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

by Close, Frank

  In 1954 Bruno joined the Communist Party of the Soviet Union. Whereas this normally involved a lengthy application process, in which two existing members served as guarantors and the applicant was required to surmount various hurdles, Bruno simply told the local party secretary that he wanted to register—“and my request was automatically accepted.” He soon found that Soviet party meetings were a far cry from his prewar experiences in Paris, however. In those earlier meetings, “the leaders had the last word but the debate took place. Here, there was none.” At Dubna, to Bruno’s surprise, “the meetings discussed more personal matters than politics. Much of the time was taken up with examination of the individual conduct of members of the cell. I found it somewhat medieval, talking about this in public and justifying one’s behaviour. I felt it an undue interference in personal life.” Typically the cell would hear reports of a man who was frequently drunk, or a woman who was betraying her husband. Bruno later confessed, “I was never able to understand the true meaning of this ceremony, which was a kind of confession of sins where punishment or absolution was administered not by the priest but the secretary of the cell.”42

  SIXTEEN

  RESURRECTION

  WITHOUT WARNING, IN EARLY 1955, BRUNO SUDDENLY SURFACED. AT the time, there was a global campaign by the World Peace Council, calling for the destruction of all atomic weapons and a ban on building new ones. In February, an article in the Soviet newspaper Isvestia associated Bruno’s name with this campaign. Bruno was indeed interviewed by the paper, but he had no idea why the authorities had allowed this to happen: “No one asked my opinion. A mid-level party official told me that a decision had been taken [that I should do this]. I had already realized that a person at my level does not decide anything.”1

  In the article, he also explained the reasons for his defection. He revealed that in 1936 he had become a committed antifascist, and had learned “undeniable facts” about the USSR’s leading role in the struggle against war. Later, after the explosion of the atomic bombs over Hiroshima and Nagasaki, he had experienced “moral suffering” as a physicist. He also claimed that, in 1950, while still in Britain, he had been subjected to intolerable “direct questioning and systematic blackmail by the police authorities.”2 He had quit the West in order to maintain his personal dignity because preparations for the military use of atomic energy made him “ashamed of my profession.”3

  In 1950, Guido Pontecorvo told MI5 that, according to Gillo, Bruno had become apolitical at Chalk River and Harwell because it “suited his circumstances.”4 We might similarly conclude that, in 1955, Bruno’s professed devotion to peace, and his criticism of Western scientists for their moral failure, suited his circumstances in that it undoubtedly pleased his new masters.

  Certainly Bruno’s statement ignores the fact that there had been many peace-loving physicists in the UK, who had preached their message throughout his time at Harwell. Given his close relationship with these scientists, and the media attention they received, it is inconceivable that he could have been unaware of their initiative. For example, Herbert Skinner, his former colleague at Harwell, was one of a growing group of British physicists concerned about nuclear weapons. Another member of this group was Rudolf Peierls, who had initiated the atomic project in 1941, was a close friend of Klaus Fuchs, and served as a consultant at Harwell. Peierls had taken part in the Manhattan Project because, as a Jewish émigré from Nazi Germany, he feared that the Nazis would create a nuclear weapon. When Germany surrendered, the moral justification for working on the atomic bomb ended, as far as he was concerned.

  The same was true for many scientists. Peierls led a significant number of UK physicists in a campaign against the proliferation of nuclear weapons. In 1947 this group wrote to the Times, making the case for international arms control. MI5 duly took note of this initiative, as did Senator Joseph McCarthy in the US. In July Skinner was part of a study group that produced a widely publicized paper on the subject, which was even noted by highly placed Soviet politicians.5 When President Truman revealed the US government’s interest in the hydrogen bomb at the start of 1950, the news was so upsetting to many British scientists, including Nobel laureate George Thomson, that they joined with American physicists in urging the president to publicly refuse to use the weapon. Peierls and other scientists published letters in major newspapers. For the rest of the year, there were articles in the media, describing the scientists’ concerns about the bomb. The Daily Mirror even ran the story on its front page in March.6 Throughout Pontecorvo’s time at Harwell, such issues were debated widely among physicists, but there was no sign that he himself was ever active in the movement.

  The ultimate irony, perhaps, is that the position offered to Pontecorvo in Liverpool had opened up due to the departure of Joseph Rotblat, who left the Manhattan Project on grounds of conscience, became one of the most vociferous critics of the arms race, and later won the Nobel Peace Prize for his work. In his statement of 1955, Bruno Pontecorvo speaks as if none of this ever happened.

  The timing of Bruno’s coming out has some significance. The USSR had by then built an arsenal of atomic weapons and detonated its first hydrogen bomb, and its nuclear-reactor program was well advanced. Stalin had died and his successor, Nikita Khrushchev, was preparing to embrace a new strategy called “Atoms for Peace” at the Geneva Summit. This strategy promoted the idea that nuclear energy could be used for peaceful purposes, such as generating electricity or powering ships, rather than for purposes of destruction, and was intended to show that the Soviet Union wanted peaceful coexistence. It therefore suited Soviet propaganda to present Bruno Pontecorvo as a peace lover who had never worked on the atomic bomb.

  Also, two of the key reasons for keeping Pontecorvo’s presence in the USSR secret had disappeared a few months earlier. The KGB was always careful to maintain firewalls around its agents, even once they were back in the Soviet Union. In 1954, the Cohens, who had been extracted from the United States in 1950 and brought to Moscow just weeks before Bruno arrived, were sent to England to run a new spy ring under the aliases Helen and Peter Kroger.7 By this time MI5 also knew of Kim Philby’s treachery and had removed him from security work, so in 1955 there were fewer reasons for the KGB to be concerned about Pontecorvo.

  ALTHOUGH WESTERN GOVERNMENTS HAD LONG SUSPECTED THAT Bruno was in the USSR, this confirmation nonetheless created a sensation in the global media. In response, the Soviets arranged a press conference for March 4, during which selected journalists would speak to Bruno at the Soviet Academy of Sciences in Moscow. Bruno later admitted, “The prospect of appearing at a press conference bothered me a little. I didn’t know what questions I would be asked and I prepared for a long time.”8

  At four o’clock in the afternoon, Bruno arrived in the hall of what used to be the czar’s summer palace. He wore a dapper gray suit, with the tip of a white handkerchief poking out from its breast pocket, and sported the gold medal and red ribbon of the Stalin Prize on his right lapel.9 Two interpreters accompanied him, and he addressed the hall in Italian.

  He began: “Journalists, friends, companions, I knew that after my appeal many journalists would want to meet me so I have come here for a frank and friendly exchange of views and to have a chat with the world’s press. The Atlantic powers want war, [whereas] my time in the USSR has convinced me that the Soviet people want peace. The government of the USSR is taking all possible measures to prevent war. I appeal to all honest men, and in particular scientists, to take a stand. Today one cannot simply remain a spectator.”

  He concluded his statement by asking the press to send greetings from himself, Marianne, and the children to all their relatives, and in particular to his and Marianne’s parents, who for nearly five years had received no news of them. With that, reporters thrust their hands in the air, anxious to ask questions.

  What followed was a tightly controlled question-and-answer session. When one journalist asked about the circumstances of Bruno’s flight to the USSR, he refused to
answer. The reporters learned something of his life since his arrival in the country, however. He revealed that he split his time between his Moscow apartment and his house at the Dubna site, near the laboratory, where he conducted experiments with the giant cyclotron, and that he had received the Stalin Prize “for work on high energy physics.” In answer to a question about his citizenship, he held up an identity document and announced that he had been a Soviet citizen since 1952.

  The audience wanted to know what his work consisted of. He offered to explain what “high-energy particle physics” was, but added, “I doubt you would understand.” When asked if this work had any military applications, he replied, “Absolutely not. I have never worked in areas that could impact the military.” To the follow-up question (“Do the results have no applications to atomic weapons?”), he maintained his position: “The USSR government has a tireless campaign for the prohibition of atomic weapons, which cannot be said for the USA.” He added, “When I came to the USSR I made several proposals in atomic energy, all of a peaceful nature,” and explained that he had also discussed issues of radiation-protection in nuclear power plants.10

  After two hours, the conference came to an end. One result was that on May 24, 1955, the United Kingdom revoked his citizenship. This is an extremely rare occurrence.11

  As far as the Soviets were concerned, Bruno must have performed satisfactorily, as the next day he and Marianne were allowed to write letters to their parents, their first communication with them—or indeed with anyone outside the USSR—in five years. Speaking thirty-five years later to Miriam Mafai, Pontecorvo claimed that communications during the preceding years had not technically been forbidden: “No one said we could not write. But we did not write.” Then he added enigmatically, “There are things that you cannot understand.” When I asked Mafai for her interpretation of Bruno’s statement, she said, “There are things you can only understand if you are communist.”

  IMAGE 16.1. Bruno Pontecorvo’s British naturalization certificate, overwritten with removal of citizenship on May 24, 1955. (AUTHOR, THE NATIONAL ARCHIVES.)

  With respect to Bruno and Marianne’s parents, letters were as good as it would ever get. Travel outside the USSR remained off limits to the couple. Marianne was refused an exit visa to attend her mother’s funeral in 1967. When Bruno’s mother died in 1958, and his father in 1975, the Soviets similarly denied him permission to attend the funerals—despite the fact that Gil was granted an exit visa to attend a conference in Italy at the end of 1974. Bruno did invite his parents to the USSR, but they declined.12 And although though they could write to their son, they could not know where he lived: Bruno’s official address in the Soviet Union was a post office box.

  AFTER STALIN DIED, NIKITA KHRUSHCHEV OVERSAW SIGNIFICANT changes in the Soviet state and its relations with the West. In 1956, the Hungarian Revolution against Soviet control led to the collapse of the Hungarian government, along with a decision to hold free elections and withdraw from the Warsaw Pact. Moscow could not tolerate this affront to its authority. On November 1, Russian troops entered Hungary and put down the uprising.

  For supporters of communism in the West, this was probably the most serious crisis of conscience since the Soviet pact with the Nazis in 1939. The explanation put out by the Soviet authorities was that dissatisfaction in Hungary had been exploited by fascists and Western powers, which had led Hungarian patriots to call for aid from the USSR in smashing the insurrection. Even within the Soviet Union, a number of intellectuals found this story implausible, but Pontecorvo was prepared to accept the official version of events, and rationalize the invasion as a necessary act.

  For Bruno, loyalty to the USSR was one of the first responsibilities of anyone who believed in communism. Mafai, after interviewing him in 1990, described the focus of a committed communist of the Cold War era as follows: “Loyalty to the USSR is the essential core of his identity. Every decision, every act of their life is dedicated to support the USSR.”13 Bruno was devastated a few months later when he learned that his favorite brother, Gillo, like many European intellectuals, saw the invasion of Hungary as an act of Soviet aggression, and had quit the Italian Communist Party. Bruno could not understand Gillo’s lack of commitment to the cause. Nevertheless, in his later years, Bruno seemed to want to distance himself from this loyalist stance. In 1990 he described himself coyly as having been interested in physics and tennis, and not in politics.14

  PROFESSOR PONTECORVO

  During his time in the West, Pontecorvo had begun to consider how one might detect neutrinos emitted by nuclear reactors, or by the sun. By 1955, Bruno’s existence had been confirmed, but his beloved neutrino still remained hypothetical.

  It was around that time that V. P. Peshkov, one of the top experimentalists at the Institute of Nuclear Problems in Moscow, told one of his graduate students, I. I. Medvedev, to think about how one might detect neutrinos, which, if the prevailing theory was correct, were pouring from nuclear reactors in great numbers. Peshkov was a senior member of the State Committee for Science and Technology, and well connected politically. One consequence of Peshkov’s position was that he had access to operating nuclear reactors. It was this that led him to muse about their possible role in revealing the neutrino.

  Medvedev knew that Semen Gershtein, one of his fellow students, was interested in the weak interaction (the fundamental force responsible for beta decay) as well as the idea of the neutrino. So he made contact with Gershtein to discuss the problem. Hardly anyone took the pursuit of neutrinos seriously at the time, so when Gershtein and Medvedev learned that Bruno Pontecorvo—one of the world’s foremost experts in neutrinos—was in residence at Dubna, with an apartment in Moscow, they decided to consult him about the feasibility of conducting an experiment to detect them. To their surprise, they soon realized that Pontecorvo had the answers ready almost before they had asked the questions.

  One problem in detecting a ghostly neutrino is that, once you have captured a faint signal, how can you be sure it is from a neutrino and not from some other source? Cosmic rays contribute to this problem. Although the atmosphere acts like an umbrella and cuts out or disintegrates the powerful primary cosmic-ray particles, there is still a gentle rain of secondary particles at ground level, enough to mask the faint trace of a neutrino in a detector. Pontecorvo recommended that the students put their detector underneath the reactor so as to increase the protection against cosmic rays. He even estimated their chances of success, and provided details on the necessary equipment.

  It was obvious that he had already given much thought to the subject. At the end of the conversation, Gershtein asked why he had not performed the experiment himself. Bruno blushed, as he frequently did when he felt uncertain, and avoided answering. During further discussions, Gershtein repeated the question, and Pontecorvo reluctantly, and “with embarrassment,” revealed that he had wanted to perform the experiment soon after his arrival but was forbidden access “to any reactor.”

  Igor Kurchatov had been an admirer of Bruno’s work for several years, but even he—the father of the Soviet atomic bomb—was unable to convince the authorities to give Pontecorvo access to a reactor.15 Gershtein was astonished when he learned this, and years later expressed his belief that “without doubt, if investigations had started in 1950, when many industrial reactors were already operating and new ones under construction, Bruno Pontecorvo could have been the first to detect neutrinos.”16

  This folk wisdom is hard to sustain, however, as Pontecorvo’s Dubna logbooks tell a different story. One journal contains notes, written toward the end of 1951, on the possibility of detecting neutrinos by means of the chlorine method, which he had advocated in 1946. He seems to have envisioned an experiment at a nuclear reactor. However, even if he had been given access to a reactor, he would not have succeeded in detecting neutrinos, for the same reason that Ray Davis failed to detect the neutrino in this way at an American reactor in 1955—namely, that a reactor produces antineutrinos, wh
ich cannot be detected by this method. In 1956, Clyde Cowan and Frederick Reines, working at the Savannah River nuclear reactor in South Carolina, succeeded in confirming the existence of these antineutrinos using a different approach. I found no evidence in Bruno’s logbooks that he considered their method.

  FORMER FRIENDS

  We saw how, in August 1950, days before Bruno left on his long journey from Rome to the Soviet Union, he had hoped to visit Edoardo Amaldi, but missed him because Amaldi was in the United States. During his time in North America, Amaldi witnessed the construction of the Cosmotron accelerator at Brookhaven, which gave him the idea that a similar accelerator should be constructed in Europe. This was the genesis of CERN, the European Council for Nuclear Research, which was formally established in 1954, as a joint venture among twelve Western European countries. CERN’s first accelerator was a relatively modest synchrocyclotron, completed in 1957, which was less powerful than that at Dubna.17 However, by 1959 CERN had finished construction on the Proton Synchrotron, which produced protons with about forty times more energy than Dubna’s, and rivaled the Cosmotron for several years as the world’s leader.

  Following CERN’s example, the nations of the Warsaw Pact decided to launch a similar venture, based at Dubna. In 1956 the Joint Institute for Nuclear Research (JINR) was inaugurated, and construction began on the Synchrophasotron, an accelerator with five times the power of Dubna’s existing one. As before, most of the construction work was done by prisoners from the Gulag, and the entire site was hidden in the woods behind two fences and a high embankment. The tilled soil between the two rings of fences gave the area the appearance of the border between two rival states, the earth ready to reveal the footprints of anyone trying to sneak across.

  The Synchrophasotron began operation in 1957, allowing scientists to explore new areas in nuclear and high-energy particle physics. However, it was unable to compete against the even-higher energies that would soon be produced by CERN’s Proton Synchrotron, or against the sophisticated electronics available to researchers in the West.