Afterglow Suppression by Codoping with Bi in CsI:Tl Crystal Scintillator

Single crystals of CsI, CsI:Tl, and CsI:Tl,Bi were grown by the vertical Bridgman method. We studied the effect of Bi3+ codoping on the CsI:Tl X-ray-induced afterglow. Thermally stimulated luminescence measurements were carried out in order to investigate the role of traps. The results showed a remarkable reduction of afterglow, of about an order of magnitude, and of trap concentration by Bi codoping. These improvements could be related to a possible role of Bi in the compensation of intrinsic nonstoichiometry defects.