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John Cockcroft Biography and Discoveries

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 Who is John Cockcroft? Information on physicist John Cockcroft biography, life story, works and contributions to science.

John Cockcroft; (1897-1967), British physicist, mathematician, and engineer, who is best known for his work in nuclear physics and for his leading role in the release of atomic energy on a large scale. In 1951 he was awarded the Nobel Prize for physics (jointly with E. T. S. Walton) for “their pioneer work on the transmutation of atomic nuclei by artificially accelerated atomic particles.”


In 1919, Rutherford had succeeded in transmuting nitrogen into oxygen by bombarding the nitrogen nuclei with alpha particles emitted by radioactive substances. However, the number of alpha particles emitted by available radioactive sources was too small and their energy was too low for their use in research on the heavier nuclei. Further, it was highly desirable that other types of bombarding particles should be available. To produce suitable beams of such particles appeared to require the use of voltages many times higher than seemed possible at the time. That the problem was not as formidable as was expected was shown by Cockcroft by applying to the penetration of nuclei by various particles the theory of alpha particle emission, put forward independently by George Gamow and by E. U. Condon and Ronald Gurney. After discussions with Gamow, Cockcroft pointed out that beams of protons accelerated by relatively low voltages would be expected to penetrate in adequate numbers of the nuclei of light elements. With the approval of Rutherford, Cockcroft, together with E. T. S. Walton, began development work that led to the production of fast protons with energies up to 700,000 electron volts. Bombardment of light nuclei with these particles Was found to produce disintegration reactions of types previously unknown. This work, carried out in the early 1930’s at Cambridge, England, opened up a large new field of nuclear study.


Following the discovery of nuclear fission, Cockcroft played an important part in directing the research and development efforts to produce nuclear reactors for scientific research and for the production of power. In 1944 he took charge of the Canadian Atomic Energy project and was director of the Montreal and Chalk River Laboratories. In 1946 he was appointed Director of the Atomic Energy Research Establishment at Harwell, England, where experimental nuclear reactors were built and used to obtain basic information for the design of the British nuclear power stations.


Cockcroft’s knowledge of engineering and mathematics enabled him to design improved equipment that was of much help to others. In collaboration with Peter Kapitza, at Cambridge, he designed apparatus for the production of intense magnetic fields and of very low temperatures. When suitable cobalt steels became available, he helped in the design of a large permanent magnet for use by C. D. Ellis in his studies of beta-ray spectra.


Born at Todmorden, Lancashire, on May 27, 1897, Cockcroft studied electrical engineering at Manchester and mathematics at Cambridge university. He became a Fellow of the Royal Society in 1936 and was knighted in 1948. He died in Cambridge on Sept. 18, 1967.


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