Quantitative Analysis and Efficiency Study of PSD Methods for a LaBr3:Ce Detector

TL;DR

This paper quantitatively analyzes and compares different pulse shape discrimination methods for LaBr3:Ce detectors, optimizing alpha/gamma discrimination and background suppression for nuclear spectroscopy applications.

Contribution

It provides a detailed quantitative comparison of PSD methods, introduces an energy-dependent threshold optimization, and verifies a correlation model for improved discrimination efficiency.

Findings

Charge comparison method effectively discriminates alpha and gamma signals.

Energy-dependent thresholds enhance discrimination efficiency.

Potential for improved low-activity gamma measurements by background suppression.

Abstract

The LaBr3:Ce scintillator has been widely studied for nuclear spectroscopy because of its optimal energy resolution (<3%@ 662 keV) and time resolution (~300 ps). Despite these promising properties, the intrinsic radiation background of LaBr3:Ce is a critical issue, and pulse shape discrimination (PSD) has been shown to be an efficient potential method to suppress the alpha background from the 227Ac. In this paper, the charge comparison method (CCM) for alpha and gamma discrimination in LaBr3:Ce is quantitatively analysed and compared with two other typical PSD methods using digital pulse processing. The algorithm parameters and discrimination efficiency are calculated for each method. Moreover, for the CCM, the correlation between the CCM feature value distribution and the total charge (energy) is studied, and a fitting equation for the correlation is inferred and experimentally verified. Using the equations, an energy-dependent threshold can be chosen to optimize the discrimination efficiency. Additionally, the experimental results show a potential application in low-activity high-energy {\gamma} measurement by suppressing the alpha background.