The discovery of the neutron and its consequences (1930–1940)

Abstract

Abstract In 1930, Walther Bothe and Herbert Becker performed an experiment, which was further improved by Irene and Frederic Joliot-Curie. These authors, however, misinterpreted their results and believed to have observed γ-rays while they had seen neutrons. After additional experimental verifications, James Chadwick gave the correct interpretation of these experiments in 1932. Immediately, the new particle, the neutron, became an essential actor of nuclear and elementary particle physics, and completely changed the whole research landscape. Enrico Fermi and his group applied it to artificial radioactivity, substituting neutrons to α-rays initially used by Joliot-Curies. They also discovered that slow neutrons were more efficient than fast ones in certain nuclear reactions. A crucial discovery of Otto Hahn, Fritz Strasmann, Lise Meitner, and Otto Frisch, after several misinterpretations of complicated experimental results, was nuclear fission. When Joliot, Halban, and Kowarski demonstrated the possibility of a chain reaction by neutron multiplication due to fission, nuclear physics became a military science, at the very moment when the Second World War was beginning. Later it led to nuclear power applications and use of neutrons as an important tool and object of scientific research at large-scale neutron facilities. The Comptes rendus de l'Academie des sciences were partner of a vivid international debate involving several other journals.