Gray (unit) Gray (unit) The gray (symbol: Gy) is a derived unit of ionizing radiation dose in the International System of Units (SI). It is defined as the absorption of one joule of radiation energy per kilogram of matter. It is used as a unit of the radiation quantity absorbed dose which measures the energy deposited in a unit mass at a certain position, and of the radiation quantity kerma, which is the amount of energy that is transferred from photons to electrons per unit mass at a certain position. The corresponding cgs unit to the gray is the rad (equivalent to
Department of Scientific and Industrial Research (United Kingdom) purposes. Large areas of research were the responsibility of other bodies - aviation, atomic energy, agriculture, health and medicine, meteorology - though it might undertake specific investigation on behalf of the responsible departments. The department encouraged and supported scientific research in universities and other institutions by means of grants for special research projects, research fellowships, studentships, grants to research associations and research contracts. The department absorbed or created a number of research organisations, which included large laboratories for special fields of work. Existing institutions for which it assumed responsibility were the National Physical Laboratory from the Royal Society in 1918,