摘要
~(37)Ar是全面禁止核试验条约现场视察重要监测核素之一,高灵敏地探测~(37)Ar活度是地下核试验监测的关键环节。本文研究建立了低本底内充气正比计数管~(37)Ar活度测量装置,在铅屏蔽室上、下各装配1个塑料闪烁体探测器,主动屏蔽宇宙射线在计数管中产生的本底。相对于原始能谱,反宇宙射线能谱中~(37)Ar峰区本底计数率降至原来的7.3%,测量24 h,~(37)Ar的最小可探测活度达2.5 mBq。
~(37)Ar is one of the important radionuclides for on-site inspection compliance with Comprehensive Nuclear-Test-Ban Treaty. High sensitive detection of ~(37)Ar is a key step for underground nuclear test monitoring. A low background internal gas proportional counter system was established in Beijing Radionuclide Laboratory. The background of proportional counter caused by cosmic-ray was actively shielded by plastic scintillator detectors which were equipped on the top and the bottom of the lead shielding. The background count rate of ~(37)Ar peak region in anti-cosmic spectrum was reduced to 7.3% of which in the original spectrum. Within 24 h measurement, the minimum detectable activity of ~(37)Ar of 2.5 mBq was achieved.
引文
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