On luminescence properties of CsI crystals scavenged by Mg2

Features of radioluminescence spectra and scintillation light decay curves of CsI crystals grown from the melt preliminarily scavenged by different amounts of Mg2+ (MgCl2) are reported. The scintillation light of CsI usually contains 3 components with the decay time constants equal to 7ns (I), 30ns (II) and 2 mu s (III). The addition of Mg2+ amount equivalent to the total concentration of oxide ions in molten CsI results in complete destruction of carbonate and sulfate ions. This is confirmed by the disappearance of 370-550nm band in the radioluminescence spectrum of CsI crystal; thereat the fraction of component III in CsI scintillation light decreases. The excessive in relation to O2- concentration amounts of Mg2+ lead to the decrease of O2- equilibrium molality in CsI melt from 10-3 to 10-10 molkg-1. That causes a considerable increase of fraction of component I as compared with component II from 0.63:0.35 to 0.88:0.07. The fraction of the slow component III approaches the minimum at the equivalent ratio of initial molalities of Mg2+ and O2-.