Iron is commonly used as a structural and shielding material in nuclear devices. The accuracy of its nuclear data is critical for the design of nuclear devices. The evaluation data of ^(56)Fe isotopes in the latest ve...Iron is commonly used as a structural and shielding material in nuclear devices. The accuracy of its nuclear data is critical for the design of nuclear devices. The evaluation data of ^(56)Fe isotopes in the latest version of the CENDL-3.2 library from China was significantly updated. This new data must be tested before it can be used. To test the reliability of this data and assess the shielding effect, a shielding benchmark experiment was conducted with natural Fe spherical samples using a pulsed deuterium–tritium neutron source at the China Institute of Atomic Energy(CIAE). The leakage neutron spectra from the natural spherical iron samples with different thicknesses(4.5, 7.5, and 12 cm) were measured between 0.8 and 16 MeV after interacting with 14 MeV neutrons using the time-of-flight method. The simulation results were obtained by Monte Carlo simulations by employing the Fe data from the CENDL-3.2, ENDF/B-VIII.0, and JEDNL-5.0 libraries. The measured and simulated leakage neutron spectra and penetration rates were compared, demonstrating that the CENDL-3.2 library performs sufficiently overall. The simulation results of the other two libraries were underestimated for scattering at the continuum energy level.展开更多
The 14 MeV neutrons produced in the D-T fusion reactions have the potential of breeding Uranium-233 fissile fuel from fertile material Thorium-232. In order to estimate the amount of U-233 produced, experiments are ca...The 14 MeV neutrons produced in the D-T fusion reactions have the potential of breeding Uranium-233 fissile fuel from fertile material Thorium-232. In order to estimate the amount of U-233 produced, experiments are carried out by irradiating thorium dioxide pellets with neutrons produced from a 14 MeV neutron generator. The objective of the present work is to measure the reaction rates of 232Th ＋ in --＊ 233Th --＊ 2a^Pa --＊ 2a3U in different pellet thicknesses to study the self-shielding effects and adopt a procedure for correction. An appropriate assembly consisting of high-density polyethylene is designed and fabricated to slow down the high-energy neutrons, in which Thorium pellets are irradiated. The amount of fissile fuel （~3~U） produced is estimated by measuring the 312 keV gammas emitted by Protactinium-233 （half-life of 27 days）. A calibrated High Purity Germanium （HPGe） detector is used to measure the gamma ray spectrum. The amount of 233U produced by Th232 （n, ~） is calculated using MCNP code. The self-shielding effect is evaluated by calculating the reaction rates for different foil thickness. MCNP calculation results are compared with the experimental values and appropriate correction factors are estimated for self-shielding of neutrons and absorption of gamma rays.展开更多
Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(1...Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(149)Nd,^(148)Nd(n,2n)^(147)Nd, and ^(142)Nd(n,2 n)^(141)Nd reactions were 1854 ± 81, 1789 ± 119, and 1559 ± 98 mb, respectively, at a neutron energy of 14.2 ± 0.2 MeV,and 1485 ± 74, 1726 ± 85, and 1670 ± 119 mb, respectively, at 14.9 ± 0.2 MeV. The results were compared with the experimental values from the reported literature, with the evaluated data from the ENDF/B-VII.1, CENDL-3.1, and JENDL-4.0 libraries, and with the curves calculated by the Talys-1.8 code.展开更多
A new concept of neutron detector based on Gas Electron Multiplier(GEM) technology is presented in this paper,in which a novel multi-layer high density polyethylene(HDPE) as neutron-to-proton converter is proposed and...A new concept of neutron detector based on Gas Electron Multiplier(GEM) technology is presented in this paper,in which a novel multi-layer high density polyethylene(HDPE) as neutron-to-proton converter is proposed and studied with Geant4 toolkit for fast 14 MeV neutron.Our preliminary results show that the detection efficiency of the detector with 400 converter units is higher than 2.3% and reconstruction accuracy of the incident neutron position is higher than 2.6%.展开更多
The cross sections for the 94Zr(n,d*)93m+gY,96Zr(n,γ)97Z,96Zr(n,2n)95Zr,90Zr(n,α)87mSr,94Zr(n,α)91Sr,90Zr(n,p)90mY,92Zr(n,p)92Y,and 94Zr(n,p)94Y reactions have been measured in the neutron energy range of 13.5-14.8...The cross sections for the 94Zr(n,d*)93m+gY,96Zr(n,γ)97Z,96Zr(n,2n)95Zr,90Zr(n,α)87mSr,94Zr(n,α)91Sr,90Zr(n,p)90mY,92Zr(n,p)92Y,and 94Zr(n,p)94Y reactions have been measured in the neutron energy range of 13.5-14.8 MeV by means of the activation technique.The neutrons were produced via the D-T reaction.A high-purity germanium detector with high energy resolution was used to measure the inducedγactivities.In combination with the nuclear reaction theoretical models,the excitation curves of the above-mentioned eight nuclear reactions within the incident neutron energy range from the threshold to 20 MeV were obtained by adopting the nuclear theoretical model program system Talys-1.9.The resulting experimental cross sections were analyzed and compared with the experimental data from published studies.Calculations were performed using Talys-1.9 and are in agreement with our experimental results,previous experimental values,as well as results of the theoretical excitation curves at the corresponding energies.The theoretical excitation curves generally match the experimental data well.展开更多
The thick target neutron yields （TTNYs） of deuteron-induced reaction on AI and Cu isotopes are analyzed by combining the improved nuclear models and particle transport effects. The modified Glauber model is employed...The thick target neutron yields （TTNYs） of deuteron-induced reaction on AI and Cu isotopes are analyzed by combining the improved nuclear models and particle transport effects. The modified Glauber model is employed mainly to produce the peak of double differential cross section for the breakup process, and the exciton model and the Hauser-Feshbach theory are used for the statistical processes. The thin-layer accumulation method is used to calculate the TTNYs considering the neutron attenuation effects in the target. The calculated results are compared with the existing experimental data, and the analysis method can predict the TTNY data well at the deuteron energy of 40 MeV.展开更多
Measurement of the neutron yield is performed at a primary energy of 400 MeV/u carbons for the Pb target.Water-bath activation-foil method is used in a moderation measurement with Au foils to detect the moderated neut...Measurement of the neutron yield is performed at a primary energy of 400 MeV/u carbons for the Pb target.Water-bath activation-foil method is used in a moderation measurement with Au foils to detect the moderated neutrons. The neutron yield is determined to be 18.4±2.1 per carbon by integrating the neutron flux over the entire water volume. The corresponding simulation values are performed by Geant4 code with three models to compare with the experimental results. The comparison shows that the calculated result with the INCL model is in good agreement with the experimental data.展开更多
基金supported by the National Natural Science Foundation of China (No. 11775311)。
文摘Iron is commonly used as a structural and shielding material in nuclear devices. The accuracy of its nuclear data is critical for the design of nuclear devices. The evaluation data of ^(56)Fe isotopes in the latest version of the CENDL-3.2 library from China was significantly updated. This new data must be tested before it can be used. To test the reliability of this data and assess the shielding effect, a shielding benchmark experiment was conducted with natural Fe spherical samples using a pulsed deuterium–tritium neutron source at the China Institute of Atomic Energy(CIAE). The leakage neutron spectra from the natural spherical iron samples with different thicknesses(4.5, 7.5, and 12 cm) were measured between 0.8 and 16 MeV after interacting with 14 MeV neutrons using the time-of-flight method. The simulation results were obtained by Monte Carlo simulations by employing the Fe data from the CENDL-3.2, ENDF/B-VIII.0, and JEDNL-5.0 libraries. The measured and simulated leakage neutron spectra and penetration rates were compared, demonstrating that the CENDL-3.2 library performs sufficiently overall. The simulation results of the other two libraries were underestimated for scattering at the continuum energy level.
文摘The 14 MeV neutrons produced in the D-T fusion reactions have the potential of breeding Uranium-233 fissile fuel from fertile material Thorium-232. In order to estimate the amount of U-233 produced, experiments are carried out by irradiating thorium dioxide pellets with neutrons produced from a 14 MeV neutron generator. The objective of the present work is to measure the reaction rates of 232Th ＋ in --＊ 233Th --＊ 2a^Pa --＊ 2a3U in different pellet thicknesses to study the self-shielding effects and adopt a procedure for correction. An appropriate assembly consisting of high-density polyethylene is designed and fabricated to slow down the high-energy neutrons, in which Thorium pellets are irradiated. The amount of fissile fuel （~3~U） produced is estimated by measuring the 312 keV gammas emitted by Protactinium-233 （half-life of 27 days）. A calibrated High Purity Germanium （HPGe） detector is used to measure the gamma ray spectrum. The amount of 233U produced by Th232 （n, ~） is calculated using MCNP code. The self-shielding effect is evaluated by calculating the reaction rates for different foil thickness. MCNP calculation results are compared with the experimental values and appropriate correction factors are estimated for self-shielding of neutrons and absorption of gamma rays.
文摘Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(149)Nd,^(148)Nd(n,2n)^(147)Nd, and ^(142)Nd(n,2 n)^(141)Nd reactions were 1854 ± 81, 1789 ± 119, and 1559 ± 98 mb, respectively, at a neutron energy of 14.2 ± 0.2 MeV,and 1485 ± 74, 1726 ± 85, and 1670 ± 119 mb, respectively, at 14.9 ± 0.2 MeV. The results were compared with the experimental values from the reported literature, with the evaluated data from the ENDF/B-VII.1, CENDL-3.1, and JENDL-4.0 libraries, and with the curves calculated by the Talys-1.8 code.
基金supported by the National Natural Science Foundation of China (Grant Nos.11075069,11075068,91026021 and 11135002)
文摘A new concept of neutron detector based on Gas Electron Multiplier(GEM) technology is presented in this paper,in which a novel multi-layer high density polyethylene(HDPE) as neutron-to-proton converter is proposed and studied with Geant4 toolkit for fast 14 MeV neutron.Our preliminary results show that the detection efficiency of the detector with 400 converter units is higher than 2.3% and reconstruction accuracy of the incident neutron position is higher than 2.6%.
基金Supported by the National Natural Science Foundation of China(11575090)。
文摘The cross sections for the 94Zr(n,d*)93m+gY,96Zr(n,γ)97Z,96Zr(n,2n)95Zr,90Zr(n,α)87mSr,94Zr(n,α)91Sr,90Zr(n,p)90mY,92Zr(n,p)92Y,and 94Zr(n,p)94Y reactions have been measured in the neutron energy range of 13.5-14.8 MeV by means of the activation technique.The neutrons were produced via the D-T reaction.A high-purity germanium detector with high energy resolution was used to measure the inducedγactivities.In combination with the nuclear reaction theoretical models,the excitation curves of the above-mentioned eight nuclear reactions within the incident neutron energy range from the threshold to 20 MeV were obtained by adopting the nuclear theoretical model program system Talys-1.9.The resulting experimental cross sections were analyzed and compared with the experimental data from published studies.Calculations were performed using Talys-1.9 and are in agreement with our experimental results,previous experimental values,as well as results of the theoretical excitation curves at the corresponding energies.The theoretical excitation curves generally match the experimental data well.
基金Supported by the Project of China Academy of Engineering Physics under Grant No 2013B0103015
文摘The thick target neutron yields （TTNYs） of deuteron-induced reaction on AI and Cu isotopes are analyzed by combining the improved nuclear models and particle transport effects. The modified Glauber model is employed mainly to produce the peak of double differential cross section for the breakup process, and the exciton model and the Hauser-Feshbach theory are used for the statistical processes. The thin-layer accumulation method is used to calculate the TTNYs considering the neutron attenuation effects in the target. The calculated results are compared with the existing experimental data, and the analysis method can predict the TTNY data well at the deuteron energy of 40 MeV.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11575267,11775284,11575289 and 11605258
文摘Measurement of the neutron yield is performed at a primary energy of 400 MeV/u carbons for the Pb target.Water-bath activation-foil method is used in a moderation measurement with Au foils to detect the moderated neutrons. The neutron yield is determined to be 18.4±2.1 per carbon by integrating the neutron flux over the entire water volume. The corresponding simulation values are performed by Geant4 code with three models to compare with the experimental results. The comparison shows that the calculated result with the INCL model is in good agreement with the experimental data.
