Factors which define the a/g ratio in CsI:Tl crystals

Abstract

Dependences of light yield and a/g ratio on the Tl concentration have been studied within a wide range of shaping times. It is shown that the a/g ratio essentially depends on the Tl concentration. Proper combination of the Tl concentration and optimum shaping time in electronics allows to obtain detectors with rather high light output for grays, a-particles and a/g ratio values. It has been shown that both the light yield at a-excitation and the a/g-ratio depend on the time of crystal storage after polishing. On the basis of the idea of the formation of deformation-induced point defects in a thin surface-adjacent layer, the causes of the temporary increasing in light yield for a-particle are explained. An explanation is given of the results obtained by Gwin and Murray concerning the fact that the a/g ratio is practically independent on Tl concentration.