A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculatio...A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculation and validation of the response matrix, are presented. The PFNS for ^235U in the energy range 1–12 MeV, induced by thermal neutrons, was obtained. The measured spectrum in the low-energy region was in good agreement with previous work and the ENDF/B-VII library, except for minor differences. In the high-energy region, however, the relative height of the measured spectrum was greater, and an analysis of the experiment indicated uncertainties of 13% at 10 MeV and 24% at 12 MeV. Experimental results showed that the recoil proton method could be used to measure prompt fission neutron spectra. Some directions for future work are included.展开更多
The prompt fission neutron spectra for the neutron-induced fission of 235U at En 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model, in which the nonconstant and con- stant temperatures ...The prompt fission neutron spectra for the neutron-induced fission of 235U at En 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model, in which the nonconstant and con- stant temperatures related to the Fermi gas model are taken into account. The calculated prompt fission neutron spectra reproduce the experimental data well. For the n（thermal）＋235 U reaction, the average nuclear temperature of the fission fragment, and the probability distribution of the nuclear temperature, are discussed and compared with the Los Alamos model. The energy carried away by γ rays emitted from each fragment is also obtained and the results are in good agreement with the existing experimental data.展开更多
In this paper, a heuristic approach based on Slavic＇s peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this metho...In this paper, a heuristic approach based on Slavic＇s peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectrum, we find it is simple and effective enough to be used together with the Statistics-sensitive Nonlinear Iterative Peak-Clipping method.展开更多
We re-study the one-dimensional electric field structure of an outer gap accelerator by considering the physical limit of trans-field height. Inside the outer gap, the charge depletion creates a large electric field a...We re-study the one-dimensional electric field structure of an outer gap accelerator by considering the physical limit of trans-field height. Inside the outer gap, the charge depletion creates a large electric field along the magnetic field lines. Electrons and/or positrons are accelerated to ultra-relativistic energies by this longitudinal electric field, and then radiate γ-ray photons by curvature radiation. The collision of these γ-rays and ambient x-ray photons further produce radiating particles, resulting in a stationary gap. We solve the structure of this longitudinal electric field together with the distributions of electrons and positrons and γ-ray photons for an aligned rotator. Our results indicate that the outer gap can extend to the light cylinder using reasonable parameters.展开更多
在工业、环境和科学研究领域,元素分析的需求越来越大,而元素标准谱的准确性直接影响元素分析的准确性。本文研究了瞬发伽马中子活化分析(prompt gamma-ray neutron activation analysis,PGNAA)技术元素标准谱的构建,通过开发标准谱生成...在工业、环境和科学研究领域,元素分析的需求越来越大,而元素标准谱的准确性直接影响元素分析的准确性。本文研究了瞬发伽马中子活化分析(prompt gamma-ray neutron activation analysis,PGNAA)技术元素标准谱的构建,通过开发标准谱生成器(East China University of Technology Prompt Gamma-ray,ECUTPG),用于生成中子活化分析应用的标准谱。本文验证了LaBr3探测器与中子发生器一体机在元素分析载荷应用中,元素标准谱库的建立和实际效果,并通过解谱方法显示该元素标准谱库的可行性与准确性。展开更多
In this paper, the least square fitting method with the cubic B-spline basis lunctions is derived to reduce the influence of statistical fluctuations in the gamma ray spectra. The derived procedure is simple and autom...In this paper, the least square fitting method with the cubic B-spline basis lunctions is derived to reduce the influence of statistical fluctuations in the gamma ray spectra. The derived procedure is simple and automatic. The results show that this method is better than the convolution method with a sufficient reduction of statistical fluctuation.展开更多
基金supported by the National Natural Science Foundation of China(No.11775196)the Chinese Special Project for ITER(No.2015GB108006)
文摘A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculation and validation of the response matrix, are presented. The PFNS for ^235U in the energy range 1–12 MeV, induced by thermal neutrons, was obtained. The measured spectrum in the low-energy region was in good agreement with previous work and the ENDF/B-VII library, except for minor differences. In the high-energy region, however, the relative height of the measured spectrum was greater, and an analysis of the experiment indicated uncertainties of 13% at 10 MeV and 24% at 12 MeV. Experimental results showed that the recoil proton method could be used to measure prompt fission neutron spectra. Some directions for future work are included.
基金Supported by IAEA-CRP(15905)the State Key Laboratory of Nuclear Physics and Technology,Peking University(SKL-NPT)
文摘The prompt fission neutron spectra for the neutron-induced fission of 235U at En 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model, in which the nonconstant and con- stant temperatures related to the Fermi gas model are taken into account. The calculated prompt fission neutron spectra reproduce the experimental data well. For the n（thermal）＋235 U reaction, the average nuclear temperature of the fission fragment, and the probability distribution of the nuclear temperature, are discussed and compared with the Los Alamos model. The energy carried away by γ rays emitted from each fragment is also obtained and the results are in good agreement with the existing experimental data.
基金Supported by Science and Technology of Development Fund of Macao (042/2007/A3)
文摘In this paper, a heuristic approach based on Slavic＇s peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectrum, we find it is simple and effective enough to be used together with the Statistics-sensitive Nonlinear Iterative Peak-Clipping method.
基金Supported by the Hundred Talents Programme of Ghinese Academy of Sciences, and the National Natural Science Foundation of Ghina under Grant Nos 10425314 and 10463002.
文摘We re-study the one-dimensional electric field structure of an outer gap accelerator by considering the physical limit of trans-field height. Inside the outer gap, the charge depletion creates a large electric field along the magnetic field lines. Electrons and/or positrons are accelerated to ultra-relativistic energies by this longitudinal electric field, and then radiate γ-ray photons by curvature radiation. The collision of these γ-rays and ambient x-ray photons further produce radiating particles, resulting in a stationary gap. We solve the structure of this longitudinal electric field together with the distributions of electrons and positrons and γ-ray photons for an aligned rotator. Our results indicate that the outer gap can extend to the light cylinder using reasonable parameters.
文摘在工业、环境和科学研究领域,元素分析的需求越来越大,而元素标准谱的准确性直接影响元素分析的准确性。本文研究了瞬发伽马中子活化分析(prompt gamma-ray neutron activation analysis,PGNAA)技术元素标准谱的构建,通过开发标准谱生成器(East China University of Technology Prompt Gamma-ray,ECUTPG),用于生成中子活化分析应用的标准谱。本文验证了LaBr3探测器与中子发生器一体机在元素分析载荷应用中,元素标准谱库的建立和实际效果,并通过解谱方法显示该元素标准谱库的可行性与准确性。
基金Supported by Science and Technology of Development Fund of Macao (042/2007/A3)
文摘In this paper, the least square fitting method with the cubic B-spline basis lunctions is derived to reduce the influence of statistical fluctuations in the gamma ray spectra. The derived procedure is simple and automatic. The results show that this method is better than the convolution method with a sufficient reduction of statistical fluctuation.
