Separation of gamma-ray and neutron events with CsI(Tl) pulse shape analysis

TL;DR

This study demonstrates that CsI(Tl) scintillators can effectively distinguish gamma-ray events from neutron backgrounds using pulse shape analysis, especially in the 5-10 MeV energy range, improving nuclear gamma-ray measurements.

Contribution

The paper introduces a pulse shape discrimination method for CsI(Tl) scintillators to separate gamma-ray and neutron events in the 5-10 MeV energy range.

Findings

Figure of merit nearly 4 between 5-10 MeV energy

CsI(Tl) scintillators effectively reject neutron backgrounds

Stable discrimination performance across the studied energy range

Abstract

Fast neutrons are a large background to measurements of gamma-rays emitted from excited nuclei, such that detectors which can efficiently distinguish between the two are essential. In this paper we describe the separation of gamma-rays from neutrons with the pulse shape information of the CsI(Tl) scintillator, using a fast neutron beam and several gamma-ray sources. We find that a figure of merit optimized for this separation takes on large and stable values (nearly 4) between 5 and 10 MeV of electron equivalent deposited energy, the region of most interest to the study of nuclear de-excitation gamma-rays. Accordingly this work demonstrates the ability of CsI(Tl) scintillators to reject neutron backgrounds to gamma-ray measurements at these energies.