Builder of the world's first nuclear power station

John Cockcraft (1897-1967)

JOHN COCKCROFT was born on May 27, 1897 in Todmorden, England. His father owned a small cotton mill; three of his brothers went into the business. John, however, was an outstanding student in the school and won a scholarship to study at the University of Manchester.

After only one year at the university, he volunteered in 1915 for war service. He was discharged in 1918. Returning to Manchester, he was apprenticed to the reputed electrical manufacturing firm, Metropolitan Vickers: the latter discovered his talents, sent him to read electrical engineering, which was later to stand him in good stead. He earned an M.Sc in 1922.

Cockcroft then received a scholarship to study mathematics at St. John's College, Cambridge. He took the Mathematical Tripos in 1924. Four years later he received his Ph.D degree.

Career profile

Cockcroft started his career in 1922 under Rutherford as a junior research assistant in the Cavendish Laboratory at Cambridge and gave lectures in physics. He was appointed in 1934 the director of the Royal Society's Mond Laboratory. He assisted in the installation of cyclotron, a new particle accelerator. He was Jacksonian Professor of Natural philosophy from 1939 to 1946. When the U.K. Atomic Energy Authority was set up in 1954, Cockcroft was appointed member for scientific research. From 1959 he was Master of Churchill College for Science and Technology, founded in honour of Winston Churchill, which position he held till his death (September 18, 1967).

From 1992, Cockcroft was a member of the great team gathered by Rutherford, who had identified alpha particles as the nuclei of heleium atoms. Rutherford's atom splitting method was accomplished by using alpha particles to change atoms of nitrogen into oxygen. This technique opened up a new field for experimental investigation to transmute atoms in far greater amounts than could be achieved by Rutherford's method.

Two different approaches were known to improve particle acceleration. In the direct method, a single surge of high voltage would be employed to supply the energy. In the indirect method, particles would be accelerated by cycling them repeatedly through a low-voltage field.

Inspired by the theory of the Russian physicist George Gamow, Cockcroft chose the direct method. Gamow had calculated from quantum mechanics that because subatomic particles have wave properties, they would occasionally penetrate the nuclear barrier even when they lacked the force to overcome it. Gamow's equations explained how alpha particles could escape the nuclei of radioactive materials: but it was Cockcroft's insight that perceived how the same principles would allow other particles to penetrate a nucleus, using considerably less energy.

The classic experiment

Cockcroft performed in April 1932 with Ernest Walton the classic experiment in an ingenious machine constructed by them. They transmuted lithium and hydrogen into helium, thus establishing the record as the first scientists to split the atom by artificial means. For this work, he and Walton received the Noble prize for physics (1951).

Their work also provided experimental confirmation of Gamow's theory and Einstein's basic equation of relativity E=mc2 (H.W. Wilson Biographical Dictionary, Noble Prize Winners, New York, 1987).

With the outbreak of World War II, he served as a member of the Ministry of Supply and played a leading role in the development of radar which played a key role in Britain's success in the war.

He was sent to the U.S. in 1940 as vice-chairman of the Tizard which negotiated an exchange of technical information with American scientists before the U.S. entered the war.

In 1944 he went to Canada to head the Atomic Energy Division of the National Research Council of Canada. He was put in charge of the Montreal and Chalk river laboratories. This group contributed to the Manhattan Project which designed and produced the first atom bomb (The Hindu, May 31, 2001).

Cockcroft returned to England in 1946 as head of Britain's first atomic energy research laboratory at Harwell.

As a member of the Atomic Energy Authority, he was responsible for building the world's first nuclear power station at Calder Hall.

Cockcroft's own scientific contributions gave him the highest standing amongst research workers. Added to this, the gift for the administration of great projects and the personal qualities earned him the affection and trust of all those, young and old staff, with whom he had to deal.

R.Parthasarathy

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