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

by Close, Frank

  They set off in two cars. In one was the Halban family; the other, a station wagon, contained the Kowarskis, along with twenty cans of heavy water piled in the back. They traveled roughly from west to east, crossing innumerable roads that spread southward from Paris. These roads, unsurprisingly, were full of refugees. It was dark when they reached Bordeaux and received their orders: “Proceed to England by ship.”

  Years later, Kowarski still recalled the drama and timing of these events. The Pétain government had been formed, and an armistice called for, but on this one day, June 17, the previous government was still concluding its business. As a last desperate act of defiance, the government “put its faith into these two departing magicians,” with heavy water serving as their magic wand. It was clear to the pair that they were “carriers of a mission,” entrusted with something of the greatest importance for the honor of France.20

  Officials from the Ministry of Armament, assisted by highly ranked military officers, carried the scientists’ household belongings and the cans of heavy water to the ship Broompark. By midnight Halban and Kowarski were on board, along with several other scientists. The few cabins had been assigned to women and children, so Halban and Kowarski had to fend for themselves. They eventually fell asleep on a heap of coal. The next day, Marshal Pétain ordered France to stop fighting, and surrendered to the Germans.

  The heavy water had begun its own odyssey, first to England and then to North America. It arrived in England on June 21, just as Bruno Pontecorvo was reaching Toulouse and completing the first stage of his own adventure. Three years would pass before he would meet his colleagues again, across the ocean.

  FROM VICHY FRANCE TO THE NEW WORLD

  The south of France was the starting point for a great migration of refugees to North America. The Emergency Rescue Committee issued permits for immigration to America but only if the applicants satisfied very rigid criteria. Bruno, at least, had a job to go to. He now entered the corrupt lottery necessary to obtain the exit visas from the Vichy government. The character of Captain Louis Renault in the film Casablanca is a perfect reflection of Vichy officialdom: people who had France in their hearts, but were forced to work within the tight constraints of realpolitik. Their motives were mixed. Power over peoples’ lives led to greed and corruption. Bruno Pontecorvo had to find his way through this labyrinth. The family planned to travel by ship from Lisbon, which required them to pass through Spain. So he also had to deal with the Spanish and Portuguese governments to obtain the necessary transit permits. Chaos and unpredictability reigned.

  Bruno’s attempt to leave Europe seems to have started on June 26 with a visit to the Portuguese consulate in Toulouse.21 He then made a three-hundred-mile round trip to Bordeaux to visit the American consulate, on June 29, seeking permission to immigrate to the United States. This cost nine dollars per person.22

  The following week was a rare period of relative calm before Bruno resumed crisscrossing France, accumulating further documents for his family’s departure. On July 9, he was issued a visa in Perpignan—120 miles away from Toulouse, near the Spanish border—allowing them to travel across France “for the USA via Portugal and Spain.” The visa was only valid until July 17; time was short. He stayed overnight in Perpignan. The next day, he visited the Spanish consulate, which issued more visas to the Pontecorvos, “good for a single voyage from Marseilles via Spain en route to Portugal.”

  Having acquired Spanish entry and transit documents, Bruno next visited Marseilles—nearly 200 miles away—to obtain Portuguese documents, which he succeeded in doing on July 12: “Good for Portugal in transit to USA, valid for 30 days.” Finally, with all these papers in place, official permission to undertake the actual journey and exit France seems to have been required; on July 17, the prefecture of the Haute Garonne department, in Toulouse, issued the last set of visas to Bruno’s family, permitting them to leave France for the United States via Spain and Portugal.

  Having come so far together, the band of refugees now went their separate ways. Gillo and Henrietta remained in southern France, as did Emilio Sereni and his family. Giuliana and Duccio joined Marianne, Bruno, and Gil en route to Portugal and the Americas.

  At last they set off by train from Toulouse. They crossed the frontier into Spain at Portbou, on the Mediterranean coast, on July 19. They had traveled through France for half a day. It would be a further 500 miles before they reached Madrid, and five more days before they arrived in Portugal.

  THE TRAIN FROM MADRID WAS PACKED SOLID WITH REFUGEES. THEIR luggage, stacked in the corridors, served as makeshift furniture for those who had not managed to grab seats. To add to the discomfort, it was the height of summer, very hot, and there was no water. Giuliana was pregnant, but stoically managed to deal with the hardships. Not so Marianne, who was also pregnant, and in pain.23 She felt a little better when she was lying down, but lost consciousness several times. Bruno did not know what to do. For a long time she was able to sleep only by lying on the floor of the corridor.

  On July 24 they reached the border with Portugal, and from there proceeded to Lisbon, the only port from which it was possible to reach the United States.24 Thousands of exhausted and frightened migrants were pouring into the city. Many had abandoned comfortable homes, and sold their precious possessions in order to buy tickets, or to bribe officials in exchange for the necessary permits. And so it was for Bruno. After handing over yet more money, he obtained a permit for the group to reside in Lisbon for thirty days. They rented rooms in a small hotel.

  After the privations of the journey, Lisbon was like heaven. Sunny and cooled by the breeze from the sea, the city also boasted coffee shops and the smells of pine trees, which added to the general ambience. The war was miles away, in all senses of the phrase. Marianne still had the “pallor of a sick child,” however, and a few days before they were due to board the ship for the United States, she had a miscarriage.

  She was in no state to travel, but they had come so far and had to continue. On the ninth of August, the two families set out together across the Atlantic Ocean, the final leg of their escape.25 Their privations were not yet over, however. Although the weather was good, the voyage on the liner Quanza was awful. The Pontecorvos’ cabin was low down in the ship, where the heat was insufferable. Marianne and Giuliana were seasick.26

  To arrive in Manhattan after crossing the Atlantic by ship is, judging from my own experience, one of the great moments in world travel. After days of gray sea, with no distinguishing features to give a sense of distance or speed, the low-lying dunes of Long Island appear on the starboard, or right-hand, side. After another hour, the coast of the mainland becomes ever more prominent on the port side. You appear to be headed for disaster as the two landmasses of the North American continent and Long Island come together in front of you. Then, gradually, a narrow channel appears between Staten Island and Brooklyn. This is the strait known as the Narrows.

  Since 1964 the Narrows have been spanned by a suspension bridge.27 On a modern liner, such as the Queen Mary 2, the funnels of the ship seem certain to pierce the bridge above you. So it is with both relief and surprise that you rush beneath, and are suddenly within the confines of the continent. In 1940 there was no bridge, but the dramatic sense of arrival and relief as the Pontecorvos passed through the Narrows, from the Atlantic Ocean to the inland waters, would have been the same. The Quanza entered the Upper Bay, and turned to starboard, revealing the skyscrapers of Manhattan Island.

  But first, for all travelers, and especially for refugees, there is one symbolic moment to savor: the sight of the Statue of Liberty. It was thus ironic that, on the day the Pontecorvos arrived, humid mist obscured this symbol of freedom. In any case, the ship reached New York on August 19; Bruno Pontecorvo was three days shy of his twenty-seventh birthday, which he spent with his brother Paolo at 503 West 121st Street. This was to be Bruno, Marianne, and Gil’s temporary home until they moved to Tulsa.28

  PARALLEL LIVES

  When Bru
no, Giuliana, and their families left France and headed for the United States, Gillo and Henrietta stayed behind. They moved to Saint-Tropez, where a strange assortment of individuals who were trying to escape the war had gathered. Gillo gave tennis lessons to the local bourgeoisie, and met exiled intellectuals such as the musician René Leibowitz, who taught him piano, harmony, and counterpoint.

  Gillo later described this period, when war raged everywhere except this bizarre bubble, as “living outside history.”29 Then he found a way to reenter it. Having been converted to communism by Bruno, Gillo became a clandestine member of the Communist Party of Italy in 1942. While living in Saint-Tropez, he met Giorgio Amendola, an Italian communist who was secretly organizing opposition to the Mussolini regime. Amendola was desperate to find someone willing to go to Italy and reestablish contact with the antifascists and communists there. Previous agents who had made the attempt had been arrested just past the border. Gillo offered to try—and succeeded, using a variety of false identities.30

  Soon he was making regular visits to Milan on courier and news-gathering missions. He worked on the party’s underground newspaper, l’Unità, throughout the summer of 1943, while Milan suffered constant Allied bombardment. In 1944 Gillo was forced to go into hiding, but then went to Turin, where he began to organize young factory workers. After the liberation, he became the director of Pattuglia, a journal for communist and socialist youth, and then returned to Paris to become the Italian representative of the communist-backed World Federation of Democratic Youth.

  Salvador Luria, as we saw earlier, reached Marseilles, and emigrated to the United States. Thus, our heroes survived, unlike some of Némirovsky’s fictional ones, or indeed Némirovsky herself. Her chronicle of the flight from Paris mirrors the experiences of our group, but her own tale ended tragically: arrested by the Gestapo, she died at Auschwitz. Emilio Sereni, the final member of the group that fled Paris with Bruno, almost suffered a similar fate.

  After fleeing Paris, Sereni was prominent in the communist partisan movement. Based in Nice, he encouraged Italians to resist Mussolini, and published a radical newspaper, The World of the Soldier. In June 1943 he was arrested, sent back to Italy, and sentenced to eighteen years in prison. He tried to escape, but was recaptured and sent to an SS camp in Turin, where he spent seven months, under threat of execution. In August 1944 he made a second escape attempt. This time he succeeded, and lived undercover for the few remaining months of the war.

  After the war ended, Emilio Sereni—by now a hero as well as a prominent communist—took up politics full-time and became Minister of Public Works in the postwar government. At the Fifth Congress of the Italian Communist Party in 1945, he was elected as a member of the Central Committee and the Directorate. He soon became an influential member of Comintern, or the Communist International—the organization whose goal was to create an international Soviet republic. By 1950 Emilio Sereni would be a regular visitor to Eastern Europe, and well connected in Moscow.

  FIVE

  NEUTRONS FOR OIL AND WAR

  1940–1941

  BRUNO’S NEW CAREER AS AN OIL PROSPECTOR TOOK HIM AWAY FROM the frontiers of nuclear physics, which were now dominated by fission and the attempt to create a chain reaction. Meanwhile, Hans von Halban and Lew Kowarski had decamped to England with the precious heavy water, and begun experiments in Cambridge. The results of these tests appeared to show that a chain reaction might be possible in uranium when heavy water is used a moderator.

  Even before Bruno’s departure, the critical questions were obvious to physicists worldwide. In 1939 Niels Bohr had pointed out that using U-235 rather than U-238 was key, but how much uranium would be required to make a chain reaction in practice? And was uranium the only possible material that could be used? It’s worth noting that if this quest was successful, it would highlight the irony of Hitler’s persecution of the Jews: many brilliant Jewish scientists fled central Europe and became key players in the scientific war against the Nazis.

  In England, at the University of Birmingham, two of these refugees, Otto Frisch and Rudolf Peierls, focused on the questions of whether a chain reaction could occur if fast neutrons hit a lump of pure U-235 and how much would be required to make a significant explosion.

  In March 1940 the two young theoreticians worked out the equations and were astonished by the answer: “The energy liberated by a 5kg bomb would be equivalent to that of several thousand tons of dynamite.”1 The British, already at war with Germany, took immediate action: Frisch and Peierls’s work was classified as top secret—so secret, in fact, that the two émigrés (technically “enemy aliens”) who had made the discovery were barred from the official committee that first evaluated it.

  The idea was not implemented efficiently, however, because of doubts that such a weapon could be built in time to influence the war, or even that it would work.2 The enrichment of uranium to produce the necessary levels of U-235 would be a huge industrial enterprise. This inspired a new thought: Could there be other elements whose nuclei might fission easily? Scientists hypothesized that there existed unstable elements beyond uranium—now known as neptunium and plutonium—and that these could be likely candidates. However, no one knew whether they would be so in practice. Several grams of these exotic elements would be needed to find the answer, and because these “transuranium” elements do not occur naturally it would be necessary to make them.

  Transuranium elements are occasionally produced, one atom at a time, when neutrons hit uranium. In June 1940, American physicists Edwin McMillan and Philip Abelson duly bombarded uranium, performed a chemical analysis of the sample, and identified the presence of some atoms of element 93—neptunium. They suggested that plutonium, element 94, might also be formed in such a way.3 In Cambridge, Egon Bretscher and Norman Feather predicted that plutonium would have a strong capacity to fission, much like U-235. To test whether this was true in practice would require a lot of plutonium, which in turn would require tons of uranium, intense sources of neutrons, and an efficient means to moderate them. A nuclear reactor is the ideal machine for the task. Indeed, the production of these transuranium elements would become one of the major motivations behind the development of nuclear reactors.4

  The project in the United Kingdom was already classified secret. When Abelson and McMillan’s paper about neptunium and plutonium appeared in Physical Review that summer, available for anyone to see, scientists in both Britain and the US protested.5 In Britain, a nation already at war, the dangers of advertising such a strategically important discovery were obvious. Although the United States was not yet involved in the war, influential refugees from fascism, such as Einstein and Fermi, were already in the country, and others, including Bruno Pontecorvo, were on their way. Thus, the Americans too became concerned at the potential implications of these discoveries. Starting in the summer of 1940, all research on fission in the West became a closely guarded secret, and no further papers on the subject were published in the open literature.

  There were three main strategies in the quest for a chain reaction. One was to find some way to enrich uranium—that is, to increase the amount of the U-235 isotope. Another was to find some other fissile element—such as plutonium—and use that. In the USSR, Igor Kurchatov examined a third possibility: Could fast neutrons fission both U-235 and U-238 and initiate a chain reaction in natural uranium without the need for enrichment?

  Early in 1940, at Kurchatov’s suggestion, two junior colleagues—Georgii Flerov and Konstantin Petrzhak—used a range of sources that emit neutrons with different energies, put them inside a sphere of uranium, and measured how the neutrons flowed.6 They found that fast neutrons create an insignificant amount of fission but also discovered something unexpected: fission appeared to occur sporadically in uranium without any neutron bombardment at all.

  Their initial explanation was that cosmic rays from outer space were hitting the uranium atoms and splitting them apart. To guard against this possibility, they repeated the exp
eriment underground in Moscow’s Dinamo subway station, where the earth and rocks would shield the uranium sample. The spontaneous fission persisted. This proved that it was a real phenomenon, albeit rare. The team announced their findings at the Soviet Academy of Sciences in May 1940, and Kurchatov sent a short report to the American Physical Review, which published it in July.7

  We now know that spontaneous fission occurs because even natural uranium is slightly unstable. Although the phenomenon is too rare to be a source of energy, it can nonetheless interfere with the delicate design of an atomic weapon. In a nutshell: to make a nuclear blast, fission must grow exponentially within a fraction of a second. Spontaneous fission, and fission induced by cosmic rays, can cause the nuclear energy to be released prematurely, before a chain reaction develops. Within a couple of years, this phenomenon would become one of the many problems to solve in designing a successful uranium bomb.

  In the USSR—which was not yet at war—investigations continued. On August 29, 1940, Kurchatov, Flerov, and some colleagues drew up a plan for the “utilization of the energy of uranium fission in a chain reaction.”8 There was a lot of discussion about the plan in November at the Fifth All-Union Conference on Nuclear Physics, in Moscow. The need for large amounts of uranium was immediately obvious. How the USSR would find supplies of the scarce element, however, was not.

  Two young Russian theoreticians, Yulii Khariton and Yakov Zel’dovich, now turned their attention to the same question that, unknown to them, Frisch and Peierls had already answered in March: How much pure U-235 was needed? In the fall of 1940 they found the same result as the British pair: a few kilograms of U-235 would do. The Soviet Union recognized the strategic importance of this discovery and classified their work as secret.9 The Soviets already suspected that a secret nuclear physics project was under way in the West. Their hunch had developed during the summer, when Flerov and Petrzhak’s paper appeared in Physical Review. Their discovery of spontaneous fission was of immense significance, and yet there was a complete lack of (visible) reaction to this in the United States.10