To develop a NaI （T1） detector for in situ radioactivity monitoring in the marine environment and enhance the confidence of the probability of the gamma-spectrum analysis, Monte Carlo simulations using the Monte Car...To develop a NaI （T1） detector for in situ radioactivity monitoring in the marine environment and enhance the confidence of the probability of the gamma-spectrum analysis, Monte Carlo simulations using the Monte Carlo N-Particle （ MNCP ） code were performed to provide the response spectra of some interested radionuclides and the background spectra originating from the natural radionuclides in seawater recorded by a NaI （T1） detector. A newly developed 75 mm × 75 mm NaI （T1） detector was calibrated using four reference radioactive sources 137Cs, 60Co, 40K and 54Mn in the laboratory before the field measurements in seawater. A simulation model was established for the detector immersed in seawater. The simulated spectra were all broadened with Gaussian pulses to reflect the statistical fluctuations and electrical noise in the real measurement. The simulated spectra show that the single-energy photons into the detector are mostly scattering low-energy photons and the high background in the low energy region mainly originates from the Compton effect of the high energy y-rays of natural radionuclides in seawater. The simulated background spectrum was compared with the experimental one recorded in field measurement and they seem to be in good agreement. The simulation method and spectra can be used for the accurate analysis of the filed measurement results of low concentration radioactivity in seawater.展开更多
为实现阵列探测器的γ能谱合成,提出了基于拉格朗日线性插值原理的相邻道址插值法合成γ能谱。使用两个10.16 cm×10.16 cm×40.64 cm探测器组成的阵列进行了方法验证。实验结果表明,用该方法合成的γ能谱的662 ke V全能峰计数...为实现阵列探测器的γ能谱合成,提出了基于拉格朗日线性插值原理的相邻道址插值法合成γ能谱。使用两个10.16 cm×10.16 cm×40.64 cm探测器组成的阵列进行了方法验证。实验结果表明,用该方法合成的γ能谱的662 ke V全能峰计数相对合成前两个能谱的662 ke V全能峰计数之和偏差为-0.5%,合成能谱的FWHM@662 ke V大于2号探测器、小于1号探测器测得的能谱。展开更多
提出了通过γ能谱全能峰测量吸收剂量的方法,定义了全能峰角响应函数。采用蒙特卡罗方法计算了50 mm×50 mm NaI(Tl)探测器的平均角响应随射线能量的变化,用标准点源137Cs、60Co、152Eu、133Ba和参考辐射场137Cs、60Co、226Ra、241A...提出了通过γ能谱全能峰测量吸收剂量的方法,定义了全能峰角响应函数。采用蒙特卡罗方法计算了50 mm×50 mm NaI(Tl)探测器的平均角响应随射线能量的变化,用标准点源137Cs、60Co、152Eu、133Ba和参考辐射场137Cs、60Co、226Ra、241Am进行了实验验证。结果证明,在近似各向同性的条件下,对标准点源的测量结果与理论值相比误差小于2%,对参考辐射场的测量结果与电离室测量结果相差小于3%。该方法适合低能到高能的较宽能谱段剂量率测量,不仅能测出某种核素对总剂量率的贡献,且能同时分辨核素种类,无需实验刻度。展开更多
为准确地得到γ射线的辐射剂量,对G(E)函数法和Gravel算法处理能谱-剂量的转换效果进行了研究。根据实际应用需求,采取蒙特卡罗方法模拟获取了?50 mm×50 mm NaI(Tl)探测器的Gravel法响应矩阵,并使用Matlab得到探测器的G(E)函数。使...为准确地得到γ射线的辐射剂量,对G(E)函数法和Gravel算法处理能谱-剂量的转换效果进行了研究。根据实际应用需求,采取蒙特卡罗方法模拟获取了?50 mm×50 mm NaI(Tl)探测器的Gravel法响应矩阵,并使用Matlab得到探测器的G(E)函数。使用NaI(Tl)探测器和多道谱仪系统测量标准源的能谱,分别使用G(E)法和Gravel法计算剂量值并与理论值进行比较,同时在计算过程中总结对比了两种方法的特点。展开更多
基金financial support from the International Science & Technology Cooperation Program of China (No. 2013DFR90220)National Natural Science Foundation of China (No. 41206076)Qingdao Applied Basic Research Project (NO. 14-2-4-94-jch)
文摘To develop a NaI （T1） detector for in situ radioactivity monitoring in the marine environment and enhance the confidence of the probability of the gamma-spectrum analysis, Monte Carlo simulations using the Monte Carlo N-Particle （ MNCP ） code were performed to provide the response spectra of some interested radionuclides and the background spectra originating from the natural radionuclides in seawater recorded by a NaI （T1） detector. A newly developed 75 mm × 75 mm NaI （T1） detector was calibrated using four reference radioactive sources 137Cs, 60Co, 40K and 54Mn in the laboratory before the field measurements in seawater. A simulation model was established for the detector immersed in seawater. The simulated spectra were all broadened with Gaussian pulses to reflect the statistical fluctuations and electrical noise in the real measurement. The simulated spectra show that the single-energy photons into the detector are mostly scattering low-energy photons and the high background in the low energy region mainly originates from the Compton effect of the high energy y-rays of natural radionuclides in seawater. The simulated background spectrum was compared with the experimental one recorded in field measurement and they seem to be in good agreement. The simulation method and spectra can be used for the accurate analysis of the filed measurement results of low concentration radioactivity in seawater.
文摘为实现阵列探测器的γ能谱合成,提出了基于拉格朗日线性插值原理的相邻道址插值法合成γ能谱。使用两个10.16 cm×10.16 cm×40.64 cm探测器组成的阵列进行了方法验证。实验结果表明,用该方法合成的γ能谱的662 ke V全能峰计数相对合成前两个能谱的662 ke V全能峰计数之和偏差为-0.5%,合成能谱的FWHM@662 ke V大于2号探测器、小于1号探测器测得的能谱。
文摘提出了通过γ能谱全能峰测量吸收剂量的方法,定义了全能峰角响应函数。采用蒙特卡罗方法计算了50 mm×50 mm NaI(Tl)探测器的平均角响应随射线能量的变化,用标准点源137Cs、60Co、152Eu、133Ba和参考辐射场137Cs、60Co、226Ra、241Am进行了实验验证。结果证明,在近似各向同性的条件下,对标准点源的测量结果与理论值相比误差小于2%,对参考辐射场的测量结果与电离室测量结果相差小于3%。该方法适合低能到高能的较宽能谱段剂量率测量,不仅能测出某种核素对总剂量率的贡献,且能同时分辨核素种类,无需实验刻度。
文摘为准确地得到γ射线的辐射剂量,对G(E)函数法和Gravel算法处理能谱-剂量的转换效果进行了研究。根据实际应用需求,采取蒙特卡罗方法模拟获取了?50 mm×50 mm NaI(Tl)探测器的Gravel法响应矩阵,并使用Matlab得到探测器的G(E)函数。使用NaI(Tl)探测器和多道谱仪系统测量标准源的能谱,分别使用G(E)法和Gravel法计算剂量值并与理论值进行比较,同时在计算过程中总结对比了两种方法的特点。
文摘论文介绍一种多功能宽量程辐射探测系统的研制。该系统选用GM管与Na I(Tl)γ谱仪,通过嵌入式设计、实验标定、能谱剂量率转换、软件开发等工作实现系统的宽剂量率量程、双参数探测、自动温漂修正、无线数据传输和探测轨迹标定等功能。该系统可搭载无人旋翼机等设备进行远程探测,具有一定的辐射环境分析能力。实验表明该系统在0.01μGy/h^100 m Gy/h的辐射场内剂量率测量误差小于8%,上位机能在3 km距离获取作业路径、γ能谱和剂量率等探测信息。
