Correlating the Temporal Luminosity Parameters to Pulse Shape Discrimination

Monte Carlo simulations were used to investigate the correlation between temporal luminosity parameters and pulse shape discrimination (PSD). Temporal luminosity parameters A_f, A_s, (fast and slow initial luminosities) and tau_f, tau_s, (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 [(A_ftau_f/A_stau_s)gamma = 1 or = 0.1], the changes to A_f, A_s, and tau_f have nearly equal influence on the PSD quality, while changes to tau_s reduce the region of poor discrimination. For the CTD method, A_f and A_s are seen to have less influence over the PSD in comparison with tau_f and tau_s when (A_ftau_f/A_stau_s)gamma = 1. For either references, the scintillator having temporal parameters such that, 0.1 < (A_ftau_f/A_stau_s)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.