低本底反康测量系统屏蔽体的设计研究
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摘要
目的根据天然辐射来源,设计一套低本底反康测量系统的屏蔽体。方法通过Geant4蒙卡程序建立探测器与屏蔽体模型,将主要的天然本底辐射作为源项输入到程序中,模拟优化低本底反康测量系统的屏蔽体的结构和尺寸,并通过实验测量对模拟结果进行了验证。结果确定了由外到内依次为10 cm铅、8 cm含硼聚乙烯、2 cm铅和1 mm无氧铜内衬的屏蔽结构,各屏蔽层实验测量和模拟结果较为符合,规律体现出一致性,测量得到的50～2 000 ke V能量范围内的积分本底计数率为1. 72 cps。结论优化设计了低本底反康测量系统屏蔽层的结构和尺寸,并通过增加含硼聚乙烯夹层来降低热中子和快中子所致本底,实验测量结果验证了设计方案的合理性和可行性。
Objective According to the natural radiation sources,a set of shielding for the low-background anti-compton measurement system is designed. Methods The model of detector and shield is established by Geant 4 Monte Carlo program.The main natural background radiation is input into the program as the source term. The structure and size of shield for the low-background anti-compton measurement system were simulated and optimized. The simulation results were verified by experimental measurements. Results The shielding structures of 10 cm lead,8 cm boron-containing polyethylene,2 cm lead,and 1 mm oxygen-free copper lining from outside to inside were determed. The experimental results are in good agreement with the simulation results,and the laws reflect consistency. The integrated background counting rates in the measured energy range of 50 ～ 2000 ke V was 1. 72 cps. Conclusion The structure and size of shielding layer of the low background anti-compton measurement system are optimized,and by adding boron-containing polyethylene interlayer to reduce the background count rates caused by thermal neutrons and fast neutrons. The experimental results verified the rationality and feasibility of the design scheme.
Objective According to the natural radiation sources,a set of shielding for the low-background anti-compton measurement system is designed. Methods The model of detector and shield is established by Geant 4 Monte Carlo program.The main natural background radiation is input into the program as the source term. The structure and size of shield for the low-background anti-compton measurement system were simulated and optimized. The simulation results were verified by experimental measurements. Results The shielding structures of 10 cm lead,8 cm boron-containing polyethylene,2 cm lead,and 1 mm oxygen-free copper lining from outside to inside were determed. The experimental results are in good agreement with the simulation results,and the laws reflect consistency. The integrated background counting rates in the measured energy range of 50 ～ 2000 ke V was 1. 72 cps. Conclusion The structure and size of shielding layer of the low background anti-compton measurement system are optimized,and by adding boron-containing polyethylene interlayer to reduce the background count rates caused by thermal neutrons and fast neutrons. The experimental results verified the rationality and feasibility of the design scheme.
引文
[1]张智勇,周春林,雷俊牛,等.一套低本底反康普顿HPGeγ谱仪系统积分本底的回顾研究//第九届全国信息获取与处理学术会议论文集.丹东:2011.2011,32(6):121-124.
[2]H.M.Badran,T.Sharshar.An experimental method for the optimization of anti-Compton spectrometer[J],Nuclear Instruments and Methods in Physics Research A,1999,435(3):423-432.
[3]R.Britton,J.L.Burnett,A.V.Davies,et al.Monte-Carlo optimisation of a Compton suppression system for use with a broadenergy HPGe detector[J].Nuclear Instruments and Methods in Physics Research A,2014,762:42-53.
[4]李蓉.天然本底外照射研究动态[J].中国辐射卫生,1998,7(4):253-255.
[5]侯铁栋,管永精,刁立军,等.反宇宙射线低本底γ谱仪本底来源及降低方法研究[D].南宁:广西大学,2010.
[6]郑国文,陈凌.宇宙射线剂量率随海拔变化规律研究[J].中国辐射卫生,2017,26(2):142-144.
[7]D.K.Haines,T.M.Semkow,et al.Muon and neutron-induced background in gamma-ray spectrometry[J],Nuclear Instruments and Methods in Physics Research A,2011,652(1):326-329.
[8]刁立军,侯铁栋,李玮,等.用反符合和热中子屏蔽降低γ谱仪本底[J].核技术,2010,33(7):501-505.
[9]丁雄,孙新利,李振,等.不同材料中子反射与屏蔽效应研究[J].核技术,2017,40(3):030201-1-030201-5.
[10]潘翔,林志凯,潘俊峰.5%含硼聚乙烯屏蔽快中子的实验与分析[J].中国辐射卫生,2013,22(4):396-397,400.
[11]S.Agostinelli,et,al.Geant4-a simulation toolkit[J].Nuclear Instruments and Methods in Physics Research A,2003,506:250-303.
[12]H M Portella LC Deoliveira,CE Lima,et al.A new approach to derive atmospheric muon fluxes[J].J.Phys.G:Nucl.Part.Phys,2002,28:415-425.
[13]Hess W N,Patterson H W,Wallace et al.Cosmic-ray neutron Energy spectrum.Physical Review,1959,116(2):445-457.
[14]A.Nachab,Ph.Hubert.210Pb activity by detection of bremsstrahlung in 210Biβ-decay[J].Nuclear Instruments and Methods in Physics Research B,2012,274:188-190.
[15]T.Schroettner,M.Schwaiger,P.Kindl.Optimization of an active anti cosmic veto shielding[J].Applied Radiation and Isotopes,2004,61(2/3):133-138.
[2]H.M.Badran,T.Sharshar.An experimental method for the optimization of anti-Compton spectrometer[J],Nuclear Instruments and Methods in Physics Research A,1999,435(3):423-432.
[3]R.Britton,J.L.Burnett,A.V.Davies,et al.Monte-Carlo optimisation of a Compton suppression system for use with a broadenergy HPGe detector[J].Nuclear Instruments and Methods in Physics Research A,2014,762:42-53.
[4]李蓉.天然本底外照射研究动态[J].中国辐射卫生,1998,7(4):253-255.
[5]侯铁栋,管永精,刁立军,等.反宇宙射线低本底γ谱仪本底来源及降低方法研究[D].南宁:广西大学,2010.
[6]郑国文,陈凌.宇宙射线剂量率随海拔变化规律研究[J].中国辐射卫生,2017,26(2):142-144.
[7]D.K.Haines,T.M.Semkow,et al.Muon and neutron-induced background in gamma-ray spectrometry[J],Nuclear Instruments and Methods in Physics Research A,2011,652(1):326-329.
[8]刁立军,侯铁栋,李玮,等.用反符合和热中子屏蔽降低γ谱仪本底[J].核技术,2010,33(7):501-505.
[9]丁雄,孙新利,李振,等.不同材料中子反射与屏蔽效应研究[J].核技术,2017,40(3):030201-1-030201-5.
[10]潘翔,林志凯,潘俊峰.5%含硼聚乙烯屏蔽快中子的实验与分析[J].中国辐射卫生,2013,22(4):396-397,400.
[11]S.Agostinelli,et,al.Geant4-a simulation toolkit[J].Nuclear Instruments and Methods in Physics Research A,2003,506:250-303.
[12]H M Portella LC Deoliveira,CE Lima,et al.A new approach to derive atmospheric muon fluxes[J].J.Phys.G:Nucl.Part.Phys,2002,28:415-425.
[13]Hess W N,Patterson H W,Wallace et al.Cosmic-ray neutron Energy spectrum.Physical Review,1959,116(2):445-457.
[14]A.Nachab,Ph.Hubert.210Pb activity by detection of bremsstrahlung in 210Biβ-decay[J].Nuclear Instruments and Methods in Physics Research B,2012,274:188-190.
[15]T.Schroettner,M.Schwaiger,P.Kindl.Optimization of an active anti cosmic veto shielding[J].Applied Radiation and Isotopes,2004,61(2/3):133-138.