Thermoluminescence in potassium dihydrogen phosphate (KDP) induced by Co/ sup 60/ gamma irradiation at liquid nitrogen temperature (-198 deg C) was investigated. Glow curves in the temperature range --196 to 0 deg C were measured for a series of gamma exposure dosages ranging from 10/sup 4/ roentgen to 5 x 10/sup 6/ roentgen. The heating rate used for glow curve measurements was 12 deg C per minute. Twice recrystallized Mallinckrodt reagent grade potassium dihydrogen phosphate, with a grain size between 100 and 170 mesh, was used for most samples. In the case of the powder samples, the glow curve for an exposure dose of 10/sup 4/ roentgen exhibited two peaks in this temperature range, one at approximately --78 deg C and the other at approximately -146 deg C. The -78 deg C peak split into two distinct peaks with increasing dosage. At still higher doses an additional peak at about -9 deg C became evident. This peak may, however, be due to aluminum oxide. Calculation of the trap depth, E, and the frequency factor, s, associated with the --78 deg C peak, by the approximate method of Grossweiner yielded values of 0.485 ev and 9.97 x 10/sup 10/ sec/sup -1/ for E and s, respectively. Calculation of the trap depth corresponding to this glow peak was also made using the method described by Bonfiglioli, Brovetto, and Cortese. The value obtained was approximates -0.2 ev. Treatment of the --148 deg C glow peak by the method of Bonfiglioli, Brovetto, and Cortese gave values of approximates 0.1, approximates 0.35, and approximates 0.2 ev for glow curves resulting from exposure doses of 10/sup 4/, 10/sup 5/, and 10/sup 6/ roentgens, respectively. Glow curves were measured for two KDP single crystals, each exposed to 10/sup 4/, 10/sup 5/, and 10/sup 6/ roentgens with subsequent warming to room temperature between exposures. The temperatures at which core glow peaks for a given exposure dose occur agreed within 5 deg C for both samples. However, the relative intensity of corresponding peaks varied rather wideiy between samples. Flashes of light of short duration were observed during warming of many of the irradiated samples, both as powders and single crystals. It is suggested that this may be some form of triboluminescence. No exact correlation of this particular phenomenon with dose was attempted but it was generally observed more often at higher doses and never at 10/sup 4/ roentgens. (auth)
