Influence of Self-Absorption on Pulse Shape Discrimination in Organic Glass Scintillators

Abstract

Organic glass scintillators are an interesting alternative to liquid scintillators, offering many advantageous characteristics with few drawbacks. In this paper we investigate the influence of light self-absorption in the organic glass scintillator on its pulse shape discrimination capability. With five scintillators of different heights but same diameter, we measure photoelectron yield and Figure of Merit in neutron-gamma discrimination. The decrease of both values with increasing size is attributed to light self-absorption, while normalized Figure of Merit remains constant. The choice of gates for charge comparison method is discussed. We also use genetic algorithm to estimate decay times and intensities of fast, medium, and slow components of light pulse shapes measured with Bollinger-Thomas setup. We compare the results to trans-stilbene reference sample.