Neutron light output function and resolution investigation of the deuterated organic liquid scintillator EJ-315

Abstract

In this paper we investigate the light response to fast neutrons and estimate the pulse height resolution of a deuterated liquid organic scintillator, EJ-315, considering the detector's non-linear light response to gamma-rays. Initially, collision data and a neutron beam trigger are recorded in coincidence mode, and incident neutron energy is calculated with a time-of-flight technique. Fast neutrons are further discriminated from gamma-ray background based on the scintillation material decay patterns using a pulse shape discrimination algorithm. A light response matrix composed of multiple neutron energy and their corresponding light outputs is derived. The pulse height resolution property of the EJ-315 is characterized utilizing the derivatives of the pulse height distributions with corrections of the measurements setup uncertainties. Additionally, the EJ-315's pulse height resolution is also characterized by comparing the smoothed derivatives of quasi-monoenergetic neutron pulse height distributions, given by the Peierls-formula-based analytic model, to match the measurement data. Results show rather consistent 10–13% pulse resolution for mono-energetic neutrons with kinetic energy above 2 MeV. The resolution decreases slightly with an increase in neutron energy indicating the improved resolution performance of EJ-315 in the higher energy events.