Correlating the Temporal Luminosity Parameters to Pulse Shape Discrimination

Abstract

Monte Carlo simulations were used to investigate the correlation between temporal luminosity parameters and pulse shape discrimination (PSD). Temporal luminosity parameters Af, As, (fast and slow initial luminosities) and tauf, taus, (fast and slow decay time constants) of a dual decay mode scintillator were applied to create a dynamic model with Crystal Balltrade simulation system. The simulated pulses were analyzed with charge comparison (CC) and constant time discrimination (CTD) PSD techniques followed by quantification of the histogrammed pulse data with Figure of Merit (FoM) and spillover. For the CC method, independent of the reference pulse characteristics [(Aftauf/Astaus)gamma = 1 or = 0.1], the changes to Af, As, and tauf have nearly equal influence on the PSD quality, while changes to taus reduce the region of poor discrimination. For the CTD method, Af and As are seen to have less influence over the PSD in comparison with tauf and taus when (Aftauf/Astaus)gamma = 1. For either references, the scintillator having temporal parameters such that, 0.1 < (Aftauf/Astaus)alpha/gamma < 2, is classified as a poor pulse shape discriminator. Thus, knowledge of temporal parameters can predict the PSD capability. Comparison of the simulation system with CsI:Tl, a very good pulse shape discriminating inorganic scintillator, is also presented.