Optical and scintillation characteristics of Lu2Y(Al5-xGax)O12:Ce,Mg multicomponent garnet crystals

Optical and scintillation characteristics of Mg2+-codoped Lu2Y(Al5-xGax)O12:Ce (x = 2, 3) multicomponent garnet crystals grown by the micro-pulling down method were investigated. At RT, the shortening of scintillation decay time and a decrease of light yield (LY) value measured for a higher Ga containing samples can be explained by thermal ionization of the Ce3+ 5d1 excited state. At 662 keV γ-rays, Lu2YAl3Ga2O12: Ce, 0.05%Mg exhibits high LY value of 29,000 ph/MeV along with scintillation decay times of 50 ns (86%) + 73 ns (14%). Co-doping with larger Mg2+ content leads to a decrease of LY value, scintillation decay time, and afterglow level. Radioluminescence quenching observed at low temperature region in correlation with large thermoluminescence peaks can be caused by trapping of electrons at intrinsic shallow traps.