by Gregg Herken
With a university attorney in tow, Underhill headed east again the following month to work out final arrangements with the army. On April 20, 1943, he signed Contract 36 on behalf of the regents, for administrating Los Alamos. Six weeks later, Underhill was back in Groves’s suite at the Biltmore to sign Contract 48, for expenses related to the Calutrons and other army projects at the Rad Lab. Both agreements were dated January 1, 1943, to account for the work already done by the university.2
At Los Alamos, work on the bomb was already under way. Oppenheimer assigned Serber the job of briefing the dozens of scientists arriving from colleges and universities around the country. In early April, the recruits assembled in the uncompleted library of T Building, future offices for the theoretical physicists. In a series of five lectures given over the next two weeks, Serber laid out the current state of knowledge about the atomic bomb, including what had been learned since the Berkeley summer seminar.
Eager to dispel any illusions about the nature of the task, Serber emphasized at the outset that the “object of the project is to produce a practical military weapon.”3 Cautioned about using the word bomb while uncleared construction workers were still crawling around in the ceiling above his head, Serber began calling it the “gadget” instead. Taking the last digit of the atomic number, 94, and the last digit of the atomic weight, 239, he referred to plutonium as “49”; uranium was simply “U” or “the material.”
The first gadget discussed by Serber was the so-called gun, the earliest image of the bomb going as far back as the M.A.U.D. report. In a gun-type bomb, two subcritical pieces of U-235 or plutonium would be “assembled” by being fired into each other by a cannon. Theoretically, the 3,000-foot-a-second acceleration would drive the pieces together into a supercritical mass before stray neutrons could predetonate it. Serber named the long, skinny device the “Thin Man,” after the character in the popular film starring William Powell and Myrna Loy.4
An alternative design, more complex but more efficient—if it worked—had been dubbed the “Introvert” by Caltech’s Richard Tolman, whom Groves had sent to Los Alamos as a kind of inspector general.5 The weapon that Tolman and Serber imagined would surround a hollow sphere of fissionable material with ordinary high explosives. When detonated, the explosives would collapse the shell of uranium or plutonium into a compact ball of supercritical density. Tolman talked of assembling the bomb by “imploding” it.6 Serber eventually called the device “Fat Man,” in honor of the figure played by Sidney Greenstreet in The Maltese Falcon.7
Using the latest critical mass figures derived by Eldred Nelson and Stanley Frankel, Serber announced that 33 pounds of enriched uranium or about 11 pounds of plutonium would be required for a single bomb.8
Before work could start on either design, however, cross-section measurements and neutron densities had to be obtained. For the purpose, huge scientific apparatuses were acquired and transported in secret to the remote site. Scouring the country, McMillan located a suitable cyclotron at Harvard and arranged to have it trucked up the treacherous road to the top of the mesa. (The army instructed McMillan to tell Harvard physicists that the machine was destined for a medical facility in St. Louis. No one believed him.)9 By mid-April, the cyclotron was safely in place, along with a team to run it.
Wilson and his graduate students had meanwhile decamped Princeton en masse and were housed in Fuller Lodge, the Lincoln log–like assembly hall of the former Ranch School that was being used as a bachelor dormitory. Conant and the OSRD had decided to abandon the Isotron and put the money saved into Lawrence’s Calutrons. On weekends, Serber tried, with varied degrees of success, to teach the Princetonians horsemanship.
Late in April, Groves sent another review committee to Los Alamos, headed by the ubiquitous Warren Lewis. Although irked by the interruption, Oppenheimer prepared three days of presentations on the lab’s experimental program, aided by Serber and Teller.10
Edward was irritated that Oppie had passed him over and picked Bethe to head the Theoretical Division. (Teller privately considered Bethe a “brick maker” among physicists—thorough, meticulous, but unimaginative and even a bit pompous. In Oppenheimer, on the other hand, Edward recognized a kindred spirit—a “bricklayer,” or synthesizer, who understood the underlying structure. “I was not happy about having him as my boss,” Teller freely admitted of Bethe.)
Despite earlier defending Groves to Oppenheimer, moreover, Teller was already objecting to the strictures that secrecy imposed upon science at the lab. Reprimanded for discussing classified subjects outside the Tech Area, Edward had replied, sarcastically, “Aren’t we all a big happy family here?”
But Teller’s real difficulty at Los Alamos was more fundamental and concerned his reaction to something that most at the lab saw not only as indispensable but as a positive advantage: teamwork. He was uncomfortable with the fact that, at Los Alamos, “almost constant collaboration was necessary, all the work was done at a feverish pace, and one’s new idea, once hatched, could be taken away and given to others to develop.” It was, he later protested, “a little like giving one’s child to someone else to raise.”11
Oppie had assigned Edward to study unorthodox approaches to the fission bomb. These included “autocatalytic” weapons—bombs where the efficiency would increase as the chain reaction proceeded. The danger of a dud and instability were the major problems with this approach.12
One concept favored by Teller was a bomb whose active material was a compressed white powder containing uranium and hydrogen. Teller had raised the possibility of a so-called hydride bomb at the Berkeley seminar the previous summer. Its theoretical advantage was that the critical mass might be as little as one-twentieth that of metallic uranium. But the hydrogen in the mixture absorbed neutrons and thus slowed the chain reaction, reducing the power of the explosion and even running the risk of a fizzle. “Some bright ideas are needed,” Serber concluded in his lecture on the subject. None had yet been forthcoming.13
On April 28, 1943, Teller, Fermi, and Bethe joined Earl Long, a University of Missouri chemist, in a presentation on the status of the Super. Long was an expert on cryogenics and in charge of the deuterium experiments that were being conducted at a shed on the mesa’s south rim.14 By way of introduction, Oppenheimer described the likelihood of sparking a thermonuclear reaction with a fission explosion as “highly probable … in principle.” Development of the Super should “follow immediately the completion of the gadget,” he felt.15
As at Berkeley, Teller described how the shock wave from an exploding atomic bomb might be used to ignite a cubic meter of liquid deuterium. But he conceded that his latest calculations showed that the fission trigger for such a superbomb would require more than 160 pounds of uranium, or nearly 60 pounds of plutonium. As all were aware, tiny flecks of uranium metal had only begun accumulating in the collectors of the prototype Calutron, and none had yet left Berkeley. It still took more than a week of bombardments on the Rad Lab’s 60-inch to make enough plutonium to be visible to the unaided eye.
Thus, when Oppenheimer told the Lewis Committee that it might take only three years to build the Super—eighteen months for experimental measurements, and another eighteen months to design the actual weapon—his assumption was that the materials for the bomb would be already in hand.16 Given the daunting task of building the first fission bomb, Oppie left no doubt that he put the Super far behind the gadget in terms of priority. Indeed, requirements for the Super, he reported to Groves that summer, were “sufficiently remote in time so that we would prefer to postpone listing them.”17
Nonetheless, Oppenheimer’s decision to subordinate work on the Super to the fission gadget further riled Teller.18 After Edward, in a fit of pique, walked out of a meeting of section leaders, Oppie agreed to meet with the temperamental Hungarian every week in private. At these meetings, the Super was a recurrent theme that, Bolero-like, increased in both intensity and tempo, until it came to dominate the sessions.19
Tell
er’s final presentation to the Lewis Committee, also at Oppenheimer’s request, concerned not the Super but a prospect that none of those at the lab was eager to contemplate: the possibility of abject failure. Vannevar Bush had raised the thought—the hope, really—that some as-yet-undiscovered quirk of Nature might make a fission weapon impossible. Edward’s lecture concerned an inelegant alternative to the bomb: the use of radioactive poisons. Even if the atomic bomb did not work, Teller noted, the waste from Hanford’s reactors could still be used to contaminate up to 100 square miles of enemy territory with persisting and near-lethal levels of radioactivity. Fission products from the atomic piles could either deny an area to the enemy or be dumped on his soldiers to kill them outright.
Oppenheimer’s decision to entertain this macabre alternative to the bomb was arguably simple prudence, a hedge against the unpredictable. Two years earlier, Compton’s review panel had given radiological warfare precedence, ahead of the fission bomb, among the possible military applications of atomic energy. The figures that Teller cited in his lecture came from a December 1941 report by Princeton physicists Smyth and Wigner, who had likened the use of radiation as a weapon to “a particularly vicious form of poison gas.” Wigner found the subject so distasteful that he subsequently tried to disassociate himself from the report.20
But eighteen months of war had changed the old way of thinking.21 Fermi had already broached the subject of radiological weapons with Oppenheimer and was surprised at the reaction. Oppie wrote Fermi, in reply, of plans to poison “food sufficient to kill a half a million men, since there is no doubt that the actual number affected will … be much smaller than this.”22
Visiting from Chicago that spring, Fermi found Oppenheimer’s callous bravado indicative of a different mood among the scientists. He was surprised to discover, Fermi told Oppie, that his friends at Los Alamos now sounded like they actually wanted the bomb to work.23
* * *
By spring 1943, the Manhattan Project was also a priority of the Soviet Union’s. Two years earlier, the NKVD—the People’s Commissariat of Internal Affairs—had ordered its intelligence officers serving under diplomatic cover in Soviet embassies and consulates to begin collecting information on the status of technical research in the West. The NKVD’s spies were supplemented by a parallel espionage network run by the Soviet army’s Intelligence Directorate, the GRU.
Thirty-five-year-old Pavel Fitin, head of the NKVD’s First Directorate (Foreign Intelligence), had been instructed to focus his efforts upon answering some technical questions of particular interest.24 One of these concerned American progress toward a fission weapon. In preparations to steal U.S. secrets, Fitin had given his enterprise a code name appropriate to the Manhattan Project: Enormous (Enormoz).25 The cryptonyms that Fitin assigned to vital intelligence targets within the United States were borrowed from history. But they also reflected an ideological slant and, in some cases, a sense of humor: Washington, D.C., was Carthage; New York City was Tyre; San Francisco became Babylon.26
Nearly a generation’s experience of running spies in the United States had given the Soviets a base of operations that was both broad and deep. In the capital alone, the Russians had two active espionage rings stealing secrets from the U.S. government. The larger ring, headed by a Berkeley-trained economist, Nathan Gregory Silvermaster (code name Robert), had twenty-seven members working in six different federal agencies.27 The spies in Robert’s ring included the assistant secretary of the treasury, Harry Dexter White (Richard), and Lauchlin Currie (Page), a senior aide to President Roosevelt.28 Others recruited by the Soviets to spy included a congressman from New York (Crook), the daughter of the U.S. ambassador to prewar Berlin (Liza), and at least three State Department officials (Ernst, Frank, and Ales.)29
With the outbreak of war, American intelligence, too, became a target of particular interest to Fitin. The Office of Strategic Services (Cabin) was compromised from its mid-1942 birth by more than a dozen agents, who reported on its activities to Moscow; as was the Office of War Information (Wireless), which split off from the OSS that same year.30 Not surprisingly, also of special interest to the Soviets were the U.S. government agencies responsible for spy hunting, the FBI (Shack) and army G-2 (Salt).31
To pass stolen secrets to Russia, Fitin established a residentura, a base for espionage operations, at the four-story townhouse on East Sixty-first Street that served as the Soviets’ New York consulate. He put an NKVD agent with a background in engineering—Leonid Kvasnikov, code-named Anton—in charge of spying on the bomb.32
Like agents at other Soviet diplomatic posts, Kvasnikov used Amtorg, the Soviet Union’s import-export agency, as a cover for espionage activities. As the clearinghouse for the wartime Lend-Lease program, Amtorg had offices in major cities on both coasts. Soviet couriers sent purloined documents by diplomatic pouch on Russian-bound ships, as well as via a special air connection operating from an Army Air Corps field in Great Falls, Montana.33
Shorter messages were encrypted and sent between Moscow and the Soviets’ diplomatic posts by regular commercial telegraphy.*34 When the volume of cable traffic, including secrets, threatened to become overwhelming, the Soviets clandestinely installed illegal short-wave radio transmitters at their consulates in New York and San Francisco.35
But since research on a fission weapon had its true origins in England, it was through the NKVD’s British spies, rather than Fitin’s American network, that Moscow Center first learned about the bomb.36
On the same day in July 1941 that British scientists completed the M.A.U.D. report, the NKVD rezident in London, Anatoli Gorski (Vadim), had informed Moscow of its contents.37 The reliability of Vadim’s information was confirmed by another spy, code-named Rest.
Rest was Klaus Fuchs, a German-born physicist and Communist who had fled to England in 1933. By 1941, Fuchs was working with M.A.U.D. Committee physicist Rudolf Peierls on gaseous diffusion and bomb physics at Birmingham University.38 Shortly after Germany’s invasion of Russia, Fuchs had begun passing information on British atomic research to Moscow through the Soviets’ military attaché in London.39
With the enemy at the gates, the Russians did not react to the news from Gorski and Fuchs until March 1942, when Lavrentii Beria, head of the NKVD, informed Stalin and the State Defense Committee of the secrets received from British spies. Beria recommended that the Soviet Union set up its own scientific panel to carry out research on the atomic bomb—which he had previously feared might be a plot by the West to trick the Soviet Union into wasting its talent and resources on a technological dead end.40
It was not until September 1942 that Vyacheslav Molotov, Stalin’s foreign minister and a member of the State Defense Committee, sent Mikhail Pervukhin, people’s commissar of the chemical industry, the NKVD reports along with a request for advice on how to interpret them. Pervukhin, too, urged an independent assessment. The Soviet Academy of Sciences recommended thirty-nine-year-old Igor Kurchatov—a tall, barrel-chested physicist born in the Urals—to lead the review.
Energetic as well as tenacious, Kurchatov had been nicknamed “the General” by his academy colleagues. In the early 1930s, after he and another scientist at Leningrad’s Institute for Physics and Technology had drawn up plans for a cyclotron, Kurchatov was invited to Berkeley’s Radiation Laboratory by Lawrence. Kurchatov did not make the trip, but the Leningrad cyclotron was built in any event.41
Shortly after the Nazi invasion, Kurchatov, adopting the custom of Roman emperors in time of war, announced that he would refuse to shave until the enemy was vanquished. Predictably, “the General” became “the Beard.”42
In the work he was assigned, Kurchatov benefited from the scientific publications that had appeared in the West prior to the secrecy embargo. These included the June 1940 Physical Review article by McMillan and Abelson, which the British had feared would tip the Germans off to the discovery of neptunium.43 Kurchatov learned about neutron cross sections from a “Letter to the Editor,” writt
en by Alvarez, appearing in a 1941 issue of the Review. Like other Soviet physicists, Kurchatov correctly surmised that his American counterparts had gone underground when they abruptly stopped publishing their research.44
Kurchatov began by putting information from the pre-embargo journals together with the fragments of intelligence gathered by the NKVD. The result was a comprehensive report on atomic research in the West, which Kurchatov submitted to Pervukhin in two handwritten memos during early March 1943.45 “The Beard” underlined in blue pencil information he considered of special interest “that it would be desirable to obtain from abroad.”46
As in the West, the Russians’ initial focus was upon isotope separation. Kurchatov’s summary reflected considerable interest in gaseous diffusion—the method favored in the M.A.U.D. report, and the one that Fuchs was most familiar with. The summary likewise showed that the Soviet Union had learned of the success of Fermi’s Chicago pile within six weeks of the event.47
But Kurchatov’s report also revealed some surprising gaps in the Russians’ knowledge. Among these was his conclusion that “the mass spectrography method … is … considered inapplicable to uranium.” His report to Pervukhin showed, too, that the Soviets were still ignorant of, and thus eager to learn, the critical mass of U-235.48
Kurchatov was most excited about the realization, arrived at through espionage, of “a new direction in tackling the entire uranium problem”—the fact that plutonium could also be used for a bomb—and stressed in his report that “prospects of this direction are unusually captivating.… In this connection I am asking you to instruct Intelligence Bodies to find out about what has been done in America in regard to the direction in question.”49
