James Chadwick

Born Oct. 20, 1891, in Manchester; died July 24, 1974. English physicist. Fellow of the Royal Society of London (1927). Student of E. Rutherford.

Chadwick graduated from the University of Manchester and received the Ph.D. degree from Cambridge University. From 1923 to 1935 he taught at Cambridge University and was assistant director of the Cavendish Laboratory. From 1935 to 1948 he was a professor at the University of Liverpool. Beginning in 1948, he was master of Gonville and Caius College at Cambridge University.

Chadwick’s main works were devoted to nuclear physics. His first papers were on radioactivity. In 1920, Chadwick experimentally confirmed that the charge of a nucleus was equal to the atomic number of the element. He then studied the artificial transmutation of elements under the action of alpha particles (with Rutherford). One of his major contributions was the discovery in 1932 of the neutron upon bombardment of a beryllium target by a stream of alpha particles, for which he was awarded a Nobel Prize in 1935. In 1934–35, Chadwick and his co-worker M. Goldhaber set up experiments on the photodissociation of the deuteron into a neutron and proton under the action of gamma quanta. From 1943 to 1945, Chadwick headed the group of British scientists who were working at the Los Alamos Laboratory (United States) on the atomic bomb.