Comparative study of Tm-doped and Tm-Sc co-doped Lu₃Al₅O₁₂ scintillator

The crystals of Tm doped and Tm-Sc co-doped Lu₃Al₅O₁₂ (LuAG) grown by the floating zone (FZ) method were examined for their optical and scintillation properties. In transmittance spectra, strong absorption lines due to Tm³⁺ 4f-4f transitions were observed. X-ray excited radioluminescence spectra were measured and broad and sharp emission peaks were detected. The former one was attributed to Sc³⁺ and the latter one was due to Tm³⁺ 4f-4f transitions. Scintillation yield enhancement due to Sc co-doping was observed by means of ¹³⁷Cs pulse height spectra. Scintillation decay times were several tens of μs under pulse X-ray excitation.