Born: 20 October 1891, Manchester, United Kingdom
Died: 24 July 1974, Cambridge, United Kingdom
Affiliation at the time of the award: Liverpool University, Liverpool, United Kingdom
Prize motivation: "for the discovery of the neutron"
Field: nuclear physics
Prize share: 1/1
In 1930, when Herbert Becker and Walter Bothe sent alfa particles (helium nuclei) against beryllium, strong penetrating radiation was emitted, there was a hypothesis that this could be electromagnetic radiation of high energy. However, in 1932 James Chadwick could show that in the reaction, a neutral particle with a mass about that of a proton, was emitted. Ernest Rutherford had earlier proposed that such a neutral particle might exist in nuclei. The particle was discovered and was named neutron.