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.

• 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.