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
Scientific Atlanta of home security and energy management during the 1970s. The company marketed wireless home alarm systems and provided equipment to utilities that enabled them to monitor home energy use. By the dawn of the 1980s, Scientific Atlanta had become the world's largest supplier of satellite earth stations. In February 2003, Scientific-Atlanta introduced their first Explorer HD set-top box, which is capable of displaying HDTV programming, at Best Buy stores in the Phoenix metropolitan area. It was later rolled out nationwide. In March 2004, Scientific-Atlanta launched the Explorer 8000HD, their first set-top box with both DVR and HD. In the set-top