Born: 29 September 1901, Rome, Italy
Died: 28 November 1954, Chicago, IL, USA
Affiliation at the time of the award: Rome University, Rome, Italy
Prize motivation: "for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons."
Prize share: 1/1
Discovered in 1932, the neutron proved to be a powerful new tool for studying atoms. When Enrico Fermi irradiated heavy atoms with neutrons, these were captured by the atomic nuclei, creating new and often radioactive isotopes. In 1934, Fermi and his colleagues discovered that when neutrons are slowed down, e.g. by paraffin shielding, the interaction rate with nuclei increases. This revelation led to the discovery of many hitherto-unknown radioactive isotopes