Atomic Bomb Design
By 1939 nuclear scientists had begun to delve seriously into the fission of uranium atoms causing a chain reaction, particularly in the U235 isotope. As a result, vast progress was made in the fields of neutron bombardment, the comparative efforts of slow neutrons versus fast neutrons in sustaining chain reactions, and the possible methods of separating U235 from U238 in natural uranium. Moreover, the possibility of an immense atomic explosion was becoming common knowledge, and calculations for a "critical mass" were just around the corner. As early as the spring of 1942, scientists and leaders across the United States were being exposed to plutonium, courtesy of Glen Seaborg's neutron bombardment of U238. With two unique isotopes of fissionable material at the disposal of the country's greatest minds, it was fitting that two unique atomic weapon designs emerged. The "gun bomb" focused around driving together two sub-critical masses, and the "implosion bomb" relied on a uniform shockwave to compress a plutonium center. Although both designs created the desired bang, they contained very unique features and lent themselves to plutonium and uranium in different ways. The primary research and design center for the bombs w
The product of the Uranium gun bomb design was "Little Boy." Little Boy was ten feet long, weighed almost 9,000 pounds, and was classified as an altimeter bomb. In other words, by measuring air pressure, the device can determine the height from the surface of the earth. Therefore, detonation occurred above the ground. This 15-kt weapon was airdropped on 06 August 1945 at Hiroshima, Japan. The device contained 64.1 kg of highly enriched uranium, with an average enrichment of 80% (Rhodes, 711). The basic gun-bomb design is shown below (Brock/Young). To virtually guarantee a good bang, the original effort centered around a simplistic gun-bomb design. The theory was that two sub-critical pieces of uranium or plutonium are driven together with great force and speed. A section of uranium would be shaped with a center section missing. The center section, a perfect fit, would be placed away from the large uranium mass. A conventional explosive would be used to propel the center section into the large section. Both sections would then weld together and start the reaction (Bracchini). Further research revealed that a plutonium based gun-design, even utilizing weapons-grade material, would spontaneously emit neutrons from its even-numbered isotopes and trigger the chain reaction much too early. This would result in a "fizzle" of dramatically reduced yield. As a result, the focus shifted entirely to a uranium based gun design (Young).
Some common words found in the essay are:
Hiroshima Japan, Robert Oppenheimer, Little Boy, Hans Bethe, Laboratory Mexico, Trinity Fat, United Uranium-238, Glen Seaborg's, , Richard Feyman, chain reaction, little boy, bomb design, center section, critical mass, supercritical mass, gun bomb, gun design, fissionable material, implosion scheme, design little boy, uranium gun bomb, gun bomb design,
Approximate Word count = 1581
Approximate Pages = 6 (250 words per page double spaced)
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