Thin Man (nuclear bomb) Thin Man (nuclear bomb) "Thin Man" was the code name for a proposed plutonium gun-type nuclear bomb using plutonium-239 which the United States was developing during the Manhattan Project. They aborted its development when they discovered that the spontaneous fission rate of their nuclear reactor-bred plutonium was too high for use in a gun-type design, due to the high concentration of the isotope plutonium-240. In 1942, prior to the Army taking over wartime atomic research, Robert Oppenheimer held conferences in Chicago in June and Berkeley, California, in July at which various engineers and physicists discussed nuclear bomb design issues. A
Nagasaki Atomic Bomb Museum Pacific War". It is there that the experience of militarism in Japan and the demands of war are juxtaposed with arguments for the end of nuclear weapons. Visitors are presented with facts on modern nuclear weapons alongside facts related to victims of the atomic bombing. It is a call for peace and an end of the nuclear age. The final room in the museum contains videos and documents related to the Nagasaki bombing. Visitors can also find answers to their questions and documents like Nagasaki’s Peace Declaration. The museum exhibits objects that were exposed to radiation from the atomic bomb.