Integral experiments on tungsten slab samples were carried out on the D-T neutron source facility at China Institute of Atomic Energy. Leakage neutron spectra from the irradiated tungsten target were measured by the t...Integral experiments on tungsten slab samples were carried out on the D-T neutron source facility at China Institute of Atomic Energy. Leakage neutron spectra from the irradiated tungsten target were measured by the time-of-flight technique. Accuracy of the nuclear data for tungsten was examined by comparing the measured neutron spectra with the leakage neutron spectra simulated using the MCNP-4C code with evaluated nuclear data of the JEFF-3.2, FENDL-3.0 and TENDL-2014 libraries. The results show that the calculations with JEFF-3.2 agree well with the measurements in the whole energy range and all angles, whereas the spectra calculated with FENDL-3.0 and TENDL-2014 have some discrepancies with the experimental data.展开更多
By introducing a general equilibrium framework to China's dual economic structure, this paper studies the microscopic mechanism of education input to narrow the urban-rural income gap and how to improve the alloca...By introducing a general equilibrium framework to China's dual economic structure, this paper studies the microscopic mechanism of education input to narrow the urban-rural income gap and how to improve the allocation efficiency of education funds in China's "new normal" economy. The empirical analysis results show that education input is effective in narrowing the urban-rural income gap and achieving a Pareto improvement state in both direct and indirect ways. However, the effect of education input at different stages varies. In particular, the impact of compulsory education on improving inequality is more significant than the other education levels. With adjustment for the macroeconomic slowdown, raising fiscal expenditures on education can improve potential economic growth by promoting human capital accumulation and labor productivity in the long run. In all, education input can promote labor migration and narrow the urban-rural income gap, which is conducive to alleviating the contradiction of the structural transformation lag in employment and achieving inclusive growth targets.展开更多
To satisfy the requirements of nuclear reaction cross sections in nuclear engineering applications and nuclear physics studies,the Neutron Activation Cross Section Data Library has been established.818 target nuclei i...To satisfy the requirements of nuclear reaction cross sections in nuclear engineering applications and nuclear physics studies,the Neutron Activation Cross Section Data Library has been established.818 target nuclei including unstable target or isomeric target nuclei are considered in this library.The induced neutron energy range region is between 10^(-5)eV and 20 MeV.The standard ENDF-6 format is adopted,including general information,reaction cross sections,multiplicities,and so on.The recommended reaction cross sections were obtained using UNF code system and FDRR nuclear model codes or systematic analysis based on available experimental data.展开更多
213Bi disintegrates (97.91±0.03) % by β-emission to the levels in 213Po, and (2.09±0.03) % through α decay to 209Tl. The evaluation of the complete decay scheme and data of 213Bi including the recent new m...213Bi disintegrates (97.91±0.03) % by β-emission to the levels in 213Po, and (2.09±0.03) % through α decay to 209Tl. The evaluation of the complete decay scheme and data of 213Bi including the recent new measurements are presented in this report. The Limitation of Relative Statistical Weight Method (LWM) was applied to average numbers throughout the evaluation. The uncertainty assigned to the average value was always greater than or equal to the smallest uncertainty of the values used to calculate the average. The half-life is determined to be 45.59±0.06 minutes. All known measured gamma-ray relative emission probabilities have been examined. And the gamma-ray emission probability of the reference γ line of 440.44keV is recommended to be (26.1±0.3) %. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new 213Bi decay scheme was re-built.展开更多
The principal contradiction facing the Chinese society has evolved to be that between imbalanced and inadequate development and the people’s ever-growing needs for a better life.Given China’s vision for achieving mo...The principal contradiction facing the Chinese society has evolved to be that between imbalanced and inadequate development and the people’s ever-growing needs for a better life.Given China’s vision for achieving moderate prosperity,it is relevant to conduct theoretical and empirical studies on the nation’s development imbalances.As a quantitative index,the Tsinghua China Balanced Development Index measures the extent to which development is uneven and insuf ficient across regions,re flecting the progress and shortfalls in China’s efforts to promote balanced development.Our findings provide implications for how policymakers may help people’s expectations for a better life materialize by spurring balanced economic,social,environmental and livelihood development across regions.展开更多
Based on the mass distribution data up to 200 MeV measured by Zoller with kinetic energy method (corrected), the systematics on dependence of chain yield on incident neutron energy for each mass number A with a linear...Based on the mass distribution data up to 200 MeV measured by Zoller with kinetic energy method (corrected), the systematics on dependence of chain yield on incident neutron energy for each mass number A with a linear and quadric function was studied. And also the systematics of mass distribution on mass A and incident neutron energy was investigated by using 5 (or 3 ) Gaussian model. A code of nonlinear squared least method was developed and the parameters were deduced by fitting the experimental data. The calculated results with the parameters obtained could reproduce the experimental data used well. But comparisons with the data measured by radiochemistry method show some systematical difference. It is shown that there is some systematical difference between the measured data with kinetic and radioactive nuclide methods, the reasons of which need to be investigate further.展开更多
The illicit trafficking of special nuclear materials(SNMs)poses a grave threat to global security and necessitates the development of effective nuclear material identification methods.This study investigated a method ...The illicit trafficking of special nuclear materials(SNMs)poses a grave threat to global security and necessitates the development of effective nuclear material identification methods.This study investigated a method to isotopically identify the SNMs,including^(233,235,238)U,^(239-242)Pu,and^(232)Th,based on the detection of delayedγ-rays from photofission fragments.The delayedγ-ray spectra resulting from the photofission of SNMs irradiated by a 14 MeVγbeam with a total of 10~9 were simulated using Geant4.Three high-yield fission fragments,namely^(138)Cs,^(89)Rb,and^(94)Y,were selected as candidate fragments for SNM identification.The yield ratios of these three fragments were calculated,and the results from the different SNMs were compared.The yield ratio of^(138)Cs/^(89)Rb was used to identify most SNMs,including^(233,235,238)U,^(242)Pu,and^(232)Th,with a confidence level above 95%.To identify^(239-241)Pu with the same confidence,a higher total number of 10^(11)γbeams is required.However,although the^(94)Y/^(89)Rb ratio is suitable for elementally identifying SNMs,isotopic identification is difficult.In addition,the count rate of the delayedγabove 3 MeV can be used to rapidly detect the presence of nuclear materials.展开更多
In this work,we study the impacts of the isospin-independent momentum-dependent interaction(MDI)and near-threshold NN→NΔcross sections(σ_(NN→NΔ))on the nucleonic flow and pion production observables in the ultra-...In this work,we study the impacts of the isospin-independent momentum-dependent interaction(MDI)and near-threshold NN→NΔcross sections(σ_(NN→NΔ))on the nucleonic flow and pion production observables in the ultra-relativistic quantum molecular dynamics(UrQMD)model.With the updated isospin-independent MDI and the near-threshold NN→NΔcross sections in the Ur QMD model,17 observables,which are the directed flow(v_(1))and elliptic flow(v_(2))of neutrons,protons,Hydrogen(H),and charged particles as a function of transverse momentum(p_t∕A)or normalized rapidity(y^(lab)_0),and the observables constructed from them,the charged pion multiplicity(M(π))and its ratio(M(π^(-))∕M(π^(+))),can be simultaneously described at certain forms of symmetry energy.The refinement of the UrQMD model provides a solid foundation for further understanding the effects of the missed physics,such as the threshold effect,the pion potential,and the momentum-dependent symmetry potential.Circumstantial constraints on the symmetry energy at the flow characteristic density 1.2±0.6ρ_(0)and the pion characteristic density 1.5±0.5ρ_(0)were obtained with the current version of UrQMD,and the corresponding symmetry energies were S(1.2ρ_(0))=34±4 MeV and S(1.5ρ_(0))=36±8 MeV,respectively.Furthermore,the discrepancies between the data and the calculated results of v_(2)^(n)and v_(2)^(9)at high p_(t)(rapidity)imply that the roles of the missing ingredients,such as the threshold effect,the pion potential,and the momentum-dependent symmetry potential,should be investigated by differential observables,such as the momentum and rapidity distributions of the nucleonic and pionic probes over a wide beam energy range.展开更多
基金supported by the National Natural Science Foundation of China(No.11605097,91426301,and 11605257)Doctoral Scientific Research Foundation of Inner Mongolia University for the Nationalities(No.BS365)the‘‘ADS project 302’’of the Chinese Academy of Sciences(No.XDA03030200)
文摘Integral experiments on tungsten slab samples were carried out on the D-T neutron source facility at China Institute of Atomic Energy. Leakage neutron spectra from the irradiated tungsten target were measured by the time-of-flight technique. Accuracy of the nuclear data for tungsten was examined by comparing the measured neutron spectra with the leakage neutron spectra simulated using the MCNP-4C code with evaluated nuclear data of the JEFF-3.2, FENDL-3.0 and TENDL-2014 libraries. The results show that the calculations with JEFF-3.2 agree well with the measurements in the whole energy range and all angles, whereas the spectra calculated with FENDL-3.0 and TENDL-2014 have some discrepancies with the experimental data.
文摘By introducing a general equilibrium framework to China's dual economic structure, this paper studies the microscopic mechanism of education input to narrow the urban-rural income gap and how to improve the allocation efficiency of education funds in China's "new normal" economy. The empirical analysis results show that education input is effective in narrowing the urban-rural income gap and achieving a Pareto improvement state in both direct and indirect ways. However, the effect of education input at different stages varies. In particular, the impact of compulsory education on improving inequality is more significant than the other education levels. With adjustment for the macroeconomic slowdown, raising fiscal expenditures on education can improve potential economic growth by promoting human capital accumulation and labor productivity in the long run. In all, education input can promote labor migration and narrow the urban-rural income gap, which is conducive to alleviating the contradiction of the structural transformation lag in employment and achieving inclusive growth targets.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11934004 and U1832201)the Science Challenge Project (Grant No. TZ2016005)the CAEP Foundation (Grant No. CX2019022)
文摘To satisfy the requirements of nuclear reaction cross sections in nuclear engineering applications and nuclear physics studies,the Neutron Activation Cross Section Data Library has been established.818 target nuclei including unstable target or isomeric target nuclei are considered in this library.The induced neutron energy range region is between 10^(-5)eV and 20 MeV.The standard ENDF-6 format is adopted,including general information,reaction cross sections,multiplicities,and so on.The recommended reaction cross sections were obtained using UNF code system and FDRR nuclear model codes or systematic analysis based on available experimental data.
基金IAEA under IAEA Research Contract No. 13339/R0/RBF
文摘213Bi disintegrates (97.91±0.03) % by β-emission to the levels in 213Po, and (2.09±0.03) % through α decay to 209Tl. The evaluation of the complete decay scheme and data of 213Bi including the recent new measurements are presented in this report. The Limitation of Relative Statistical Weight Method (LWM) was applied to average numbers throughout the evaluation. The uncertainty assigned to the average value was always greater than or equal to the smallest uncertainty of the values used to calculate the average. The half-life is determined to be 45.59±0.06 minutes. All known measured gamma-ray relative emission probabilities have been examined. And the gamma-ray emission probability of the reference γ line of 440.44keV is recommended to be (26.1±0.3) %. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new 213Bi decay scheme was re-built.
基金the final result of the “Tsinghua China Balanced Development Index” Project of the China Data CenterTsinghua University+1 种基金Sponsored by the Minshan Public-Interest Fund of the China Siyuan Foundation for Poverty Alleviation (CSFPA) with special sponsorship from the China Post-Doctoral Science Foundation (2018T110079)general sponsorship from the China Post-Doctoral Science Foundation (2017M620719)。
文摘The principal contradiction facing the Chinese society has evolved to be that between imbalanced and inadequate development and the people’s ever-growing needs for a better life.Given China’s vision for achieving moderate prosperity,it is relevant to conduct theoretical and empirical studies on the nation’s development imbalances.As a quantitative index,the Tsinghua China Balanced Development Index measures the extent to which development is uneven and insuf ficient across regions,re flecting the progress and shortfalls in China’s efforts to promote balanced development.Our findings provide implications for how policymakers may help people’s expectations for a better life materialize by spurring balanced economic,social,environmental and livelihood development across regions.
文摘Based on the mass distribution data up to 200 MeV measured by Zoller with kinetic energy method (corrected), the systematics on dependence of chain yield on incident neutron energy for each mass number A with a linear and quadric function was studied. And also the systematics of mass distribution on mass A and incident neutron energy was investigated by using 5 (or 3 ) Gaussian model. A code of nonlinear squared least method was developed and the parameters were deduced by fitting the experimental data. The calculated results with the parameters obtained could reproduce the experimental data used well. But comparisons with the data measured by radiochemistry method show some systematical difference. It is shown that there is some systematical difference between the measured data with kinetic and radioactive nuclide methods, the reasons of which need to be investigate further.
基金supported by the National Key Research and Development Program(No.2022YFA1603300)the National Natural Science Foundation of China(Nos.U2230133,12305266,11921006,12405282)National Grand Instrument Project(No.2019YFF01014400)。
文摘The illicit trafficking of special nuclear materials(SNMs)poses a grave threat to global security and necessitates the development of effective nuclear material identification methods.This study investigated a method to isotopically identify the SNMs,including^(233,235,238)U,^(239-242)Pu,and^(232)Th,based on the detection of delayedγ-rays from photofission fragments.The delayedγ-ray spectra resulting from the photofission of SNMs irradiated by a 14 MeVγbeam with a total of 10~9 were simulated using Geant4.Three high-yield fission fragments,namely^(138)Cs,^(89)Rb,and^(94)Y,were selected as candidate fragments for SNM identification.The yield ratios of these three fragments were calculated,and the results from the different SNMs were compared.The yield ratio of^(138)Cs/^(89)Rb was used to identify most SNMs,including^(233,235,238)U,^(242)Pu,and^(232)Th,with a confidence level above 95%.To identify^(239-241)Pu with the same confidence,a higher total number of 10^(11)γbeams is required.However,although the^(94)Y/^(89)Rb ratio is suitable for elementally identifying SNMs,isotopic identification is difficult.In addition,the count rate of the delayedγabove 3 MeV can be used to rapidly detect the presence of nuclear materials.
基金supported by the National Natural Science Foundation of China(Nos.11875323,12275359,12205377,12335008,U2032145,11790320,11790323,11790325,and 11961141003)the National Key R&D Program of China(No.2018 YFA0404404)+2 种基金the Continuous Basic Scientific Research Project(No.WDJC-2019-13)the China Institute of Atomic Energy(No.YZ222407001301)the Leading Innovation Project of the CNNC(Nos.LC192209000701 and LC202309000201)。
文摘In this work,we study the impacts of the isospin-independent momentum-dependent interaction(MDI)and near-threshold NN→NΔcross sections(σ_(NN→NΔ))on the nucleonic flow and pion production observables in the ultra-relativistic quantum molecular dynamics(UrQMD)model.With the updated isospin-independent MDI and the near-threshold NN→NΔcross sections in the Ur QMD model,17 observables,which are the directed flow(v_(1))and elliptic flow(v_(2))of neutrons,protons,Hydrogen(H),and charged particles as a function of transverse momentum(p_t∕A)or normalized rapidity(y^(lab)_0),and the observables constructed from them,the charged pion multiplicity(M(π))and its ratio(M(π^(-))∕M(π^(+))),can be simultaneously described at certain forms of symmetry energy.The refinement of the UrQMD model provides a solid foundation for further understanding the effects of the missed physics,such as the threshold effect,the pion potential,and the momentum-dependent symmetry potential.Circumstantial constraints on the symmetry energy at the flow characteristic density 1.2±0.6ρ_(0)and the pion characteristic density 1.5±0.5ρ_(0)were obtained with the current version of UrQMD,and the corresponding symmetry energies were S(1.2ρ_(0))=34±4 MeV and S(1.5ρ_(0))=36±8 MeV,respectively.Furthermore,the discrepancies between the data and the calculated results of v_(2)^(n)and v_(2)^(9)at high p_(t)(rapidity)imply that the roles of the missing ingredients,such as the threshold effect,the pion potential,and the momentum-dependent symmetry potential,should be investigated by differential observables,such as the momentum and rapidity distributions of the nucleonic and pionic probes over a wide beam energy range.
