Enhanced neutron-gamma discrimination in Pr³⁺-activated Cs₂LiYCl₆ scintillator: Dual roles of Pr³⁺ luminescence

Neutron-gamma discrimination is essential for neutron-sensitive scintillators, while effective approaches for improving pulse shape discrimination (PSD) performance remain limited. Here, a Pr³⁺-activated Cs₂LiYCl₆ (CLYC:Pr) elpasolite scintillator single crystal was grown and systematically investigated. The crystal exhibits a light yield of 20589 ph/MeV and an energy resolution of 4.8% at 662 keV. Under moderated ²⁵²Cf irradiation, excellent neutron-gamma discrimination was achieved with a figure of merit (FoM) of 5.73, which is significantly higher than that of conventional CLYC:Ce scintillators. Spectroscopic studies show that Pr³⁺ causes much weaker self-absorption of host core-valence luminescence (CVL) than Ce³⁺, thereby preserving the ultrafast emission component. Meanwhile, CLYC:Pr exhibits both fast 4f5d→4f emission and slow 4f→4f emission, which further enlarges the waveform difference between γ-ray and neutron excitation. These results clarify the luminescence origin of the enhanced PSD behavior in CLYC:Pr and highlight the potential of Pr³⁺ activation for developing high-performance neutron-gamma scintillators.