检查和选取闪烁法测氡仪的工作高压、阈值电压是保证仪器正常工作的重要环节，α检查源作为确定工作高压和阈值电压的有效工具，可简便、快速地测试测氡仪“高压坪曲线”和“甄别阈值曲线”。使用下关地震台原有和新配的239Pu标准固体α检查源，对新购置FD-125型室内氡钍分析器进行对比检查实验，结果表明：使用原示值为24 000脉冲/min的固体α检查源进行检查，误差≤ 5%的坪区为210 V，符合相应规范要求，确定工作高压为-663 V、阈值电压为2.0 V；用测值为860脉冲/min的固体α检查源进行检查，误差≤ 5%无坪区，误差≤ 10%的坪区为120 V，误差范围大，坪区不稳定，确定工作高压为-673 V、阈值电压为2.0 V。分析认为：固体α检查源的强度弱，检查结果不稳定，坪区窄、误差大，坪区特点表现不显著，选择239Pu固体α检查源时需充分考虑其强度对坪区长度的影响。
In order to ensure that the radon measuring instrument works normally, inspection and selection of the working high-voltage and the threshold voltage of the scintillation radon measurement instrument is an important work. The α-check-source is a kind of simple, quick and efficient instrument for measuring the high voltage plateau area curve, identifying threshold value curve and deriving the working high-voltage and the threshold voltage of the radon measurement instrument. The new FD-125 radon-thorium analyzer of Xiaguan Seismic Station is comparatively checked by use of the new 239Pu and the old stander solid α-check-source. The result shows that, for the old solid α-check-source with original value of 24 000 pulse/min, the plateau area of error of 5% or less is about 210 V, meeting the specifications(the plateau area not less than 200 V with the error of 5% or less), and working high-voltage reachs -663 V, the threshold voltage is 2.0 V, while for the new 239Pu solid α-check-source with measured value of 860 pulse/min, there is no plateau area within error of 5% or less to be found, and the plateau area within error of 10% or less is in only 120 V. It means that the error range is big and plateau area is not stable. The working high-voltage reaches -673 V with a deviation of 10 V, and the threshold voltage is 2.0 V. This result shows the strength of new solid α-check-source is weaker, its check result is unstable, and with larger error, its plateau area is narrower and no obvious characteristics. We concluded that to choose 239Pu solid α-check-source should be fully considered the influence of the length of the plateau area caused by the strength of source.
2018,39(2): 165-172 收稿日期：2017-05-24
DOI：10.3969/j.issn.1003-3246.2018.02.024
基金项目：地震行业科研专项（项目编号：201308006）
作者简介：李朝明(1971-),男,白族,云南大理市人,高级工程师,主要从事地震监测研究工作
参考文献：
段鸿杰, 唐岱茂, 曹为民. 测氡技术圈定采空区影响边界的应用[J]. 华北地质矿产杂志, 1999, 14 (1):71-76.
冯延强, 徐健, 王玮. 基于复合闪烁体实现 α、β 射线的高效探测[J]. 铀矿地质, 2015, 31 (3):408-412.
国家地震局. 地震水文地球化学观测技术规范[M]. 北京:地震出版社, 1985:5.
李朝明, 杨志坚, 金明培, 等. 下关 34 井气氡高值异常特征分析[J]. 地震地磁观测与研究, 2011, 32 (5):83-89.
李朝明, 杨志坚, 朱培耀, 等. KJD-2000R 测氡仪 (α 谱仪)观测结果分析[J]. 地震研究, 2012, 35 (3):399-405.
李金凤, 张兆山, 胡小华, 等. 闪烁室法现场水中氡浓度测量及其仪器功能开发[J]. 世界核地质科学, 2016, 33 (1):39-44.
李婷, 周训, 龙汩, 等. 射气-闪烁法测定地下热水的镭 -226 和氡 -222 浓度[J]. 地球科学与环境学报, 2014, 36 (4):127-133.
张昱, 刘小凤, 常千军, 等. 大震前水氡同步异常变化及其预测意义探讨[J]. 地震研究, 2010, 33 (3):253-258.
中国地震局. 地震水文地球化学观测技术规范[M]. 北京:地震出版社, 2014:3.
中国地震局监测预报司. 地震地下流体理论基础与观测技术[M]. 北京:地震出版社, 2007:23-130.
