Half-Life: The Divided Life of Bruno Pontecorvo, Physicist or Spy

by Close, Frank

  33. Mafai, Il lungo freddo, p. 130. Niels Bohr was Danish; Marianne Pontecorvo was Swedish. Nils is the Swedish variant of Niels.

  34. Before the project started, it was known that light elements, such as boron and nitrogen, absorb slow neutrons. Today this property is exploited in control rods, made of elements such as boron, which can prevent a nuclear fission reaction from getting out of control.

  35. This was on January 6–7. Bruno Pontecorvo was also in the US on January 12 and in New York on January 20–24. TNA KV 2/1888.

  36. Broda, Scientist Spies, p. 130.

  37. TNA AB 2/643, AB 2/645, AB 2/647.

  38. TNA KV 2/1888.

  39. This is in part what Fermi had in mind, following Pontecorvo’s defection, when he said that Pontecorvo’s presence in the Soviet Union was far more important than any information that he might have passed before 1950.

  40. Broda, Scientist Spies, p. 128.

  41. Broda, Scientist Spies, p. 134.

  42. One idea was to look for helium, as the presence of this gas is a sign of alpha particles—the nuclei of helium atoms.

  43. The issue was not finally resolved until later that year, after the war had ended. This investigation by B. Pontecorvo and D. West is reported in TNA AB 2/318.

  44. TNA AB 2/653.

  45. Broda, Scientist Spies, p. 133 and TNA AB 2/653.

  46. Lew Kowarski interview, AIP, http://www.aip.org/history/ohilist/4717_4.html.

  47. Lew Kowarski interview, AIP, http://www.aip.org/history/ohilist/4717_4.html.

  48. Kowarski recalls that the party began shortly before 4:00 p.m.

  49. If Alan Nunn May had passed information to an enemy, he could have faced the death penalty for treason. However, the Soviet Union was an ally, and he was convicted of breaking the Official Secrets Act.

  50. Letter from Geoff Hanna to Giuseppe Fidecaro, October 24, 1996. I am indebted to David Hanna for access to this letter and other correspondence linked to Chalk River.

  CHAPTER 8

  1. B. Pontecorvo, “Inverse Beta Process,” Report PD-205, National Research Council of Canada, Division of Atomic Energy, Chalk River, November 13, 1946.

  2. B. Pontecorvo, “On a Method for Detecting Free Neutrinos,” Report PD-141, National Research Council of Canada, Division of Atomic Energy, Chalk River, May 21, 1945.

  3. This discussion must have occurred when Otto Frisch visited Chalk River from Los Alamos; papers of Otto Frisch, TNA CSAC 87.5.82/A.64.

  4. When it was declassified in 1964, it was lodged among papers at the National Archives, unnoticed. Most physicists, myself included, were either unaware of its existence, or assumed that it contained nothing more than the public 1946 paper. The received wisdom on the history of Bruno Pontecorvo and solar neutrinos has thus been based on the 1946 paper.

  5. Pryce’s calculation dealt with neutrinos that are produced by the fusion of protons in the sun. The energy of these neutrinos is too low to convert chlorine into argon. There are neutrinos with higher energies, produced by other processes in the sun, for which the chlorine method works. Their quantity, however, is relatively trifling. Ray Davis succeeded in finding these neutrinos, but only after several decades of refinements in his experiment. That story has been told elsewhere, and American theorist John Bahcall plays a leading role in it; see for example Close, Neutrino.

  6. H. R. Crane, “The Energy and Momentum in Beta-Decay and the Search for the Neutrino,” Reviews of Modern Physics 20 (1948): 278.

  7. In 1951, Frederick Reines, who had worked on atomic explosions in the aftermath of the war, expressed interest in looking for neutrinos produced by an atomic blast, but in 1952 he decided to use a reactor instead. Fermi pointed out that a reactor had an advantage over an atomic blast—one could repeat the experiment. Reines and Cowan’s first attempt to detect neutrinos at the Hanford nuclear reactor was unsuccessful, but in 1955 they began their successful attempt at the Savannah River reactor in South Carolina, around the same time that Davis was pursuing his own quest. Reines later won the Nobel Prize in Physics in 1995. Clyde Cowan, who died in 1974, missed out, as Nobel Prizes are not awarded posthumously.

  8. Marcello Conversi, Ettore Pancini, and Oreste Piccioni announced their discovery in Physical Review 71 (1947): 209.

  9. A single neutrino paired with an electron would be unable to balance the rotary angular momentum. A pair of photons would also be unlikely compared to a single photon.

  10. B. Pontecorvo, “Nuclear Capture of Mesons and the Meson Decay,” Physical Review 72, no. 246 (1947).

  11. E. P. Hincks and B. Pontecorvo, “The Absorption of Charged Particles from the 2.2-μsec. Meson Decay,” Physical Review 74 (1948): 697.

  12. J. Steinberger, “On the Range of the Electrons in Meson Decay,” Physical Review 74 (1948): 500.

  13. The history of muon decay is as follows: Hincks and Pontecorvo had shown that muon decays don’t make an electron and a heavy particle, but they didn’t eliminate the possibility that it decays into an electron and a photon. Steinberger measured a spectrum that was consistent with decay into three particles. By January 1949 Steinberger stated that he had “some evidence” that the decay produces three light particles (Physical Review 75: 1136). In March, R. Leighton, C. Anderson, and A. Seriff gave “strong evidence [that the muon] decayed to an electron and two neutrinos” (Physical Review 75: 1432). They showed that the spin of the muon can be the same as the electron. (Technically, they showed that it is “half-integer,” like the electron.) They also measured the mass of the muon. Not until later that year did Hincks and Pontecorvo explicitly mention the decay into an “electron and two neutrinos” (Physical Review 77: 102).

  14. This is widely credited to G. Puppi, Nuovo Cimento 5 (1948): 587. However, Puppi was not the first to come up with this hypothesis. Bruno Pontecorvo had elucidated such ideas in a letter on May 8, 1947, to Gian Carlo Wick (copy in Fondo Wick, Archivio Scuola Superiore Normale di Pisa). This includes the remarks “se ne deduce una similarita tra processi beta e processi di assorbimento ed emissione di mesoni, che, assumendo non si tratti di una coincidenza, sembra di carattere fondamentale” (A similarity can be deduced between beta processes and the absorption or emission of mesons [i.e. muons], which, assuming that it is not a coincidence, seems to be of fundamental character.”) In Physical Review 72 (1947): 246, Pontecorvo proposes a “fundamental analogy between beta processes and the process of emission or absorption of charged mesons.”

  15. http://www.universitystory.gla.ac.uk

  16. S. C. Curran, J. Angus, and A. L. Cockcroft, “Beta Decay of Tritium,” Nature 162 (1948): 302–303. D. H. W. Kirkwood, B. Pontecorvo, and G. C. Hanna. “Fluctuations of Ionisation and Low Energy Beta Spectra,” Physical Review 74 (1948): 497–498.

  17. http://www.universitystory.gla.ac.uk. Curran, Pontecorvo, and their respective teams had developed the concept in order to measure the energy of beta particles. A proportional counter for alpha particles was invented in 1943, by John Simpson in Chicago. See https://www.orau.org/ptp/collection/proportional%20counters/simpson.htm

  18. Giuseppe Fidecaro, “Bruno Pontecorvo: From Rome to Dubna,” in BPSSW, http://www.df.unipi.it/~rossi/PONTE_5.pdf.

  19. TNA KV 2/1887.

  20. Henry Arnold memo of January 5, 1948, TNA KV 2/1887 8a.

  21. TNA KV 2/1889.

  22. Wallace, “Atomic Energy in Canada,” p. 131.

  CHAPTER 9

  1. Unless otherwise stated, all correspondence is from TNA KV 2/1888 or TNA KV 2/1889, or Churchill College papers.

  2. Turchetti, The Pontecorvo Affair, chap 2, note 47; Bruno Pontecorvo letter to John Cockcroft, February 2, 1946, CAC.

  3. On December 29, 1945, Bruno told George Uhlenbeck at the University of Michigan that he would be writing to Segrè for advice, but felt it to be unlikely that he would come to Michigan, although “I am not yet decided.” On January 5, 1946, Michigan expressed regret that he wouldn’t be coming, and upped their offer to that of a full professorship a
t $5,500 a year. In response, on January 17, Bruno said that he had “not yet made a decision” but would do so immediately after a physics meeting in New York, due to take place at the end of the month.

  4. Formal letter of employment sent June 5, 1946; Pontecorvo accepted on July 8, 1946. TNA KV 2/1892.

  5. Confirmed in Cabinet Office telegram to British Joint Services Mission, Washington, October 21, 1950, and report to prime minister, TNA KV 2/1888, memo 25a.

  6. Godfrey Stafford interview, December 20, 2012.

  7. L. Fermi, Atoms in the Family, p. 254.

  8. Bruno Pontecorvo, Autobiographical notes.

  9. According to Laura Fermi, this was the “end of 1948” (Atoms in the Family, p. 255). The APS meeting in Chicago was held November 26–27 and Bruno was present. TNA KV 2/1888.

  10. L. Fermi, Atoms in the Family, p. 255.

  11. J. David Jackson e-mail, August 28, 2012.

  12. TNA KV 2/1889.

  13. Peter Watson e-mail, January 2, 2014.

  14. Anonymous source, 2013.

  15. Mafai, Il lungo freddo, p. 127.

  16. The letters exchanged between Bruno and Marianne in 1938 refer more than once to some unspecified illness, and hint that Marianne changed travel plans at the last minute (see Chapter 3). I am grateful to Sven-Olof Ekman, a Swedish journalist from Marianne’s hometown, for help with my research.

  17. F. W. Marten memo, TNA KV 2/1888.

  INTERLUDE

  1. Holloway, Stalin and the Bomb, p. 90.

  2. Kurchatov as quoted in Holloway, Stalin and the Bomb, p. 90.

  3. Holloway, Stalin and the Bomb, p. 94. KGB stands for Komityet Gosudarstvennoy Bezopasnosti (Committee for State Security), and the agency of that name was established in 1954. The KGB succeeded the MGB, the Soviet Ministry of State Security, which was itself formed in 1946. The MGB was immediately preceded by the NKGB, in existence from 1943 to 1946, and before that by the NKVD, or Narodnyi Kommissariat Vnutrennikh Del (People’s Ministry of Internal Affairs), which operated from 1934 to 1943. For a guide through this labyrinth, see Andrew and Gordievsky, KGB, p. 9. For ease of comprehension, I shall refer to all these entities in the main text as the KGB, to distinguish them from the second, independent intelligence agency of the Soviet Union—the GRU, or Glavnoye Razvedyvatelnoye Upravleniye. The GRU was founded in 1926 as the Chief Intelligence Directorate of the Red Army.

  4. The security corps of the Manhattan Project suspected that several scientists were passing information to the Soviet embassy in San Francisco. Holloway, Stalin and the Bomb, p. 103.

  5. Oleg Gordievsky and Christopher Andrew in various works; Oleg Gordievsky in communications, April 27 and April 30, 2012; Sudoplatov et al., Special Tasks.

  6. Joint Committee on Atomic Energy, “Soviet Atomic Espionage,” April 1951, http://archive.org/stream/sovietatomicespi1951unit/sovietatomicespi1951unit_djvu.txt.

  7. See Sudoplatov et al., Special Tasks, p.182, and discussion in footnote on p. 81 of Rhodes, Dark Sun.

  8. Andrew and Gordievsky, KGB, p. 318; Oleg Gordievsky e-mail, April 30, 2012.

  9. Oleg Gordievsky e-mail, April 30, 2012.

  10. References are either circular—Gordievsky being cited as the source of the claim in his own book—or anecdotal. There appears to be no clear answer as to how Gordievsky knows all this. See discussion of Gordievsky in Afterword for further commentary.

  11. Holloway, Stalin and the Bomb, p. 99.

  12. Holloway, Stalin and the Bomb, p. 104.

  13. Fuchs’s confession to Michael Perrin on March 2, 1950, notes that before August 1944 he had “no real knowledge of the pile process or of the significance of plutonium.” This is reprinted in Appendix B of Williams, Klaus Fuchs.

  14. Andrew and Mitrokhin, The Mitrokhin Archive, p. 174.

  15. Boris Ioffe e-mails and Skype interviews, February 16, March 9, and July 19, 2011; Boris Ioffe interview with Giuseppe Mussardo, 2012. The source seems to be someone other than Nunn May, in that the blueprints were apparently transmitted after he had left Canada. There is also the evidence of Nunn May’s deathbed confession. His stepson, Paul Broda, has described this in detail in Scientist Spies. In Broda’s judgment, Nunn May’s statements at that singular time were “very honest”; if Nunn May did not mention some significant action at that point, then “he didn’t do it” (Paul Broda interview, August 12, 2012).

  16. Andrew and Gordievsky, KGB, p. 318.

  17. Comment from Skinner to Ronnie Reed, TNA KV 2/1888. Bruno Pontecorvo’s stated reason for these periodic trips was that he needed to deal with his ongoing desire to retain US residency status. The dates in his passport confirm these visits occurred at intervals of roughly six months.

  18. Gibbs, “British and American Counter-Intelligence.”

  19. As mentioned earlier, technically this was the Soviet NKVD (“People’s Ministry of Internal Affairs”), which later transformed into the KGB (“Committee for State Security”).

  20. Pincher, Treachery, chap. 8. Hall’s courier, Lona Cohen, worked with the KGB, controlled via the Soviet consulate in New York. Fuchs had worked with the GRU during his time in the UK, but in the US his control was transferred to the KGB. His courier during his time at Los Alamos was Harry Gold. Fuchs and Hall were completely independent. Hall had no knowledge that Fuchs was a spy—Ted’s wife, Joan, confirmed that “Ted thought he was the only one” (Joan Hall interview, May 1, 2013). There was no direct testimony in Fuchs’s trial, but all the evidence suggests that he was also ignorant of Hall’s role.

  21. Report of the Canadian Royal Commission on Espionage (the Kellock-Taschereau Commission). The full title of the report is “The report of the Royal Commission appointed under Order in Council PC 411 of February 5, 1946, to investigate the facts relating to and the circumstances surrounding the Communication by Public Officials and Other Persons in Positions of Trust, of Secret and Confidential Information to Agents of a Foreign Power.” Access to the document may be traced through http://catalog.loc.gov/vwebv/holdingsInfo?&bibId=8343655&searchId=6517&recPointer=1&recCount=100.

  22. A Nunn May confession, reported in Broda, Scientist Spies, p. 140; Paul Broda interview, August 12, 2012, and October 10, 2013.

  23. Broda, Scientist Spies, p. 142.

  24. During the previous months, Nunn May had become worried about the quality of the people he was dealing with. They offered him money, which he declined. He began to wonder if his information was actually being delivered to qualified scientists in Moscow. So he decided to assess the Soviet reaction by handing over samples of uranium. This would give Moscow proof that he was actually working at an atomic project, and the samples would have to be sent to proper experts to be evaluated. This is why he handed over the minute samples of U-233 and U-235, which he had originally intended to retain as trophies of his time on the project.

  25. Joint Committee on Atomic Energy, “Soviet Atomic Espionage,” April 1951; reprinted from report of the Canadian Royal Commission, June 27, 1946, which states, “These samples were considered so important by the Russians that upon their receipt, Motinov flew to Moscow with them” (pp. 447–457). The quoted texts in these paragraphs are accessible online at http://www.ebooksread.com/authors-eng/united-states-congress-joint-committee-on-atomic/soviet-atomic-espionage-tin.shtml on pages 9 and 10.

  26. Pincher, Treachery, Chapter 2, Kindle edition location 421.

  27. Andrew and Gordievsky, KGB, p. 317.

  28. However, there is no public record to support this claim. It is clear that although MI5 later expressed strong suspicion of Pontecorvo’s motives and freely encouraged authors to accuse him of having spied, it had no evidence that Pontecorvo ever transmitted any classified information to Soviet contacts. This is clear from the released files along with the frank diaries of Guy Liddell (TNA KV 2/1887–1891 and KV 4/472). Gordievsky’s claims are doubly anecdotal, in that they are his memory of remarks that others had made to him.

  29. Japan surrendered on August 15, 1945. The formal
documents were signed on September 2.

  30. Philby, My Silent War, Introduction: “I regarded my SIS [Secret Intelligence Service] appointments purely cover jobs, to be carried out sufficiently well to ensure my attaining positions in which my service to the Soviet Union would be most effective. My connection with SIS must be seen against my prior total commitment to the Soviet Union.”

  31. Gibbs, “British and American Counter-Intelligence,” note 253 discusses at length Philby’s role in the Nunn May case.

  32. In the summer of 1949, Meredith Gardner, an American linguist, cracked the Soviet diplomatic codes. The resulting decrypts were known by the code name VENONA.

  33. KGB is a modern name, which, as remarked in note 3, I shall use for convenience. Before 1943 its analogue was known as NKVD. KGB stands for Komityet Gosudarstvennoy Bezopasnosti (Committee for State Security). The second, independent intelligence agency of the Soviet Union was GRU, or Glavnoye Razvedyvatelnoye Upravleniye, founded in 1926 as the Chief Intelligence Directorate of the Red Army.

  34. Broda, Scientist Spies, p. 146.

  35. Philby’s tip-off about Nunn May is discussed in Andrew, Defence of the Realm, p. 344.

  36. Letter from Bruno Pontecorvo to GEC, February 1946, CAC.

  37. Albright and Kunstel, Bombshell, p. 100.

  38. The first mention of MLAD was picked up in codes in 1946. The Fuchs case took up much of the code-breakers’ attention, and it was probably in the spring of 1950 that MLAD was identified as Hall. See Albright and Kunstel, Bombshell, chap. 22.

  39. Andrew and Mitrokhin, The Mitrokhin Archive, p. 173.

  40. Morris Cohen had become a Soviet agent during the Spanish Civil War, while serving in the International Brigades.

  41. The story of these adventures has been told in Albright and Kunstel, Bombshell. Hall’s information was at least as important as that of Fuchs, and possibly more so. There is also speculation that Stalin was wary of Fuchs, who was German, and hence confirmation via Hall proved important.

  42. Albright and Kunstel, Bombshell, p. 332, note 135; “first chilly months” p. 133.

  43. Albright and Kunstel, Bombshell, pp. 179–181.