大尺寸掺氯化铈的溴化镧晶体生长及闪烁性能研究

摘要

采用真空密封的石英坩埚,使用改进的下降法生长了以氯化铈为掺质的溴化镧晶体( LaBr3:CeCl3),获得尺寸φ40 mm×45 mm无宏观缺陷晶体.测试了LaBr3:CeCl3晶体的X射线激发发射谱、透射光谱及光输出、能量分辨率、衰减时间等闪烁性能.结果表明:在X射线激发下,Ce3+激发发光主峰位于385 nm附近,且其光透过率高达70％.在137 Cs放射源作用下,LaBr3:5％ CeCl3晶体的光产额可达到12 000 photoelectrons/MeV,能量分辨率高约2.9％,并且衰减时间达16.4 ns.与Nal晶体相比,LaBr3:CeCl3晶体以其优良的闪烁性能更加适用于放射性核素识别设备上.%It presented the growth method and scintillation properties of large - size LaBr3 crystals. LaBr3 crystals doped with CeCl3 concentrations, I. E. LaBr3: CeCl3 crystals were grown by modified Bridgman technique from the melt of the mixtures of anhydrous lanthanum bromide and cerium chloride powders in sealed fused silica crucibles in vacuum. Their X - ray excited luminescent spectra, optical transmittance spectra, light yields, decay times and energy resolutions were measured at room temperature. The results show that the emission of 5%CeCl3doped crystal is peaked at 385 nm under X -ray excitation and its optical transmittance at the wavelength is about 70% besides, the crystal has 2.9% energy resolution and about 12 000 photoelectrons/MeV light yield under γ - ray excitation of Cs radioactive source, and its decay time is about 16.4 ns. LaBr3: CeCl3 crystal has more excellent scintillation properties and is very suitable for the radio - isotope identification device.