Enrico Fermi – Atomic Heritage Foundation
Enrico Fermi (1901-1954) was an Italian physicist and winner of the Nobel Prize in Physics in 1938.
In 1942, Fermi moved to the Chicago Meteorological Laboratory, where he built an experimental reactor stack under Stagg Field at the University of Chicago. construction was completed on December 1, and the reactor went critical the next day. In August 1944, Fermi went to Los Alamos as an associate director and key consultant.
at the hanford site in 1944, fermi inserted the first uranium block into the “b” stack reactor, just as he had inserted the first stack in the cp-1 reactor two years earlier. during the test of the “b” reactor, fermi was in charge of directing the operations. His meticulous calculations, completed with a slide rule, determined how much uranium needed to be added to the reactor; measurements confirmed that his calculations were astonishingly accurate.
however, the start-up failed when the reactor shut down. John Wheeler hypothesized that some unknown substance was being formed during fission and was absorbing the neutrons needed to sustain the reaction. Fermi immediately agreed with Wheeler’s explanation and began working with him to find the unknown poison. By comparing the half-life of different radioactive gases to the amount of time the reactor failed, Wheeler and Fermi were able to discover that the troublesome substance was xenon-135.
at los alamos, fermi served as associate director of the laboratory. after the trinity test, fermi commented: “my first impression of the explosion was a very intense flash of light and a sensation of heat in the parts of the body that were exposed. although I did not look directly at the object, I had the impression that the field suddenly became brighter than in broad daylight.”
always the inquisitive scientist, fermi seized the opportunity to conduct his own experiment. just as the explosion hit, he dropped several pieces of paper. having measured its displacement and doing a quick mental calculation, fermi declared: “that corresponds to the burst produced by ten thousand tons of tnt.”
fermi advised the interim committee on targeting, recommending that the bombs be used without warning against an industrial target.
In 1944, Fermi became a US citizen and, at the end of the war, accepted a professorship at the Institute for Nuclear Studies at the University of Chicago, a position he held until his untimely death. there he turned his attention to high energy physics and conducted research on the pion-nucleon interaction. He also served on the General Advisory Committee of the Atomic Energy Commission.
The Enrico Fermi Award, a prestigious science and technology award granted by the United States government, bears his name.
scientific contributions
In 1938, Fermi received the Nobel Prize in Physics “for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions caused by slow neutrons.” His research on the bombardment of elements to produce fissile isotopes was critical to the success of the Manhattan Project.
for more information on fermi’s research and scientific achievements, visit the nobel laureate’s website.
