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J.R. Oppenheimer and General Groves
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Time Periods

1890s-1939:
Atomic Discoveries

1939-1942:
Early
Government Support

1942:
Difficult
Choices

1942-1944:
The Uranium
Path to
the Bomb

1942-1944:
The Plutonium
Path to
the Bomb

1942-1945:
Bringing It All Together

1945:
Dawn of the
Atomic Era

1945-present:
Postscript --
The Nuclear Age


General Leslie GrovesPICKING HORSES
(November 1942)
Events > Difficult Choices, 1942

Leslie Groves (right) moved swiftly to make good on his new timetable by scheduling a decisive meeting of the Military Policy Committee for November 12, 1942, and of the S-1 Executive Committee for November 14.  The scientists at each of the institutions doing isotope separation research knew these meetings would determine the uranium-235 separation method to be used in the bomb project; therefore, the keen competition among the institutions added to the sense of urgency created by the war.  Ernest Lawrence's team working on the electromagnetic method at the University of California, Berkeley, remained the most optimistic team working on uranium enrichment.  The gaseous diffusion research being conducted at Columbia University continued to meet serious difficulties, but it was still considered a viable option.  The big loser of the November meetings was the centrifuge process, which was finally dropped from consideration.  

Drawing of CP-1By November 1942, it was the path to the bomb via plutonium, not uranium, that appeared the most promising.  Shortages of uranium and graphite delayed construction of CP-l (Chicago Pile #1) (left), but this frustration was tempered by calculations indicating that a completed pile would produce a fission chain reaction.  With Enrico Fermi's move to Chicago in April, all pile research was now being conducted at the Metallurgical Laboratory as Arthur Compton had planned, and Fermi and his team anticipated a successful experiment by the end of the year.  Further optimism stemmed from Glenn Seaborg's inventive work with plutonium, particularly his investigations on plutonium's oxidation states that seemed to provide a way to separate plutonium from the irradiated uranium to be produced in the pile.  In August, Seaborg's team produced a microscopic sample of pure plutonium, a major chemical achievement and one fully justifying further work on the pile.  The only cloud in the Chicago sky was the scientists' disappointment when they learned that construction and operation of the production facilities, now to be built near the Clinch River in Tennessee at Site X, would be turned over to a private firm.  An experimental pile would be built in the Argonne Forest Preserve just outside Chicago, but the Metallurgical Laboratory scientists would have to cede their claim to pile technology to an organization experienced enough to take the process into construction and operation.  

Glenn T. Seaborg looks through a microscope at the world's first sample of pure plutonium, Met Lab, August 20, 1942.While each of the four processes fought to demonstrate its "workability" during summer and fall 1942, equally important theoretical studies were being conducted that greatly influenced the decisions made in November.  Robert Oppenheimer headed the work of a group of theoretical physicists he called the luminaries, which included Felix Bloch, Hans Bethe, Edward Teller, and Robert Serber, while John H. Manley assisted him by coordinating nationwide fission research and instrument and measurement studies from the Metallurgical Laboratory in Chicago. Despite inconsistent experimental results, the consensus emerging at Berkeley was that approximately twice as much fissionable material would be required for a bomb than had been estimated six months earlier.  This was disturbing, especially in light of the military's view that it would take more than one bomb to win the war.  The goal of mass-producing fissionable material, which still appeared questionable in late 1942, seemed even more unrealistic given Oppenheimer's estimates.  Oppenheimer did report, with some enthusiasm, that fusion explosions using deuterium (heavy hydrogen) might be possible.  The prospect of thermonuclear (fusion) bombs generated some optimism since deuterium supplies, while not abundant, were certainly larger and more easily supplemented than were those of uranium and plutonium.  S-1 immediately authorized basic research on other light elements.  Groves also, on November 25, 1942, chose Oppenheimer as the head of the bomb research and design laboratory to be built at Los Alamos in the mountains of northern New Mexico.  In a month of critical decisions, none would prove more important than this one.  

The president of DuPont, Walter Carpenter, with Generals Levin H. Campbell, Everett Hughes, and Charles T. Harris.Final input for the November meetings of the Military Policy Committee and the S-1 Executive Committee came from DuPont.  One of the first things Groves did when he took over in September was to begin courting DuPont, hoping that the giant chemical firm would undertake construction and operation of the plutonium separation plant to be built in Tennessee.  He appealed to patriotism, informing the company that the bomb project had high priority with the President and maintaining that a successful effort could affect the outcome of the war.  DuPont managers resisted but did not refuse the task, and in the process they provided an objective appraisal of the pile project.  Noting that it was not even known if the chain reaction would work, DuPont stated that under the best of circumstances plutonium could be mass-produced by 1945, and it emphasized that it thought the chances of this happening were low.  This appraisal did not discourage Groves who was confident that DuPont would take the assignment if offered.  

The Military Policy Committee met on November 12, 1942, and its decisions were ratified by the S-1 Executive Committee two days later.  The Military Policy Committee, acting on Groves's and James Conant's recommendations, cancelled the centrifuge project.  Gaseous diffusion, the pile, and the electromagnetic method were to proceed directly to full-scale, eliminating the pilot plant stage.  The S-1 Executive Committee approved these recommendations and agreed that the gaseous diffusion facility was of lower priority than either the pile or the electromagnetic plant but ahead of a second pile.  The scientific committee also asked DuPont to look into methods for increasing American supplies of heavy water in case it was needed to serve as a moderator for one of the new piles.  Now that the various committees had finally chosen which horses to back, the only things left to do were to get final presidential approval and to run the race.

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Sources and notes for this page.

The text for this page was adapted from, and portions were taken directly from the Office of History and Heritage Resources publication: F. G. Gosling, The Manhattan Project: Making the Atomic Bomb (DOE/MA-0001; Washington: History Division, Department of Energy, January 1999), 14-16.  The portrait of Leslie Groves is courtesy the Los Alamos National Laboratory.  The drawing of CP-1 is courtesy the National Archives.  The photograph of Glenn Seaborg looking at the first sample of pure plutonium at the Met Lab in 1942 is courtesy the Lawrence Berkeley National Laboratory.  The photograph of Walter Carpenter and the generals is courtesy the DuPont Corporation; it is reprinted in Stephane Groueff, Manhattan Project: The Untold Story of the Making of the Atomic Bomb (Boston: Little, Brown, and Company, 1967).

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