Li-Based Thermal Neutron Scintillator Research; ${\hbox {Rb}}_{2}{\hbox {LiYBr}}_{6}:{\hbox {Ce}}^{3+}$ and Other Elpasolites

We investigated gamma- and neutron-scintillation properties of A₂LiLnX₆:Ce³⁺ (A=Cs, Rb, K, Na, Li; Ln=La, Y, Lu, Sc; X=Br, I) with the aim to develop new scintillators with high neutron detection efficiencies. Among the investigated thermal neutron scintillators, Rb₂LiYBr₆:Ce³⁺ shows an excellent neutron peak resolution of 3.6%. This is the best neutron peak resolution ever reported. Together with the large alpha/beta ratio of 0.74, Rb₂LiYBr₆:Ce³⁺ offers the possibility of excellent neutron/gamma discrimination. The highest thermal neutron scintillation light yield of 83,000 photons/neutron is also reported for Rb₂LiYBr₆:Ce³⁺.