On luminescence properties of CsI crystals scavenged by Mg 2+

Abstract

Features of radioluminescence spectra and scintillation light decay curves of CsI crystals grown from the melt preliminarily scavenged by different amounts of Mg 2+ (MgCl 2) are reported. The scintillation light of CsI usually contains 3 components with the decay time constants equal to 7 ns (I), 30 ns (II) and 2 μs (III). The addition of Mg 2+ 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 370–550 nm band in the radioluminescence spectrum of CsI crystal; thereat the fraction of component III in CsI scintillation light decreases. The excessive in relation to O 2− concentration amounts of Mg 2+ lead to the decrease of O 2− equilibrium molality in CsI melt from 10 − 3 to 10 −10 mol kg − 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 Mg 2+ and O 2−.