掺Sr^(2+)溴化铈晶体的生长与闪烁性能研究

Growth and Scintillation Properties of Sr^(2+)Doped CeBr_(3) Crystal

采用坩埚下降法生长了直径为25.4 mm的纯溴化铈晶体和0.1%、0.2%和0.5%(摩尔分数)Sr^(2+)掺杂的溴化铈晶体。将所生长晶体加工成直径25.4 mm、厚度10 mm的坯件,并进行紫外和X射线激发荧光光谱、137 Cs源激发多道能谱等测试。结果表明:Sr^(2+)掺杂会导致晶体X射线激发下的发射光谱出现轻微红移,而随着Sr^(2+)掺杂量的增加,晶体的能量分辨率依次提高,光输出依次降低;当Sr^(2+)掺杂量为0.5%时,溴化铈晶体的能量分辨率最高,达3.83%@662 keV,但过高含量的Sr^(2+)掺杂会造成晶体生长困难。综合考虑晶体性能和生长情况,Sr^(2+)掺杂量为0.2%时较为适宜,所获得的∅25.4 mm×25.4 mm CeBr_(3)∶0.2%Sr晶体封装件的能量分辨率为3.92%@662 keV。

25.4 mm diameter crystals of CeBr_(3)and three analogues doped with 0.1%,0.2%and 0.5%of Sr^(2+)in molar ratio were grown by the vertical Bridgman method.The grown crystals were processed into 25.4 mm diameter wafer with a thickness of 10 mm and characterized by fluorescence spectra excited by UV light and X-ray as well as multi-channel analysis with ^(137)Cs source.Results show that the emission bands of the crystals under X-ray excitation are slightly red-shifted by Sr^(2+)doping,and with the increase of Sr^(2+)doping content,the energy resolution of the crystals are successively improved,while the light yield are gradually reduced.The CeBr_(3)crystal doped with 0.5%Sr^(2+)exhibits the best energy resolution of 3.83%@662 keV.However,high Sr^(2+)doping also causes difficulty in crystal growth.A doping content of 0.2%is considered appropriate with regards to both scintillation property and crystal growth availability.An encapsulated CeBr_(3)∶0.2%Sr crystal with dimension of∅25.4 mm×25.4 mm is obtained and the energy resolution is 3.92%@662 keV.