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 in such a way that the audience can see just what effect the bomb had on the city, the reconstruction, and the lasting effects of the atomic bomb. The museum opens with a room dedicated to the city as it was just before the bomb decimated Nagasaki. A clock which stopped at 11:02, the precise time the bomb hit the city, is also on display to demonstrate how so many people were killed in an instant. In the next section, visitors enter a room which shows Nagasaki just after the bombings. Included in this room is a water tank with