gamma rays. Electromagnetic radiations of high photon cnergy originating in atomic nuclei and accompanying Tany nuclear reactions (e.g., Fission, radioactivity, and neutron capture). Physically, gamma rays are identical with X-rays of high energy; the only essential difference is that X-rays do not originate from atomic nuclei of high energy. Gamma rays can travel great distances through air and can penetrate considerable thickness of material, although they can neitner be seen nor felt oy human beings except at very high intensities, which cause an itching and tingling sensation of the skin. They can produce harmful effects even at a long distance from their source (The Effects of Nuclear Weapons, 3rd edition). Geiger-Mueller counter. A gas discharge pulse counter for ionizing radiation. 1on-chamber-type survey meter. GMT. gray See also AN/PDR-39 and Greenwich Mean Time. (Gy). A recently introduced ICRP term; 1 Gy equals 100 rad. ground zero (GZ). The point on the surface of land or water at, or vertically below or above, the center of the burst of a nuclear weapon. xo A viscous commercial preparation that is soluble both in water and petroleum derivatives. It acts as a wetting agent in removing grease and particulate matter from metal and other nonporous surfaces. U.S. Army helicopter developed for close support with Tanding-skid-mounted armament. for Enewetak airlift. Used in CASTLE Large utility helicopter manufactured by Sikorsky Aircraft Division af United Aircraft Corporation. Used in CASTLE for Enewetak airlift. | x t ms oO w ’ e gunk. H-hour. Time zero, or time of detonation. When used im connection with planning operations it is the specific hour on which the operation event commences. See D-day. half-life. The time required for a radioactive materia] to lose half of its radioactivity Each radionuclide has a unique half-life. HASL, NYKOPQ. HE. due to decay. Atomic Energy Commission's Health and Safety Laboratory, New York Operations Office. High explosive. high-altitude burst. Defined, somewhat arbitrarily, as a detonation in or above the stratosphere. The distribution of the energy of the explosion between blast and thermal radiation changes appreciably with increasing altitude. HMNZS. His (Her) Majesty's New Zealand Ship. HMR, Marine Helicopter Transport Squadron. hodograph. A common hodograph in meteorology represents the speed and direction of winds at different altitude increments. hot; hot spot. Commonly used colloquial term meaning a spot or area relatively more radioactive than some adjacent area. HRS-2. IBDA. [CRP. Helicopter manufactured by Sikorsky Aircraft. Used in CASTLE for Bikini airlift. Indirect Bomb Damage Assessment. A revised target analysis based on new data such as actual weapon yield, burst height, and ground zero obtained by means other than direct assessment. International Commission on Radiological Protection. initial radiation. Also known as prompt radiation. Electromagnetic radiations of high energy emitted from both the fireball and the radioactive cloud within the first minute after a detonation. [t includes neutrons and gamma rays given off almost instantaneously, as well as the gamma rays emitted by the fission products and other radioactive species in the rising cloud. [nitial radiations from graund or near-ground bursts activate both Earth materials and device debris to create cantamination,. inverse square law. The decrease in radiation intensity with distance from a single-point source is proportional to the square of the distance removed. 477 in-