THERMOLUMINESCENCE IN ALKALINE-EARTH DOPED KCl IRRADIATED AT ROOM TEMPERATURE

The thermoluminescence of KCl : Ca, KCl : Sr and KCl : Ba single crystals gamma or X-irradiated at room temperature has been studied. Each impurity induces a different set of glow peaks. The pre-exponential factors and the activation energies of these peaks have been obtained. All of them obey first order kinetics. It has been found that the thermal annealing processes of the F and V (226 nm) centres have the same pre-exponential factors activation energies that the thermoluminescent processes. It is concluded, as in a previous work on pure Harshaw KCl crystals, that the observed thermoluminescence is due to the recombination of mobile chlorine atoms, thermally released from traps, with F centres ; during this process an electron-hole recombination occurs and light is emitted. As in undoped KCl, with increasing vacancy centre (F, M...) concentration the glow peaks at low temperatures vanish while glow peaks at higher temperature appear. The light sum to the vacancy centre concentration in KCl : Sr is two orders of magnitude higher than in KCl : Ca, KCl : Ba and undoped KCl (Harshaw). The experimental results also support that in the radiation induced F coloring processes, these impurities act as interstitial traps