Pulse height analysis and pulse shape discrimination of pure LaCl3 scintillation crystal across a broad neutron energy range

Abstract

A pure LaCl${}_3$ crystal scintillation detector has been developed and shows strong potential for fast neutron detection, particularly via the ³⁵Cl(n,p)³⁵S and ³⁵Cl(n,$\alpha$)³²P reactions. These reaction channels make it a promising candidate for neutron spectroscopy applications in nuclear fusion research. In this study, a comprehensive characterization of the pure LaCl${}_3$ scintillation detector was performed in a mixed neutron and $\gamma$-ray radiation field. Pulse height analysis and neutron–$\gamma$ pulse shape discrimination were systematically evaluated over a wide neutron energy range, from approximately 2.46 MeV to 16.89 MeV, using both a ²⁵²Cf spontaneous fission source and a mono-energetic neutron beam at the Fast Neutron Laboratory, Tohoku University. The results reveal a clear separation between neutron- and $\gamma$-induced signals, with figure-of-merit values exceeding 1.18 at specific energies, demonstrating the detector’s excellent pulse shape discrimination performance. The pulse height response associated with charge generation in the pure LaCl${}_3$ scintillation crystal was systematically characterized. Energy calibration and linearity for neutron energies up to 5.61 MeV were verified through the peak corresponding to the ³⁵Cl(n,p)³⁵S ground-state reaction. These findings confirm that pure LaCl${}_3$ scintillators exhibit excellent neutron–$\gamma$ discrimination, enabled by differences in the pulse height and decay time characteristics of the induced signals, making them well-suited for high-resolution neutron spectroscopy in mixed radiation fields typical of magnetic confinement fusion environments.