. Do you know anything about that? The only reference I saw to it was in this biography.

Kowarski:

I don’t know anything about it. Especially I’m not aware of the appearance of Lord Suffolk on the scene before the heavy-water adventure of June l9i0.

Weiner:

That’s how the reference in the biography was made, I think — commenting that he had known Lord Suffolk earlier through this group.

Kowarski:

That comes as a complete surprise to me.

Weiner:

I’ll check it out downstairs later. I didn’t put the page number down, but it’s in there. Well, this leads me to another question about the military status. Joliot was commissioned at some time — I’m not clear when. He became, I guess, captain.

Kowarski:

Yes. Joliot was mobilized from the beginning, and he was what was known in France as “affectation speciale;” that is, he was mobilized in his lab. And, theoretically speaking, henceforth he was conducting his labs as a part of the French military system.

Weiner:

What effect did that have on your status and Halban’s?

Kowarski:

Not much.

Weiner:

First of all, you weren’t a citizen in the early part of it.

Kowarski:

Well, I became a citizen about two and a half months after the war erupted, and Halban was a citizen a little before. There was some talk about our joining some special unit for mobilized foreigners and freshly naturalized foreigners, and then Joliot said, “Above all, no zeal, gentlemen, please. No zeal. Don’t show your patriotism.” And then he had this superb sentence: “Consider yourself as those national monuments which for the duration are hidden behind sacks of sand.” A typical Joliot statement. It was about the same time that he made this comparison of us with Alvarez.

Weiner:

Why don’t you go into that a little bit? We were talking about it before, but…

Kowarski:

You want it to be recorded?

Weiner:

Yes, I think it’s a very characteristic…

Kowarski:

It was early 1940, and we were talking a little bit about how to behave and what we should be doing, and Joliot said, “You must realize that your status by now has changed.” He said, “You know what it is when some very reputable foreigner comes to visit us. You are at your work and suddenly a lab boy announces to you that there’s a gentleman downstairs who has come to visit the lab, and you ask his name and he says that the name is Alvarez. So you drop everything and rush down to greet him.” He said, “You will be now like this.” I quoted it to you previously as an illustration of Joliot’s perception. Alvarez in 1940 was not quite 29 yet, and Joliot unerringly chose him as an exalted example.

Weiner:

Of someone worth seeing.

Kowarski:

Yes.

Weiner:

Let’s make a decision on next steps. It seems to me that the next part of this takes us right over to England.

Kowarski:

Not quite. The episode of Desert Islands is before.

Weiner:

I just wanted to know if you wanted to go on now or take a break…?

Kowarski:

Perhaps we can do the Desert Islands still.

Weiner:

Good.

Kowarski:

By the end of ‘39 or January ‘40, I managed to convince my two colleagues that heavy water was not only the most desirable way but the only practical way. Halban was convinced by the experiments leading to the number 5 1/2. Joliot was a bit further away from that, but he accepted the reasoning; and we decided to concentrate on heavy water. Joliot had the idea of a document to be given to the French minister of supply, Dautry, stating that we want heavy water. I wrote the document myself. I was by that time firmly ensconced as the writer of the group, also in English, God help me. I still couldn’t speak English. I wrote it. I typed this paper myself, I think — I’m not sure. We led our reasoning to the statement: “We believe that the bulk of the world’s stock of heavy water is now kept at the Norwegian factory.” And then I wrote this magnificent sentence: “We would need the whole of this stock.” It was quite thrilling to write a sentence like that. Joliot went to see Dautry. I got from various sources photostatic copies of that letter. Then in February, around the 20th of February or so, which was probably not the first meeting on that subject, there was a discussion in Dautry’s staff office where Dautry presented several of his collaborators and said, “I’ve decided to get the heavy water for you.” And one of his collaborators was an officer who before mobilization was a banker. And the bank had the majority control of the Norwegian factory.

So he was sent to Norway with a few tough guys of the Secret Service to fetch the heavy water. His name was Jacques Allier, and he appears in various books. It was a few weeks before Norway was invaded, and Norway was desperately trying to appear neutral in spite of its obvious sympathy. It had to be very secret — this whole business, oh yes, it had. “Now, who knows about it?” “Nobody.” “But you know.” “Yes,” said Joliot. “And your collaborators.” “Yes.” “Who are they?” “Oh, well, they’re both French citizens. One is called Halban.” “Where was he born?” “In Germany. The other called Kowarski.” “Where was he born?” “Russia.” Russia at that time practically was worse than Germany. It was during the Russian-Finnish war. “Humph. That’s bad, you know.” “What do you mean, it’s bad? I completely vouch for them’ “That’s all right, we believe you. But if anything goes wrong with our men, leakages will be suspected; and your collaborators will be immediately singled out. So we have to somehow guarantee that they will not be accused.” “That’s easy,” said Joliot. “Put them in prison for the duration of the operation.” “In prison? Why should they go to prison?” “Well,” said Joliot, “if I tell them.” He was right. We would go. “Well, that’s perhaps excessive. Let’s send them to some residence where they could be under close supervision — on an island.” “All right,” said Joliot. “Different islands preferably.” “Well,” said Joliot, “Halban has a delicate health. We must send him to the Southern coast.” It was the end of February, not a very pleasant time for maritime adventures. “Let’s send him to the Cote d’Azur somewhere. There are islands.” “Kowarski,” went on Joliot with a gleam in his eye, “needs a bracing climate. We will send him to an island off Brittany.” So we went, spent about three weeks on our respective islands under close supervision. I don’t know exactly what Halban did. Halban always having the manner of Eric von Stroheim was of course immediately suspected of everything. He got in all sorts of hot water.

I was less conspicuous in spite of my bulk. I was supposed to do some geological researches. I hired a bicycle and I rode in all directions, having ideas about the slowing down of neutrons and a few other things. I also read the whole of Gone with the Wind. I don’t know what the local inhabitants thought of me. They probably thought I was some kind of suspicious character held under close watch. Then an open telegram was received: “16th of March top level meeting at the Ministry of Armament, your presence requested, absolute secrecy.” So probably the landlord of the inn where I was staying was completely lost. If I am a suspicious character, why am I invited to such a place? “Oh well, our poor country is always being betrayed by all sorts of shady persons.” Off I went. The heavy water had arrived — 40 gallons of it. That was mid-March. We started to devise the experiment which would show convincingly that when you put neutrons in a mixture of uranium and heavy water, more neutrons come out than what you put in. That is the essential precondition of the chain reaction. Well, that was the episode of the Desert Islands.