John Douglas Cockcroft

Person

John Douglas Cockcroft

• Cockcroft, J D

1897-1967

Sir John Douglas Cockcroft was a physicist and engineer. He was born on 27 May 1897 in Langfield, Yorkshire, to John Arthur Cockcroft and Annie Maude Fielden.
Cockcroft was educated at Todmorden secondary school from 1909 and he went with a scholarship to the University of Manchester in 1914 to study mathematics. He volunteered for war service in 1915 and spent three years as a signaller in the Royal Field Artillery. He returned to Manchester in 1919 to the College of Technology, where he gained a first-class BScTechn. in 1920. He was then accepted as a college apprentice in engineering by the Metropolitan-Vickers Company. He then won a scholarship at St John's College to read mathematics.
In 1925 Cockcroft married (Eunice) Elizabeth Crabtree whom he had known since childhood. Their first child, a boy, died at two years. Subsequently they had four daughters and then a son.
Cockcroft was recommended to Edward Rutherford at the Cavendish Laboratory, Cambridge, and he was accepted as a research student supported by a foundation scholarship from St John's College, a state scholarship, and a further grant from Vickers. He gained his PhD in 1928. At Rutherford’s request, Cockcroft joined up with E.T.S. Watson. In April 1932 their proton beam was directed on to a lithium target and bright scintillations were observed. They were shown to be due to helium atoms. By developing a high voltage high energy beam, the atom had been disintegrated, transformed, and the whole scientific world realized that a new era of nuclear physics had arrived.
Outside of his laboratory work, in 1933 Cockcroft had been appointed junior bursar of St John's College responsible for the buildings, some of which had been neglected for years. The gatehouse of the college was partly taken down to replace roof damage and destruction by death-watch beetles; two new courts were built and rewiring done. In 1935 Cockcroft took over direction of the Mond Laboratory; a new wing of the Cavendish Laboratory. In 1936 Cockcroft was elected FRS, and in 1939 he was elected to the Jacksonian professorship in natural philosophy just as he was becoming increasingly involved with efforts being made in technical fields to prepare for war with Hitler's Germany.
Sir H. T. Tizard spoke confidentially to Cockcroft early in 1938 about RDF, the highly secret radio technique for finding aircraft. Cockcroft played a major role in persuading about eighty physicists to spend a month at various coastal radar defence stations, and he also persuaded a number of leading physicists to participate in the RDF project. Some of these scientists made major advances in radar and Cockcroft's part was one of his greatest contributions to the war effort.
Cockcroft became chief superintendent of the Air Defence Research and Development Establishment at Christchurch in late 1940. Radar was then being applied to direct anti-aircraft gunnery upon unseen targets. Coastal defence radar and radar for combat use by the army to detect moving vehicles and tanks in the darkness were other major projects he undertook.
Cockcroft was assigned to Canada in 1944 to take charge of the Montreal laboratory, and then to build the NRX heavy water reactor at Chalk River. His calm but energetic direction gave the laboratory a firm sense of purpose. The nuclear explosions at Hiroshima and Nagasaki brought the war to an abrupt end, but the nuclear work continued. The Canadians wanted Cockcroft to stay but he was wanted at home to direct the new establishment which was being built at Harwell for atomic energy research. Cockcroft commuted for a while and did both jobs but he then moved full-time to Harwell in 1946.
Cockcroft's name and the excitement of atomic energy attracted many able people of all ages to work at Harwell. Work on pressurized gas-cooled reactors made it possible in 1953 to base the production of additional plutonium on dual-purpose reactors to be built at Calder Hall. The justification was primarily military, but for the first time the vision of cheap nuclear power began to have a practical endorsement. The government decided in 1954 to take the responsibility for atomic energy from the Ministry of Supply and create the Atomic Energy Authority (AEA). Cockcroft became the first member for research, while also remaining director of Harwell.
In December 1954 a technical conference was held under the auspices of the United Nations on the peaceful uses of atomic energy. An advisory committee from seven countries was formed and Cockcroft was chosen as the British representative. This conference, held at Geneva in August 1955, was a political event of outstanding importance which might have heralded the end of the cold war. Scientists from the communist countries fraternized so easily with those from the west, that, just as they shared science, they thought there must be a way to share political philosophies. Scientifically it was an enormous success. Cockcroft was able to invite I. Kurchatov, of the USSR, to give a lecture at Harwell on a subject (fusion research) which only a few months earlier was regarded as extremely secret.
Cockcroft gathered much of the British work on fusion research at Harwell and the major project was the torroidal discharge machine called ZETA which was a major step forward in fusion research. Cockcroft was able to give a great deal of help and encouragement to the Medical Research Council in their work on radiological protection. His influence led to the creation of the Rutherford High Energy Laboratory. He was also closely concerned with the early years of CERN.
Cockcroft resigned as a full-time member of the AEA in 1959 but remained a part-time member and moved to Cambridge to become the first master of the new Churchill College, having been nominated by Sir Winston Churchill himself. Cambridge had accepted the offer of finance for a college which would have nearly as many advanced scientists and fellows as undergraduates, all living in college. Churchill was gratified that this college would bear his name, and Cockcroft was about the most famous scientist or engineer in Britain at that time.
Alongside his duties as Master of Churchill College, Cockcroft represented Britain in the conference which in due course led to the signing of the test ban treaty relating to atomic weapons. He supported the Pugwash conferences on science and world affairs, and was their president in 1967.
Cockcroft received many honorary degrees, awards, and honours, the three principal being the Order of Merit (1957), the Nobel prize for physics, jointly with E. T. S. Walton (1951), and the atoms for peace award (1961). He was appointed CBE in 1944, knight bachelor in 1948, and KCB in 1953. Cockcroft wrote few scientific papers, but from 1935 devoted his outstanding ability to organizing and administering research in science and technology. Cockcroft died on 18 September 1967 at Churchill College. On 17 October a service of memorial and thanksgiving was held in Westminster Abbey.

T. E. Allibone, Oxford Dictionary of National Biography, 2008: https://www.oxforddnb.com/view/10.1093/ref:odnb/9780198614128.001.0001/odnb-9780198614128-e-32473?rskey=qf2uP3&result=2