Optimized Bi4Si3O12 scintillation crystals grown in dynamic atmosphere for future particle physics experiments

This work deals with the optimization of bismuth silicate, Bi₄Si₃O₁₂ (BSO) scintillation crystals as candidates for future high energy physics experiments at colliders involving the registration of both scintillation and Cherenkov light. Crystals with a high transparency in UV-band and a high timing resolution are required for this application. Czochralski process was employed for BSO crystal growth in Pt crucibles in a dynamic growth atmosphere. After the growth of a series of crystals in air, as well as mixed Ar-air static and dynamic atmospheres, it was shown that the mixed atmosphere minimizes Bi₂O₃ evaporation and reduces the amount of Pt dissolved in the melt by several times. This caused the reduction in the number of foreign inclusions in the grown crystals, providing a transparency of over 70 % in the > 300 nm range, a light output of up to 2140 ph/MeV, an energy resolution of 21.5 % at 662 keV γ-rays, while a coincidence time resolution was improved from 148 to 125 ps.