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

by Close, Frank

  Laura Fermi also hints that Marianne was less sociable than her husband. We have seen how the Fermis were upset not to have met Marianne and Gil in 1940, soon after the Pontecorvos arrived in America. Laura recorded that she was disappointed again in 1943, when Bruno visited the Fermis en route to Canada, but, as on the previous occasion, “his wife and son were not with him.” The first and only time that the Fermis met Marianne was at the end of November 1948, shortly before Bruno moved to Harwell.9 Bruno and Enrico had been attending a meeting of the American Physical Society in Chicago, and Enrico invited the family to dinner. The occasion was memorable for the impression that Marianne made.

  Earlier, she had been in the city shopping, and had become lost on her way back to the hotel. This made the Pontecorvos late for dinner, which upset Bruno “out of proportion to the trouble it might have caused.”10 Throughout the evening, Bruno talked “as easily and volubly as ever,” but was clearly annoyed. Marianne, by contrast, “kept silent,” and in Laura’s opinion was “painfully shy.”

  A colleague from Canada recalled Marianne at that time as a beauty. Of Bruno, he said, “Handsome, flirtatious, very Italian, he was the heartthrob of all the single women.” These memories mirror those of David Jackson, who in 1947 was a graduate student, doing routine computations for the experimenters at Chalk River. Although he had been only a junior member of the laboratory, Jackson recalled, “we all were aware of Ponte, the glamorous Italian who played a lot of tennis and cavorted with the single young women at [the nearby town of] Deep River. I am sure Marianne was not happy, although she was also a very attractive woman then.”11

  There is a story from that era in which Bruno and his colleague Ted Hincks, while traveling to a conference in Montreal in June 1947, gave a ride to two attractive girls—in some accounts, secretaries from the laboratory chemistry division.12 The two women wanted to visit their family in the Montreal area for a few days, and the two physicists obligingly provided transportation. The plan was to bring the women back to Deep River after the conference, but during the convention a science issue arose, which Bruno felt could be answered if he and Hincks consulted another physicist at MIT, outside of Boston.13 The name of the physicist is long forgotten, but what happened next would become part of Chalk River folklore: Bruno and Hincks invited the two secretaries to join them on the trip to Boston, after which they would take the women back to Deep River. Meanwhile, other participants from the Montreal meeting returned to Chalk River, and word got around of Bruno’s latest exploit. Marianne took offense, withdrew all of Bruno’s money from the bank (a sum of $1,800), and went to the Canadian resort town of Banff with the three children—Gil and Tito now had a younger brother, Antonio, born in July 1945. Marianne and the three boys stayed in Banff for some time. When Bruno returned, three days late, he asked friends if they knew where Marianne had gone; finally, one of these friends managed to find Marianne and convince her to return home.

  As a result of this adventure, for the rest of his time in Canada, Bruno was saddled with the nickname of “Ramon Novarro,” a film actor who had become the latest sex symbol following the death of Rudolph Valentino. Novarro and Bruno bore a vague resemblance: the same dark, slicked-back hair, bedroom eyes, and Latin elegance. Marianne, with her fair skin, blond hair, and Nordic features, contrasted with Bruno physically no less than she did temperamentally. A colleague who knew the couple in both Canada and Harwell recalled Marianne as very quiet and beautiful, but also as a “mixed up Scandinavian, [who] seemed a funny choice for a randy Italian.”14

  Toward the end of his life, Bruno was interviewed by the Italian journalist Miriam Mafai. She concluded that Marianne’s reticence and long silences were exacerbated by the fact that “Bruno was very much courted and wooed, and this could not please his wife.” This, however, was only part of a more serious problem: during their time in Canada, Marianne began to show the first signs of a nervous condition, which peaked years later.

  Bruno told Mafai he had noticed that Marianne had a “few oddities,” which first manifested themselves when they were invited to social functions. For instance, when they were about to leave home to go to a friend’s house for dinner (such as the Fermis’ perhaps), Marianne would suddenly announce that she was not coming. Bruno, naturally cross, would say, “You’re crazy,” in what he described as “a normal voice,” unaware that her intense shyness was a symptom of a deep malaise.15

  These descriptions were given by Bruno later in life, after Marianne had suffered a catastrophic mental collapse in the USSR. However, signs of trouble had been there all along. As we’ve seen, in 1938, during her yearlong separation from baby Gil, Bruno’s letters refer to a mysterious illness, which she seems unwilling to discuss.16 For a girl predisposed to depression, abandoning Gil to a French nursery when he was only weeks old could only have added to her misery. Let’s now consider the ensuing years from Marianne’s point of view: Reunited with Gil and Bruno, she flees to North America immediately after having a miscarriage. Her parents and siblings now thousands of miles away, her life is built around the demands of her husband’s career. By 1943 she is living in the United States with a closet communist, who is about to work on a secret project in Canada. When such experiences are added to her inherent shyness, one can understand her reluctance to meet her husband’s teacher, a world-famous Nobel Laureate. A woman in her situation merited sensitivity and support.

  Marianne was as pretty as Bruno was handsome. Bruno, the peacock, enjoyed presenting himself in the company of his attractive wife. He was the charmer, everyone’s best friend. Whether his scientific intelligence was matched by emotional maturity is less clear. On the other hand, it’s possible that Bruno’s decision to move to Harwell was influenced by a consideration of Marianne, who, like Bruno, would be within easy reach of her family, and might therefore feel more at ease. Although there is no proof that this was a factor in his decision, it could have been a powerful attraction.

  Whatever the reasons for the move, by the end of 1948 the Pontecorvos’ time in North America was coming to an end. From November 2 to December 3, 1948, Bruno used his accumulated vacation time to visit the western United States. This trip included visits to various West Coast universities and a side trip to Mexico. From that point on, Bruno’s career moved ever eastward. The Pontecorvos left Chalk River for the last time on January 24, 1949, and flew to Britain, via New York. Bruno started work at Harwell on the first of February.17

  INTERLUDE

  WEST TO EAST

  BACK IN 1942, WHEN THE AWESOME IMPLICATIONS OF FISSION WERE first realized, scientists in the USSR had doubted that an atomic bomb could be made in time to influence the war. Furthermore, Klaus Fuchs had sent information that the British and American nuclear teams were working on an industrial scale. Thus, by 1943, Stalin had received enough intelligence to know that, for the immediate war, a Soviet bomb was irrelevant. The relatively small atomic bomb project that he authorized was a “hedge against future uncertainties”1

  When Igor Kurchatov took on the design of the Soviet atomic bomb, one of the first things he did was to find out what was known elsewhere. He spent several days in the Kremlin, where he studied material relating to the British atomic project. The information from Fuchs enabled Kurchatov “to bypass many labor-intensive phases of working out the problem.”2

  The news, gathered from spies, that a chain reaction could take place in a mixture of uranium and heavy water was invaluable for Kurchatov. Soviet scientists had believed this to be impossible, because they thought the chance of a neutron being absorbed by material before meeting a nucleus of U-235 was too high. Soviet physicists didn’t have enough heavy water to perform the test for themselves, so “borrowing” the data from others was critical.

  Other borrowed intelligence concerned plutonium. Kurchatov checked the last published papers before secrecy had taken over, and deduced that plutonium could be a novel route to the bomb, which would eliminate the need to separate U-235. He arrived at this rea
lization due to the interest in plutonium revealed in these final open papers, as well as his general knowledge of nuclear physics and some technical calculations of his own. However, he lacked some critical data on the subject. He needed to know the answers to two questions: Is plutonium fission caused by slow neutrons or fast ones? And does it suffer from spontaneous fission?

  The phenomenon of spontaneous fission limited the amount of uranium that could be kept in one place. Neutrons released by fission may induce further fissions if they hit appropriate nuclei, or alternatively may escape from the sample entirely without hitting anything. The latter is more likely for small samples than for large ones. The reason is that the ratio of volume (where fission can occur) to surface area (which enables neutrons to escape) grows with the radius of the sample. A tiny baby needs to be kept wrapped up even when a mature adult is lightly clad because, relative to its size, the baby has a greater surface area through which it can lose body heat. Analogously, small samples of uranium lose neutrons more easily than large lumps of the element. There is a critical mass of uranium or plutonium below which fission is not self-sustaining.

  Fission might occur accidentally, for example due to a cosmic ray colliding with a uranium atom, or due to spontaneous radioactivity. This carries the danger of causing a spontaneous chain reaction and an uncontrolled explosion. To prevent this, the size of enriched uranium samples is kept small enough that that neutrons are more likely to escape through their surface than feed a chain reaction within their heart. To make an atomic bomb from U-235, two such “subcritical” samples need to be prepared; later, the samples must be brought together very rapidly to trigger the explosion. Kurchatov understood this principle in the USSR, and discovered that the West had understood it too.

  Kurchatov prepared a research-and-development plan, which outlined the problems to be solved, and in March 1943 he drew up a list of laboratories in North America where solutions might have already been found. The Soviet intelligence agency, the NKVD (the forerunner to the KGB), sent the questions on to its agents abroad.3

  The USSR was already setting up a network of informants scattered throughout the West’s atomic project. At the end of 1942 or early in 1943, Peter Ivanov, an employee of the Soviet consulate in San Francisco, asked British engineer George Eltenton, who had worked in Leningrad but was now at the Radiation Laboratory in Berkeley, to obtain secret information about its research. Ivanov spoke to Haakon Chevalier, a communist friend of J. Robert Oppenheimer, who in turn approached Oppenheimer, but the latter would have nothing to do with the scheme. Ivanov then approached others at the Radiation Laboratory in search of information. He seems to have been successful.4

  The Soviets spread their intelligence net very wide among the US laboratories. The Gouzenko defection and the arrest of Nunn May show that the net encompassed Canada too. Ever since Bruno Pontecorvo fled to the USSR in 1950, there has been debate about whether he too passed information.5 The members of the congressional Joint Committee on Atomic Energy seemed to have no doubt. They dubbed him the “second deadliest betrayer,” but no evidence other than his disappearance was produced. Their report, issued in 1951, included this cogent assessment: “Whether or not Pontecorvo in fact betrayed secrets before disappearing behind the Iron Curtain, his recollection of those secrets is now available to Russia. His unusual scientific mind is also available for Soviet reactor development.”6

  If Pontecorvo was indeed as important to the Soviets during the 1940s as some have claimed, then he must have left a footprint. By studying the known history of the Soviet atomic project, including the chronology of what the Soviets knew about Western progress and when, one might hope to identify his contributions, or lack thereof. For example, it seems plausible to dismiss one claim immediately—namely, that Pontecorvo gave the Soviets information about Fermi’s successful nuclear-pile experiment in December 1942.7

  In Kurchatov’s memo, written on March 22, 1943, which specified the questions that agents should answer, he recorded that it was “still unclear if a natural uranium and graphite system is possible.” As this was the very method that Fermi had already demonstrated with his Chicago reactor three months earlier, news of the Americans’ success had clearly not yet reached the USSR. As we have seen, Pontecorvo visited Fermi in April 1942, and although they discussed aspects of the experiment, this was long before the outcome of Fermi’s experiment was known. Pontecorvo didn’t join the Anglo-Canadian project until 1943, and had no direct contact with Fermi’s operation until 1944. Thus he initially had limited knowledge of the Chicago pile. Given that Kurchatov’s own memorandum suggests his ignorance of Fermi’s success, it seems unlikely that Pontecorvo had leaked the information.

  During 1943 and 1944, several employees at the Metallurgical Laboratory in Chicago were suspected of having passed information to the Soviets and were summarily dismissed. It is more natural to suspect that one of these employees eventually informed the USSR about Fermi’s operation, rather than the remote and disconnected Pontecorvo.

  The US intelligence network suspected that information about the gaseous diffusion plant in Oak Ridge, Tennessee, was also being sent to the USSR. Pontecorvo had no involvement with Oak Ridge at any stage. If he passed any information to the Soviets at all, it would be restricted to knowledge gained during his time in Canada, from 1943 to 1948, or at Harwell, from 1949 to 1950.

  OLEG GORDIEVSKY, THE FORMER KGB DOUBLE AGENT, ASSERTS THAT Pontecorvo passed significant amounts of information to the Soviets. The claims are fairly specific, but unsubstantiated. For example, in a book coauthored with the historian Christopher Andrew, who later wrote the authorized history of MI5, he stated that “at some point” after joining the Canadian project, Bruno had made contact with the Soviet embassy, “probably” in Ottawa. The tale becomes more detailed in claiming that Bruno’s report was sent not to the GRU (the USSR’s military intelligence agency) but to its “neighbor,” the KGB. The KGB “resident” at the embassy initially ignored Pontecorvo, apparently suspicious that he was a provocateur working on behalf of the Canadians. Eventually convinced of Pontecorvo’s reliability, the KGB adopted him. Years later, contacts in the KGB told Gordievsky that they “rated Pontecorvo’s work as an atom spy almost as highly as that of Fuchs.”8

  When Gordievsky subsequently repeated this claim to me, he added, “Bruno Pontecorvo was an agent of the KGB for a long time. Probably he was recruited during the Spanish war. His information was very valuable.”9 When pressed, Gordievsky did not provide any source or even specific facts, such as what secrets Pontecorvo had supposedly passed. Nor did Gordievsky substantiate the allusion to Pontecorvo’s “probable” recruitment during the Spanish Civil War.

  This latter claim in particular is hard to reconcile with Gordievsky’s previous account, in which the Soviet agents in Canada were initially suspicious of Pontecorvo’s aims. Furthermore, the chronology does not fit well. The Spanish Civil War overlapped with Pontecorvo’s time in Paris. During this period he had nothing to offer as a spy: there was no reason to suspect that he would become involved in a program whose existence had yet to be imagined, and whose core focus (nuclear fission) had yet to be discovered; what’s more, once fission had been discovered, research on the subject occurred in the open for some time. It is possible, even likely, that Pontecorvo attracted attention as a prominent communist sympathizer, with a glittering scientific career ahead of him. As such, he might well have been singled out by the Soviets, especially as he joined the Communist Party in 1939. However, this still does not fit easily with Gordievsky’s original account of Pontecorvo’s approach to the Soviets in Canada.10

  ON APRIL 12, 1943, “LABORATORY NUMBER TWO” (THE CODE NAME for the Soviet Union’s reactor project) was set up on Kurchatov’s behalf. He estimated that a reactor would require two tons of uranium and fifteen tons of heavy water (for a heavy-water pile), or fifty to one hundred tons of uranium and one thousand tons of graphite (for a graphite pile). Graphite was easier to obtain than hea
vy water, so he chose the latter route. He didn’t have the uranium but asked theoreticians to figure out how to optimize the construction of the reactor. One of these theoreticians was Isaak Pomeranchuk, a superb theoretical physicist who would later meet with Pontecorvo.

  As it would take years to construct a practical reactor, Kurchatov built a cyclotron to make small quantities of plutonium for research as fast as possible. The cyclotron, which worked by accelerating a beam of deuterons (the nuclei of heavy hydrogen), began operation on September 25, 1944. Even with this advanced machine, however, the Soviets didn’t succeed in separating plutonium from irradiated uranium until 1946.11

  Kurchatov’s biggest problem was obtaining uranium and ultrapure graphite for the pile. At the very start, in January 1943, the Soviet government asked the US for ten kilograms of uranium metal and one hundred kilograms of uranium compounds under the Lend-Lease arrangement. This was a clever move. The USSR was an ally, and, within the context of the war effort, the request might appear to be entirely innocent. For the US, of course, uranium was highly valued, its importance a jealously guarded secret. General Groves, the head of the Manhattan Project, agreed to the request in order to avoid raising suspicion, unaware that the Soviets already knew about about the West’s “secret” atomic project. The search for local uranium in the USSR ramped up starting in 1943, but, given that Stalin was only hedging for the long-term future, it received a low priority. Not until 1945 did large-scale exploration begin.

  IN JULY 1943 KURCHATOV WROTE ANOTHER REPORT FOR THE KREMLIN. Like the March memo, it reveals that his knowledge about nuclear projects in the West was of a general nature and short on detail. Indeed, his knowledge at this time was less complete than it had been in 1941 and 1942, when he had received reports of British progress via Klaus Fuchs.12 He stressed that he needed information about elements 93 and 94 (neptunium and plutonium), which were being researched by Emilio Segrè and Glenn Seaborg at Berkeley.