Improved Pulse Shape Discrimination in EJ-301 liquid scintillators

TL;DR

This paper evaluates various digital pulse shape discrimination algorithms for EJ-301 liquid scintillators, introducing a novel Laplace Transform method that improves nuclear recoil identification across energy ranges.

Contribution

The paper presents a new Laplace Transform-based algorithm and compares it with existing methods, demonstrating improved discrimination performance in liquid scintillator detectors.

Findings

Laplace Transform algorithm enhances discrimination accuracy.

Standard Event fit improves over traditional methods.

Charge Comparison Method performs poorly in recoil identification.

Abstract

Digital pulse shape discrimination has become readily available to distinguish nuclear recoil and electronic recoil events in scintillation detectors. We evaluate digital implementations of pulse shape discrimination algorithms discussed in the literature, namely the Charge Comparison Method, Pulse-Gradient Analysis, Fourier Series and Standard Event fitting. In addition, we present a novel algorithm based on a Laplace Transform. Instead of reducing the performance of these algorithms to a single Figure of Merit, we evaluate them as function of recoil energy. Specifically, using commercial EJ-301 liquid sctintillators, we examine both the resulting acceptance of nuclear recoils at a given rejection level of electronic recoils, as well as the purity of the selected nuclear recoil event samples. We find that both a Standard Event fit and a Laplace Transform can be used to significantly improve the discrimination capabilities over the whole energy range. Furthermore, we show that the Charge Comparison Method performs poorly in accurately identifying nuclear recoils.