1英寸Cs2LiLaBr6∶Ce闪烁晶体的生长及性能研究

Cs₂LiLaBr₆∶Ce(CLLB∶Ce)晶体n/γ双读出闪烁性能优异,其实用化瓶颈在于大尺寸、高光学质量晶体的生长。本研究采用非化学计量比配比,避开CLLB∶Ce非一致熔融组分区域,通过改进研制坩埚下降法晶体生长炉,并优化温度场和降低坩埚下降速度等晶体生长工艺,从而克服组分过冷,保持生长界面稳定,得到了直径1英寸(1英寸=2.54 cm)的CLLB∶Ce晶体毛坯,等径透明部分长度达40 mm,单晶比例由52%提高至79%,可见光区光学透过率达到70%以上。在¹³⁷Cs激发下能量分辨率达3.7%,在²⁵²Cf激发下晶体的品质因子达到1.42,可以很好地甄别中子和γ射线。

Growth and Properties of 1-Inch Cs2LiLaBr6:Ce Scintillation Crystal

Cs₂LiLaBr₆:Ce(CLLB:Ce)crystal has excellent neutron-gamma dual readout performance, while its application bottleneck is to grow single crystals with large size and high optical quality. In this study, non-stoichiometric ratio was used to avoid the phase region of in-congruent CLLB:Ce. By improved Bridgman furnace, optimizing the temperature field and reducing the lowering speed, the constitutional supercooling was overcame and the stability of the growth interface was maintained during the crystal growth process. 1-inch diameter CLLB:Ce crystal ingot was obtained, the length of the equal diameter transparent part is 40 mm, the proportion of single crystal increases from 52% to 79%, and the optical transmittance in the visible light region is above 70%. The energy resolution of CLLB:Ce is about 3.7% under ¹³⁷Cs excitation while the Figure-of-Merit of CLLB:Ce is about 1.42 under ²⁵²Cf excitation. This shows good properties for discriminating gamma-ray and neutron.