Louis Harold Gray

Louis Harold Gray (10 November 1905 – 9 July 1965) was an English physicist who worked mainly on the effects of radiation on biological systems, is one of the earliest contributors of the field of radiobiology. 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.

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 Hospital
• 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 - Established the Gray Laboratory at Mount Vernon Hospital
• 1953 - 1960 - Under Gray's direction, Jack W. Boag developed pulse radiolysis
• 1962 - Ed Hart, of Argonne National Laboratory, and Jack Boag discovered the hydrated electron using pulse radiolysis at the Gray Laboratory - This discovery initiated a new direction of research that is still very active today and is vital for understanding the effects of radiation on biological tissue, for instance in cancer treatment.