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The demon core was a , subcritical mass of plutonium which was involved in two criticality accidents. It briefly went supercritical in two separate accidents at the Los Alamos laboratory in 1945 and 1946, and resulted in the acute radiation poisoning and subsequent deaths of scientists Harry K. Daghlian, Jr., and Louis Slotin. After these incidents the spherical plutonium core was referred to as the "demon core". It was eventually used in the ''Gilda'' bomb detonated during Operation Crossroads, the first nuclear test to be conducted after World War II, five weeks after the second fatal accident. It performed normally and with the same explosive yield as the other core used in this set of two tests. ==Manufacturing and early history== The demon core (like the second core used in the bombing of Nagasaki) was a solid sphere. It consisted of three parts: two plutonium-gallium hemispheres and a ring, designed to keep neutron flux from "jetting" out of the joined surface between the hemispheres during implosion. The core of the device used in the Trinity nuclear test at the Alamogordo Bombing and Gunnery Range in July did not have such a ring.〔 An error: the illustration caption states the ''Fat Man'' core was plated in silver; it was plated in nickel, as the silver plating on the gadget core blistered. The disk in the drawings is a gold foil gasket.〕 The refined plutonium was shipped from the Hanford Site in Washington state to the Los Alamos Laboratory; an inventory document dated August 30 shows Los Alamos had expended "HS-1, 2, 3, 4; R-1" (the components of the Trinity and Nagasaki bombs) and had in its possession "HS-5, 6; R-2", finished and in the hands of quality control. Material for "HS-7, R-3" was in the Los Alamos metallurgy section, and would also be ready by September 5 (it is not certain whether this date allowed for the unmentioned "HS-8"'s fabrication to complete the fourth core). The metallurgists used a plutonium-gallium alloy, which stabilized the δ phase allotrope of plutonium so it could be hot pressed into the desired spherical shape. As plutonium was found to corrode readily, the sphere was then coated with nickel. On August 10, Major General Leslie R. Groves, Jr., wrote to General of the Army George C. Marshall, the Chief of Staff of the United States Army, to inform him that: Marshall added an annotation, "It is not to be released on Japan without express authority from the President", as President Harry S. Truman was waiting to see the effects of the first two attacks.〔 On August 13, the third bomb was scheduled. It was anticipated that it would be ready by August 16 to be dropped on August 19.〔 This was pre-empted by Japan's surrender on August 15, 1945, while preparations were still being made for it to be couriered to Kirtland Field. The third core remained at Los Alamos.〔 Raemer Schreiber being interviewed by Richard Rhodes〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「demon core」の詳細全文を読む スポンサード リンク
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