Thermal-neutron scintillator: Ce³⁺ activated Rb₂LiYBr₆

Scintillation and luminescence characteristics of Rb₂LiYBr₆ doped with 0.1%, 0.5%, 1%, and 5% Ce³⁺ are presented. Under optical and x-ray excitation, Ce³⁺ doublet emission is observed at 385 and 420 nm. Rb₂LiYBr₆:0.5% Ce³⁺ shows very high thermal neutron scintillation light output of 83 000 photons/neutron. An excellent neutron peak resolution of 3.6% (full width at half maximum over peak position) is observed for the 4.8 MeV neutron-reaction products energy response in Rb₂LiYBr₆:0.1% Ce³⁺. This peak shows up at 3.6 MeV γ-equivalent energy and therefore it gives an α/β ratio of 0.74. The combination of a large fraction of neutron absorption in natural ⁶Li (62%), a sharp neutron response peak, high light yield, and large α/β ratio makes Rb₂LiYBr₆:Ce³⁺ an efficient scintillator for thermal neutron detection.