OPERATION GREENHOUSE. Scientific Director's Report. Annex 5.1 - Annex A. Alkali Halide and Phosphate Glass Radiological Casualty Dosimeters,
NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CA
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Photochemical reactions induced by ionizing radiations can produce color centers in alkali halide crystals and fluorescent centers in silver-bearing phosphate glasses. These reactions are being investigated as a basis for casualty-badge radiation dosimeters. Potassium bromide and potassium chloride crystals were satisfactorily sensitized by heating in a combined atmosphere of alkali vapor and hydrogen. Doses of 25 r of cobalt 60 gamma rays were detected by the visible color changes in sensitized KBr and KCl. The sensitivity of the phosphate glass is comparable to the crystals however, a reading device is needed for the fluorescent measurements. The crystals and glasses are strongly energy dependent for X-ray energies below about 150-kv effective. In a test atomic bomb detonation the crystals and glasses were exposed to total dosages of 17 to 4,460 r at varying dosage rates. In general, there was a good agreement among the dosage readings for samples of a given material but the readings for different materials varied from 0.81 to 2.3 times the readings obtained with National Bureau of Standards NBS film badges.