Editing Ernest Lawrence (section)

=== Oak Ridge ===
Responsibility for the design and construction of the electromagnetic separation plant at [[Oak Ridge, Tennessee]], which came to be called [[Y-12 National Security Complex|Y-12]], was assigned to [[Stone & Webster]]. The calutrons, using 14,700 tons of silver, were manufactured by [[Allis-Chalmers]] in Milwaukee and shipped to Oak Ridge. The design called for five first-stage processing units, known as Alpha racetracks, and two units for final processing, known as Beta racetracks. In September 1943 Groves authorized construction of four more racetracks, known as Alpha II.{{sfn|Jones|1985|pp=126–132}} When the plant was started up for testing on schedule in October 1943, the 14-ton vacuum tanks crept out of alignment because of the power of the magnets and had to be fastened more securely. A more serious problem arose when the magnetic coils started shorting out. In December Groves ordered a magnet to be broken open, and handfuls of rust were found inside. Groves then ordered the racetracks to be torn down and the magnets sent back to the factory to be cleaned. A [[Pickling (metal)|pickling]] plant was established on-site to clean the pipes and fittings.{{sfn|Fine|Remington|1972|p=684}}

[[File:Alpha 1 racetrack, Uranium 235 electromagnetic separation plant, Manhattan Project, Y-12 Oak Ridge.jpg|left|thumb|300px|Giant electromagnet Alpha I racetrack for uranium enrichment at Y-12 plant, Oak Ridge, Tennessee, circa 1944–45. The [[calutron]]s Lawrence developed are located around the ring.|alt=A large oval-shaped structure.]]
[[Tennessee Eastman]] was hired to manage Y-12.{{sfn|Jones|1985|p=140}} Y-12 initially enriched the uranium-235 content to between 13% and 15%, and shipped the first few hundred grams of it to Los Alamos laboratory in March 1944.{{sfn|Jones|1985|pp=143–148}} Only 1 part in 5,825 of the uranium feed emerged as final product. The rest was splattered over equipment in the process. Strenuous recovery efforts helped raise production to 10% of the uranium-235 feed by January 1945. In February the Alpha racetracks began receiving slightly enriched (1.4%) feed from the new [[S-50 (Manhattan Project)|S-50 thermal diffusion plant]]. The next month it received enhanced (5%) feed from the [[K-25]] gaseous diffusion plant. By April 1945 K-25 was producing uranium sufficiently enriched to feed directly into the Beta tracks.{{sfn|Jones|1985|pp=143–148}}

On July 16, 1945, Lawrence observed the [[Trinity nuclear test]] of the first atomic bomb with Chadwick and [[Charles A. Thomas]]. Few were more excited at its success than Lawrence.{{sfn|Childs|1968|pp=358–359}} The question of how to use the now functional weapon on Japan became an issue for the scientists. While Oppenheimer favored no demonstration of the power of the new weapon to Japanese leaders, Lawrence felt strongly that a demonstration would be wise. When a uranium bomb was used without warning in the [[atomic bombing of Hiroshima]], Lawrence felt great pride in his accomplishment.{{sfn|Childs|1968|pp=360–365}}

Lawrence hoped that the Manhattan Project would develop improved calutrons and construct Alpha III racetracks, but they were judged to be uneconomical.{{sfn|Herken|2002|p=128}} The Alpha tracks were closed down in September 1945. Although performing better than ever,{{sfn|Hewlett|Anderson|1962|p=624}} they could not compete with K-25 and the new K-27, which commenced operation in January 1946. In December, the Y-12 plant was closed, thereby cutting the Tennessee Eastman payroll from 8,600 to 1,500 and saving $2&nbsp;million a month.{{sfn|Hewlett|Anderson|1962|pp=630, 646}} Staff numbers at the Radiation laboratory fell from 1,086 in May 1945 to 424 by the end of the year.{{sfn|Childs|1968|p=370}}

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