Enrico Fermi (1901-54) Italian-American physicist who did fundamental theoretical and experimental work on nuclear and quantum physics and built the first nuclear reactor. In the 1930s he established the theory of beta decay and discovered the statistical laws obeyed by such elementary particles as the electron. Fermi won the 1938 Nobel Prize for Physics for his work on using neutrons to initiate nuclear reactions. His research at Chicago University into ways of producing a self-controlled, self-sustaining nuclear fission reaction led in 1942 to the construction of the first atomic pile i.e., nuclear reactor, thus beginning the age of nuclear power. A year later, at Los Alamos, he worked on the Manhattan Project developing the atomic bomb.