Cockcroft, Sir John Douglas

Cockcroft, Sir John Douglas (1897-1967), British physicist and Nobel laureate, who is best known for his work on the nature of the atomic nucleus. Cockcroft was born in Todmorden, Yorkshire, and educated at the University of Manchester and St John's College, University of Cambridge.

In 1928 Cockcroft became a Fellow at St John's College, a post he held until 1946. In 1932 Cockcroft, in collaboration with another British physicist, Ernest Walton, became the first to disintegrate an atomic nucleus with artificially accelerated subatomic particles. The two scientists used a particle accelerator that they had developed, called the Cockcroft-Walton accelerator, to bombard lithium atoms with protons. Some of the lithium atoms absorbed a proton and disintegrated into two helium atoms. The Cockcroft-Walton accelerator became an important experimental tool in laboratories throughout the world.

From 1941 to 1944 Cockcroft was chief superintendent of the British Air Defence Research and Development Establishment, and from 1944 to 1946 served as director of the atomic energy division of the Canadian National Research Council. His nuclear work with lithium and hydrogen proved of great importance in the development of the hydrogen bomb (see Nuclear Weapons). He was knighted in 1948 and with Walton shared the 1951 Nobel Prize for Physics. Cockcroft received the Niels Bohr Medal in 1958 and the Atoms for Peace Award in 1961.