Scintillation Properties and Pulse Shape Discrimination Capability of CLLBC at Ce Concentration

Elpasolite scintillators such as Cs2LiYCl6 (CLYC), Cs2LiLaBr6 (CLLB), and Cs2LiLa(Br,Cl)6 (CLLBC) are known for their exceptional scintillation properties and ability to detect both neutrons and gamma rays. Although Ce doping is crucial for enhancing luminescence, a quantitative analysis of its impact on pulse shape discrimination (PSD) has not been thoroughly explored. This study focuses on CLLBC crystals, grown with nominal Ce concentrations of 2%, 3%, and 4% using the vertical Bridgman method. Characterization revealed that increasing Ce concentrations improve energy resolution and light yield while reducing decay times. Importantly, the figure of merit (FoM) for n- $\gamma $ discrimination increased from 1.6 to 2.0, indicating enhanced PSD capability. The coupled rate and transport model quantitatively explains this improvement by demonstrating that higher Ce doping enhances dipole quenching of excited states, thus improving n- $\gamma $ pulse shape differentiation. These findings are crucial for optimizing Ce concentrations in CLLBC, and the approach demonstrated here can also be extended to other Elpasolite-based n- $\gamma $ dual-mode scintillators.