in FBI paraphrase, “the high-explosive lens approach to the problem of constructing an atomic bomb was an entirely new one to him.” Greenglass's information on implosion, however limited, was the first news the Soviets had of the radical new approach.
Greenglass returned the Russian to their starting point. Rosenberg was waiting. “‘Go home now,’” Greenglass testified Rosenberg told him. “‘I will stay with him.’ He was going to have something to eat with him.” The Russian got out and the two conspirators went off together. Greenglass drove home and told his wife about his unusual encounter.
The identity of this mysterious Russian has never been established. He was almost certainly not Yatzkov/Yakovlev, since Greenglass noticed that he spoke almost accentless English, while Yatzkov had begun learning English only three months before he came to the United States. Sam Semenov spoke excellent English, having attended MIT, but he had left for Vladivostok through Kalama, Washington, on September 30, 1944. Yatzkov is nevertheless the likeliest person to have sought the information, whomever he sent to collect it, since he was evidently managing atomic-bomb espionage out of New York City at the time.
David Greenglass returned to Los Alamos on January 20, 1945, prepared to observe and to memorize. With Julius Rosenberg's explanation of how an atomic bomb worked, he testified, “I knew what to look for.” Now Los Alamos sheltered at least two active Soviet spies, both of them positioned fortuitously at the very heart of the project.
8
Explosions
Walking from the Moscow subway station to Laboratory No. 2 for the first time, one morning in 1944, the Soviet physicist Anatoli Alexandrov lost his way and stopped to ask a gang of neighborhood children for directions. “It's over the fence where they're making the atomic bomb,” one of the children told him. Work proceeded slowly at the secret laboratory, paced by the exigencies of the war and the limited support that the Soviet bomb program had managed to win from Molotov. “These talented scientists and engineers,” comments chemical industry commissar Mikhail Pervukhin, “started theoretical work aimed at determining the critical masses of U235 and pluto-nium despite having on hand not a single milligram of either substance.” Igor Kurchatov had begun designing a first small graphite-natural uranium reactor in July 1943, but the Soviet Union lacked industrial sources of metallic uranium and high-purity graphite and would not produce sufficient supplies of either material until after the defeat of Germany. When physicist Boris G. Dubovsky joined the lab in 1944 the staff was still, he recalled, “very small — only several dozen people. There was enough nuclear ‘virgin land’ for all of us to plow. Work on the main problem — the nuclear reactor — had already begun. We were supposed to confirm the theoretical concept of the possibility of a chain reaction. The same reactor was meant to produce the first weighable quantities of the new nuclear fuel which is now known as… plutonium… ”
Other research toward a bomb was ongoing at Laboratory No. 2 and elsewhere in the USSR Espionage may have been a source of ideas and information, but ultimately every experiment would have to be replicated and every number checked. “It looks as though we're going to live in Kharkov again,” Eddie Sinelnikov wrote her sister in England on February 15, 1944:
As I wired you today, Kira has been appointed Director of the old Institute… I'm not
Continuing a tradition he had begun at Cambridge, Peter Kapitza instituted seminars — Kapitza Wednesdays, they were called, something like an American journal club — to keep Soviet physicists up to date on unclassified aspects of the work. The experimental physicist Veniamin Aronovich Zukerman describes his debut on a Kapitza Wednesday in March 1944 on the same program with Yuli Khariton; both men's reports related to bomb research:
The first report was given by Yu. B. Khariton. It was on mechanisms of explosive reactions. The second report — on flash [X-ray] radiography of explosions — was mine. Kapitza chaired. That was my first meeting with Peter Leonidovich Kapitza. I was struck by his engineer's grasp of subject matter and by his high voice. I remember he pronounced the Russian word
That year, Zukerman's group took up “intensely studying extremely sensitive explosive primers, such as lead azide and fulminate of mercury,” dangerous objects which Zukerman often carried illegally in his pocket, “in a special container with shock-mounts,” by streetcar from the institute that manufactured them to his laboratory. Zukerman's eyesight was deteriorating from retinitis pigmentosa, and one evening when he was transporting lead azide primers and his streetcar was late his fellow passengers had to help him find his way. When his colleague Lev Altshuler heard about Zukerman's adventures he commented, “For a few hours there, you were just a roaming torpedo, weren't you.” (“During the last year of the war,” Zukerman explains, “the seas and oceans were full of torpedoes that had missed their targets; they were christened ‘roaming torpedoes.’ There were many incidents where military and merchant vessels were blown up by such torpedoes.”)
The big Leningrad cyclotron was rebuilt and operating by the time Boris Dubovsky arrived at Laboratory No. 2 in August 1944, and using it, in October, Boris Kurchatov produced the first micrograms of plutonium transmuted outside the United States. “Just look at this date, please,” Dubovsky appeals. “The end of 1944. The war has just moved from our territory. Half of the country lay in ruins. The fascist beast is still alive and thousands of people are dying on battlefields and in concentration camps.” Soviet scientists did better than overburdened wartime industry. “At that time,” says State Defense Committee science deputy Sergei Kaftanov, “we practically possessed no raw materials… The country's existing uranium mines had been flooded and abandoned… We had to restore them and we had to look for new uranium deposits.” As late as May 1944, V. I. Vernadski complained in a letter to the government Committee on Geological Affairs that he had “not received from you, in spite of your promise, news of the results of the pumping-out of Tiuia-Muiun. Money was allocated in sufficient quantity, there is ore, why the delay? This ought to have been done long ago.” The Soviet reactor would need roughly fifty tons of purified uranium, Kurchatov told Mikhail Pervukhin. The first bags of uranium ore came out of the central Asian mines on the backs of donkeys. The State Institute of Rare Metals purified a first small piece of metallic uranium only in November 1944, and graphite production had not yet begun at Moscow Electrode.
With the Anglo-American invasion of Normandy on June 6, 1944, Stalin finally had his Second Front; the Allies, Soviet and Western, now pushed from opposite directions toward Berlin. “The roads are all cluttered up with the traces of a German retreat,” Konstantin Simonov wrote back from the advancing Soviet front:
… I am amazed day after day by the quantity of machines… abandoned by the Germans. Here are the notorious Tigers and Panthers, burnt and whole, and tanks of older types, and self-propelled guns, and huge armored carriers, and small carriers with one driving wheel looking like motorcycles, and huge, snub-nosed Renault trucks stolen from France, and numberless Mercedes and Opel staff cars, wireless units, field kitchens, antiaircraft installations, disinfection-chamber vans — briefly everything that the Germans had thought up and utilized in their past impetuous advances. And all that is now smashed, burned, or simply abandoned, stuck in the mud of these
