Manhattan Project

[[Image:Calutrons at Oak Ridge.jpg|thumb|right|300px|Control panels and operators for calutrons at the Y-12 National Security Complex|Y-12 Plant in Oak Ridge National Laboratory|Oak Ridge, Tennessee.

The two different paths to the bomb

The industrial problem centered on the production of sufficient fissile material, of sufficient purity. Two parallel and completely separate efforts were undertaken. One project produced a Uranium bomb and the other project produced two Plutonium bombs, all of which were successfully detonated.

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The Hiroshima bomb, Little Boy, was made from Uranium-235, a rare isotope of uranium that has to be physically separated from more prevalent Uranium-238 isotope, which is not suitable for use in an explosive device. The separation was effected mostly by gaseous diffusion of uranium hexafluoride (UF6), but also by other techniques, such as thermal diffusion, and the calutron method, using the mass spectrometer principle of magnetic separation. Most of this separation work was performed at Oak Ridge. The Uranium bomb used the so-called "gun" mechanism to assemble a critical mass of the U-235; one mass of U-235, the "bullet," was fired down a tube into another mass of U-235, creating a critical mass of U-235 and resulting in a huge explosion.

Related Topics:
Hiroshima - Little Boy - Isotope - Uranium - Physically separated - Uranium hexafluoride - F - Calutron - Mass spectrometer - Oak Ridge - Critical mass

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In contrast, the bombs used in the first test at Trinity Site, New Mexico (the gadget of the Trinity test), and also in the Nagasaki bomb, Fat Man, were made primarily of Plutonium-239. Plutonium is a synthetic element that, in the form created by the reactors used to produce it, contains too much of an isotope that too readily undergoes fission for it to be used in gun type device. (Because of the relatively slow speed of the gun type device, a Plutonium bomb might "fizzle" (i.e. blow itself apart), before it develops maximum power.) A so-called "implosion" device, using a sphere of Plutonium that collapsed inward on itself, was faster and promised a better solution to the problem. Many scientists at Los Alamos concentrated on the design of an implosion device during the Project.

Related Topics:
Trinity Site - The gadget - Trinity test - Nagasaki - Fat Man - Plutonium - Los Alamos

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Although Uranium-238 is useless for making an atomic bomb, U-238 is necessary to produce Plutonium -- because U-235 produces relatively slow neutrons, U-238 will absorb neutrons and, after a trip through a reactor and a few days of decay, U-238 will turn into Plutonium-239. The production and purification of plutonium was at the center of wartime, and post-war, efforts at the Hanford Site, using techniques developed in part by Glenn Seaborg.

Related Topics:
Hanford Site - Glenn Seaborg

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The first live test of the Plutonium bomb was on July 16, 1945, near Alamagordo, New Mexico, and was code-named "Trinity". "The energy developed in the test was several times greater than that expected by scientific group." (Official report)

Related Topics:
July 16 - Alamagordo - Trinity

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