Cockcroft was sent first to the Walsden Church of England School.
Gallery of John Cockcroft
Ewood Ln, Todmorden OL14 7DG, UK
After attending the Todmorden Elementary School, Cockcroft went to the Todmorden High School in 1909.
College/University
Gallery of John Cockcroft
Oxford Rd, Manchester M13 9PL, UK
Cockcroft entered the University of Manchester in the autumn of 1914 with a county major scholarship, chiefly to study mathematics under Horace Lamb, and was fortunate enough to be able to attend some first-year lectures given by Rutherford.
Gallery of John Cockcroft
St John's College, St John's Street, Cambridge CB2 1TP, United Kingdom
On Walker’s advice he went on to Cambridge to study mathematics at St. John’s College and distinguished himself in part two of mathematical tripos, obtaining a Bachelor of Arts degree in 1924.
Cockcroft entered the University of Manchester in the autumn of 1914 with a county major scholarship, chiefly to study mathematics under Horace Lamb, and was fortunate enough to be able to attend some first-year lectures given by Rutherford.
St John's College, St John's Street, Cambridge CB2 1TP, United Kingdom
On Walker’s advice he went on to Cambridge to study mathematics at St. John’s College and distinguished himself in part two of mathematical tripos, obtaining a Bachelor of Arts degree in 1924.
John Cockcroft was a British physicist. He was a joint winner, with Ernest T.S. Walton of Ireland, of the 1951 Nobel Prize for Physics for pioneering the use of particle accelerators in studying the atomic nucleus.
Background
Cockcroft was born on 27 May 1897, in Todmorden, England, the eldest son of a mill owner, John Arthur Cockcroft, and his wife Annie Maude née Fielden.
The Cockcrofts have lived in the Calder Valley of the West Riding of Yorkshire for generations. During the nineteenth century they owned a cotton mill in Todmorden, but the business declined and in 1899 was transferred to Birks Mill, situated a few miles away at Walsden. Cockcroft’s father devoted himself to rebuilding the prosperity of the farm, with the wholehearted support of his wife.
Education
Cockcroft was sent first to the Walsden Church of England School and then, after attending the Todmorden Elementary School, went to the Todmorden Secondary School in 1909. Perhaps because physics and mathematics were well taught there, he read more widely in the physical sciences, and accounts of the work of J. J. Thomson, Rutherford, and others gave him the ambition to do research. Cockcroft entered the University of Manchester in the autumn of 1914 with a county major scholarship, chiefly to study mathematics under Horace Lamb, and was fortunate enough to be able to attend some first-year lectures given by Rutherford.
In the summer of 1915, after only one year at the university, Cockcroft volunteered for war service with the Y.M.C.A. Later in the year he was called up for military service and became a signaler in the Royal Field Artillery. In 1920 he became a college apprentice at the Metropolitan Vickers Electrical Company, where he carried out some work in the research department under the direction of Miles Walker. He was awarded the degree of M.Sc.Tech. in 1922. On Walker’s advice he went on to Cambridge to study mathematics at St. John’s College and distinguished himself in part two of mathematical tripos, obtaining a Bachelor of Arts degree in 1924.
Cockcroft had an exceptionally long period of training - seven years excluding the war years - before joining Rutherford’s team at the Cavendish Laboratory. His work with Miles Walker on the harmonic analysis of voltage and current wave forms at commercial power frequencies was published in 1925 and was followed by two further papers describing some detailed studies of boundary effects in electrical conductors. By this time Cockcroft had acquired a deep insight into certain aspects of electrical engineering and commanded some powerful theoretical techniques. He helped the Russian physicist Peter Kapitza, who was in Cambridge, with his work on very high magnetic fields by designing extremely efficient magnet coils in which the stresses were minimized. Later, he designed an electromagnet for a-ray spectroscopy for Rutherford and a permanent magnet for /3-ray spectroscopy. Cockcroft also carried out an elegant investigation into the properties of molecular beams, following the classical work of Otto Stem and Immanuel Estermann. It was shown that the Frenkel theory of surface condensation applied, and attention was drawn to the role of adsorbed gaseous impurities. This work, published in 1928, afforded valuable experience in vacuum technology that was later to be crucial.
In the meantime, Thomas Allibone and E. T. S. Walton had been experimenting with different methods of accelerating electrons, and after Cockcroft had calculated from George Gamow’s theory of an emission that protons of a few hundred kilovolts energy should have an appreciable probability of penetrating the energy barriers of light nuclei, he became interested in the possibility of designing an accelerator for protons. Walton decided to join him, and with Rutherford’s support, they eventually constructed a voltage multiplier of a type originally proposed by Greinacher in 1920 and connected this to an accelerating tube provided with a proton source designed by M. L. E. Oliphant. This was the first nuclear transformation to be brought about by artificial means. At the same time, E. O. Lawrence and M. S. Livingston were constructing another device for accelerating protons, later known as the cyclotron, at the University of California, and they were soon able to confirm Cockcroft and Walton’s results. By adding further stages to the voltage multiplier, the beam energy of the Cockcroft-Walton machine could be increased to about 3 MEV, whereas the cyclotron was capable of reaching much higher energies.
The year 1932 became an outstanding one for the Cavendish Laboratory with the discovery of the neutron by James Chadwick. In 1933 Rutherford received, through Cockcroft, some of the first heavy water from G. N. Lewis at Berkeley, and Cockcroft and Walton bombarded lithium, boron, and carbon with deuterons from their accelerating apparatus. After the announcement of the artificial production of radioactivity by Irène Joliot-Curie and Frédéric Joliot in 1934, Cockcroft and Walton showed that radioactive nuclei were produced from boron and carbon exposed to proton and deuteron beams from the machine. Finally, a more detailed study of the disintegration of boron by protons and deuterons was carried out in collaboration with W. B. Lewis, using highly purified deuterium and with magnetic separation of unwanted ions from the beam.
From 1935 until the outbreak of war, Cockcroft was made personally responsible by Rutherford for a major reconstruction and reequipping of the Cavendish Laboratory, including the building of a cyclotron. He became involved in the development of radar during the war. After building radar stations for detection of submarines and low-flying aircraft at various remote sites, he went to the United States in August 1940 as a member of the famous Tizard mission to negotiate scientific and technical exchanges of military importance. On his return, he was appointed a chief superintendent of the Air Defence Research Development Establishment at Christchurch, Hampshire, and during the same year, he became a member of the committee which had been formed to investigate the possible applications of nuclear fission.
After three more grueling years on radar development, Cockcroft was sent as director to the Anglo-Canadian atomic energy research laboratory in Montreal in April 1944. There he was faced not only with technical and scientific problems but also with a delicate diplomatic situation involving Canadian, British, American, and French interests. The NRX reactor, built under his direction at Chalk River, Ontario, was for a long time a unique instrument for nuclear research as well as for technology.
Cockcroft returned to Britain in 1946 to become director of the new Atomic Energy Research Establishment at Harwell, where he remained until 1959. During this period, in the latter part of which he was a member for research of the Atomic Energy Authority, he guided and stimulated nuclear developments of all kinds, from basic research to power stations. He was especially concerned with the succession of particle accelerators constructed at Harwell and was largely responsible for obtaining approval to build the 7 GEV proton synchrotron and the Rutherford Laboratory at nearby Chilton. Cockcroft also did a great deal to promote science through international organizations such as CERN, the European laboratory for high-energy physics, and in many other ways. Nor did these activities cease when he became master of Churchill College, Cambridge, in 1959. Indeed, he was elected president of the well-known Pugwash Conferences on Science and World Affairs just before his death on 18 September 1967.
Perhaps the finest personal characteristic of Cockcroft was his disarming kindness. It earned him countless friends both within and outside his professional field. The same quality made him also a much admired family man.
Although habitually economical in the use of words, Cockroft was always genial and approachable yet made firm, impartial, and prompt decisions that were accepted almost without question.
Connections
Cockroft married Eunice Elizabeth Crabtree at Todmorden on 26 August 1925. She was the daughter of Herbert Crabtree of Stansfield Hall, a cotton manufacturer, and John had known her since childhood. They had four daughters and one son. Their happy, close-knit family life was a source of great strength to Cockcroft.