Tl2LiYCl6:Ce: A New Elpasolite Scintillator

Tl
₂
LiYCl
₆
:Ce (TLYC), a new cerium doped-thallium based, dual mode gamma and neutron elpasolite scintillation crystal, has been grown and evaluated at RMD. Energy resolution of 4.2% at 662 keV (FWHM) is measured for samples of this material. From comparison with a
¹³⁷
Cs spectrum collected with NaI:Tl, a gamma-ray induced light yield of 26,000 ph/MeV is estimated for TLYC. The material also shows better proportionality of response than both LaBr
₃
:Ce and NaI:Tl in the energy range between 32 keV to 1275 keV. Single thermal neutron interactions produce a peak measured at a gamma equivalent energy of 1.9 MeVee, corresponding to a (neutron induced) light yield of approximately 47,000 ph/n. Decay times obtained from gamma-ray interactions in TLYC are measured at about 57 ns, 431 ns, and 1055 ns, with slightly shorter values measured for neutron interactions. These differences allow for gamma-neutron pulse shape discrimination (PSD) and a PSD Figure-of-Merit (FOM) of 2 is measured with TLYC.