反宇宙射线γ谱仪系统测量氙同位素活度

Activity Measurement of Xenon Isotope by Anti-cosmic Ray γ Spectrometer

放射性氙同位素是全面禁止核试验条约(CTBT)重要的监测内容。针对CTBT氙同位素样品活度低的特点,建立了一套反宇宙射线γ谱仪系统。相对于原始γ能谱,在20~2 400keV能量范围内,采用反宇宙射线屏蔽后,全谱积分本底降低了约6倍。使用反宇宙射线HPGeγ谱仪系统对氙同位素样品测量3d,^(131) Xe^m、^(133) Xe^m、^(133) Xe和^(135) Xe的最小可探测活度分别为3.2、4.3、2.8、6.1mBq,达到了全面禁止核试验条约对核素实验室核准认证的技术要求。

Radioxenon isotopes are important monitoring components of comprehensive nuclear-test-ban treaty （CTBT）. An anti-cosmic ray γ spectrometer was set up for measuring low-level active xenon isotope sample in CTBT verification regime. Compared with the original γ spectrum, the suppression factor of integrated background is about 6 times in the energy range of 20-2 400 keV. Within 3 days measurement by anti-cosmic HPGe γ spectrometer, the minimum detectable activities of ^131Xe^m, ^133Xe^m, ^133Xe and ^135Xe are 3.2, 4.3, 2.8 and 6.1 mBq respectively, which satisfies the requirements of CTBT.