Measurement of stored energy of KBr after 4·6°K reactor irradiation

Four KBr single crystals were irradiated at 4·6°K in the core of the Munich Nuclear Reactor for periods of 100 sec, 10 min or 1 hr, respectively. After irradiation the stored energy of the samples was measured in a differential-heat-flow calorimeter at heating rates of 0·29°K/min and 1·1°K/min. At 0·29°K/min peaks of stored energy release were resolved near 11 and 20°K and at 25, 38 and 45°K. An attempt was made to evaluate the corresponding activation energies using two different methods (see Table 1 in the text). The 25°K annealing stage is due to a first order recombination reaction. The anneling states near 20, at 38 and at 45°K do not correspond to first order reactions. Our results are compared with annealing studies on low temperature X-irradiated KBr crystals. A similar experiment was performed on KCl single crystals and is reported, together with a more detailed comparison and discussion of both experiments, in a later paper14].