Measures for Progress: A History of the National Bureau of Standards

THE BUREAU AND THE ATOMIC BOMB 385
isotopes had become available and two of them, the gaseous and liquid diffu-
sion methods, were successfully pursued to the production stage.
Construction of a steam power plant for the gaseous diffusion process,
one of the largest ever built anywhere, based on research at the Naval
Research Laboratory, began in June 1943 at the Clinton Works. Before
the summer of 1945 it was in operation, furnishing enriched U235 for concen-
tration at the nearby electromagnetic plant. The plant for electromagnetic
separation of uranium isotopes, based on the research of Lawrence at the
Radiation Laboratory in California, had gone up at Clinton beginning in
March 1943. By the winter of 1944—45 it was in operation, producing U235
of sufficient purity for use in the bomb.64
While the basic scientific and engineering research in plutonium and
had been in progress, in the spring of 1942 Gregory Breit at the Metal-
lurgical Laboratory initiated the experimental planning on a "fast neutron"
reaction such as would be required by the bomb. Almost a dozen univer-
sities, the Carnegie Institution of Washington, and the Bureau became en-
gaged in basic mechanics and instrumentation for the project. That summer
a group at Chicago under J. Robert Oppenheimer of California's Radiation
Laboratory began the theoretical work on the physics of the bomb.65
Upon transfer of the project to the Manhattan District, search was
made for a safe and secret site for the laboratory where the bomb was to
be assembled. A remote mesa at Los Alamos, N. Mex., on which a handful
of empty structures marked the site of a former boarding school, was found
that November. In March 1943, Oppenheimer arrived to direct operations,
construction of the laboratory began, apparatus from the laboratories at
Harvard, Wisconsin, Illinois, and Princeton. arrived, and the first of an
extraordinary body of scientists and technicans, including a British group
headed by Sir James Chadwick, settled in.
Drawing on research groups from almost a dozen universities, the
Metallurgical Laboratory, and the National Bureau of Standards, the Los
Alamos staff comprised theoretical and experimental physicists, mathemati-
cians, armament experts, specialists in radium chemistry and in metallurgy,
specialists in explosives and in precision measurement, and their technical and
housekeeping assistants. Among Bureau members was the group from the
proximity fuze program, drafted in the spring of 1943, and Wichers, Schoon-
Thid, pp. 185, 201, 204—205.
°' Hewlett and Anderson, pp. 43, 104; Smyth Report, p. 103.
A chain reaction in Fermi's uranium pile required neutrons slowed by graphite. In mid-
1941 the British predicted that fast neutrons acting on no more than 10 kg of pure
would produce a chain reaction. A year later Oppenheimer, Teller, and Serber confirmed
the theory of the fast-neutron reaction in U" or in plutonium when sufficient quantities
were brought together in a critical mass.