Single crystal and optical ceramic multicomponent garnet scintillators: A comparative study

Abstract

Multicomponent garnet materials can be made in optical ceramic as well as single crystal form due to their cubic crystal structure. In this work, high-quality Gd3Ga3Al2O12:0.2at% Ce (GGAG:Ce) single crystal and (Gd,Lu)3Ga3Al2O12:1at% Ce (GLuGAG:Ce) optical ceramics were fabricated by the Czochralski method and a combination of hot isostatic pressing (HIPing) and annealing treatment, respectively. Under optical and X-ray excitation, the GLuGAG:Ce optical ceramic exhibits a broad Ce3+ transition emission centered at 550nm, while the emission peak of the GGAG:Ce single crystal is centered at 540nm. A self-absorption effect in GLuGAG:Ce optical ceramic results in this red-shift of the Ce3+ emission peak compared to that in the GGAG:Ce single crystal. The light yield under 662keV γ-ray excitation was 45,000±2500 photons/MeV and 48,200±2410 photons/MeV for the GGAG:Ce single crystal and GLuGAG:Ce optical ceramic, respectively. An energy resolution of 7.1% for 662keV γ-rays was achieved in the GLuGAG:Ce optical ceramic with a Hamamatsu R6231 PMT, which is superior to the value of 7.6% for a GGAG:Ce single crystal. Scintillation decay time measurements under 137Cs irradiation show two exponential decay components of 58ns (47%) and 504ns (53%) for the GGAG:Ce single crystal, and 84ns (76%) and 148ns (24%) for the GLuGAG:Ce optical ceramic. The afterglow level after X-ray cutoff in the GLuGAG:Ce optical ceramic is at least one order of magnitude lower than in the GGAG:Ce single crystal.