Scintillation Properties of Large BSO Crystals for Future High-Energy Physics Experiments

Bismuth silicate (Bi₄Si₃O₁₂) crystal, due to their high stopping power, fast decay and low raw material cost, are expected to be applied in future high-energy physics (HEP) experiments. However, the high-quality and large crystal growth has restricted its practical HEP applications as a cost-effective scintillator. In this study, BSO crystals with dimensions up to 22.6 mm × 22.6 mm × 369 mm (SIC-BSO-369) and 18.6 mm × 18.6 mm × 259 mm (SIC-BSO-259) were successfully grown in Shanghai Institute of Ceramics, Chinese Academy of Sciences. These are the longest BSO single crystals reported to date. Their scintillation properties were measured, including transmittance, photoluminescence, X-ray excited emission, energy resolution, and light response uniformity. The results show that the SIC-BSO-259 crystal exhibits a high longitudinal transmittance (78.32%@480 nm) close to the theoretical limit value, demonstrating excellent optical quality. Due to internal scattering, the longitudinal transmittance of the SIC-BSO-369 crystal is 45.27% at 480 nm. The average energy resolution of the SIC-BSO-259 and SIC-BSO-369 for 662 keV gamma rays are 27.2% and 29.0%, respectively. And their average absolute light output is 776 and 735 ph/MeV, respectively. The optimal light response uniformity (δ value) of SIC-BSO-259 is (-0.52 ± 0.5) % with a combination of all polished surfaces and ESR as high-reflector material, while for SIC-BSO-369 is (1.41±1.8) % with Tyvek wrapped.