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
Emergency Committee of Atomic Scientists Emergency Committee of Atomic Scientists The Emergency Committee of Atomic Scientists (ECAS) was founded by Albert Einstein and Leó Szilárd in 1946. Its aims were to warn the public of the dangers associated with the development of nuclear weapons, promote the peaceful use of nuclear energy, and ultimately work towards world peace, which was seen as the only way that nuclear weapons would not be used again. The Committee was established in the wake of the "Szilárd petition" (July 1945) to United States president Harry S. Truman opposing the use of the atomic bomb on moral grounds, which was signed