The German Atomic Bomb Scientists - ACS Publications

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Captives of Their Fantasies: The German Atomic Bomb Scientists Irving M. Klotz Department of Chemistry, Northwestern University, Evanston, IL 60208-3113 Background From the very beginning of World War II, American and British scientists were intensely fearful that the Germans would develop an atomic bomb, in which case “the war would be over in a few weeks… . There was therefore no choice but to work on [atomic bombs] in this country” (1). The possibility of a nuclear explosive became obvious after Hahn, Strassmann, and Meitner in 1938 recognized that the bombardment of uranium by neutrons led to nuclear fission. During the first third of this century, Germany was preeminent in physics, and was so recognized universally. The aura of that dominance carried over through the war. It seemed obvious that the Nazis had the advantage in intellectual talent and in a highly organized and determined dictatorship that could create devastating new weapons. When Allied troops landed in France in June 1944, they were accompanied by a scientific mission code-named Alsos, whose assignment was to discover as quickly as possible what was the status of the German atomic bomb effort. Ironically, even before the Western armies reached the Rhine, it became apparent that the Germans had not designed, let alone created, an atomic bomb. In fact they had not even succeeded to construct a self-sustaining nuclear reactor, they had failed in their efforts to separate the explosive uranium-235 from the nonexplosive natural form of the element, and they had never obtained even a trace of plutonium (2) (see Table 1). Shortly after the war, German physicists began to offer rationalizations of their failure. They claimed that they had fully understood the theoretical physics of an atomic bomb with uranium-235 and that they had recognized the potential of plutonium as an alternative nuclear explosive. As early as 1946, in an article giving

his account of the German fission research project (4), Heisenberg, an ardent German nationalist, elevated himself to a high moral plane by implying that moral scruples had restrained him and his colleagues from trying to produce an atom bomb for Hitler. This theme has been inflated and embellished in subsequent writings by Heisenberg (5) and others (6, 7). The Farm Hall Recordings Chroniclers of recent history depend frequently on interviews with individuals who played key (or peripheral) roles in events of the times. “Oral history” can be a source of valuable information and insights. On the other hand, as critical historians realize, recollections may be misleading not only because memory can be faulty or distorted by subsequent experiences, but also because they reflect the individuals’ emotional, intellectual and social biases. Cross-checking is essential, with other oral recollections and particularly with documentary materials. What is unique about documentation of the history of the German wartime atomic bomb efforts is the existence of surreptitious recordings (3) of the conversations of the participants in 1945 just before and immediately after the explosion of the first military atom bomb at Hiroshima. These have provided an unparalleled source of information. Never before then had there been

Table 1. Condensed Chronology of Wartime Atomic Bomb Development (1–3 ) Year

United States

1939 1941

Germany "Uranium Club" formed

Minute samples of 235U isolated Visible quantity of 239Pu obtained from cyclotron reaction

1942

First self-sustaining nuclear reaction achieved (Fig. 1) Manhattan Project established

1943–44 Industrial-scale plants constructed for 235U and 239Pu production 1945

204

July 16: First atomic bomb explosion (239Pu)

Self-sustaining nuclear pile not achieved

August 6: Hiroshima explosion (235U)

235U

not isolated unknown

239Pu

Figure 1. Sketch of the first self-sustaining nuclear reactor, CP-1 (Chicago Pile-1). This was designed and constructed after systematic examination of thirty experimental subcritical piles of increasing size. It is constituted of a lattice of bricks of very pure graphite, alternating layers of which had cones of uranium (oxide or metal). Its size is apparent by comparison with the human figure at the left. After much planning, the assembly of CP-1 was started on November 16, 1942, and the first self-sustaining nuclear reaction was achieved (under Enrico Fermi’s direction) on the afternoon of December 2, 1942. The scientific team comprised 43 individuals (including one woman). The design was due to E. Fermi and L. Szilard, who are listed on the U.S. patent as the inventors. The cost of this project was about 1.5 million dollars. The sketch is from The First Reactor, published by the U.S. Department of Energy, Washington, DC, in December 1982.

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a recording of conversations, contemporary with the events, in which the participants were unaware that what they were saying was being secretly recorded and in which they thought they were speaking freely and totally privately within a small group of associates isolated in a secluded house. How did this scenario arise? Not because anyone was planning to provide materials for future historians. It was an operation undertaken for intelligence and political reasons during the terminal stages of the war in Europe. As the Nazi government collapsed in May of 1945, the Alsos mission took into custody nine of the leading German physicists who had played important roles in the “Uranium Club”: W. Heisenberg, C. F. von Weizsäcker, W. Gerlach, O. Hahn, P. Harteck, K. Wirtz, E. Bagge, H. Korsching, K. Diebner. The famous, but aging, Max von Laue was added to this group, probably for his own protection, for he was one of the rare individuals who at great personal risk had shown displeasure with the Nazi regime. This group was transported in steps to a large country house, Farm Hall, situated near Cambridge in England. There they were very comfortably ensconced, but kept isolated from outside contacts. Furthermore, Farm Hall, which was one of the wartime facilities of the British intelligence services, was outfitted with hidden microphones in every room so that the conversations of the interned “guests” could be surreptitiously recorded at all times. Transcripts of these conversations were classified as TOP SECRET and were available to a very few select individuals including Professor S. A. Goudsmit, the scientific head of the Alsos mission, and General Groves, the military head of its Manhattan District in the United States. For reasons that are not clear, for 47 years British intelligence refused to release these transcripts. At least one modern historian (Walker [8]) doubted their existence, referring to them as “the so-called Farm Hall tapes… if they exist” (9). Finally, in 1992 they were made available to the public (3). These transcripts provide some fascinating insights into the personalities of the “guests” and invaluable information on what the Germans really understood about the physics and chemistry of a nuclear reactor and of an atomic bomb. Let us focus first on two issues that are centrally pertinent to how sound was the Germans’ grasp of the technical requirements for an atom bomb: 1. What was their value for the critical size of the explosive core of the bomb? 2. What did the Germans know about plutonium-239?

Before each excerpt below I give the page number and date of the entry in the Farm Hall transcript. The italics are mine. Pages 50–51, 6 August

HEISENBERG: It’s got nothing to do with atoms… . All I can suggest is that some dilettante in America who knows very little about it has bluffed them into saying, “If you drop this it has the equivalent of 20,000 tons of high explosive” and in reality doesn’t work at all… . I don’t believe a word of the whole thing. WEIZSÄCKER: I don’t think it has anything to do with uranium. HEISENBERG: I don’t believe it has anything to do with uranium, but that it is a chemical thing where they have enormously increased the speed of the reaction and enormously increased the whole explosion. Pages 52–53, 6 August

HEISENBERG: I still don’t believe a word about the bomb but I may be wrong. I consider it perfectly possible that they have about 10 tons of enriched uranium but not that they have 10 tons of pure uranium-235. OTTO HAHN: But if they have 30 kilograms of pure 235, couldn’t they make a bomb with it? HEISENBERG: It still wouldn’t go off. HAHN: You used to tell me that one needed 5 kilograms of 235 in order to do anything. Now you say one needs 2 tons. HEISENBERG: I wouldn’t like to commit myself for the moment… . If it has been done with uranium-235, then we should be able to work it out. It just depends upon whether it is done with 50, 500 or 5000 kilograms and we don’t know the order of magnitude. Page 60, 6 August

HEISENBERG: About a year ago I heard from the Foreign Office that the Americans had threatened to drop a uraniunm bomb on Dresden if we didn’t surrender soon. At that time I was asked whether I thought it possible, and with complete conviction, I replied “No.” Page 64, 6 August

HAHN: Do you think they would need as much as that [30 kilos]? HEISENBERG: Quite honestly I have never worked it out. Page 65, 6 August

HEISENBERG: I must have a lump… [of] about a ton… . It is conceivable that they could do it with less. Page 68, 6 August

P AUL HARTECK: The weight is 200 kilograms, then it explodes. Page 69, 6 August

Critical Size of Core of Atomic Bomb According to Major T. H. Rittner, the “host” of the detainees at Farm Hall, on August 6, 1945, shortly before dinner, he informed Professor Hahn that a British radio program had announced that an atom bomb had been dropped that day, over Hiroshima. After being calmed down “with the help of considerable alcohol stimulant,” Hahn, with Rittner, went down to dinner, where the former transmitted the news to the other “assembled guests.”1 It took some time before the Germans overcame their initial incredulity and their subsequent conclusion that the announcement was a propaganda stunt. One must keep in mind, therefore, that all of their statements thereafter were made after they slowly realized that a self-sustaining nuclear reaction and an atomic bomb had indeed been created.

WALTHER GERLACH: I would really like to know how they have done it. Page 72, 7 August

HEISENBERG: To produce fission in 1025 atoms [4 kg uranium]… . Page 98, 8 August

KARL W IRTZ: I feel sure that the bomb is not big. HEISENBERG: It might be of the order of 400 kilos. Page 99, 9 August

HEISENBERG: This [calculation] would then come to about a ton. Page 99, 9 August

HEISENBERG: Well how have they actually done it? … It is a disgrace if we … cannot at least work out how they did it.

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Page 102, 9 August

HEISENBERG [discussing with Harteck how much protactinium would be needed for a fission bomb]: One or 2 kilograms. Page 114, 14 August

GERLACH: Do you think they put the graphite in to prevent melting? HEISENBERG: It could be something like that. Page 115, 14 August

HEISENBERG: If I assume the smallest value [of fission cross section], 0.5, I get a critical radius of 13.7 cm [180 kg], and if I assume the greatest, 2.5, I get 6.2 cm [16 kg].

Thus, even after becoming convinced that an atomic bomb had indeed been achieved, the Germans’ calculated critical size for the core encompassed the following range of values: 2 kg, 4 kg, 10 kg, 50 kg, 180 kg, 200 kg, 400 kg, 500 kg, 5000 kg, 1 ton, 2 tons, 10 tons. The clear conclusion is that stated by Heisenberg himself: “Quite honestly I … never worked it out.” Several historians and commentators have pointed out that the entry from page 115, August 14, 1945, of the Farm Hall transcript follows a lecture2 by Heisenberg to his colleagues, which has been described as “a sophisticated and surprisingly accurate lecture on the Allied atomic bomb” (10). Actually, this lecture “is a primitive, unsophisticated treatment of the subject, treating a bomb as though it were a reactor.”3,4 And Heisenberg’s lecture came after the fact that an atomic bomb had been exploded. It is not surprising that Goudsmit, from his investigations as head of the Alsos team (2) and having access to the Farm Hall recordings (3), concluded that the Germans thought that a nuclear reactor was at the heart of a fission bomb (Fig. 2). So what did the German atomic scientists know about element 94 and its potential as a superexplosive? Their discussions at Farm Hall are fascinating. Plutonium and Its Cousins Page 50, 6 August

GERLACH: Would it be possible that they have got an engine [nuclear pile] running fairly well, that they have had it long enough to separate “93”? HAHN: I don’t believe it. Page 54, 6 August

WEIZSÄCKER: Do you think it is impossible that they were able to get “93” or “94” out of one or more running engines [nuclear piles]? WIRTZ: I don’t think that is very likely. HAHN: Well, I think we’ll bet on Heisenberg’s suggestion that it is bluff. Page 93, 8 August

KURT DIEBNER: I don’t know why it is easier to produce fission in element 94. I don’t know all that. Page 97, 8 August

HAHN: The fission of ionium was experimentally proved in the Radium Institute at Vienna… . Thorium undergoes fission… . Ionium is also fissile. GERLACH: Can one make a bomb with it? Can you make a bomb out of 2 kg ionium? HAHN: I don’t know. Page 98, 8 August

BAGGE : This they call “Pluto.” This might be 93. HEISENBERG: I still do not understand what they have done. If they have this element 94, then it could be that this 94 has quite a short mean free path… . We did not have

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Figure 2. Diagram of the German experimental nuclear pile, in documents captured by the Allied Alsos mission (2). The pile consisted of alternating layers of uranium and paraffin. It had dimensions of about 2 feet in height and 1.5 feet in breadth, and a shape like a bomb. Lacking a lattice configuration, it could not have achieved a self-sustaining fission reaction.

this element… . How they have obtained this element is still a mystery. Page 99, 9 August

HARTECK: I believe it would be technically possible to produce 2 kg of protactinium… . For ten such bombs this would mean 50 kilos of radium in three years, which is unbelievable. HARTECK: They would have to have a billion tons to get out sufficient material [of protactinium] for man to weigh. Page 100, 9 August

HARTECK: This [93] could be the decay product of 23minute-halflife uranium from which they have made 93. HEISENBERG: If they have made it with a machine [that is, a nuclear pile], then there is the fantastically difficult problem that they have had to carry out chemical processes with this terrifically radioactive material… . I do not believe that the Americans could have done it. Pages 101–102, 9 August

HEISENBERG: I believe it almost more likely that they have done something quite original such as getting out protactinium in quantity from colossal quantities of material… . Perhaps the facts are that they thereby discovered “Pluto.” Pluto is a code name. “Protactinium also starts with a “P”… . Perhaps the others have used protactinium; this is almost easier to imagine than all other methods… . If one has pure protactinium in considerable quantity, then the whole thing would blow up… . Page 104, 9 August

HEISENBERG: You can of course have luck if you make element 94… . perhaps just as many [neutrons] come out in the case of protactinium… . Let us assume that they have done it with protactinium, which to me at the moment appears to be the most likely… . They would have had to work with 140,000 tons of material. “Pluto” may be a code name… . American work [1940–41] appeared to establish that protactinium was fissionable below about 50,000 volts… . They might also have thought that they had discovered that it was spontaneously fissionable… . There are now three quite clear ways in which they have done it and only three: isotope separation, protactinium and a machine with D2 O and element 94. Page 107, 13 August

HAHN: Element 93 decays in 2–3 days into 94. They have of course 94. This is obviously plutonium.



It is clear from these excerpts that on 6–9 August 1945, the Germans’ knowledge of the properties of the fissile heavy elements was comparable to that of American graduate students in nuclear chemistry or nuclear physics in 1940–41. Thus a contemporary textbook of the time (11) covering published literature subsequent to the discovery of fission points out that

Table 2. National Origins of Some Scientists of the Manhattan Project Individual

Native Country

Individual

Native Country Poland

Fermi

Italy

Ulam

It was finally proved by McMillan and Abelson that the resulting 93239 [from 239 U] decays to 94239.

Segre

Italy

Zinn

Canada

Szilard

Hungary

Chadwick

England

In the same chapter, this book also makes the following comment:

Wigner

Hungary

Lawrence

USA

If someone could succeed in isolating a few pounds of U235… , very interesting developments would almost certainly follow… . If the reader wakes some morning to read in his newspaper that half the United States was blown into the sea overnight, he can rest assured that someone, somewhere, succeeded [italics added].

For his foreword in Alsos, Goudsmit (2), having listened to the Farm Hall recorded conversations, and having earlier directly examined seized German documents and laboratories and taken part in personal interrogations of German scientists, wrote in 1946: “The plain fact of the matter is that the Germans were nowhere near getting the secret of the atom bomb… . They did not yet know how to produce a chain reaction in a uranium pile. They did not know how to produce plutonium.” A reading of the Farm Hall transcripts abundantly confirms Goudsmit’s assessment. Bending Perception to Wish The Farm Hall transcripts reveal abundantly that the German “guests” were out of touch with reality in regard to their scientific standing in nuclear physics and chemistry. Taking preeminence therein for granted, they presumed that whatever their state of progress toward developing a nuclear “engine” or a bomb, American and British scientists must be far behind. As mentioned earlier, Heisenberg says (on August 6, 1945) that when asked in 1944 by the German Foreign Office whether the Americans might have a uranium bomb, he replied “with complete conviction… ‘No’.”5 In another context, Bagge quotes von Weizsäcker as saying “the only man in the world who can do it is Heisenberg.” Bagge, in the early stage of custody, says “they [the Americans] will certainly have the ambition to imitate our experiments” [italics added]. And of course the most overwhelming exhibition of arrogance is displayed in the “guests’” expressions of utter incredulity when informed on August 6, 1945 of the nuclear explosion in Hiroshima. This hubris is displayed in their other perceptions. Thus when magazines in mid-August 1945 published, with other historical information, the names of scientists who played major roles in atomic research, Heisenberg remarks, “Of course, they are mostly Germans.” It is ironic that a list of individuals who had leading roles in creating the first nuclear bomb (Table 2) contains few native Germans. Of the scientists who came from Europe, most were in the United States because their lives were endangered by Nazi Germany. Similarly, a historical list of the towering individuals of science during the past several centuries contains only a small minority of German names. As their host Major Rittner remarked, “The fact that this statement [of Heisenberg’s] was untrue merely emphasizes the inborn conceit of these people, who still believe in the ‘Herrenvolk’. This applies

von Neumann

Hungary

Urey

USA

Teller

Hungary

Compton

USA

Bohr

Denmark

Oppenheimer

USA

Franck

Germany

Tolman

USA

Bethe

Germany

Feynman

USA

Frisch

Germany

Seaborg

USA

Peierls

Germany

Libby

USA

Kistiakowsky

Russia

Kirkwood

USA

Metropolis

Greece

Bacher

USA

to every one of the guests with the possible exception of von Laue.” Their attitude also shines through in other observations made by members of the Farm Hall Ten. Thus, in August 1945, Heisenberg asserts “[the English] are naturally frightened that one fine day they will be attacked just as we were attacked” (italics added). Two months later Major Rittner, summarizing the caviling of the guests at the behavior of American and French occupation forces in Germany (the latter forces, for example, having required Frau Bagge to cook for the troops billeted in her house), summarizes his impressions as follows: “The general attitude seems to be that the German war was a misfortune forced on the Germans by the malignancy of the Western Powers, who should by now have forgotten that it had taken place ... the United Nations should all be largely concerned to set Germany on her feet again” (italics added). Rittner also notes, somewhat earlier, that “[the guests] seem to think that the Allied military authorities have nothing better to do than to send couriers [with letters from the Farm Hall Ten] around Germany for their benefit.” One of Heisenberg’s recorded statements is typical of this attitude: “our first interest is our future, whereas [the English] are interested firstly in the fate of the world.” The moral scruples retroactively discovered by the German atomic scientists after the war are not apparent in their conversations at Farm Hall. Although postwar statements stressed their horror of the thought of creating an atomic bomb for Hitler, during their custody at Farm Hall they repeatedly discussed placing their expertise on nuclear fission at the disposal of Stalin. Even at the outset of their confinement, June of 1945, Major Rittner in one of his summaries notes that Heisenberg has spoken of going over to the Russians. Later on among the conversations printed explicitly in the transcripts, one finds remarks of Heisenberg’s such as the following: I can understand someone saying that we ought to join up with Russia. That is a standpoint which could be discussed. We can do it [switching over to the Russians] in good conscience.


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The Russians would make very good offers to some of the physicists. [If] the Russians say “you will get an institute with a yearly budget of half a million, then I would consider if I shouldn’t go to the Russians.

Harteck in August tells his colleagues [If] we had been in Russia and had the necessary material and had to start from nothing, then we would undertake to make a machine work in nine months.

Bagge and Diebner, the two physicists who were selfadmitted members of the Nazi Party,6 in their conversations discuss the possibility of approaching some of Diebner’s friends who are working for the Russians. Statements from W. Gerlach, the “general”7 in the German uranium project, show his deep “moral” perceptions. For example: If Germany had had a weapon that would have won the war, then Germany would have been in the right and others in the wrong.

Von Weizäcker remarks that he is reluctant to fraternize with the English because “so many of our women and children have been killed” (italics added). Bagge, the Nazi Party member, notes in passing: During the war, we (put) people in concentration camps—I didn’t do it. I knew nothing about it, and I always condemned it [sic] when I heard about it … if Hitler ordered a few atrocities in concentration camps during the last few years, we can always say that these occurred under the stress of war but now we have peace … and they can’t do the same things to us now.

Bagge’s pitiful narcissism shows up throughout his confinement in Farm Hall. I’m frightened. I’m reaching the end of my tether. I shall go mad. I can’t stand it any longer. I shall refuse to go downstairs. I shall eat nothing. I shall go on a hunger strike.

Parenthetically Major Rittner notes, “Bagge is much too fat and a course of bread and water would be good for his health.” Only once in the entire Farm Hall transcript does one find a glimmer of sensitivity about the atrocities perpetrated by the Nazis. During a conversation with Heisenberg in July 1945 about some specific individuals murdered by the Nazis, K. Wirtz interjects, We have done things which are unique in the world. We went to Poland and not only murdered the Jews in Poland, but for instance, the SS drove up to a girls’ school, fetched out the top class and shot them simply because the girls were High School girls and the intelligentsia were to be wiped out. Just imagine if they arrived in Hechingen, drove up to the girls’ school and shot all the girls. That’s what we did [italics added].

The Farm Hall Ten were the leading scientists of the German atomic bomb project. As the transcripts show, in their technical efforts during the war years, they were “all second-raters” (O. Hahn’s words on August 6, 1945). As human beings (with one exception, von Laue) none stands out as admirable. Johann Wolfgang von Goethe once wrote In knowledge as in action prejudice casts the deciding vote.

How apt a description of the scientists of the Third Reich.

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Notes 1. It is of interest that Heisenberg’s recollection of this event, described in his reminiscences in Physics and Beyond (5, p 193) differs in significant details from that recorded at Farm Hall on August 6, 1945. He claims that he heard of the Hiroshima explosion in the afternoon of August 6, 1945, from Karl Wirtz, not from Otto Hahn. There is another incident described by Heisenberg in Physics and Beyond that is also at variance with documentary evidence. He states that he first became aware in 1922 of anti-Einstein propaganda in Germany, when he went to hear a lecture by Einstein in Leipzig. According to Helen Dukas, Einstein’s long-time secretary, the records show that the lecture referred to was given by von Laue, not Einstein. It seems clear that Heisenberg’s memory was not infallible. 2. The Farm Hall transcript also presents the original German text of this lecture. 3. This assessment comes from Robert Serber (12), the theoretical physicist who in 1943 at Los Alamos delivered the series of lectures (13 ) on atomic bomb theory to the incoming assembly of young and older geniuses, who still needed over two years to overcome enormous obstacles to the actual creation of a working bomb. 4. It was this failure of Heisenberg’s theoretical approach to distinguish between a nuclear reactor and a nuclear bomb that led S. A. Goudsmit ( 2) to surmise that the Germans did not recognize the essential differences between the two (see Fig. 2). This assessment is confirmed further in the Farm Hill August 14 lecture by Heisenberg’s summarizing comment, “the machine [sic] works and the bomb [sic] explodes.” In August 1945, Heisenberg thought that in a uranium-235 bomb, fission would be essentially 100% ( 3, p 72). The Allies knew in November 1941 that only 1– 5% of fission energy could be directed into an explosion (1, p 72). 5. Twenty-four hours later, Heisenberg described either the same incident or a related one very differently. As recorded in the Farm Hall transcript, in July 1944 he was asked by the Nazi SS whether the Americans could produce an atomic bomb, and this time, contrariwise, he told them that it was possible. 6. It is also very likely that W. Gerlach had strong connections with the Nazi regime. He knew Goering personally. His brother was in the SS and involved in secret large money deals therein. Gerlach himself was placed in charge of the German atomic bomb research in the last years of the war. Bagge also comments at one point about his contemporaries: “They were all in the SA.” According to Major Rittner, Gerlach had connections with the Gestapo. 7. A few hours into the evening of August 6, Gerlach left his colleagues and “went straight to his bedroom, where he was heard to be sobbing. Von Laue and Harteck went up to see him and tried to comfort him. He appeared to consider himself in the position of a defeated General, the only alternative open to whom is to shoot himself.” These words come from Major Rittner’s comments in the Farm Hall transcripts.

Literature Cited 1. Smyth, H. D. Atomic Energy for Military Purposes; Princeton University: Princeton, NJ, 1945; pp 71, 224. 2. Goudsmit, S. A. Alsos; Henry Schuman: New York, 1947. 3. Epsilon, 1 May to 30 December, 1945; Public Record Office, London, 1992. See also Operation Epsilon: The Farm Hall Transcripts; Institute of Physics: Bristol, 1993, and University of California: Berkeley, 1993; and Bernstein, J.; Cassidy, D. Phys. Today 1995, 48(8, Part 1), 32–37. 4. Heisenberg, W. Naturwissenschaften 1946, 33, 325–329. 5. Heisenberg, W. Physics and Beyond; Harper and Row: New York, 1971. 6. Jungk, R. Brighter Than a Thousand Suns; Penguin: Harmondsworth, Middlesex, England, 1960. 7. Powers, T. The Secret History of the German Bomb; Knopf: New York, 1993. 8. Walker, M. German National Socialism and the Quest for Nuclear Power, 1939-1949; Cambridge University: New York, 1989. 9. Walker, M. Phys. Today 1991, 44(5), 94–96. 10. Walker, M. Nature 1992, 359, 473–474.



11. Pollard, E.; Davidson, W. L. Applied Nuclear Physics; John Wiley: New York, 1942. 12. Logan, J. L.; Serber, R. Nature 1993, 362, 117.

13. Serber, R. The Los Alamos Primer; University of California: Berkeley and Los Angeles, 1992.


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The German Atomic Bomb Scientists - ACS Publications

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