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In 1934 he received his PhD from Columbia University, both in the United States, and began research at Columbia University in atomic fission, with the help of Leó Szilárd. The two showed that uranium underwent fission when bombarded with neutrons, converting part of its mass into energy (according to Albert Einstein's famous equation relating mass and energy).
He worked closely with Enrico Fermi to initiate the first self-sustaining nuclear chain reaction at the Chicago Pile-1 reactor on December 2, 1942. He was responsible for removing the control rod that started the reaction.
After the war, he supervised the decommissioning the Chicago Pile-1 reactor and became the director of the Argonne National Laboratory between 1946 and 1956. He also supervised the construction of several new nuclear reactors, including the Experimental Breeder Reactor I (EBR-I) in Idaho, USA. He served as chief scientific advisor on the design of the USS Nautilus, the first nuclear-powered submarine.
If you want to know more about this scientist, click on the following link: Walter Zinn