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
Teller’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
