Response of the Li-6-enriched Cₛ₂LiYCl₆:Ce³⁺ (CLYC) detector to gamma-rays, fast and thermal neutrons

Abstract

Cₛ₂LiYCl₆:Ce³⁺ (CLYC) is a novel scintillator suitable for dual-detection of gammas and neutrons. CLYC can distinguish gamma-ray and neutron radiation using pulse height discrimination (PHD) as well as pulse shape discrimination (PSD), and it is also capable of high-resolution gamma-ray spectroscopy. Characterization result of a CLYC crystal with a ⁶Li enrichment of 95% that has dimension (diameter×thickness) of 3"× 1" was presented. The gamma-ray response of the CLYC was characterized using photon sources including ¹³⁷Cs, ¹³³a, ⁶⁰Co and ²²Na. The detector's neutron capture capabilities were characterized with ²⁵²Cf source and a Pu-Be source. Detailed simulations of the measurements performed with the CLYC detector using Monte Carlo N-Particle Transport Code (MCNP, version 6.1) were carried out. A digital data acquisition system was used to collect the data from the detector and stream the digitized data to disk. Data acquisition software provided by the digitizer vendor was modified to perform pulse shape analysis and multi-channel analyzer functions.

Pulse shape discrimination of gamma-ray and neutron events was carried out using the charge comparison method by taking the ratio of a delayed and prompt integration region of the detector pulse. The energy of the outgoing proton or α particle from neutron capture reactions scales linearly with the incident neutron energy. The linearity of the responses may enable CLYC to be used for fast-neutron spectroscopy via well-defined peaks in the pulse-height spectrum. The linearity of responses was investigated with different neutron sources (²⁵²Cf source and a Pu-Be source).