低本底内充气正比计数管测量~(37)Ar活度
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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.
~(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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[5] AALSETH C E, DAY A R, HAAS D A, et al. Measurement of 37Ar to support technology for on-site inspection under the Comprehensive Nuclear-Test-Ban Treaty[J]. Nuclear Instruments and Methods in Physics Research A, 2011, 652: 58-61.
[6] AALSETH C E, HUMBLE P H, MACE E K, et al. Shielding concepts for low-background proportional counter arrays in surface laboratories[J]. Applied Radiation and Isotopes, 2016, 108: 92-99.
[7] AALSETH C E, DAY A R, FULLER E S, et al. A new shallow underground gas-proportional counting lab: First results and 37Ar sensitivity[J]. Applied Radiation and Isotopes, 2013, 81: 151-155.
[8] LOOSILI H H, MARTIN M, HANS O. Low-level gas proportional counting in an underground laboratory[J]. Radiocarbon, 1980, 22(2): 461-469.
[9] 向永春,龚建,李伟,等. 气体正比计数管测量37Ar的效率研究[J]. 核技术,2007,30(10):828-832. XIANG Yongchun, GONG Jian, LI Wei, et al. Efficiency of gas proportional counter for 37Ar[J]. Nuclear Techniques, 2007, 30(10): 828-832(in Chinese).
[10] WILLIAMS R M, AALSETH C E, BOWYER T W, et al. Development of a low-level 37Ar calibration standard[J]. Applied Radiation and Isotopes, 2016, 109: 430-434.
[2] CARRIGAN C, HEINLE R, HUDSON G, et al. Trace gas emissions on geological faults as indicators of underground nuclear testing[J]. Nature, 1996, 382: 528-531.
[3] BARSANOV V I, DZHANELIDZE A A, ZLOKAZOV S B, et al. Artificial neutrino source based on the 37Ar isotope[J]. Physics of Atomic Nuclei, 2007, 70(2): 300-310.
[4] 向永春,龚建,李伟,等. 37Ar测量系统的研制与能谱测量方法研究[J]. 物理学报,2008,57(2):784-789. XIANG Yongchun, GONG Jian, LI Wei, et al. Development of a system of measuring 37Ar spectrum method[J]. Acta Physica Sinica, 2008, 57(2): 784-789(in Chinese).
[5] AALSETH C E, DAY A R, HAAS D A, et al. Measurement of 37Ar to support technology for on-site inspection under the Comprehensive Nuclear-Test-Ban Treaty[J]. Nuclear Instruments and Methods in Physics Research A, 2011, 652: 58-61.
[6] AALSETH C E, HUMBLE P H, MACE E K, et al. Shielding concepts for low-background proportional counter arrays in surface laboratories[J]. Applied Radiation and Isotopes, 2016, 108: 92-99.
[7] AALSETH C E, DAY A R, FULLER E S, et al. A new shallow underground gas-proportional counting lab: First results and 37Ar sensitivity[J]. Applied Radiation and Isotopes, 2013, 81: 151-155.
[8] LOOSILI H H, MARTIN M, HANS O. Low-level gas proportional counting in an underground laboratory[J]. Radiocarbon, 1980, 22(2): 461-469.
[9] 向永春,龚建,李伟,等. 气体正比计数管测量37Ar的效率研究[J]. 核技术,2007,30(10):828-832. XIANG Yongchun, GONG Jian, LI Wei, et al. Efficiency of gas proportional counter for 37Ar[J]. Nuclear Techniques, 2007, 30(10): 828-832(in Chinese).
[10] WILLIAMS R M, AALSETH C E, BOWYER T W, et al. Development of a low-level 37Ar calibration standard[J]. Applied Radiation and Isotopes, 2016, 109: 430-434.