A Levenberg–Marquardt Gaussian fitting algorithm has been used for analyzing the overlap of three peaks(the 583-ke V peak of^(208)Tl, the 609-ke V peak of214 Bi, and the 662-ke V peak of^(137)Cs) using an in situ Na ...A Levenberg–Marquardt Gaussian fitting algorithm has been used for analyzing the overlap of three peaks(the 583-ke V peak of^(208)Tl, the 609-ke V peak of214 Bi, and the 662-ke V peak of^(137)Cs) using an in situ Na I(Tl) scintillation spectrometer. The algorithm, in addition,was compared with a genetic algorithm used for multiple deconvolution. The three fitted peak areas(583, 609, and662 ke V) were calculated from the measured gamma-ray spectra obtained from a simulation experiment in which a^(137) Cs source was buried at different soil depths(from 18 to38 cm). The application of the Levenberg–Marquardt algorithm yielded similar results compared to the genetic algorithm. A lack-of-fit test showed that the fitting is good when the instrumental noise levels were estimated from replicated analyses. The relative fitting error of the total net area and the residual standard deviation were within 5 %and 0.04, respectively, and the goodness of the fitting was better than 0.98. While the methods used in this paper give high performance, the results may lead to incorrect estimation when the signal-to-noise ratio is smaller than-30 d B. This study is useful for the determination of radioactive specific activity of^(137) Cs by in situ spectrometry.展开更多
NaI(T1) scintillation detectors have been widely applied for gamma-ray spectrum measurements owing to advantages such as high detection efficiency and low price.However,the mitigation of the limited energy resolution ...NaI(T1) scintillation detectors have been widely applied for gamma-ray spectrum measurements owing to advantages such as high detection efficiency and low price.However,the mitigation of the limited energy resolution of these detectors,which detracts from an accurate analysis of the instrument spectra obtained,remains a crucial need.Based on the physical properties and spectrum formation processes of NaI(T1) scintillation detectors,the detector response to gamma photons with different energies is represented by photopeaks that are approximately Gaussian in shape with unique full-width-at-half-maximum(FWHM) values.The FWHM is established as a detector parameter based on resolution calibrations and is used in the construction of a general Gaussian response matrix,which is employed for the inverse decomposition of gamma spectra obtained from the detector.The Gold and Boosted Gold iterative algorithms are employed to accelerate the decomposition of the measured spectrum.Tests of the inverse decomposition method on multiple simulated overlapping peaks and on experimentally obtained U and Th radionuclide series spectra verify the practicability of the method,particularly in the low-energy region of the spectrum,providing for the accurate qualitative and quantitative analysis of radionuclides.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
基金supported by the National Natural Science Foundation of China(No.41474107)
文摘A Levenberg–Marquardt Gaussian fitting algorithm has been used for analyzing the overlap of three peaks(the 583-ke V peak of^(208)Tl, the 609-ke V peak of214 Bi, and the 662-ke V peak of^(137)Cs) using an in situ Na I(Tl) scintillation spectrometer. The algorithm, in addition,was compared with a genetic algorithm used for multiple deconvolution. The three fitted peak areas(583, 609, and662 ke V) were calculated from the measured gamma-ray spectra obtained from a simulation experiment in which a^(137) Cs source was buried at different soil depths(from 18 to38 cm). The application of the Levenberg–Marquardt algorithm yielded similar results compared to the genetic algorithm. A lack-of-fit test showed that the fitting is good when the instrumental noise levels were estimated from replicated analyses. The relative fitting error of the total net area and the residual standard deviation were within 5 %and 0.04, respectively, and the goodness of the fitting was better than 0.98. While the methods used in this paper give high performance, the results may lead to incorrect estimation when the signal-to-noise ratio is smaller than-30 d B. This study is useful for the determination of radioactive specific activity of^(137) Cs by in situ spectrometry.
基金supported by the National Natural Science Foundation of China(Grant No.11365001)National Major Scientific Equipment Development Projects(Grant No.041514065)+2 种基金the Educational Commission of Jiangxi Province of China(Grant No.GJJ13464)Plan of Science and Technology of Jiangxi Province(Grant No.20141BBE50024)the Fundamental Science on Radioactive Geology and Exploration Technology Laboratory,East China Institute of Technology(Grant No.RGET1316)
文摘NaI(T1) scintillation detectors have been widely applied for gamma-ray spectrum measurements owing to advantages such as high detection efficiency and low price.However,the mitigation of the limited energy resolution of these detectors,which detracts from an accurate analysis of the instrument spectra obtained,remains a crucial need.Based on the physical properties and spectrum formation processes of NaI(T1) scintillation detectors,the detector response to gamma photons with different energies is represented by photopeaks that are approximately Gaussian in shape with unique full-width-at-half-maximum(FWHM) values.The FWHM is established as a detector parameter based on resolution calibrations and is used in the construction of a general Gaussian response matrix,which is employed for the inverse decomposition of gamma spectra obtained from the detector.The Gold and Boosted Gold iterative algorithms are employed to accelerate the decomposition of the measured spectrum.Tests of the inverse decomposition method on multiple simulated overlapping peaks and on experimentally obtained U and Th radionuclide series spectra verify the practicability of the method,particularly in the low-energy region of the spectrum,providing for the accurate qualitative and quantitative analysis of radionuclides.
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。
