Chadwick, James (1891-1974)

English physicist. He was awarded the Nobel Prize for Physics in 1935 for his discovery in 1932 of the particle in the nucleus of an atom that became known as the neutron because it has no electric charge. He was knighted in 1945.

Chadwick established the equivalence of atomic number and atomic charge. During World War II, he was closely involved with the atomic bomb, and from 1943 he led the British team working on the Manhattan Project in the USA.

Chadwick was born in Cheshire and studied at Manchester under Ernest Rutherford, investigating the emission of gamma rays from radioactive materials. In 1913 he went to Berlin to work with German physicist Hans Geiger, inventor of the Geiger counter. There he was interned as an enemy alien during World War I. After the war, he joined Rutherford at Cambridge. Chadwick was professor of physics at Liverpool 1935-48 and master of Gonville and Caius College, Cambridge, 1948-58. Chadwick investigated beta particles emitted during radioactive decay. With Rutherford, he produced artificial disintegration of some of the lighter elements by alpha-particle bombardment. He returned to this at Liverpool, where he ordered the building of a cyclotron and developed a research school in nuclear physics.