Scintillation properties of CsI(Tl) co-doped with Tm۲+

In this research, the Tm content as codopant in CsI(Tl) was optimized for reducing the afterglow. As an experimental reference, CsI(Tl) and CsI(Tl-۰.۰۵%Eu) single crystals were grown by Bridgman method. The grown crystals were characterized through photoluminescence analysis, and the measurements of charge collection time, energy resolution, photon light yield as well as the amount of afterglow were performed. It was observed that the change in codopant shifted the emission curve of Tl+. For CsI(Tl) codoped with Tm in the range of ۰.۰۲ to ۰.۱ mol%, the afterglow of ۰.۰۵ mol% Tm reduced in comparison with Tm-free CsI(Tl). The results showed that the Tm codopant resulted in a decrease of ۳۲ to ۴۲% in afterglow depending on the Tl concentration. The addition of various contents of Tm also decreased the light yield, up to ۲۳%, and as well as the resolution about ۲ to ۳۳%. The light yield exhibited insignificant changes, whilst the measured energy resolution was about ۸.۸% at ۶۶۲ keV. Overall, the improvement in the afterglow, as well as the insignificant reduction in both the energy resolution and light yield of CsI(Tl-Tm), may motivate some researchers to consider it as a good candidate for fast spectroscopy and high-frequency imaging applications.

Keywords:

CsI(Tl) , Codopant , Afterglow , Light yield , Gamma-ray spectroscopy