Los Alamos was atypical in that it was the only Army post in the United States that housed civilians on a permanent basis. And unlike any other Army base, this one was predominantly civilian. Ernest Orlando Lawrence (August 8, 1901 - August 27, 1958) was an American physicist and Nobel Laureate, known for his invention, utilization, and improvement of the cyclotron atom-smasher beginning in 1929, based on his studies of the works of Rolf Wideroe, and his later work in uranium-isotope separation for the Manhattan Project. Enrico Fermi (1901-1954) was an an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics. He was awarded the 1938 Nobel Prize in Physics for his work on induced radioactivity. Isidor Isaac Rabi ( July 29, 1898 - January 11, 1988) was an Austrian-born American physicist. He was awarded the 1944 Nobel Prize for his resonance method for recording the magnetic properties of atomic nuclei. Rabi invented this method in the 1930s. It became the basis of the magnetic resonance techniques of NMR and MRI, and has also been applied to the maser, laser and atomic clock.