一台反康普顿HPGeγ谱仪的性能改造和应用  

Improvement and application of an anti-compton HPGe γ-spectrometer

作　　者：张佳媚[1] 常永福[1] 师全林[1] 王中录[1] 钱绍钧[1] 

机构地区：[1]西北核技术研究所

出　　处：《核电子学与探测技术》2004年第2期172-176,158,共6页Nuclear Electronics & Detection Technology

摘　　要：主要描述了一台反康普顿HPGeγ谱仪系统改造前后的结构和性能。由于原有系统的积分本底偏高,在对它进行性能测试、本底来源分析之后,采取了改造屏蔽室,更换低本底主探测器等措施。通过细致的调试,测试了主要性能指标。积分本底(能区50～2000keV)由原67min-1(主探测器相对探测效率为40%)降至约20min-1(主探测器相对探测效率为50%)。标定了滤材样品的探测效率曲线,计算了大气气溶胶取样样品中140Ba核素的最低可探测浓度(MDC)。在大气中212Pb浓度约0.3Bq/m3时,140Ba的MDC可达10μBq/m3。The structure and performance of an anti-Compton HPGe gamma-spectrometer before and after reconstruction are described. As the background of old system is somewhat high (about 67cpm, when the relative efficiency of HPGe main detector is about 40%), the source components have been studied after examining the system. The shield has been reconstructed by adding lead and the main detector has been replaced by a low background one. Some other measures have been taken also. Through careful adjustment, the performance of the new system has been measured. Now the integral background (50～2000keV) is about 20cpm (the relative efficiency of HPGe main detector is about 50%). The ratio of peak to Compton of ^(137)Cs with Compton suppression is about 900. The efficiency curve for filter samples is determined. The MDC of ^(140)Ba in the air is calculated as a function of the concentration of ^(212)Pb. The MDC is below 10μBq/m^3 when the concentration of ^(212)Pb in the air is below 0.3 Bq/m^3.

关 键 词：反康普顿HPGEΓ谱仪 性能改造 积分本底 光电倍增管 屏蔽室 

分 类 号：TL817.2[核科学技术—核技术及应用]