Sir John Douglas Cockcroft (May 27, 1897 - September 18, 1967) was a British physicist. He received the Nobel Prize in Physics for splitting the atomic nucleus, and was instrumental in the development of nuclear power.

Cockcroft was born in Todmorden, England. He was educated at Todmorden Secondary School and studied mathematics at the University of Manchester. He received a mathematics degree from St. John's College, Cambridge in 1924, and began research work under Ernest Rutherford. In 1929 he was elected a Fellow of St. John's College.

In 1928 he began to work on the acceleration of protons with Ernest Walton. In 1932 they bombarded lithium with high energy protons, and succeeded in transmuting it into helium and other elements. This was the first occasion on which an atomic nucleus of one element had been successfully changed to a different nucleus by artificial means. This feat was popularly — if not somewhat inaccurately — known as splitting the atom.

At the outbreak of the Second World War he took up the post of Assistant Director of Scientific Research in the Ministry of Supply, working on radar. In 1944 he took charge of the Canadian Atomic Energy project and became Director of the Montreal and Chalk River Laboratories. In 1946 he returned to Britain to set up the Atomic Energy Research Establishment at Harwell, charged with developing Britain's atomic power programme. He became the first director of AERE. Even when leaving the post he continued to be involved with Harwell. He was knighted in 1948, and was created Knight Commander of the Bath in 1953.

In 1951 Cockcroft, along with Walton, was awarded the Nobel Prize in Physics for his work in the use of accelerated particles to study the atomic nucleus. In 1959 he became the first Master of Churchill College, Cambridge. He was president of the Institute of Physics, the Physics Society and the British Association for the Advancement of Science. Cockroft served as chancellor of the Australian National University from 1961-65.

Cockcroft married Eunice Elizabeth Crabtree in 1925 and had four daughters and a son.

Today, a building named after him exists in the New Museums Site of the University of Cambridge, comprising a lecture theatre and several hardware laboratories.

Further reading

Cathcart, Brian, The Fly in the Cathedral, Penguin, 2005. ISBN 0-14-027906-7

Links

• Biography from the Nobel Museum
  
• Another Nobel biography
  
• Speech to the Empire Club of Canada