what progress might have been made. He could always be counted on for suggestions… He followed things really quite closely, spent very generous amounts of time here and was of course very helpful. He was also personally very interested. Not only in the work on thermonuclear problems, possible thermonuclear systems, but also on what was going on in the fission bomb studies… He really expressed an interest in everything. But the thing on which he was most inclined to try to work was the Super problem.”
After his 1947 summer consultancy, Teller assessed the H-bomb effort at Los Alamos in a technical report, “On the Development of Thermonuclear Bombs,” a marker of the lab's progress and of Teller's own contemporary judgment of where the work stood. The report found that the Super was “probably feasible” but judged that “its complex construction gives little hope that it can actually be made to work in the next three to four years.” Mentioning what Carson Mark calls “some adverse effects not previously taken into account,” it doubled the April 1946 Super Conference estimate of the amount of tritium the Super would require.
Teller's memorandum also reviewed problems with his 1946 Alarm Clock system — the system that incorporated layers of fusion materials into the concentric shells of an enlarged implosion device. Whether or not such a device was feasible, Teller concluded, depended on how much the light fusion materials would mix with the heavy fission materials in the course of the implosion. Physicists refer to an element's atomic number generically as Z Hydrogen has a Z of 1, helium 2, and so on to uranium at Z = 92 and plutonium at Z = 94. Elements of higher Z radiate more rapidly at higher temperature than elements of lower Z So mixing of high-Z and low-Z materials within an Alarm Clock system, while such mixing would compress the fusion materials and enhance their reaction, would also increase the mixture's cooling by radiation. Hans Bethe thought Teller's Alarm Clock conclusions in this 1947 report were “most pessimistic.” On the other hand, Teller noted in the report that the Alarm Clock was a possibility “that may be open to our competitors as well as ourselves,” although he thought a Soviet Alarm Clock was “not very probable.”
For the Super or the Alarm Clock or both, Teller proposed exploring the production and use of a gray salt-like compound of a lithium isotope and deuterium, lithium6 deuteride, as a fuel alternative to liquid deuterium. Lithium, a soft, silvery-white metal, atomic number 3, was already in use in the American bomb program in the form of lithium fluoride slugs, which were irradiated in the Hanford reactors to produce tritium. Theoretically, lithium in a bomb would pick up neutrons from D + D reactions or from fission and make tritium
Teller concluded significantly that both the Super and the Alarm Clock designs needed to be explored further before it would be possible to choose between them. That exploration would require calculation on electronic digital computers that were only then being developed. With such development in mind, Teller proposed a deliberate delay: “I think that the decision whether considerable effort is to be put on the development of the [Alarm Clock] or the Super should be postponed for approximately two years; namely, until such time as these [proposed] experiments, tests and calculations have been carried out.” Carson Mark explains why calculations were so important for a device that could only be tested at full scale: “The very proof of feasibility required the fully detailed calculation of [the Super's] behavior during an explosion. Without this, no conclusive experiment was possible short of a successful stab in the dark, since a failure would not necessarily establish unfeasibility, but possibly only that the system chosen was unsuitable, or that the required ignition conditions had not been met.” Testing a system that sputtered and fizzled would not teach them how to design one that caught fire.
In the meantime, they needed a detailed calculation of the full course of
In the meantime, atomic-bomb production had begun to pick up. Although the official stockpile number for 1947 is thirteen Mark series pluto-nium bombs, by the end of the year there were in fact fifty Mark series cores at hand of which nine were all-plutonium Christy (solid) cores, thirty-six were composite Christy cores and five were levitated composite cores (a design which had still not been tested). Eleven more Mark series cores were in the process of being certified. The stockpile contained fifty Class A initiators with another twenty-two being certified and thirteen Class B older initiators in which the polonium had partly decayed. There were sufficient nonnuclear components on hand to make 104 complete Fat Man (FM) assemblies; fifty-four more were being certified. The stockpile was short of aluminum pusher shells for FM assemblies, with only sixty-three on hand. Ten Little Boys (LB) were being certified and six LB initiators; the program to manufacture these penetrator weapons, which could also be used as free-fall bombs, was ahead of schedule. In an emergency, then, the United States at the end of 1947 had available an arsenal of at least fifty-six atomic bombs (fifty FM and six LB with initiators), each one sufficient, in the judgment of the Joint Chiefs of Staff, to destroy a city. But available bomb-assembly teams would need up to thirty days to put together even twenty bombs, and delivery would be problematic. The US Air Force (as the former Army Air Forces were now called) had thirty-five Silverplate B-29s operational at the end of 1947 to deliver atomic bombs with thirty flight crews available to man these planes, but only twenty crews were fully trained in handling atomic weapons.
With Robert Oppenheimer's election in January 1947 as chairman of the AEC's General Advisory Committee, the charismatic physicist came into his own as an influential government adviser. “In the early days [of the AEC],” he testified later, “we [on the GAC] knew more collectively about the past of the atomic energy undertaking and its present state, technically and to some extent even organizationally… than the Commission did… It was very natural for us not merely to respond to questions that the Commission put, but to suggest to the Commission programs that it ought to undertake.” As of early 1947, though negotiations were still ongoing at the UN, prospects were fading for agreement on international control. “The problem that we faced then,” Oppenheimer noted, “was to devise a program which would regain some of the wartime impetus and vigor, and above all to make available the existing know-how, the existing plant, the existing scientific talent… in the form of actual military strength. It was not so available as of the first of January 1947.” Without debate — “I suppose with some melancholy” — they concluded immediately “that the principal job of the Commission was to provide atomic weapons and good atomic weapons and many atomic weapons.” The AEC should look into atomic power, the GAC advised, as well as military uses of atomic energy such as submarine propulsion, and it should stimulate basic science. But its primary job was to make bombs and better bombs and more bombs. The GAC set to work to facilitate those goals, meeting monthly throughout the year, pushing initiator manufacture, production reactor development and improvement and bomb tests.
Oppenheimer was still trying to teach at Caltech, but a new opportunity had presented itself. AEC commissioner Lewis Strauss was a member of the board of trustees of the Institute for Advanced Study in Princeton, a place Oppenheimer would come to characterize as “an intellectual hotel,” and the institute needed a new director. Its faculty, an independent centenary of geniuses that included John von Neumann, Albert Einstein and mathematicians Oswald Veblen and Kurt Godel, thrashed out a list of five recommendations. Oddly, Strauss's name appeared as a fifth choice on the list (though he was a man of considerable intelligence, Strauss was entirely self-educated and a specialist only in making money; he had left school at sixteen to sell shoes). Oppenheimer was
