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Interview of Lew Kowarski by Charles Weiner on 1969 October 20, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/4717-3
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Childhood in Russia, family and early schooling; Paris University, first publication, work on crystal growth in Jean Perrin’s lab, doctoral thesis. History of Frederic Joliot-Curie’s work, his lab, character, and collaboration with Irene Curie and other scientists in context of pre-war scientific establishment in France; Kowarski’s work as Joliot’s secretary at Radium Institute, reactions to Joliot’s Nobel Prize; work on magic numbers. Work on fission: Hans von Halban, Enrico Fermi, Otto Hahn, Leo Szilard, ca. 1939; effects of science in wartime France. Applications of fission chain reaction and patents; flight to England with Halban and heavy water supply. Kowarski’s integration into English scientific community: James Chadwick, John Cockcroft, the Maud Committee, Marcus Oliphant; course of development of Halban’s group in Canada; Kowarski’s work between Great Britain and U.S. Return to Europe in 1946; political climate of postwar France, particularly the influence of communism. French Commission on Atomic Energy (CEA), its internal politics, science and scientists in postwar France: Joliot, Pierre Auger, Jean Perrin, Curie, Jules Gueron, Bertrand Goldschmidt. Growth of energy. Family life and marriages; visit to U.S., 1946; comparison of postwar science in U.S. and France. History of French reactors. Kowarski’s impressions of French scientific unity and his role in it; introduction of computer technology into nuclear topics; European Nuclear Energy Agency (ENEA); Kowarski’s involvement. Contemporaries: J. Robert Oppenheimer, Niels Bohr; developments in CERN and ENEA; reflections on attainment of goals and shortcomings of CERN; thoughts about being a scientist in an international community.
Then maybe we should take a break. The events, as I understand them, from here on do lead in a straight sequence to the shift over to England. We’re resuming now. It’s Monday morning, October 20th. And we left off about in March after the return from the islands with the heavy water being available.
Well, I’ve already said that we started devising the experiment in detail. There were a few preliminary measurements on heavy water itself — not much time was left before the events began to race. On May 16th the people from the ministry came — in particular Allier himself. And after a very quick consultation in Joliot’s office it was decided that Halban, together with Joliot’s deputy director of the lab, the chemist Henri Moureu, would go south, that is south of the Loire. The Loire for some reason was given a mystical significance. It was considered that the Germans might occupy France as far as the Loire but certainly not below the Loire. So they had to go below the Loire and put in safety the heavy water, perhaps the gram of radium that we had, and a few other things and then we would see. This was done. The last days of May were essentially spent in preparation, since the Germans were getting closer and closer to Paris, for the bulk of the evacuation of the lab — the amplifiers, counters, the large number of lead bricks which are necessary in all these experiments and which are the main weight to carry. In the meantime, Halban established himself in Clermont-Ferrand and rented a villa. The idea was that we would continue on experiments in Clermont-Ferrand in that villa, which had to be fitted out as an emergency laboratory.
On about the 5th or 6th of June I left Paris with a few trucks carrying all this. To my astonishment, I found that I was by far the oldest member of that particular group. I wasn’t in any way in uniform, but they considered, since the whole thing was commanded by the military in a military framework, that I was somehow the commanding officer. So I found myself commanding four or six soldiers considerably younger than myself. And so we trekked to Clermont-Ferrand. We arrived on June 7th or something like that. Halban was there. All these facts have been recorded in many books. The heavy water was put in a women’s prison in the city of Riom. It became famous a few years later, because all the war criminals were tried there — criminals, that is, from the German point of view: the French political leaders responsible for France declaring war on Germany. Incidentally, this is a well-forgotten fact — that it was England and France who declared war on Germany, not the other way around.
You were married at the time. So did this mean moving your family also?
One child, a girl of not quite four. She suffered a rather serious accident involving boiling water a few days before, and her leg was heavily bandaged. My wife and child were sent off by train — we secured a place for them — and everybody seeing this little girl with the bandaged leg assumed that we had been in some way bombed out, or something. There had already been some bombings in Paris. There was plenty of sympathy. I found them in Clermont-Ferrand, in due course. There was also Halban with his family. A few days later Joliot arrived with Irene. They were completely exhausted, and I remember, characteristic of Irene, as soon as they arrived, Irene immediately lay down on the floor and went to sleep. She had this simplicity of behavior. That was about June 11th or 12th. The Armistice was officially asked for on June 16th or early 17th — I don’t quite remember which. I was somewhat surprised to see that Halban was very seriously organizing the villa, he even went to Vichy, which had not yet become the notorious Vichy of a few weeks later, to buy a lot of furniture for the villa at some auction sale.
He also got in touch with personnel from Paris — lab boys and so on who were also evacuated in Clermont-Ferrand, and in fact he was ensconcing himself in that villa for the duration. I personally saw no mystical value in the River Loire, and I considered that we would have to leave Clermont-Ferrand very soon. It was a bit delicate in those conditions to talk about such things explicitly. Still I remember that I very definitely threw out the idea that Halban and I should constitute ourselves as the high priests of heavy water. I said that we might have difficulty in passing borders and being admitted to other countries and so on in this time, but once we are attached to heavy water, that will be our passport. I think Halban did not like the idea that a mere 40 gallons of a liquid were more important than himself, but he finally admitted that there was something in it. But that again stressed my personal position in the group as specifically the heavy water man.
This remains with me practically until this day. I am the heavy water man in nuclear affairs. A few days after Joliot’s arrival it became obvious that greater happenings were preparing. On the 16th of June, Allier, still in the uniform of Dautry’s cabinet, came to our villa; and between Halban, Joliot and Allier, it was concocted that Halban and I should leave at dawn of June 17th and go to Bordeaux where the main body of the government was; and there we would receive our orders. But the main thing was to get as far as Bordeaux with all of our cargo. During June 16th I don’t remember exactly who went to Riom, but finally everything was gathered in that villa in Clermont-Ferrand. On the evening of June 16th we held our last session with Joliot. Here I open a parenthesis just for Joliot’s characterization. Joliot made a forecast of what was going to happen. I have no proof other than my memory, and people will be free to believe me or not. Joliot said: “Germany will overrun the whole of France, but it will not occupy the whole of France, only the territories which they consider necessary.” This, of course, was what happened a few days later, only Joliot made one mistake: He said, “For psychological reasons they will leave Paris an unoccupied territory. There will be some kind of gerrymandering, so that Paris will remain unoccupied.” In fact, Paris was occupied. Then he said, “France will remain for a time in this divided state, occupied in part. Eventually there will be an uprising in the nonoccupied part, and the Germans then will occupy the whole of France,” which also happened about two years later. He went on: “From the occupied coast the Germans will prepare a seaborne attack on England. As one aspect of the preparation, they will try to knock out England by air raids, and they will fail. So the seaborne attack will not take place, and England for a while will resist alone, but then both the United States and Russia will enter the war. And then Germany after a suitable number of years will be defeated.” As I say, I have no evidence to prove that what I’m saying is true, but that’s what he did tell us on the 16th of June.
This was your final session with him.
He also had a separate session with Halban, and he told Halban that “you will guard and be responsible for the heavy water.” Now, the word “you” in most European languages has two senses — it’s a plural and a singular. And I’m convinced to this day that what happened was a genuine misunderstanding. He meant it in plural, and Halban meant it singular. After this interview, Halban emerged and constituted himself as the head of the expedition, saying that Joliot charged him with the whole responsibility. This sounded plausible, because Halban’s status was, after all, senior to mine since the beginning. After the war, Joliot denied that his intention was to single out Halban. So maybe my grammatical interpretation is true, but this is something which I shall never know. On the 17th at dawn we started out in two cars — one of them driven by Halban and containing his wife and his very small child, not quite a year old, and the other car driven not by me (since at that time I didn’t know how to drive), but by one of the lab assistants; it was a bigger car. It contained on the front seat the driver, my wife and my daughter, still with a bandaged leg.
It was a kind of station wagon, and on the back were piled up some 20 cans of heavy water, with a few blankets and so on, and I was lying on the blankets and reacting in an obvious way to a rather fast drive through very curved roads and the deep hills of French central Massif. It would be interesting to dwell again on that trek that started at dawn on the 17th and ended at something like 11 p.m. in Bordeaux. It was going from east to west more or less horizontally, and we crossed innumerable roads radiating north-south from Paris. That was the time of the famous exodus and the roads were quite crowded. Our transversal way from Clermont-Ferrand to Bordeaux was relatively free — not many blockages. We arrived in Bordeaux in late evening and went immediately to look for the Ministry of Armament, which was occupying some school or other. Dautry’s aide, who was looking after us, tore a sheet out of a schoolboy’s copybook lying somewhere around and wrote the order of mission: that we are ordered to go to England on Lord Suffolk’s commandeered ship.
The order was very short, and we had to put ourselves at the disposal of the British authorities and observe absolute secrecy. Also we had to put at their disposal our materials and our records. That was that. This brief wording had one interesting consequence: it made rather difficult later on our situation with de Gaulle and his Free France. De Gaulle was not “British authorities,” and communicating with de Gaulle would mean an infringement of the “absolute secrecy.” And so we stayed apart from Free France during our whole stay in England, because we were carrying out the wording of our mission order. As a little historical anecdote I might add that that particular assistant of Dautry, whose name was Bichelonne, a few years later distinguished himself by organizing the transfer of French labor to Germany, and after the war he was tried as a notorious collaborator and shot, if I can remember rightly. So obviously our transfer to England was a sort of early rehearsal of his later activities.
Was there any question about Joliot’s going?
I will come to that in a moment. When we were leaving him in Clermont-Ferrand, he definitely said that this was our business and not his. He reserved himself for later decisions, whatever they would be. We were brought on board of the ship Broompark, a Scottish collier, which had been commandeered by Lord Suffolk. We arrived there, I think, soon after midnight, the night of June 17th to 18th. All sorts of officials of the Ministry of Armament — fairly high military rank, shall we say, colonels or so, were carrying not only the cans of heavy water, but also our household belongings. They knew enough about our connection with this new force of nature and they obviously wished that we should continue in England or perhaps beyond England — and that would be a valuable French contribution to the Allied effort. They gave this eager help already after the Armistice was asked for, and after the Petain government was formed. But that was this one day (June 17th) when the previous government before Petain’s was still concluding the current business, and we were one item of the current business, still handled by a belligerent government and not by the government of the Armistice. This midnight scene left quite an imprint on my memory. I took my mission very seriously.
The last gasp of the belligerent France quite naively and touchingly put its faith into these two departing magicians, and that obviously meant that we were not just refugees leaving the country. We were carriers of a mission, we had been entrusted with something important. So we went on board ship. There were a few cabins which were left for women and children — we were not the only scientists who were gathered by Lord Suffolk on that ship. Halban and I were left to fend for ourselves as well we could. I found in the hold a heap of coal, collapsed on it and fell asleep. I was wakened from time to time by some kind of noise. It turned out that the Bordeaux harbor was very heavily bombarded that night, but I was too busy sleeping on my heap of coal. In the morning things got organized. There was a captain of the ship, but Lord Suffolk was obviously in charge — a very picturesque personality looking like an unkempt pirate. I read a lot of stories about the eccentricities of the British aristocracy, and here was Lord Suffolk, something like the 19th or 20th Earl in a line which was considerably older than the house of Windsor. It went together.
Was he in military attire?
No. He was dressed in rags, with a very picturesque beard. He walked with a noticeable limp, which had nothing military about it; its origin was purely civilian. He was limping around the ship with two secretaries, one blond and one brunette. The blond one was killed a couple of years later together with him in a bomb disposal accident. She was actually part of the bomb disposal squad, and so they died together. I don’t think I have to go any more into the details of that trip. I have now something to say about Joliot. After the bombardment, the boat was transferred to another part of the Bordeaux harbor — rather unexpectedly. The next day, June 18th, we spent in that new place, and it was reported by some kind of a grapevine that Joliot was in town and looking for us. It was discussed whether he should come on board or whether we should come down to greet him. We did not know at that time that we would not be allowed to disembark. Lord Suffolk considered us as some kind of war booty, to be kept securely on board. Also, if Joliot came on board to see us, he would not be allowed to leave. In fact, Joliot didn’t find the boat. He actually went to the place where it was moored the day before, but in the big confusion after the heavy bombardment nobody was able to tell him where it was. He told me later on that he debated within himself whether to look for it and took his decision: “Oh, well. Anyhow I have to stay. They will carry on and I will stay here.” It is still interesting to speculate on what would have happened if he had found the boat. He would certainly have gone on board without knowing that he would not be allowed to leave.
Bur Irene was still…
Irene was not in Bordeaux. Irene was weak and sick and she was left in a sanatorium near Bordeaux. This, of course, was one of the reasons why Joliot did not seriously consider looking anymore for the boat. There were other reasons. Joliot never considered seriously the prospect of leaving France. The French are that way. They cannot conceive of a life outside of their island. They are more insular than the British. He considered that his duty was to stay in France. So he didn’t pursue this line of exit. Eventually the boat moved out, stopped again, still in the estuary of Gironde, and there we stayed for a longish time and then started moving on towards the sea. The boat next to us in the convoy ran on a mine and sank under our eyes. There were no casualties; everybody was transferred to other boats in the same convoy. This sinking episode enabled Dautry’s people to tell the arriving Germans a few days later that so far as they knew the heavy water was put onto a boat which was sunk in the estuary. This little play for time was apparently successful. We left the estuary on the 19th and crossed the Channel in about 36 hours. There were a few picturesque episodes, such as Lord Suffolk making a raft on which he moved all of the cans of heavy water and a huge sack of industrial diamonds. There were seasick people; he was limping around the ship to treat them with champagne, which he proclaimed to be the best remedy against seasickness. All this was completely in keeping with the ideas of British aristocracy I had gathered from the works of P. G. Wodehouse.
There were about 50 passengers on board: prominent scientists, less prominent scientists, technical people — some of their families, not very many. The ladies immediately organized communal feeding. Quite a few of these people, including ourselves, had some canned food with them. All this was pooled. On the 21st we arrived in Falmouth right in the beautiful harbor. Several masts were visible sticking out of the water, marking the place of some recent sinkings right in the harbor itself. This was hardly a surprise: we had spotted some German planes on our way, but then we were told that they had no bombs, having spent them previously on somebody else. It was a picturesque detail. As a relic of this adventure, I still keep my copy of the curious document which was produced during the journey, a sort of witness account about heavy water and industrial diamonds, signed by Suffolk and Halban and myself and the captain and so on.
Witnessing that this had been loaded?
Yes. On the raft, in case of its disappearance.
So you could explain it.
Yes. During the 21st we stayed in Falmouth, and then late in the evening we were loaded on a special train to London. We arrived there on the 22nd in the morning. The heavy water was in the baggage van under military guard. We arrived, all of us. There was the typical British muddle. Nobody knew what to do with us. The government didn’t know whether we were a valuable addition to the wartime effort or refugees to care for or potential spies. A lot of infiltration was going on at that time, there were signs of fear all around us, and the fear was quite founded. We never knew whether we were honored guests or war prisoners. We were given a rather sumptuous breakfast: the rationing of food was introduced only a few weeks later. There we sat, in that spotless breakfast room, our clothes still full of coal dust. In those days my wife had some relatives living in London. We asked whether we could leave the Paddington Station and its Great Western Hotel, where all were provisionally quartered.
There was nobody to decide whether we were to be kept under surveillance or free to leave, and since there was nobody to decide, we just left. Halban also left: he went to a luxury hotel, the May Fair. This was the beginning of the contrasting behavior of Halban and myself in English conditions. I, without knowing it, probably because of my knowledge of relevant English authors, such as P. G. Wodehouse, was doing, on the whole, the right thing. For example, it was very good for the English to know that we were relatives of a highly respected dentist living in a very respectable London suburb. That was just the right touch in the circumstances. Halban by moving into the luxury hotel behaved in exactly the opposite way. That was not the right note at all, but he couldn’t know it. Halban, essentially being German, had repeated some of the mistakes the Germans were making in their relations with the English. I, free from the handicap of being German, and having been nurtured mainly on current English literature, was better armed, without realizing it, with what it took to fit better, even in spite of my being, at that time, as yet completely unable to speak English. Well, what next?
You said June 22nd. This was about the time you started to write your report, wasn’t it?
Let me add a few little touches. I remember very well saying to my wife during the trip, and with a touch of drama suited to the circumstances, that we had escaped the German occupation but now we were carrying our German occupation with us. Halban was very much in command and very much Erich von Stroheim type of behavior.
Did he react especially to this situation with a sense of tenseness?
There was a lot of that. I think in his mind he had a very definite place for me, a place which I think I mentioned before. His vision was that he was the hub of the whole thing. On a level above him there was a benevolent protector whose technical knowledge was somewhat deficient and who therefore had to rely always on the all-knowing Halban, and below Halban there was a somewhat obstreperous and comic, but on the whole valuable, assistant. Of course, now that the benevolent boss was no longer there, he was the boss; and the obstreperous assistant could still be used, but he had to be shown his place all the time — so he was showing me my place.
Other than in personal relations, how did this manifest itself in terms of your relations with the English authorities?
Well, at first I had no relations at all with the English authorities. I couldn’t speak any English. Halban took it over. He knew Blackett. He knew Cockcroft. And there he had a somewhat difficult task. He was a gentleman, very much an Austrian-German gentleman. He had to behave in accordance with a German gentleman’s rigid code of behavior. So since Halban-Joliot-Kowarski in that order were the signatories of the work already published, or awaiting the proper time to be published, Halban and Kowarski were to be treated as equals formally. But then, of course, beneath this cover of formality, there were the realities of what’s what, who’s who. On the whole the position was that the trusted assistant, because of the benevolence of the higher-ups, was permitted to sign the papers; and so formally had certain considerable rights; but any knowledgeable person would instantly recognize the reality. This view dictated a certain line of conduct which he observed all the time. I could not even speak English, and he, on the whole, had reason to feel far more familiar in our new surroundings — he was, to begin with, the son of a prominent professor, and on the academic scale of social values to be a professor’s son is more important than to be a professor. A professor can come from heaven knows where, but a professor’s son comes definitely from a good family. Blackett for me was Blackett, an obvious candidate for the Nobel Prize and so on. For Halban he was Patrick. In these first evenings in London he visited all of them privately. I didn’t even know what he was doing. But we also had an official appointment in the Ministry of Supply with Cockcroft, and there the visible relationship immediately changed. We appeared together as a group because the occasion was official and therefore formal.
That was your mission.
Yes. And the mission made no formal distinction between us. This continuous superposition of formal equality and implied inequality was a very interesting game to play.
How long were you in London before it was clear what the next thing was?
We spent about three weeks, and during these weeks we made two trips, one to Liverpool and one to Birmingham. We also met Sir George Thomson, who was the chairman of the Maud Committee, but this was in London. We met Cockcroft at the Ministry of Supply, I think on the very first weekday after our arrival. Then we went to see Chadwick, who was quite undisputed number one, scientifically speaking. That was my first meeting with him. We stayed there two days talking to him. During these two days Cockcroft arrived from London to Liverpool especially for that. Then I think we met Sir George Thomson first, and then we went to see Oliphant, and there we also saw Peierls and Frisch.
In Birmingham. Frisch very soon afterwards changed and went to Liverpool, but at that time he was still in Birmingham. That was my first meeting with Frisch.
What was your impression of Chadwick when you first met him?
I was going to start on that myself. Chadwick held for me an enormous prestige. I knew how Joliot spoke about him. I knew something of his prior work prior to the discovery of the neutron. I knew his paper with Goldhaber on the photoelectric effect.
Photodisintegration you mean?
Yes. Of deteurium. Which I considered then and still consider one of the most beautiful papers I’ve ever seen. Chadwick met us at the station at Liverpool. That’s characteristic of him. That also went together with my idea of the British behavior. He was the master, and it was the master’s duty to be there. I don’t remember what the first words were. Knowing Chadwick well afterwards I could well imagine something like “Sorry I couldn’t quite make it for the exact arrival of the train. I suppose, for a minute or two, you were wondering where I was. My health is so bad,” and groaning in a characteristic way and otherwise saying little. I learned later on that Chadwick was famous in those days for being silent and laconic, even more so than Cockcroft in a different way, in a more groaning way. But on the background of my literary knowledge of English behavior this appeared to me quite natural: of course, the English are that way. He was surrounded by a sort of halo in my mind; I saw him as a very great man. I still think he is a very great man, as you know. In fact, I always say he is probably, all round, the greatest man I’ve ever met. We were stationed in the Adelphi Hotel in Liverpool, and we spent quite a lot of time at his home discussing things, and then Cockcroft came and all this time the groaning was going on, together with a sharp and shrewd discussion of our experiments.
I might introduce here another little personal note. As I said previously, Halban, because of his wish to be in a position of strength, relied more on his traditional knowledge, put a heavier accent on that and tended to minimize the value of new ideas, which was in a way not very clever, because he also (when I say “also,” I say it in quotation marks) had new ideas. But since all I had was new ideas, and only he had the necessary traditional knowledge, he put more accent on the value of traditional knowledge — and less value on new ideas. That made him neglect somewhat some of the new ideas, and that meant that from time to time he would turn to me and I would explain in detail some formula or some detail of an experiment. That gave, I think, both Chadwick and Cockcroft, but especially Cockcroft, a completely mistaken idea that I was the mainspring of physics in that team. If anything, it was rather the other way around, but that was the impression which emerged, which shows again and again how dangerous in life it is to be too clever by half. Some of the seeds of subsequent distinctions which were made by the British between Halban and me were sown in that first meeting.
Chadwick was thoroughly informed about who you were and what you had done and was by this time immersed in his part of the project, the British activity. So this was really getting down to business.
Yes. We described our planned experiment in detail. The famous Report BR 94 by that time had already been written, and we used the first copies as a kind of working document for this meeting in Liverpool.
This was a report that you and Halban had written in London?
Yes, in the bedroom of the luxury hotel where Halban was staying — the May Fair.
That was one of the other things you were doing during this two-week period.
Yes. And there and then it was decided between Chadwick and Cockcroft — Cockcroft in his more official capacity as something in the Ministry of Supply; Chadwick was still purely academic — that … The question arose, by the way, whether we should stay in England or go to the United States. Halban made a declaration with my consent and approval that we considered ourselves as belligerents — United States in those days was neutral — and therefore we expressed a preference to stay on belligerent soil. Whether it should mean the British Isles or Canada, we didn’t venture to say. Privately we would have preferred Canada, but we considered that it was unseemly to express it.
What would the basis be for the preference?
Let’s say more quiet conditions for work for one, better food for another; because obviously the squeeze was already coming in England. And then there was simply the physical danger, the danger of invasion. It was June 1940, and lots of people thought that England would be invaded. I naively was unafraid: I was even reasonably sure that England would not be invaded at all. I turned out to be right, but for the wrong reasons.
During this period of the first several weeks when you wrote your report and then when you conferred with Chadwick and Oliphant and the others, was there any indication that all of this would soon lead to a wartime project with a desire to produce a weapon to be used in the war?
The wartime project already existed at that time. It was launched by the famous memorandum by Frisch and Peierls a few months before. We were not told much about that at that time, but there was the Maud Committee. I don’t think I should spend too much time explaining that. That’s been covered elsewhere.
I meant in your mind as you were doing this, did you project to a later stage of your work which would result in something that was usable in the war itself?
We had some talk very soon afterwards in Cambridge with Feather and Bretscher, and our ideas of plutonium began to take shape, so we began almost immediately to think of the slow-neutron chain reaction as a means of producing plutonium. As regards the other part — isotope separation and simple explosive Uranium 235 — we knew about it, but that was none of our business. There was a certain amount of putting things in compartments — not as rigid as it was going to become in the United States, but still there was some. And we were in a somewhat delicate position of being almost enemy aliens — almost, not quite. Even if we considered ourselves purely French, France was an occupied country wavering towards collaboration — governmentally so. Our status was not quite clear in those days in this respect. So we knew that asking too many questions would be unhealthy. As we expressed the wish either to stay in England or to go to Canada but not to the United States, it was decided that our experiments would be performed in Cambridge. Cambridge in those days was declared a dangerous area, the whole of East Anglia being immediately exposed to any invasion, but it was still considered that we could work there. We didn’t know then that actually Cambridge was practically evacuated as a dangerous area. We were put there, and that was the result of these first three weeks in London. Of course, the divergences of opinion between Halban and me were quite a few, and one of them was still about the patents. But since it was clear that patents already existed and there were French rights and the French rights had to be safeguarded, and heaven knows what would happen to the French applications in France itself, it was decided that we would file again in England. Since I was the writer, I was sent by Halban to discuss the patents’ formulation with a patent gentleman in a firm in Lincoln’s Inn Fields. That was one more case of my landing amidst the familiar particularities of London professional life as it was well known to me from literature. Mr. Triggs complimented me on my fine understanding of the subtler niceties of the English language, and he didn’t at that time realize that it was the first sustained conversation in English which I ever had.
And that was within just a few weeks after you arrived.
Well, I’d been reading English literature for many years before that, and I already wrote some of the papers in English; so obviously it was just a question of spoken language.
Now, you approached him on a private basis…
It was as private individuals but in obvious contact with the authorities. Actually, his name was given to us by the Ministry.
There was no objection to your doing this?
And there was no secrecy problem?
Oh, there was a secrecy problem.
But since they recommended him, then that was all right.
Yes, it was all right. I don’t quite remember how the secret was supposed to be formally kept.
Had the desirability of doing this been discussed with Joliot before?
That I don’t know. That was the famous session between Joliot and Halban, the last one. Here again Halban was in his curious position. On the one hand, he was the leader and he was responsible and so on. On the other hand, formally we were quite symmetrical. And also my obvious ability to handle the linguistic niceties could be useful. So, as a matter of fact, in spite of my being then, as ever, anti-patent, I was handling most of the patent business — in the aspects of practical detail.
Now, these patents — was anything new introduced then?
The first five were exact replicas of the French ones.
In terms of the individuals involved…
Specifications and so on. I think we did have the copies of the French patents with us. I don’t quite remember. Anyhow the essentials could be done very easily from memory. Later on a few more patents were taken, which were originated purely on the British soil; and gradually the whole thing began to degenerate. At one moment Halban discovered a mistake in the reasoning in one of the former patents, and he immediately made a patent specification on the correction of that mistake. He was to some extent obsessed by the patents. You see, German tradition was the cooperation between scientists and progressive industrialists. And in this respect Germany (this is what I called once the second industrial revolution) showed the way to the rest of the world. In other countries, including Britain, there was far more mistrust between the industrialist circles and the academic longhairs. Halban’s far-seeing plan was to establish himself in the eyes of the British industrialists as the coming man of this new force of nature. That was the early days of the Churchill government, the industrialists held a considerable power in the Tory Party, and British organization of the war-time effort was such that great industrial concerns became practically the government in many respects. So when Halban wanted to impress the government for having the purpose of getting access to big resources, he also at the same time had to impress the industrialists by appearing as one of those practical German wizards. The idea of German scientific wizardry in those days was still very strong to an extent which it is quite difficult to imagine today. I.C.I. wistfully envied I. G. Farben in those days: see how reasonable the Germans are, what good cooperation there is between German scientists and German industry, and look at our own long-hairs sitting in Oxford and Cambridge and feeling purely academic.
And yet Lindemann, of course, with the German tradition, was a link with I.C.I.
Lindemann was not only a bearer of the German tradition — he was born in Germany.
Well, that’s what I mean. And he was working closely with I.C.I., which perpetuated this image.
Yes. So for Halban the patent applications — not the patents themselves, but the applications — were important in order to situate him as a man they could understand. It’s a situation fairly similar to the Russian classical novel, The Dead Souls, in which the hero is the owner not of a certain number of slave peasants but of the official documents concerning them. The patent application as a hallmark of practical-mindedness, of belonging to that particular brand of scientist was more important to him at that moment than having the patents themselves. And in this sense I must say that my own strictures as to our never getting the patents, or that they would have no value whatsoever, were to Halban totally irrelevant.
So the first stage of the patents was done during those first weeks in London.
Yes, the first applications — the five patents as applied for in France.
Now, after the preliminary round of meetings, writing the report, taking care of the patents, it seems that all the preliminary business was out of the way
So we came to Cambridge.
Is that the time that you came under difficult circumstances?
Why don’t you remind me of the details of that.
The 14th of July. De Gaulle, in the morning of that day, held a festive gathering of the free French in London, but we did not attend. We traveled by car. Before leaving, I memorized the names of the biggest pubs on the way, out of guidebook, in the expectation that finding ourselves on a main square featuring the White Hart and the Coach and Horses, we would know which town it was. I don’t think this device proved really useful. One of the reasons why it was not useful was that the British yokels (bless them) when they saw a gentleman in a car asking for a way, even if it was in an atrocious German accent, they still were very affable and told him all the details of where to go, although they were not supposed to.
The reason you had to ask is that you were allowed no maps…
No maps, and there were no road signs.
Because of the semi-evacuation conditions.
How about your family? Did they join you on this trip?
On the trip to Cambridge, no. They arrived a week later by train. Let me say something about the first impact of Cambridge, which was quite unforgettable. It was in July. We came from the south, by Trumpington, Trumpington Road and King’s Parade past King’s Chapel. We stayed in the Blue Boar, which is opposite Trinity Gate. The impact on me was definitely king-sized. We were invited by Fowler, the statistical mechanics man, to dine in Hall in Trinity that evening. I saw for the first time the whole paraphernalia of a dinner in college. I had read about it before. And after dinner we strolled in the garden and talked about our work, and Fowler was just on the eve of going on the famous Fowler Mission in the United States. By that time I was beginning to realize that my ideas that England would never be successfully invaded were not shared by everybody. There was a certain issue of Life magazine, which appeared in early July, all of which was devoted to England — how beautiful it still was, how great it used to be, and now of course it shall disappear forever. I was a bit taken aback by this pessimism; I could not quite exclude the possibility of its being justified after all. I was looking at this extraordinary beauty thinking: “Well, perhaps it is true; all this will soon pass — everything of it.” It gave a poignant note to my first contact with Cambridge, to the mood of this talk with Fowler, about our scientific business, which in itself was a piece of science fiction. After all, you know the story of these two scientists fleeing for their life from an implacable enemy and carrying the world’s supply of rare material which will enable them to master a new force of nature, it was preposterous, it was dime-novel stuff. And, on top of it, the sudden contact with this extraordinary beauty of setting and tradition and feeling that maybe we were witnessing the last days of all this.
It was quite a mix all at once.
Yes. It was one of the earliest episodes (I had several later on) which made me think that I really didn’t need to read any thrillers. What I was going through was quite passable as a thriller by itself.
When you met with Fowler, it was for the purpose of discussing how you would get settled at Cambridge. Was that his role?
No. We met him mainly in order to brief him, because he had to go to America very soon afterwards. Cockcroft immediately offered us his house, because at that time he was not living in Cambridge; he was in London. Actually, one could have a choice of accommodation. And then there turned up a second interesting episode of our “Foreigners-in-England” show. Of course, Halban being the boss, he offered the house Halban and as to me, we would see to that next. Halban turned it down, explaining to me that he didn’t want to appear to be obliged to a colleague. He wanted to show that he was as good as Cockcroft, and therefore he should not be personally obliged to Cockcroft. I reasoned exactly the opposite way, and again I proved to be right. My knowledge of English literature, heavily loaded with Agatha Christie, and especially with P. G. Wodehouse (always one of my masters) was very useful. It is nowadays a truism, and there is a famous French comedy about it — that if you want to be well treated by someone, don’t be a benefactor to him; accept benefactions from him. By accepting to live in Cockcroft’s house, I put myself in some way under Cockcroft’s protection, which remained a factor of my life for many years. By not accepting Cockcroft’s house, Halban set himself apart. In this typically German way, he probably made many more mistakes of that sort, which I never heard about, in his relations with the English. So I accepted Cockcroft’s house and moved in and we spent many weeks there. But then after a certain decent interval I decided I couldn’t stay there forever. We didn’t know when Cockcroft would return. I was perhaps a little too shy. As soon as I was settled and we had a certain definite income, I said “Well, I am now able to pay my way, and I should not accept indefinitely the privilege of staying in somebody else’s house.” So we moved out. I stayed in Cockcroft’s house about ten weeks. These were essentially the weeks of the Battle of Britain.
It was during the summer then, really the entire summer?
Yes. As soon as my family arrived in late July until sometime in October or so.
What did working in Cambridge mean in terms of daily routine? — in terms of relationship to the laboratory?
The supplies which came with us from France were brought to the Cavendish, and we started going through the process again — getting the dysprosium for the detectors, making the detectors, having the counters made to our design, building the amplifiers and ordering the vessel in which uranium oxide had to be mixed with heavy water We were helped quite a lot by various Cavendish and University Scientists with such aspects as suspension of oxide in water. I used to walk around in the Cavendish courtyard shaking big two-gallon bottles, shaking mixtures of water — ordinary water for this purpose –- and uranium oxide and seeing how it settles and how it’s kept in suspension and so on. It was very picturesque. And then the vessel with all its gear arrived from its Birmingham manufacturer. It was a relatively complicated machine. One of our ideas was that the outside water bath should not be water but mineral oil, because if there is a leak in the sphere, then the heavy water leaks out; and if the outside is water, then It’s completely lost — whereas if it’s mineral oil, then it does not mix and there is a hope to save some. I don’t remember which one of us was responsible for that idea. Little gimmicks of that sort certainly appealed to my chemically trained mind.
You say you got some help from other people in the lab. Were any technicians or assistants supplied directly to you?
We had a junior graduate student, who is now assistant director of Harwell.
Who was this?
Fenning — whom I considered always my star pupil. Then we gradually began to build the amplifiers. For that purpose, we acquired an electronic engineer, who turned out to be the son of Herbert Freundlich. This was consistent with my lasting interest in Freundlich and his family. That was its second manifestation. As you know, there was another one later on.
The first one was reading his book.
Reading his book and noticing his remarkable German style. I’m always a sucker for a good style. And so I became a sucker for Herbert Freundlich. When I knew that his son was an electronic engineer and was available, it was interesting for me to work with the son. The daughter was the next episode later on. So we had Fenning; we had Freundlich. Fairly soon Kemmer joined us. Kemmer is now professor of natural philosophy at Edinburgh. All these were more or less enemy aliens of German or Austrian origin. Freundlich actually spent some time in a camp and then was taken out of the camp for his special knowledge of electronic engineering.
Yes. The father at that time was still alive; he and his daughter were living in Minnesota. Kemmer’s status was at that time not quite clear. The Germans claimed him as a German because, for them, he was legally an “ethnic German.” In fact he was mostly Russian because of the successive dilution of German blood, but he undoubtedly belonged to a descending line of Baltic Germans. Fenning, Freundlich, Kemmer formed our earliest group. We also had a few undergraduates to help us as lab boys.
Was there any sense of urgency about your work, or was it on a regularly scheduled daily basis?
There was an enormous sense of urgency. Actually that doesn’t mean that one has to spend 12 hours at the lab, because there is nothing to do for 12 hours. If the work consists chiefly in designing things, rounding up supplies and so on, very often there is nothing to do and one can spend some time reading. But gradually our working days became more and more filled up. The sphere began actually turning and so on some time in November (probably), and most of the experiment was performed in December. By that time the Maud Committee was fully organized; there was a policy committee and a technical committee, and both Halban and I were on the technical committee.
Which meant that you went to meetings in London?
From time to time, yes. It was very picturesque. London was being bombed. We spent many night hours in shelters and things like that. That was after the first attack, according to Joliot’s predictions, was beaten off. The Battle of Britain was won. I was rather interested to see how the events seemed to follow exactly Joliot’s prediction.
During this period you had no contact with anyone in France?
Not through any of the missions or anything?
And you say that you deliberately had stayed away from the de Gaulle government.
Yes. The de Gaulle government in those days was still in a very incipient way — the Committee of a Free France or something like that. I began to make my first friends in Cambridge, and the really first was David Shoenberg, the magnetism man. He is of Russian origin, and he speaks Russian. My English began to be really serviceable only sometime in September. Before that it was very difficult. I first spoke to Frisch in French. Of course, with Chadwick and so on, I had to speak English. I was fairly retiring. Halban was the spokesman, and that also contributed to our respective images in a way which, for me, turned out to be rather beneficial. By September my English became reasonably fluent, but during these first two months or so, Shoenberg played a very great role because of his Russian, and he’s still a close friend.
He wasn’t involved in the work, but he was a colleague.
No, completely different work. We had a certain code of courtesy: never ask questions about anything. During that time Cambridge was once bombed, slightly. There was an incendiary bomb which fell on the Cavendish, right in the middle of the Cavendish, and landed in a sink full of water. But one junior physicist was killed by another bomb. He was about the only casualty in our immediate surroundings during the whole war. There was a far heavier raid on Cambridge in ‘41.
Did any semblance of normal scientific activity continue in the laboratory either in terms of laboratory work or in terms of discussions?
Well, teaching went on and training in physics was an important feature of the war effort. I didn’t know much about teaching in those days, so I can’t tell you much, but I think it was quite regular teaching. Most English physicists were mobilized in radar. Norman Feather was not mobilized, and therefore he became an important person in teaching at the Cavendish. And then, of course, there were aliens. Aliens could not be mobilized, and therefore they were employed in all sorts of wartime work. Bretscher was prominent among them. That’s about all I can mention until the month of December.
Let me ask a question just on the background of this. You said that after a while you started to receive a salary. What was the source of the salary?
We were formally employed by the Ministry of Aircraft Production, which was a new ministry and had a new budget and therefore all sorts of things could be done with it. The salary was not very high. My basic yearly figure was 400 pounds and Halban had 50% more. Because of progressive income taxes, the actual difference was not as high as his. I’m still describing 1940. This salary, I realize now, was fairly low; but for me it was the first regular income on a regular scale of a working scientist. And here comes the fundamental meaning I have to explain. I did acquire a certain status in France, but because it coincided with the disruption of the war and also because of the adverse French traditions, it was like a check, and no cash as yet. As soon as arrived in Cambridge, I did cash in. So France drew the check, and Britain honored it. I knew that. I knew that that was not the particular merit of the British, but still it was unavoidable that Britain for me was the country where for the first time I started the normal life of a scientist. During my whole period of scientific activity in France it was not so. But in Britain here I was: Cambridge and the Cavendish, and a modest salary. Maybe most people of my age had a somewhat higher one, but my career as a scientist had started rather late, as there was nothing really abnormal in my situation for the first time. This contrast played a dominant role in my relations with Britain on the one hand and France on the other.
You mean from then on?
Yes, from then on.
Were you responsible to any single person at the Cavendish?
Not at the Cavendish, although it was understood that Feather in practice was the leading nuclear physicist left at the Cavendish, but we were in no way responsible to him. We were responsible to the committee in London, and in the committee in London it was Chadwick especially who was in charge of us.
You mentioned that you got a positive result in mid-December.
The completely positive result was obtained, I think, by the 16th of December. The result was very simple, subject to all the imperfections of the experiment — and I insist that there were quite a few imperfections. A really scientific experiment should have meticulously gone after all sorts of corrections and not just say, “According to our estimate this correction has such and such value. And besides,” we would say, “it doesn’t matter because we are looking for a 20% effect, and the correction is a 3% effect.” But, of course, if you pile up enough corrections in one direction, then you destroy the result — as in the previous episode I told you about yesterday, if you are unlucky. So our result was not a strict scientific proof, and Chadwick with his wonderful sense of language, in the British White Paper, used the expression: “They obtained strong evidence …” I asked him about that expression in 1966. He said, “Yes, I said that. Very strong evidence — I would say that again.” But he never used the wording, “They proved that …” He said, “There is strong evidence that …” Now what we obtained strong evidence of was that more neutrons were streaming out of the sphere filled with the mixture when the mixture was in than when the mixture was not in. And according to the formula I had developed myself in September 1939, this was a positive proof that the mixture in the sphere was of a nature to sustain a chain reaction, and the reaction would actually be self-sustaining if there was enough of it.
We didn’t put the whole of heavy water in one experiment. Our experiment contained something like 120 liters of heavy water, and we know now that to obtain a self—sustaining chain reaction with natural uranium and heavy water, one has to have about 25 times more than that. So we were still far from the real self-sustaining chain reaction, but the proof was there — or strong evidence. The Germans obtained a similar result, also with heavy water, about a year and a half later, in mid-1942. And in Irving’s book, it’s remarked that they were the first people in the world to obtain the actual multiplication of neutrons. This is not quite true. Some of Fermi’s experiments with graphite by that time were already at that level, and our experiment was of course 18 months earlier. I might concede, without going into details, that probably Heisenberg’s experiments were more accurate than ours. But this rough 18 months’ headstart was ours all right.
You presented the results at the Maud Committee about January 8th.
Yes. This, of course, was a very memorable day. In the morning Halban presented the results, and then occurred a rather interesting interlude. I’m sorry — it’s malicious gossip — Halban knew perfectly well that, no matter how much the scientists would be impressed, the industrialists would not, because the industrialists were not going to respond to a recipe asking for several tons of a product, of which there were 40 gallons at our disposal and very little beyond that in the whole world. So Halban insisted that there were ways of obtaining chain reactions without any deuterium compounds, just with ordinary hydrogen; and he mentioned certain favorable secondary effects which might be gained by using not the water, for instance, but compressed hydrogen gas. He put forward a definite hope that these effects would be enough to produce a self-sustaining chain reaction.
I knew perfectly well at that time, by my sense of the orders of magnitude, that there was no hope of obtaining a chain reaction in that way, but I kept my mouth shut. And this interlude is still in the minutes of the Maud Committee, of which I have a copy now. In the afternoon Halban went to confer with one of the members of the Maud Committee, Dr. Slade, who was also the director of research of I.C.I. The afternoon was spent in the I.C.I. headquarters in the Nobel house in London. And then he insisted far more on this aspect of the question. Many many years later, some sworn statements were made before the American authorities about priorities and patent values. In one of them, Michael Perrin said that, on that day, Halban explained how chain reactions could go with compressed deuterium gas. It was, of course, so incredible after the war that this possibility of using ordinary hydrogen with natural uranium could be seriously discussed at that stage. I suppose it was a genuine confusion on the part of Perrin.
But the fact is that I remember perfectly well that it was not deuterium gas but ordinary hydrogen gas which was mentioned on that occasion. And Halban was already then acting more and more resolutely on the assumption that academic colleagues on the Maud Committee are all right but the real business will be on this side from this very afternoon onwards. Not much later on I reflected on this paradox: on that day we appeared before the Maud Committee in the position of alchemists who had achieved the philosopher’s stone. And characteristically, he soft-pedaled it. For him the tie-up with I.C.I. was far more important. Still later, Bretscher had occasion to ask me: “Listen, why were you silent all the time? Why couldn’t you explain?” Well, the relations between Halban and me were such that when Halban was taking the lead at a public meeting, I had not to speak until spoken to. There was no longer any difficulty with the English language, but there were other difficulties.
So this meeting was January 8th, and this became a turning point in the work.
Oddly enough, no. What followed, was a complete anti-climax. After we made our experiment, what next? We puttered around a bit with carbon, a bit with various secondary effects through all the first half of ‘41. The Irving book on the German effort says casually that the Germans had mistakenly concluded that carbon couldn’t work, and then it remarks that Halban and Kowarski at Cambridge arrived at the same conclusion. This is not true. We did not arrive at any such conclusion. I think our carbon work simply was not conclusive. There were vague indications that carbon was just at the edge of working; it might or it might not; more experiments are necessary. Meanwhile, heavy water is a sure thing. This, of course, was true.
We’re resuming now after many hours, and we were just talking about the period in the first half of 1941. You were characterizing the work of that period.
Yes. I would like now to sum up the state of things about, shall we say, mid-1941. In July ‘41 the Maud Committee met to produce a report which turned out to be its final report, because the committee was abolished soon after that. By that time Halban and I, starting from our somewhat different viewpoints, began to arrive at completely different conclusions about what should be done next. My view was that nothing much could be done in England. It should be continued in the United States. I considered that in the United States the effort had not yet started at full speed, but it would start very soon, and that meanwhile since we were in some ways one jump ahead, we should cash in on that situation to secure us a good place in the first ranks of the continuing American or Anglo-American effort. I wanted to cash the chips we had won so far. Halban wanted to continue the game. That was his way. I visualized things as a future cooperation in which we would work with the American scientists, above all Fermi, and in some ways it was the dream of my life to work one day under Fermi. This dream, I’m sorry to say, never came true. Halban did not want to work under Fermi. He did not want to work under anybody.
If my paradise was the high—not academic but high scientific achievement world — Halban’s paradise was the industrial — government complex which under Churchill was ruling England; and the way to this complex for him lay not through the academics and their influence on the government, but directly through the industrialists. So all sorts of conversations went on, which I was no longer on, about the industrialists moving in and taking over the effort — if not on the explosive, at least on the future peaceful reactors. Halban was to be the star scientist and the passport to this position were the patents. I was always against the patents, so this began to drive a sharper and sharper wedge between us. Halban spent a lot of time henceforth with the I.C.I. people, and the spirit of some of these meetings is very well told in the British book, The Birth of the Bomb, by Ronald Clark;  he mentions there one meeting which took place in the Nobel house and comments on how naive were their ideas about how they could move in and play a role in the future industrial exploitation of atomic energy.
Clark is a shrewd man, and he breaks off his story at precisely the moment when this naive crowd had taken over and started working according to their naive ideas. Clark says that their ideas were naive quite justly, but then he becomes diplomatic and clearly doesn’t say that they actually had taken over very soon afterwards. This was done in a far more resolute, and yet diplomatically gentle enough way by Margaret Gowing.  If one reads Margaret Gowing’s book with one’s own knowledge of what was happening in those days, one can read a lot between her lines — not that a lot of reading between lines is necessary; there is quite a lot straight on the lines. Margaret Gowing does say that the Maud Committee was one of the most successful committees ever assembled, and then the chapter after that is called “The Doldrums.” So it’s quite easy to appreciate what had really happened. Anyhow Halban was very much in these councils with the I.C.I. preparing the future takeover.
By the time the Maud Committee submitted their report in July ‘41, the conclusion was still that there should be a tie-up — on the British basis alone. Terrific sums of money were mentioned, at one moment something likes 55 million pounds, if I’m not mistaken, which of course was rather ludicrous considering what was spent in America later on. I’m not quite sure of that figure. It was to be checked in Margaret Gowing’s book. So although the Maud Report made very definite recommendations for establishing close cooperation with the Americans, a very significant part of the Maud membership — the industrial researchers and some of the scientific people, mostly those of German origin — were in fact already then of a different opinion.
I remember rather vividly one conversation with Halban in August ‘41: he informed me for the first time of the negotiations for the takeover by I.C.I., which aimed at the creation of a special section of the Department of Scientific and Industrial Research to be put under Wallace Akers, who was in peacetime one of the heads of research at I.C.I. His deputy would be another I.C.I. man. So in fact the “Directorate of Tube Alloys” was to be a front for I.C.I. within the government. This very strong connection between an industrial concern and the government was quite a current thing under the Churchill cabinet. Halban had just come to Cambridge from one of these current planning sessions; he was now ready to inform me that our salaries under the new regime were to be substantially increased. At that time they were still at the level I have mentioned before: 600 pounds for him and 400 for me. He said apologetically that if one does increase the salaries, then because of the quickly growing confiscating income tax, the ratio of one and a half would have to be seriously changed.
The higher you get, the bigger becomes the nominal spread of the ratio. He said that he had proposed for himself 3000 pounds and for me 1200 pounds, hurriedly explaining that the real after-tax difference would be a factor substantially lower than two and a half. Then be became even more apologetic and said that I.C.I. turned that proposal down and offered to him only 2000 pounds and me only 600 pounds. So the ratio of one and a half between us in I.C.I.’s eyes became three and one third. I concluded from that that, for I.C.I., the cherished academic symmetry between Halban and Kowarski no longer existed. I’m deliberately dwelling on these sordid arguments — on the whole I always accepted the American point of view that money has a spiritual value. Money values so often are the true indicators of the underlying situation. A lot of things happened at that time which I learned later on from historical books. For example: a couple of months later, the American government officially proposed to the British government to set up a joint effort on everything atomic and to produce the fissile material in joint factories established in Canada.
The British government, after a certain deliberation, turned that proposal down. It’s lucky that I didn’t know at the time that this proposal existed. I don’t know what would have gone through my head if I knew that it was made, and was turned down. Frankly, I can say now today that this refusal was one of the most incredible pieces of folly I’ve ever heard of. I already said that, in my opinion, not only Halban and myself but also the British government were in an extraordinarily lucky position, owing to all sorts of circumstances — the Frisch-Peierls memorandum and our own work and a few other things and Chadwick’s ideas — and there was this incredible opportunity of cashing in, which would quite obviously evaporate very soon. The opportunity was thrown away. Margaret Gowing’s book tells the story in some detail, and it turns out that the people who proposed to turn it down were in no way ill-intentioned or criminal. It was an honest mistake on the part of many. Curiously enough, one of the reasons invoked was security; that British security was so tight and American security was so lax. It’s rather a wry joke when one thinks about that, knowing what happened afterwards. It was a period when the work in the Cavendish was sort of grinding to a stop.
Then in late ‘41, finally the takeover by the new organization, which was I.C.I.-controlled, was complete. The Maud Committee was dismissed. There was no longer a policy committee and a technical committee; there was only one committee. Halban was on it; I wasn’t. Halban hired a few more refugee scientists. He had not quite got the 25 graduates he was always dreaming of, but he made a big step towards this shining goal. Then in October ‘41 I began to discuss things with Oliphant, who was very disgusted by the way things had turned. He had just visited America. Oliphant was held in high esteem by the Americans, because Oliphant was the first who had performed a nuclear physics experiment with separated isotopes a few years before; and he was personally friendly with Ernest Lawrence, and he knew that the Americans wanted to cooperate. He said, “I bet they will now send a team of British scientists consisting of Franz Simon, Peierls, Halban and a few industrialists.” That’s exactly what happened. That team went to America to negotiate for cooperation with the Americans in January of ‘42. Chadwick was asked to join and turned it down on his usual health reasons. But there they went and made a few mistakes. For example, Akers, the head of Tube Alloy Directorate, conducted at first the negotiations, I’m told (this has to be checked), from the I.C.I. office in New York. Halban presented the Cambridge results as if they were absolutely solid, fully up to all scientific standards, scientific experiments, whereas I was always vividly aware of the fact that it was a credible enough demonstration, but not a complete scientific proof. His claims were met with some incredulity by the American scientific community.
Margaret Gowing made a remark somewhere in her book that Peierls tended to lecture to the Americans. It is not a remark of her own; she quotes somebody. Many years later I asked him about it and Peierls with very good humor said that in his opinion there was no foundation for this remark. It doesn’t surprise me. Sometimes one doesn’t notice these things in oneself, as I know only too well. I have talked to many American scientists since then. On the whole the impression this expedition made was that of a combination of somewhat ambiguous-looking, private capitalists masquerading as government officials, with a few scientists who were no doubt worthy scientists but who seemed to be not quite aware that an effort on a rather larger and more rigorous scale was already well underway in America. There was a certain lack of contact … things somehow didn’t click. They came back in the summer of ‘42 and said that America refused to cooperate simply because they were an uncooperative people obviously. This was perfectly true; the Americans did refuse to cooperate. The moment of profitable advance of the British over the American effort, which was so obvious in the fall of ‘41, by that time had passed. And on the whole I think the Americans were quite right to take the attitude which they did.
The Americans involved in the negotiations were Conant and Bush?
All this is told in the books. I think you could just as well read the books as a check on my memory. My private opinion is that Halban was considered by the refugee scientist community — Wigner and so on, possibly Fermi — as a somewhat wayward son of the Central-European scientific establishment but still a member of it, and that he certainly would have to be chastised, but by the community itself, not by the outsiders. And it was certainly not my job, of a junior man who was considered to be Halban’s assistant, a somewhat unschooled and obstreperous assistant, to spread the idea that perhaps our experiments were not as completely precise as they used to be presented. By that time it became quite well known that Halban and I disagreed on many aspects of the value of our work and so on.
In fact, it was Peierls who raised the alarm in late ‘41. He said, “The fact that it is now becoming widely known that Halban and Kowarski are not in agreement does no good to the community.” But the fact that the American scientists did not agree with Halban and that I didn’t either, did not mean that the American scientists agreed with me. They could afford to be in disagreement but considered that I was in even a more questionable position. This remark of Fermi’s on a meeting with Urey in March ‘43, to which I alluded before, was about the only manifestation of a certain approval of my attempts — that’s the word — to bring our work somewhat closer to the standards of scientific seriousness. Halban came back and wrote a report to the British government.
He described the quickly growing size of the American effort in somewhat patronizing terms, saying that here was the usual American gigantism; in Chicago there are already 120 trained scientists, a completely idiotic scale of effort — it’s not necessary — that on the whole he thinks the British (including ourselves) are still in advance, and the best thing to do is to establish a purely British outfit in Canada which would quickly impose itself on the attention of Americans and a very nice cooperation would then be established. This report was quite official. He still was playing completely fair with me as regards the official position and he offered me to sign it with him. I refused as politely as I could. I don’t remember what terms I used, but I think I did convey the meaning, which was this report was, shall we say, a little misleading. That was the end. The breach became official. That is: Halban began to prepare to go to Canada, to establish the lab in Canada of which he would be the first director. The decision of whether I would go or not was suspended. The last half of ‘42 was a rather unpleasant time for me. I received a proposal to go to Canada in order to see whether the cooperation is possible between Halban and me. There was always a tendency to consider our disagreement as a purely personal rift. And in case it was possible, I would be finally approved in a position in Canada and my family would be brought over.
But it was proposed that I should go first without my family, and I was the only one in that position: everybody else went with their families if they had any. So I said: I’m afraid I cannot accept this proposal, which looks like my going on a kind of probation. The true difficulty between Halban and me was not a personal rift at all. We always had personal disagreements, and we always managed to work together as long as we had the same ideas on what had to be done. I was not against Halban as a person. I was at that time against the whole British Empire, which supported Halban’s policies. The Tube Alloy people could not imagine that size of rebellion. They concluded, quite rightly, I think, from their point of view, that I was a dangerous element in the whole situation, and it was finally decided that a team would go to Canada and I would be left behind with a few collaborators in Cambridge and putter with what I could. There was a picturesque episode of the team refusing to go without me and being finally talked over: “Be reasonable. Wartime and all that.” It’s told on the whole, I think, in the right way in the Margaret Gowing story. I will not go into that. I learned quite a few things on that occasion about the protest movements started by academics and intellectuals and what happens in these movements when the real whip is cracked over them. Halban left sometime late in the fall of ‘42 as an advance guard of the new project. He started this lab in Montreal, and took the bulk of the team, which had become more or less my team because in the whole of the year ‘42 Halban was hardly ever in Cambridge anymore. I was the deputy leader of the group in an acting leader’s position all through that year. In January of ‘43 most of them sailed away, and I was left behind with a few collaborators, including Kemmer, who refused to go with the team on purely moral grounds.
On the basis of disagreement with the decision?
He considered that what was happening was immoral, and he preferred to stay in Cambridge.
Immoral? I know your reasons for not wanting to go. You regarded it from the personal point of view.
By that time I was nicknamed “leader of the free Halbanians”. There were some sympathizers with free Halbania movement. They sailed away in January of ‘43, and the most incredible story started of what happened to this group in Canada. For nearly a year and a half they had nothing to do. There was no cooperation with the Americans anymore, because just at the time when Halban was starting in Montreal, General Groves took over all of the American atomic effort, and all cooperation ceased. I might brutally add: and quite rightly. There was no need for cooperation anymore other than purely political. Individual British scientists could bring in quite a lot. Quite a few processes were developed in Britain before they were developed in America — for example, the making of very pure uranium metal was first developed by a British chemical engineer. I’m happy to mention his name, because he was completely forgotten later on. He himself was somewhat obstreperous. His name was Crawford. Peierls, in spite of certain — according to some observers — unfortunate tendencies to lecturing, would have been and was really a valuable addition to the cooperation.
Franz Simon, who at that time began to be called Sir Francis Simon, was a first-rate thermodynamic physicist, very first-rate. All of this would have been valuable. In our own group my opinion was that by that time Fermi’s work left ours far behind, not only in quality, which was always higher for reasons I’ve already explained — he worked in a more leisurely, more academic way and besides he was Fermi — but simply time had passed, and by late ‘42 he was obviously far far ahead of what we had ever done. And the news of the first chain reaction at the end of ‘42 reached us in England pretty quickly. So in my opinion the Americans were quite right not wishing to be involved with this bunch of international scientists, which would make all the problems of security and so on far more complicated. The gain derived from it would be too small. Of course, the group established in Canada viewed the situation quite differently. The sudden cutoff from the American cooperation left them practically without a single Geiger counter. For nearly a year the whole group stayed in some hired rooms, on Simpson Street in downtown Montreal.
This period I know only by hearsay — I was in Cambridge. The year ‘43 was for me personally a year of frustration in the sense that I was left behind, although I knew from various grapevine sources and so on that the Montreal experiment was not running very well, but I considered that sooner or later it will all be straightened out and finally the heavy water work will be resumed and this time without me. And that after a while would justify completely Halban’s contention that I was essentially a helpful assistant for a while, who was in no way indispensable and I would fade out completely from the scene, not only for the future but also from the acquired past. By the late summer of ‘43, the first news began to appear that the doldrums in Montreal began to cause serious concern among the British authorities and that some kind of move to change things was being envisaged.
The British politician, Sir John Anderson, one of Churchill’s closest men, went to America to ask what was going on –- “Why don’t you cooperate with our people?” And, as I was told, he more or less received the reply: “Well, why don’t you send some of your best scientists here?” He asked whom they meant, and the answer was: “Well, Chadwick and Oliphant.” Oliphant, during this whole year, was very restless, and although he was the first to encourage me in my firm stand for my ideas about what the cooperation between America and Britain should have been, and I think he agreed with the reasons for my disagreement with Halban, his restlessness stood in the way of his being taken seriously as a power. Back in late ‘42 just before his departure from Europe, Halban sort of made approaches to me, displaying a genuine pain that my behavior hurt him more than its consequences hurt me. He said, “Why are you standing so stubbornly on your own point of view? You are practically isolated. Who are your supporters? They are very few. Who are the people who more or less believe in you? Chadwick, Cockcroft, Frisch — that’s about all.” I looked at him somewhat astonished and I refrained at the last moment from saying, “Thank you.” That he would have taken as a supreme insult, so I refrained. Chadwick stood firm by me all the time. He was dismayed when the rebellion started just before the group’s leaving Cambridge and tried to convince me not to influence my people. I said that I was not aware that I was in any way influencing them. I certainly never asked them to go on strike for my sake. Possibly I put my own points of view in a more convincing way than it was, perhaps, political to do.
I passed through a few sordid episodes of intercepted letters or misrepresentations — how in early ‘43 the group in Montreal was told that I was made an honorable offer to go to Montreal and I had turned it down. This offer had never reached me, but they ou1dn’t know it. All this is standard apparatus of power politics; all means are fair in war. A far more important event was that when Chadwick and Oliphant were told by Sir John Anderson that the Americans wanted to see them, they left; and it was quite obvious that a new chapter was about to start. Chadwick went in August of ‘43 to America, came back. He saw me in November of ‘43 and I remember our last conversation in London. I remember we were near St. James’s when he said, “We have lost two years between the autumn of ‘41 and that of ‘43. Now we have to try to repair what can be repaired. It’s of course far too late for many things. The time has been lost.” Then he also told me that at first they would attend to the more urgent business such as British participation at Los Alamos and then the turn would come to Montreal. Until then there would be nothing new, but then he would see what to do. And Halban, of course, has to be replaced in Montreal by somebody in whom America could have confidence as an established British scientist. I said, “Well, obviously Cockcroft.” Chadwick said, “You always think you are so clever. Do you think you are the only one who thought of that? But, you know, so far he has refused.” Chadwick went off. At the same time there were some events in my private life which took my attention off these things. And also, at exactly the same time, Bohr arrived in England, and I had my first meeting with him.
He took a bit of paper and began to sketch for me his ideas of the cross sections at various energies of neutrons and so on, with these beautiful little drawings he used to make, because his ideas were always immediately understandable at a glance. He was not a mathematician. He was a man of ideas, not a man of formula, and he could express his ideas very well by little drawings. I still have them. The winter of ‘43-‘44 was partly dominated by my private affairs and partly by patient and yet somewhat impatient expectation of the news from the other side. In February of ‘44 the news came. Cockcroft was to be appointed as the director of Montreal; and as Chadwick put it, “And Kowarski soon will receive an order to come immediately to America and then to Montreal.” As it turned out, it was not that soon. Cockcroft was somewhat delayed. He went there in May, then came back to recruit the personnel. Finally I left Cambridge in July ‘44 bound for New York and Montreal. This time I also had to leave without my wife and child but for completely different reasons. The invasion of Europe had started; shipping was extremely scarce; and there were priorities, and I went with a certain order of priorities and my family joined me about three weeks later. Cockcroft’s family also joined him about three weeks later — I think in August of ‘44. There was a delightful conversation with Cockcroft.
I went to Montreal without asking what I was going to do there. I only said, “I only wish one thing — to see what I can see of the American researches as early as I can.” That was — I wouldn’t say my only condition, because I didn’t put any condition — my only request. I said, “I’m not interested in rank. I’m not interested in what I’m going to do. I trust Cockcroft for that completely.” When I arrived Cockcroft said, “Well, we decided we’d first have to build a small experimental heavy water pile, and we thought that you might lead the project.” I remained slightly gasping. It was a considerable change from my previous position. Cockcroft said somewhat alarmed, “Well, don’t you like the proposal?” I said, “Well, I think I can do it.” That was that. Halban by that time was no longer director. He was demoted to head of the nuclear physics division, a position which turned out to be somewhat nominal, because he spent most of his time in New York.
With what, the Columbia group?
No, no — private affairs. By that time his wife had become Mrs. Placzek, and he had married another lady, a French heiress, a very remarkable woman, by the way. She is now the wife of Sir Isaiah Berlin. The first Mrs. Halban was rich; the second Mrs. Halban was really rich. Still she was and is the kind of woman one could marry even if she was not rich at all.
What had you done in Cambridge after the group left? Was it pretty much the same kind of work?
I taught — there were a few new assistants to be trained.
There was no clear assignment?
I did a thing here and there. I continued these experiments about which Fermi was so grudgingly complimentary. I did a few little things, such as, by very elementary means, showing that the relative yield of barium as a fission product is about the same whether the fission is by slow neutrons or by fast neutrons. I performed an experiment measuring the resonance absorption by new methods which were carved out of a proposal by Frisch. This was one of the very rare occasions on which Frisch’s reasoning was wrong. Frisch proposed to me a method to measure, I think, the thermal absorption by uranium, and I proved to him in five minutes on the proverbial back of an envelope that it was no good for measuring thermal absorption. But, as Frisch did not suspect at that time, it was quite good for measuring the resonance absorption. He immediately agreed to my arguments, and I thereupon performed the experiment. That was still in late ‘42 before the group left. I had to tie up some loose ends.
On the whole the period between my having been marooned, through a definite abandonment of all ideas of my coming to Montreal, and the new start of ideas of my coming to Montreal was not much more than two or three quarters of a year. Besides, toward the end of that period, as I said fore, I was occupied with my private affairs. So I was established in Montreal as the head of a small group which was given this very glamorous assignment. It was not an unmixed blessing. For instance, Cockcroft, as turned out later from his notes, did not consider me at that time any longer as a physicist. He considered me as a kind of engineer who would be very good for leading this construction. This is somewhat contradictory, because also had a report of somebody’s private conversation with Cockcroft (in late 1943 or early 1944) in which he said that “we definitely consider that Halban is a promoter and that Kowarski is a physicist,” which was, I think, a rather crude assessment of the situation. And yet later on he behaved as if he did not longer consider me a physicist. It is a confused picture in which probably some role was played by the fact that Cockcroft’s own position in this respect was academically a bit dubious. Formally it was all right.
He was the holder of the most prestigious physics chair in Cambridge, but he, after all, came from pure engineering, and his great feat was the building of that electrostatic generator, with which he performed the first successful artificial nuclear reaction. So his own standing as an academic physicist was somewhat dubious. He may have been vacillating on this subject when it came to me. Cockcroft was an ideal boss, who made quick and firm decisions. One could have a conversation with him of three minutes and would come out of it with a clear “yes” or “no.” His “no’s” were somewhat more frequent than I would have liked, but after all, when one feels a firm and competent hand over oneself, one is rather pleased even if the man says “no” a shade too often. I was given a strictly limited role, but this role suited n perfectly. I was given limited means but of first quality. I only had to state a request, and a serious effort was made to do what could be done about this request. My first request again was to go to Chicago. There were some visa difficulties.
It took about three weeks and I went to Chicago in September ‘44, where for the first time I saw a working atomic reactor. Herb Anderson showed me the CP 2 pile. I was led in the room, and I saw. It looked very unprepossessing. It was a big cube of painted concrete, and Herb led me straight to it and said, “Touch it. It’s warm.” On the same occasion in September ‘44 I met Zinn for the first time. Zinn showed remarkable patience with me. For two days we were discussing his own heavy water reactor and what I should be doing with my Canadian project. He proposed a few ideas which I adopted. Some other ideas were my own — there were differences between some of his approaches and mine. His reactor was not zero energy; it was 300 kilowatts. Mine had to be zero energy, so that mine had to be simpler; and there were various ways of making the simplifications. Zinn is of rather caustic temperament. He was wonderfully patient with me, and I had a very deep gratitude to him, and remained very good friends for many years after that. I also met there for the first time Phil Morrison. We had a pleasant and interesting contact. That was only a few days. After the trip I was ready to make my official proposal on what the reactor would look like, the personnel, what materials were necessary and so on. I made the official proposal in early October ‘44. Since the reactor started working in early September ‘45, it means that the whole project from its official inception took 11 months. That was the pace at which we worked at that time. Well, what can I say about my life in Montreal?
Say something about the group there, what the atmosphere was.
In general, or my own team?
Your team in particular and then also the general atmosphere, the type of relationships and how the group held together.
Cockcroft was universally admired and I would say loved. The Halban era was considered as a somewhat unpleasant initial period. It was, I think quite rightly, laid at the door not of necessarily Halban’s personality but of the unpleasant circumstances of these 18 months in which Halban’s stewardship had passed from early ‘43 to the summer of ‘44.
You mean because of the lack of cooperation?
Yes. In a deeper approximation, this lack of cooperation was, I think essentially due to the mistakes made mainly by Halban himself. This was, of course, not universally accepted. I was (it’s a human weakness) sometimes apt to dwell on these things. Pontecorvo in particular was very impatient with me. He sort of considered that all this should be forgotten, and I should stick to my job. He, in fact, was the man who introduced me to the fundamental ideas of pile structure as it had been emerging from the American experience since December ‘42. He did this in a sort of lecture in a single afternoon, which was quite enough. The ZEEP itself was calculated again in a day or two by a very young theoretical physicist, Ernest Courant, which shows that a day or two by a really good person is worth more than a year by a lesser one. The Montreal lab at that time — I don’t quite remember the numbers of its staff. All this can be found in Mrs. Gowing’s book. It had a “divisional” structure.
The physics division was still headed by Halban more or less nominally. Alan Nunn May later on became the acting chief of that division. There was a general physics division, a chemistry division, an engineering division and soon. My ZEEP project was a little bit in a corner, because the main effort was directed toward the much more powerful heavy water reactor, which later on became known as NRX, and which for several years offered the most powerful neutron flux available in the western world. But here I’m anticipating. The atmosphere on the whole I would say was that of a happy activity. The group was not always happy.
We lived very much among ourselves. The British Canadian project was far more British than Canadian. There were some very good Canadians who later on became prominent in the Chalk River project. Chalk River itself — I paid the first visit to it in March of ‘45, where already I found a sort of groundwork for the ZEEP building. What else can I say? My group cut across completely the Divisions. At first it was under Engineering, then was transferred to physics. But I didn’t report to any Division head. I reported directly to Cockcroft. I remember when I was finally added to the Physics Division I came to see Alan May, and he told me that he felt like the British king in the Bernard Shaw play, “The Apple Cart,” where the American ambassador comes and says, “We decided to join the British Empire.” On the whole I was considered to be on a special project, very urgent, not very academic, more a construction job. I had some of the most lively people in it, some pure physicists. I myself was not considered to be a pure physicist but more of a master builder.
Of course, all pretenses to my past as a neutron physicist were by then totally irrelevant because the amount of information on nuclear physics that began to flow from America was so enormous that whatever my past contributions and whatever I could contribute any more didn’t count. I was a member of a few groups for future planning, in particular the Graphite Group. I remember that the first meeting of the Graphite Group included a younger British physicist by the name of Dunworth, who is now the head of the National Physical Laboratory at Teddington near London. He was particularly close to Cockcroft. They worked together on radar during the war. Cockcroft asked Dunworth to report on the first meeting of the Graphite Group. I was present at that conversation. Dunworth started reporting and eventually came to this immortal sentence: “During this meeting Kowarski was speaking most of the time, partly because he was the most competent person present and partly for other reasons.” I think this was the beginning of my deep friendship with Dunworth. Dunworth himself said that one of the first things he heard was my system of classifying the degree of secrecy of documents, and the most secret document I said was marked I.C.I., meaning Ighly Cecret Information.” I added, “That was Lord McGowan’s own spelling.” Lord McGowan was the head of I.C.I., and I implied by that that I didn’t think very highly of his educational standards. It was entirely gratuitous, of course, but it was good for a joke.
About the social atmosphere and the general feeling of togetherness of the group, were you that much in contact with other teams which added up to a real sense of community that was self-contained?
Oh, yes, very much. In fact, we were a little too ingrown and all thrown on one another. It was a very lively and, in cross section, very young group. The leading persons, like the Division leaders, or myself (I was never a Division leader, but I was considered as one of the leaders), they were all at most in their middle thirties. In ‘45 I was 38, which made me practically a veteran. The year of the ZEEP construction, between the fall of ‘44 and the fall of ‘45, was very busy; and yet, as it has been usual in all my very busy periods I seemed to have an infinite amount of time on my hands. When things are going very fast and very efficiently, then the man on the top — and I was on the top of that team — finds that he has little to do finally. I made several trips to the United States. Three times I went to see Chadwick in Washington. On the 7th of August 1945 I received a cryptic call from Cockcroft’s secretary. It turned out that at that time I was the senior scientist on the Chalk River site — not for long but for a few weeks because ZEEP was nearly finished by that time. On the 6th of August I received the cryptic telephone message: “President Truman just made an announcement. You can now tell people.” That was all. I knew, of course, from my previous contacts with Chadwick that the Trinity test was imminent. I had a conversation with Chadwick at the end of June. Chadwick had told me that there unfortunately was no longer any hope that the bomb would not work.
Did he put it that way?
Yes. He considered that if the bomb did work, then Britain must have the bomb. It would be better for everybody if the bomb did not work. Unfortunately, there was no longer any hope.
Did he speculate about the use of the bomb once it was built?
At Montreal we were far too remote for that. There was a rigid compartmentalization, and most of the lab was at the task of building that bigger reactor. Chadwick visited Montreal from time to time. I remember one moment he was frowning. He said to me that things were not going as fast as they should. I said, “Well, you know, after all, ZEEP is advancing. Maybe we will be late a couple of weeks, not more.” Chadwick turned and with complete ferocity said, “I am not talking about ZEEP. ZEEP is going all right. Why do you think that only what you are doing is important?” That was his way of praising me.
Were you aware during this period of the dimensions of the rest of the project?
Well, Chalk River was a building site essentially. ZEEP was about the only thing which was going on already as a full-scale technical thing. There were a few others, water purification plants and so on.
No, but I mean Los Alamos.
What about Los Alamos?
Were you aware of what was going on?
You never visited, though.
Never. The only place which I had visited was the Chicago laboratory.
But you knew of the whole project. Did very many people in Montreal know of the whole project?
Well, we got quite a lot of reports from it — of all kinds. Not on the explosives. That was rigidly excluded.
That’s what I meant.
Yes. On the slow neutron work. But there were grapevines. On the whole, there was this wartime ethics that it’s neither good, not very healthy, to show too much curiosity.
But what interested me is here the telegram comes with an allusion to Truman making an announcement.
This was by telephone.
Yes. And that implied that you knew what was planned.
Yes, I knew it from Chadwick mostly by very few allusions. When was the Trinity test? The 16th of July, I think. We knew very soon that the Trinity test was successful — by grapevine. I went to see Cockcroft and said, “Well, now obviously the post-war era is starting, and there are a few points about our return to France and so on. So since there will very soon be official disclosures, I would like to suggest that such and such things be presented in such and such way.” Cockcroft was quite shocked that I knew that the time has come that there will very soon be official disclosures. I was not supposed to know that. He sort of asked, “Well, where did you get that news?” said, “Well, one hears this and that, and one puts two and two together. Maybe I’m all wrong, but that’s what I think. This is my conclusion, and I sort of expect that there will be an announcement any time.” So we knew very soon by grap1ine that the Trinity test was successful and the bomb was soon to be tried over Japan. I knew something of it already from Chadwick again — about the ideas, whether the bomb should be thrown on a Japanese city and all these ideas about internationally supervised demonstrations and so on. Chadwick took the view which, as you probably know, was also taken by Compton, Fermi, Lawrence and Oppenheimer, that there was no way of avoiding throwing the bomb on a city. These arguments have been vastly discussed in various books, and Chadwick more or less sketched his arguments to me — all in a very fleeting way and in a sometimes cryptic way. That was at the end of June.
That was on one of your trips to Washington?
If you want to continue now, it seems to me the one thing that we can touch on is the thing you mentioned in the kitchen about the moment of success of the reactor, the circumstances of it and your particular role.
Oh, that one.
Yes, since this is the culmination of part of that story.
The last month of ZEEP building was essentially the month of August, because ZEEP was launched on the 5th of September. With most of the group I started actually living in Chalk River or rather Deep River since mid-July approximately. It was quite feverish. They worked like mad, and Fenning was sometimes quite bitter about it and making dark allusions that I was driving my people too hard. I had never given them a single direct order. What Fenning meant was that in some way I influenced them with the urgency of the task in such a way that they were driving themselves very hard. I didn’t have to give them orders. They worked harder than me because they were more competent in the actual work, putting the thing together. By the second half of August they began to try out the whole system. It was a purely hydraulic preoccupation. There were a few gadgets. Some of the gadgets were suggested by myself. For instance, there was an interesting example of the kind of problem which may occur.
In order to know the level of the heavy water in the tank, we had no time to devise complicated optical arrangements — it had to be a gauge: simply a big glass tube outside the tank in which one sees the level of heavy water in the glass tube on a centimeter or inch scale. But then the question arises: what happens if somebody comes with a long pipe or something, and then turns around and breaks the glass tube? Then all the heavy water will gush out. So I suggested (it was the typical kind of thing at which I think I was good) that the tubing, the glass tube, should be surrounded by a wooden box with a plastic window going the whole height of it. It was rather unlikely that the same piece of tube would break both the box with the plastic window and the glass tube. So this was done. General Groves by that time once visited Chalk River and told me severely, “Are you the man who is building this damn fool unnecessary experimental reactor?” I said, “I am.” “Well, America gives most of the heavy water for it, and it’s very very costly stuff. You see that you don’t squander it.” That was my first contact with General Groves.
Straight out like this?
Straight out. I always respected him. I still respect him. Chadwick also impressed it on me. He said, “There should be no loss of heavy water at all.” I said, “You know, it can be reduced to a very small minimum, but in any real system there are always minimum losses.” He said, “Well, you should arrange so that the minimum is zero.” Kemmer produced a limerick which was duly typed and put on the famous plastic box: “When building a thing like a ZEEP/One thing in your mind you must keep/Do not waste heavy water/Anymore than you ought to/Because the damned stuff isn’t cheap.” Then came the great day. We finally decided that the Z-Day would be in the 5th of September, Wednesday. I reflected very soon afterwards that Wednesday seemed to be always the day of launching reactors. I don’t remember whether the 2nd of December 1942 was also a Wednesday. It can easily be calculated. It’s because after the weekend one realizes that one still has to do a few things, so that takes Monday. Then one puts it on Tuesday. And then on Monday one decides that one has still a few more last-minute things to do, so it finally comes on Wednesday.
The first French reactor was also launched on a Wednesday for similar reasons. The great day dawned, and my little group was dispersed at various measuring instruments, and my second in command, Watson Munro, who was more an electronic man, had to supervise a group of ionization chambers; my third in command, Fenning, had to be the general steward; and I didn’t know what I could do. Another of my little gadgets was this pump with a button. The pump was to work for three minutes, and then automatically it would switch itself out as a precaution against overpumping too high over the critical level. So I had to stand there and press the button and after three minutes decide whether to press it again. The whole pumping was to take several hours, so there was quite a lot of these three-minute installments. When it was decided to put me there, Fenning turned to Watson Munro and said very genuinely and with not at all faked anxiety, “Don’t you think he can do that?” After some hesitation they decided that I could.
Then on that day it worked.
We started out with the usual expectation that the theoretical calculations were somewhat pessimistic. It was calculated that the critical level would be somewhere between four and a half and five tons of heavy water. Incidentally, one can start a simple heavy-water reactor with far less than that — even, probably and under the best circumstances, slightly under three tons. But ZEEP for various quite legitimate reasons was not the optimum shape, so it was calculated between four and a half and five. But we knew that calculations were usually pessimistic, and we expected the criticality would be probably reached before the four-and-a half mark. But I counted without Ernest Courant. When he calculated, it was bound to become critical at the level he calculated. The result was that we were a bit short of heavy water. We didn’t foresee that we would have to pump that much. At one moment it turned out that we had to bring on the last reserve can of heavy water. (They were quite big.) We had to try with that one, and if that was not enough, then we would have to telephone Montreal that we needed more cans of heavy water. That would make in a way somewhat of a fiasco of the ceremony.
So I was vastly relieved when practically at the last moment suddenly there was this climbing of all radiation levels and so on. I think at that time there was in the circuit outside the tank something like three gallons left. So, as it is duly recorded in Arthur Compton’s book, The Atomic Quest, my secretary telephoned immediately to Montreal: “Operation condition reached at 3:50 p.m.” And that was that. Cockcroft came to inspect it three days later. As I already said, I think, to you privately, after the level was reached there was a general kind of quiet jubilation in the room. Quite a few people were present—an American delegate from the liaison office. There was my whole team and a lot of others. It was always reduced to the indispensable people, but one likes to be nice; the criteria for indispensability are a bit loose. Alan May, who was still my acting chief, declared that being a Frenchman I should receive an accolade and kissed me loudly on both cheeks. As I already said, at this same moment which was shortly before 4 p.m., Igor Gouzenko was about to leave the Ottawa Embassy with his collection of documents. I think he left at about five, so he must have been feverishly putting in his little suitcase all the documents.
How much later was it that you learned of that?
The Alan May case broke in early March ‘46.
By that time you were back home. Well, I think this is a good time to break. We’re talking now about post-war — that moment itself was the beginning of post-war, when you reached success with ZEEP. [pause in recording] I think I made a mistake the other day. Today is October 21st in late afternoon, and we are resuming for a while. We had just come to the point of the success, which was in what month of 1945?
And now you indicated you wanted to sum up the state of your situation at that time.
This is a suitable moment, because even before ZEEP was launched, I already had the vision that as soon as this is done, I will become overnight — I will stop being a promising youngish applied scientist and will become a veteran. This is exactly what happened. I became a man with a past and with a somewhat dubious future. I had two or more bad marks on my future. There was a certain tendency to consider me as a physical-chemical engineer more than as a nuclear physicist in spite of some obvious claims to this latter status. But my success in this purely managerial and building venture made the side of the practical engineer heavier than the physicist’s. This was immediately shown by one of the members of my team who joined it very late, who always said that building did not interest him at all; he was a physicist with a big “P.” And as soon as the machine started working, he told me in no uncertain terms (he was one of those uncomfortable phenomena amply described in English literature, a Britisher lacking tact) that my time was over and his time came because he was a physicist and I obviously wasn’t. That was one facet of the situation.
The other was that by that time Halban was completely out of the project. The reason he was taken out of the project is amply described in Margaret Gowing’s book, and I will not return to it. On the 1st of April 1945 he officially left the Montreal lab, where he already was hanging by a thread for several months, but this time it was official, and my acting chief, Alan Nunn May, gave me a nice chit, which was the official bureaucratic paper current in the lab: “Mr. So-and-So is authorized to remove from the lab a package of books” or perhaps a radio amplifier or something. So May filled ft in: “Dr. L. Kowarski is authorized to remove from the lab Dr. H. H. Halban, date April 1st 1945 (signed) A.N. May.” I still have this chit. And so in some ways the legend was spreading that Halban’s removal, which was, Heaven knows, due to reasons which had very little to do with me, in some ways I did him in. Kemmer, who is always playing with words, decided to propose a title for Halban’s autobiography. A few years before some British Minister, not terribly well inspired, declared to somebody else at the Atheneum Club, “We have decided to bet on the horse Halban.” So Halban immediately came to be known as “the horse,” which went well with his initials, H.H.H. He had the habit of strolling around the Cavendish and whistling one of the main tunes of Beethoven’s violin concerto. He whistled it in a somewhat strange way, including a few augmented fourths that should not be augmented, and this peculiarly distorted tune immediately became known as “The Horse Whistle Lied.” So Kemmer proposed a title: “Memoirs of a Horse, or How I Met My Heavy-Waterlew.” I’m dwelling on these little jokes to show that there was some aura about it, and people retained one thing — that somehow it was unhealthy to have Kowarski as a subordinate.
This was never stated by anyone outright, but I felt this cloud over me in many subsequent years. I already said something about the attitude of the central European refugee community to Halban and how the fact that I was opposed to Halban, although I was opposed to him in exactly the same way as they were opposed to him, was not approved by them. I was getting out of my role such as they saw it, in addition to my being an accomplice in his misdemeanor, and not as a deduction from it. So I entered my veteran era with these two marks against me: an increasing insistence on my being an engineer or a builder or a manager, but not a true-blue physicist, and also something about it being unhealthy to have me as a subordinate. The other thing was the crisis of my national status. I already explained before that I considered myself to be not a refugee but a belligerent citizen of France on a wartime mission. Hence it was obvious that I had to return and give France the benefit of my mission. Chadwick had offered to me at the end of ‘44 to stay in England and, to acquire British nationality thanked him. I thanked him and said that he was very perceptive in realizing that that’s what I would have liked but I couldn’t, for the reason I just mentioned.
So I was preparing to return to France with somewhat mixed feelings about it. I will say more about that in the next installment. Finally my private affairs went from bad to worse. My marriage was completely destroyed by that time. Divorce proceedings were envisaged. On the other hand, the attachment which would normally follow the termination of my former married status didn’t materialize, and I was suspended in a somewhat unpleasant void. Those were the last months of 1945. I had not much to do anymore in Chalk River. I was commuting between Chalk River and Montreal, and I learned that Cockcroft decided that I should spend the remaining weeks or months in the Montreal lab library and browse about and reflect on what is secret and what is not secret. I was also told that Cockcroft added to someone with a chuckle: “It seems that he has a remarkable memory.” This was the first inkling I had that Cockcroft was perfectly aware of the difficult position we would have in France with respect to the British Official Secrets Act and yet he was full of most generous ideas about how the recognized French contribution to the English project should in some way benefit France.
I asked Cockcroft at that time at one moment: “All right, I am now studying various things. Am I allowed to take notes and take them to France?” He said, “You should take no written documents to France.” I asked, “What is a written document?” He said, “Well, you know, a few consecutive written sheets. Of course, if you have a little pocketbook in which you write a few words to pin your memories on, a little pocket calendar or some diary or something like that, that hardly could be considered as a written document. For example,” he said, and drew out of his side pocket one of his black books which were famous all over England and Canada. He had a very small and meticulous writing, and these black books, which were roughly of the size of a paperback novel, would contain amounts of information about which people talked with admiring incredulity. “This could not be considered as a written document.” I thanked him for this information, and I didn’t ask him any more questions. As you know, my handwriting can also be quite small and quite legible.
Not quite as small as his. You need a glass to read it.
So here we come to the date of my departure. Joliot communicated with us not in writing but by verbal messages from people who had been recently to Paris and to Montreal. I knew that Joliot was founding an entirely new atomic organization in France and, without mentioning any specified job, it was obvious that Joliot wanted me there. This went along with my idea that the fruits of my mission should be made available to the French Republic, so I accepted this; and it became arranged that I would leave the project some time at Christmastime. In fact, we sailed from New York on the Queen Mary — my wife, my child and I — I think on January 5th. We had left Montreal by night train on January 4th, and on the morning of January 4th there occurred a curious episode. My former colleague from College de France, Charles Leblond came to Canada from France where he had taken an offer from McGill University, a biology chair, which I think he still occupies with considerable distinction. I already reported earlier that because of political and religious differences he never was quite in tune with Joliot. Soon after the war, he wished to obtain a chair in the University of Strasbourg for which there was another candidate.
The other candidate was a Jewish deportee, and in the atmosphere which prevailed in France in 1945 Leblond had no chance. That was the time when the obvious victims of the Nazi regime had all the rights, and Leblond being Catholic and rather rightist, found himself in a difficult position with respect to that candidacy. So he pointed out to Joliot that after all, without any false modesty, he probably was worth more than the other candidate; and Joliot explained to him that on the whole this was rather irrelevant. So Leblond said that he had this offer from McGill, and in view of this situation, he was inclined to take it. And Joliot said rather disdainfully, “Oh, well, if you are one of those people who want to leave France and go heaven knows somewhere abroad for reasons of personal pique, the way is open.” Leblond took the open way. I don’t think he ever had reasons to regret it. I’ve seen him several times after that in McGill, the last time in the spring of ‘67. And on this morning on the 4th of January 1946, I suddenly had an illumination of what it would be for me — to what atmosphere I would return in France. And it was so vivid that I suddenly thought that I was making an awful mistake. But it was too late.
We had to leave Montreal on that same evening. The baggage was already all crated and shipped to the pier in New York, and all papers made and passage and passports and visas. We were expected first at the French Embassy in London, then in France. It was too late to hold back. In the light of what happened afterwards I wonder whether my intuition of that morning on the 4th of January perhaps was worth giving a further thought, but it’s very difficult to say. I know what inconveniences I suffered from coming back to the European continent. I also know what benefits I have derived from it. It’s very difficult to say what the balance would have been if things had turned out otherwise.
To say nothing of the achievements of that period when you did go back.
I think that’s the thing I wanted to say.
Let me ask just one question. That’s quite a good statement of the transition period. Had any word come to you during the war or immediately afterwards regarding Joliot’s position in France? Was there any question in your mind about his role?
We knew that he became an orthodox Communist. It is a bit difficult to remember how things stood in 1945. The Communists were still our brave allies. The British, who were mistrustful of the Communists — and particularly Churchill — were always held back by their sleeves by the Americans, who wanted to be mediators between the progressive Russia and the reactionary Britain. The French government at that time was still de Gaulle’s provisional government, and his Vice President of the Council was a Communist. That was what the French called later on the three- party system. De Gaulle relied chiefly on a coalition of three political parties — the Progressive Catholics, the Socialists and the Communists. The official split with the Communists came much later, in May ‘47. So the fact that Joliot was a very prominent Communist intellectual did in no obvious way interfere with his very leading position in France, and his position at that time was something quite dizzy. He was the member of several academies. In ‘45 he was the head of the French science foundation, CNRS. And although he relinquished that post as soon as the Atomic Commissariat was set up, he still retained an enormous influence in it. In fact, in early ‘46 he was still almost the actual head of CNRS, although not nominally. He also held several chairs — no, one chair in Collage de France, and he had, apart from College de France lab, also the Ivry lab, which I described previously, and he would be the head of whatever lab would be founded under the Commissariat of Atomic Energy. He was really what is known as an orchestra-man. And since I was his star pupil I could be expected to be somewhere on the main floor of the whole show — in what capacity, I had no idea at that time.
There was no later discussions of his role during the war, of resistance or collaboration. Was there any discussion of this?
Well, we knew the frame of mind in which he was when we were leaving France in 1940. I described previously his ideas about the world politics and war developments, which were so uncannily right that I’m almost embarrassed to present them in a factual reminiscence with nobody else to vouch for the exactitude of what I say. We knew from the grapevine that in the very first months of the Vichy regime, he tried to act as a kind of adviser to the Vichy government as to what was to be done with French science under these conditions. I recognized in these attempts and this somewhat unstable leaning toward forces which were half leftist, half national, the danger of his becoming a fascist. But I was also quite aware of the fact that he had on the whole a healthy judgment and a very exalted moral sense; so I was not too worried about that. We began to receive the news that he got far closer to the Communist Party somewhere during the war. I know now from documents such as Biquard’s book that he became formally a party member, under conditions which were not exactly propitious for his continuing personal safety, sometime in early ‘42, which places this decision definitely earlier than the time when resistance in France became something almost fashionable. He was thereafter not a full-time Resistant, but his Resistance status was affirmed in a very irrevocable way definitely at a time when it was still very very unpopular and unhealthy. I never had any doubts of his moral courage, so I didn’t need this as a proof.
This clarifies the situation before you returned, and that was the final ingredient. You didn’t stay over in New York. You sailed directly.
No, the next day. The 5th or 6th of January, something like that. Halban left New York on the same boat, and the story went in the Montreal lab that Cockcroft said, “What do you think? Halban and Kowarski coming back to Europe on the same boat.” And he commented, “It’s a very large boat.”
David Irving, The German Atomic Bomb, New York, Simon & Schuster, 1967.
Ronald W. Clark, The Birth of the Bomb, London, Phoenix House, Ltd., 1961.
Margaret Gowing, Britain and Atomic Energy 1939-1945, London, Macmillan, 1964.