低本底反康普顿HPGe　γ谱仪的调试

The Alignment of the Low-Background Anti-Compton HPGe Gamma-ray Spectrometer

本文报道的低本底反康普顿ＨＰＧｅγ谱仪．ＨＰＧｅ探测器对￣（６０）Ｃｏ的１３３２ｋｅｖγ射线的相对探测效率为３８．３％．能量分辨率为１．７７ｋｅＶ。在阱型反符合屏蔽下．对放在探测器端面的￣（１３７）Ｃｓ点状薄膜源的峰康比可达６８５．８：１；测量时间１００ｍｉｎ．置信度９５％时．￣（１３７）Ｃｓ点源的最小判断限为１．１２ｘ１Ｏ￣（－４）Ｂｑ。在物质屏蔽和阶型反符合屏蔽下，在５０～２１５２．８ｋｅＶ能区的积分本底为０．３４３ｓ￣（－１）。与无反符合屏蔽时相比，压缩系数大于４．５．对￣（１５２）Ｅｕ体源，谱仪积分非线性为０．０２７％。

This paper reports a set of anti-Compton gamma-ray spectrometer which uses HPGe asthe main detector and NaI(T1)as the anticoincidence shielded detector. The spectrometeradopts a steel-lead-steel construction as a main compound material shield. For 1332 keV gam-ma ray of￣(60)Co,the relative detection efficiency of HPGe detector is 38.3%,and the energyresolution is 1.77keV. Under the condition of the well-type anticoindence shield,the peak-to-Compton ratio for the thin film ￣(137)Cs point source on the top of HPGe detector can be as muchas 685.8.If the measuring time is 1000 minutes and the confidence level is 95%,the minimumdetectable level(detection limit)of the thin film ￣(137)Cs point source is 1.12x 10￣(-4) Bq.Under thecondition of material shield and well-type anticoincidence shield,the integral background of thisspectrometer is 0.343s￣(-1) in the energy range of 50 to 2152.8 keV. In comparison with thenonanticoincidence shield.its compression factor is greater than 4.5.For the ￣(152)Eu cylindricalbody source which is out on the top of HPGe detector,the integral non-linearity of the spec-trometer is 0.027% (