Optical and Scintillation Properties of $Bi_{4}(Ge_{x}S_{1-x})_{3}O_{12}$ Single Crystal

The solid solution crystals, $Bi_{4}(Ge_{x}Si_{1-x})_{3}O_{12}$ (BGSO) with x=0, 0.05, and 0.15, have been grown by the modified vertical Bridgman method. The as-grown crystals show 80% of transmittance with an absorption edge of 285 nm. The relative light yields of BGSO crystals are found to be 7.2%, 6.3%, and 4.2% of CsI(Tl) crystal for x=0, 0.05, and 0.15, respectively. The energy resolutions of these crystals are 18.9%, 21.3%, and 24.7%, respectively, with PMT for 662 keV gamma rays at room temperature when exposed to $\text{}^{137}Cs$ γ -ray. The scintillation performance of BGSO crystals clearly deteriorates with the increase of Ge content. However, the appropriate number of germanium ions doped to BSO crystal can improve its crystallization behavior and effectively restrain component segregation. It is expected that large size crystals of BGSO will be grown and applied to the dual readout calorimeter in the nearest future.