摘要
本文提出了基于碲锌镉(CZT)探测器的无准直器土壤含水率测量方案,利用蒙特卡罗方法模拟~(241)Am和~(137)Cs点源γ射线穿透土壤样品的过程,对比分析单源法和双源法,以及不同能量γ射线对含水率测量的异同。结果表明:模拟测量值与真实值的误差小于4%,本设计方案有效可行;γ射线透射法的含水率最小可分辨间隔(MDI)达到10~(-3)cm~3/cm~3,灵敏度高,具有实用、简单、无损、快速等特点。本文的结论可为小型便携化γ射线测水仪的研制提供理论参考。
This article designed a scheme of water content measurement by a CZT detector without collimators with the help of Monte Carlo method for simulating the interaction process of soil samples with gamma rays emitted by ~(241)Am and ~(137)Cs.According to the simulation results,we calculated the water content with two methods and analyzed the similarities or differences of them.The simulations revealed that the error between calculating values and real values was less than 3% which indicated that the scheme above was feasible.The gamma-ray transmission method was sensitive enough with a MDI of about 10~(-3) cm~3/cm~3 and had lots of advantages such as practical,inexpensive,non-destructive and fast analysis.These results can provide a proof for the development of a portable water-content measurement unit.
引文
[1]L.F.Pires,J.A.Ros,A.B.Pereira,et al.Gamma-ray attenuation method as an efficient tool to investigate soil bulk density spatial variability[J].Annals of Nuclear Energy,2009,36:1734-1739.
[2]P.Priyada,R.Ramar,Shivaramu.Determining the water content in concrete by gamma scattering method[J].Annals of Nuclear Energy,2014,63:565-570.
[3]常冬梅,郭红霞,林东生.双能γ射线穿透法测量土壤密度和水含量[J].核电子学与探测技术,1998,18(5):375-378.
[4]M.A.Abdel-Rahman,E.A.Badawi,Y.L.Abdel-Hady,et al.Effect of sample thickness on the measured mass attenuation coefficients of some compounds and elements for 59.54,661.6 and 1332.5 keV gamma-rays.Nucl.Instrum.Methods Phys.Res.A[J].2000,447:432-436.
[5]艾宪芸,魏义祥.室温半导体CdZnTe(CdTe)探测器性能综述[J].核电子学与探测技术,2004,24(3):325-328.
[6]吴明清,文启忠,潘景瑜,等.中国黄土的平均化学成分:上部大陆地壳的一种典型代表[J].岩相古地理,1995,15(2):127-136.
[7]艾宪芸.碲锌镉探测器性能分析及其γ谱解析方法研究[D].清华大学,2005.
[8]A.tin,D.Demir,Y.Sahin.Determination of density and volumetric water content of soil at multiple photon energies[J].Radiation Physics and Chemistry,2011,80:863-868.