HPGe探测器对圆形面源探测效率的研究
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摘要
实验刻度了GEM60P4型高纯锗(High Purity Germanium,HPGe)探测器在H=250mm处对三种圆形面源(φ24 mm、φ80 mm和φ90 mm)的峰探测效率,结果表明,这三种源的效率基本一致。采用MCNP模拟了φ40–160mm内的圆形面源效率,研究了探测效率随样品直径的变化关系,并采用Geant4计算了圆形面源对同轴探测器的有效立体角。对φ90mm以上的样品源,探测效率随源直径的增大在逐渐减小,且高能γ射线效率减小程度较快,需采用标准源进行效率刻度。
Background: Calibrating the detection efficiency accurately is the key process to the disc filter sample activity detected by High Purity Germanium(HPGe) gamma spectrometer, and the diameter of the disc filter source is varied with the specification of the sampler filter. Purpose: To study further the relation between detection efficiency and the source size, the HPGe detector peak efficiency(relative detective efficiency is 60%) was performed for disc sources with diameters of 24 mm, 80 mm and 90 mm, respectively. Methods: The efficiency and the solid angle for disc source with diameter ranging 40–160 mm were simulated using the MCNP and the Geant4. Results: The result shows that the detecting efficiency of three sources is consistent, and the efficiency gradually decreases with the increasing size of the disc source with diameter greater than 90 mm. Conclusion: The efficiency for disc sources with diameter less than 90 mm is directly calibrated by the standard point sources, while for disc sources with diameter larger than 90 mm which is needed to be calibrated by the standard disc sources.
Background: Calibrating the detection efficiency accurately is the key process to the disc filter sample activity detected by High Purity Germanium(HPGe) gamma spectrometer, and the diameter of the disc filter source is varied with the specification of the sampler filter. Purpose: To study further the relation between detection efficiency and the source size, the HPGe detector peak efficiency(relative detective efficiency is 60%) was performed for disc sources with diameters of 24 mm, 80 mm and 90 mm, respectively. Methods: The efficiency and the solid angle for disc source with diameter ranging 40–160 mm were simulated using the MCNP and the Geant4. Results: The result shows that the detecting efficiency of three sources is consistent, and the efficiency gradually decreases with the increasing size of the disc source with diameter greater than 90 mm. Conclusion: The efficiency for disc sources with diameter less than 90 mm is directly calibrated by the standard point sources, while for disc sources with diameter larger than 90 mm which is needed to be calibrated by the standard disc sources.
引文
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2 张佳媚,师全林,包敏,等.气溶胶滤材样品γ探测效率与测量源尺寸的关系[J].核电子学与探测技术,2003,23 (3):212–216ZHANG Jiamei,SHI Quanlin,BAO Min,et al.Relation between γ-ray detection efficiency and the source size of prepared aerosol filter sample[J].Nuclear Electronics&Detection Technology,2003,23(3):212–216
3 Firestone R B.Table of isotope CD-ROM[R].Eighth Ed,Version 1.0.Lawrence Berkeley National Laboratory,University of California,1996:5755–5757
4 朱传新,陈渊,郭海萍,等.高纯锗探测器探测效率研究[J].核电子学与探测技术,2006,26(2):191–194ZHU Chuanxin,CHEN Yuan,GUO Haiping,et al.The detecting efficiency of HPGe detector[J].Nuclear Electronics&Detection Technology,2006,26(2):191 –194
5 张建芳.高纯锗探测器探测效率的MCNP模拟[D].长春:吉林大学,2009ZHANG Jianfang.The MCNP simulation of HPGe detector efficiency[D].Changchun:Jilin University,2009
6 张新军,王世联,王军,等.大气颗粒物滤材样品探测效率的模拟计算[J].原子能科学技术,2008,42(增刊):303 –306ZHANG Xinjun,WANG Shilian,WANG Jun,et al.Efficiency simulation of atmospheric particle filter sample[J].Atomic Energy Science and Technology,2008,42 (Suppl):303–306
7 刘宗良,周剑良.圆面探测器对圆面源几何因子的蒙特卡罗计算[J].科技咨询,2008,6(6):251–254LIU Zongliang,ZHOU Jianliang.Calculation of geometry efficiency of disc source to disc detector by Monte Carlo method[J].Science and Technology Information,2008,6 (6):251–254
8 魏信苗,吴治华.圆盘探测器几何因子的一种计算方法[J].核技术,1991,14(1):48–53WEI Xinmiao,WU Zhihua.A new and simple method of calculation geometric factor of disc detector[J].Nuclear Techniques,1991,14(1):48–53
9 张艳丽.用小立体角法测定α放射性样品质量[J].沈阳师范大学学报(自然科学版),2005,23(2):155–157ZHANG Yanli.Determine α radioactive sample quality with small solid angle law[J].Journal of Shenyang Normal University(Natural Science),2005,23(2):155 –157
10 王俊阳.低本底高纯锗探测器探测效率及其屏蔽系统的GEANT4模拟[D].郑州:河南师范大学,2011WANG Junyang.Low background High Purity Germanium detector detection efficiency and its shielding system of GEANT4 simulation[D].Zhengzhou:Henan Normal University,2011