Influence of excitonic processes in the energy resolution of scintillators

Abstract

A phenomenological approach is used to derive the light yield in a scintillator. Both absolute and relative yields are derived and then calculated for four scintillators, namely NaI:Tl, BaF2, Gd2SiO5:Ce (GSO) and LaCl3:Ce. The objective is to present a comprehensive theoretical study of the nonproportionality occurring in the yield of inorganic scintillators. This nonproportionality produces low energy resolution in most scintillators known to date. The dependences of absolute and relative yields on various rates of linear and nonlinear radiative and quenching processes are studied. The results are analysed with a view to present a recipe for achieving an inorganic scintillator with optimal proportionality in its yield and hence optimal energy resolution. The theory presented here forms the fundamental background desired for understanding the nonproportionality observed in scintillators.