New thermal neutron scintillators:: Cs2LiYCl6 : Ce3+ and Cs2LiYBr6 : Ce3+

The thermal neutron detection properties of Cs2LiYCl6 : 0.1% Ce3+ and Cs2LiYBr6 : 1% Ce3+ single crystals are presented. The compounds show high scintillation photon yields of 70 000 and 88 200 photons emitted per absorbed thermal neutron, respectively. Events caused by primary electrons with energy below 2.9 and 3.4 MeV, respectively, can be separated from neutron-induced events by pulse-height discrimination. For Cs2LiYCl6 : 0.1% Ce3+, due to the presence of a 4-ns fast core-valence luminescence, thermal neutrons and gamma rays can also be discriminated by means of the shape of the scintillation pulse. The main part of the scintillation pulse in Cs2LiYCl6 : 0.1% Ce3+ is relatively slow, however, Cs2LiYBr6 : 1% Ce3+ has a relatively intense component with tau = 85 ns decay time.