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Louis Harold Gray

Louis Harold Gray (10 November 1905 - 9 July 1965) was a British physicist who worked mainly on the effects of radiation on biological systems, inventing the field of radiobiology as he went. A summary of his work is given below. Amongst many other achievements, he defined a unit of radiation dosage which was later named after him as an SI unit, the Gray.

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Summary of Career

1933 Hospital physicist at Mount Vernon Hospital, London
1936 Developed the Bragg-Gray equation, the basis for the cavity ionization method of measuring gamma-ray energy absorption by materials
1937 Built an early neutron generator at Mount Vernon
1938 Studied biological effects of neutrons using the generator
1940 Developed concept of RBE (Relative Biological Effectiveness) of doses of neutrons
1952 Initiated research into cells in hypoxic tumors and hyperbaric oxygen
1953 Set up Gray Laboratory at Mount Vernon Hospital
1953 - 1960 Under Gray’s direction, Jack W. Boag developed pulse radiolysis
1962 Ed Hart (ANL) and Boag discovered the hydrated electron using pulse radiolysis at Gray Lab

This discovery initiated a new direction for chemistry research that is still very active today and is vital for understanding of the effects of radiation on biological tissue, for instance in cancer treatment.