Double differential cross sections of n + Cu reactions

The energy spectra and double differential cross sections of neutron, proton, deuteron, triton, helium and alpha-particle emissions for n + ^63,65,nat.Cu reactions are calculated and analyzed at incident neutron energies below 200 MeV. The optical model, the intra-nuclear cascade model, direct reaction theories, the unified Hauser–Feshbach and exciton model which includes the improved Iwamoto–Harada model are used. Theoretically calculated results are compared with the existing experimental data.     

Calculation and analysis of cross-sections for p+Zr reactions up to 200 MeV

Proton-induced reactions on ^{90,91,92,94,96,nat}Zr were studied in the energy range from threshold to 200 MeV. All cross-sections, elastic and inelastic scattering angular distributions were calculated and analyzed by using nuclear theoretical models which integrate optical model, distorted born wave approximation theory, intra-nuclear cascade model, pre-equilibrium and equilibrium reaction theories. Theoretical calculated results are compared with existing experimental data.     

Calculation and analysis of n+Zr reactions in the En ⩽ 250 MeV energy range

All of reaction cross sections, angular distributions, energy spectra, γ-ray production cross sections, and the double differential cross section for neutron, proton, deuteron, triton, helium and alpha emission are calculated and analyzed for n+^{90,91,92,94,96,nat}Zr at incident neutron energies from 0.1 to 250 MeV. The optical model, intranuclear cascade model, the unified Hauser–Feshbach theory and the exciton model which included the improved Iwamoto–Harada model are used. Theoretical calculated results are compared with existing experimental data and other evaluated data from ENDF/B-VI.8, ENDF/B-VII.0 and JENDL-3.3. The optical model potential parameters are obtained according to the experimental data of total, nonelastic cross sections and elastic scattering angular distributions.     

Theoretical calculations and evaluations of n+23Na reaction

The data for neutron-induced reactions are indispensable in a lot of applications of nuclear science and technologies. All reaction cross sections, angular distributions, energy spectra, and double-differential cross sections of neutron, proton, deuteron, triton, and alpha-particle emissions are consistently calculated and analyzed for n+~(23)Na reactions at incident neutron energies below200 Me V, based on nuclear theoretical models. The calculated results are compared with the experimental data and the evaluated data in the ENDF/B-VII, JENDL-4.0,and JEFF-3.2 libraries. In most cases, the calculated results describe the corresponding experimental data well. At the resonance energy region, evaluated experimental data are adopted to fit to the resonance structures.     

Formation cross sections of nuclei with (n,2n) reactions

Ｆｏｒｍａｔｉｏｎｃｒｏｓｓｅｃｔｉｏｎｓｏｆｎｕｃｌｅｉｗｉｔｈ（ｎ，２ｎ）ｒｅａｃｔｉｏｎｓＣｈｅｎＸｕｅＳｈｉ，ＸｉｅＫｕａｎＺｈｏｎｇ，ＺｈｏｕＳｈｅｎｇＭｏ，ＹａｎＱｉｎｇＱｕａｎ（ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＮｕｃｌｅ...     

Calculation of cross-sections for p+ Mo reactions up to 160 MeV

Proton-induced reactions on ^{92,94,95,96,97,98,100}Mo have been studied in the energy range from threshold to 160 MeV. All cross-sections for neutrons, protons, deuterons, tritons, helium and alpha particles emission have been calculated by using nuclear theoretical models which integrate the optical model, the intra-nuclear cascade model, direct, pre-equilibrium and equilibrium reaction theories. Theoretical calculations have been compared with existing experimental data; in most cases, the calculated results are in good agreement with the experimental data.     

Theoretical calculation and analysis of the p+Co reaction

All cross sections, elastic and inelastic scattering angular distributions, energy spectra, and double differential cross sections of neutron, proton, deuteron, triton, helium and alpha particle emission for the p+⁵⁹Co reaction have been calculated and analyzed at incident energies from threshold to 200 MeV. The optical model, the intra-nuclear cascade model, direct, pre-equilibrium and equilibrium reaction theories are used. It is found that the theoretical calculated results are in good agreement with experimental data.     

中子与58,60Ni反应的理论计算

根据中子与天然Ni及其同位素反应的总截面、去弹截面和弹性散射角分布的实验数据，得到中子的光学模型势参量。应用得到的光学模型势参量，根据光学模型、统一的Hauser-Feshbach和激子模型理论以及扭曲波玻恩近似理论，系统计算和分析了中子与^58,60Ni反应的非弹散射角分布和双微分截面，理论结果与实验很好地一致。     

Response of multi-step compound pre-equilibrium reaction cross sections for the (p,n) reactions to forms of optical model parameters

In furtherance to improving agreement between calculated and experimental nuclear data, the nuclear reaction code GAMME was used to calculate the multistep compound(MSC) nucleus double differential cross sections(DDCs) for proton-induced neutron emission reactions using the Feshbach-Kerman-Koonin(FKK) formalism. The cross sections were obtained for reactor structural materials involving ~(52)Cr(p, n)~(52)Mn,~(56)Fe(p,n)~(56)Co, and ~(60)Ni(p, n)~(60)Cu reactions at 22.2 MeV incident energy using the zero-range reaction mechanism. Effective residual interaction strength was 28 MeV, and different optical potential parameters were used for the entrance and exit channels of the proton-neutron interactions. The calculated DDCs were fitted to experimental data at the same backward angle of 150°, where the MSC processes dominate. The calculated and experimental data agree well in the region of pre-equilibrium(MSC) reaction dominance against a weaker fit at the lower emission energies. We attribute underestimations to contributions from the other reaction channels and disagreement at higher outgoing energies to reactions to collectively excited states. Contrary to the FKK multi-step direct calculations, contributions from the higher stages to the DDCs are significant. Different sets of parameters resulted in varying levels of agreement of calculated and experimental data for the considered nuclei.     

Gamma ray production cross sections from the bombardment of Mg, Al, Si, Ca and Fe with medium energy neutrons

Gamma ray production cross sections for the stronger gamma rays from nuclei excited by neutron bombardment of Mg, Al, Si, Ca and Fe have been measured using a time analyzed, quasi-mono-energetic neutron beam and a high-purity germanium detector. The results for neutron energies of 6.5, 17.4, 22.2, 32.5, 42.1 and 64.5 MeV are presented.     

Calculation of Photo-Ionisation Cross Sections and Radiative Recombination Rate Coefficients for CO and CO+ Molecules

A method based upon the weighted total cross section （WTCS） theory is proposed to calculate the photo-ionisation cross sections and the radiative recombination rate coefficients between the fundamental level of CO and the main electronic states of its corresponding ion. Total photo-ionisation cross sections and radiative recombination rate coefficients are determined from the calculation of elementary vibrational photo-ionisation cross sections. Transitions be- tween CO＋（X, A and B） and CO（X） are considered. Total photo-ionisation cross sections and recombination coefficients are computed in the temperature interval 500-15000 K.     

Activation Cross Sections for (n, 2n) Reaction on Neodymium,Samarium, Gadolinium and Ytterbium at 14.6 MeV

Activation cross sections for the (n, 2n) reaction on Nd, Sm, Gd and Yb have been measured at 14.6 MeV by using a Ge(Li) γ-ray detector. The following cross sections (mb) have been obtained: ¹¹²Nd 1,675±160, ¹⁴³Nd 1,789±147, ¹⁵⁰Nd 1,720±128, ¹⁵⁴Sm 2,010±137, ¹⁶⁰Gd 2,173±152, ¹⁶⁰Yb 2,226 ±152. These (n,2n) cross sections are compared with the theoretical calculations performed by a new model including pre-equilibrium and statistical models. A good agreement between the experimental and calculated cross sections is obtained.     

Analysis of (n, 2n) Cross Sections at 14.7 MeV in Region of Rare-Earths

Heat transfer by simultaneous conduction and radiation through ceramic fiber insulation is studied experimentally. The temperature profiles and the effective thermal conductivity are determined over a wide range of porosities of the insulation and of temperature provided at the hot boundary.

The resulting data are analyzed in detail to gain an understanding of the mechanism of heat transfer through such medium. A semi-empirical formula is derived for quantitatively predicting the thermal performance of ceramic fiber insulation. The formula incorporates as parameters the porosity and temperatures of the hot and cold boundaries.     

Cross sections for neutron-induced reactions up to 1.6 GeV for target elements relevant for cosmochemical, geochemical, and technological applications

We determined neutron excitation functions from the respective reaction thresholds up to 1.6 GeV for almost 100 target-product combinations relevant for cosmochemical, geochemical, and technological applications. We started with thick target production rates that have been obtained by irradiating iron and stone spheres with protons having energies between 600 MeV and 1.6 GeV. From the particle spectra of primary protons, secondary protons, and secondary neutrons, and the usually well known cross sections for the proton-induced reactions we calculated the production rates only due to protons. By subtracting these data from the measured total production rates we obtained production rates only due to secondary neutrons. With the modelled neutron spectra, guess functions calculated using nuclear model codes, and sophisticated energy-dependent deconvolution procedures we were able to determine almost 100 neutron excitation functions with their uncertainties. With the thus obtained neutron cross sections we are able to describe the experimental production rates in the thick target experiments, meteorites, the lunar surface, and terrestrial surface samples usually within the uncertainties, i.e., to within 10-15%. The adjusted neutron cross sections (a posteriori) are compared to results from the theoretical nuclear model codes INCL4.5/ABLA07 and TALYS. The TALYS code usually describes the a posteriori data reasonably well, i.e., mostly within a factor of a few. The quality of the INCL4.5 + ABLA07 predictions depends on the reaction type and increases with increasing number of ejectiles, i.e., increasing target-product mass difference. The neutron cross section database, though successful in quantifying production rates in terrestrial and extraterrestrial matter, presents by no means a final step and experiments with quasi-monoenergetic neutrons are needed.     

Activation cross sections for (n, p) reactions on nickel isotopes induced by neutrons around 14 MeV

The cross sections of ⁵⁸Ni(n, p)^58(m+g)Co,⁶⁰Ni(n, p)^60mCo,⁶¹Ni(n, p)⁶¹Co and ⁶²Ni(n, p)^62mCo reactions induced by neutrons around 14 MeV were measured using activation technique and a coaxial HPGe γ-ray detector. The natural nickel foils of 99.9% purity were used as target materials. Fast neutrons were produced by the T(d, n)⁴He reaction. The neutron flux was determined using the monitor reaction ²⁷Al(n, α)²⁴Na and the neutron energies were measured with the method of cross-section ratios for ⁹⁰Zr(n, 2n)⁸⁹Zr to ⁹³Nb(n, 2n)^92mNb reactions. The results of this work are compared with the collected partial recent data published previously and the estimations obtained from the published empirical formula based on the statistical model with dependence on the Q-value and odd-even effect taken into consideration.     

多群蒙特卡罗程序MCMG的开发与基准校验

基于连续能量蒙特卡罗程序MCNP开发了多群蒙特卡罗程序MCMG.利用由栅元程序WIMS产生的随燃耗变化的多群宏观均匀化截面取代连续能量点截面,大大提高了程序的计算速度,同时也解决了蒙特卡罗程序不能进行燃耗计算等问题.针对输运修正引起的自散射截面导致的负概率抽样现象,提出了一种非负修正方法,并用基准计算验证了该方法的正确性.     

An empirical expression for total scattering cross sections of normal hydrocarbons, and experimental total cross sections of C2H2 and C3H4

The total electron scattering cross sections (TCS) of C₂H₂ and C₃H₄ have been obtained for 200-4500 eV electrons by measuring the attenuation of the electron beam through a gas cell. An empirical expression is deduced to express the TCS of normal hydrocarbons as a function of the number of atomic constituencies in the hydrocarbon and the electron energy.     

Pre-equilibrium cross section calculations in alpha induced reactions on Cu and Bi

The nuclear data on (α, xn) reactions are very important in the fields of radiation shielding, long-term safe handling of spent fuel and spallation neutron-production. In this study, neutron-production cross sections have been calculated for some target nuclei such as ⁶⁵Cu and ²⁰⁹Bi. Hybrid model and geometry dependent hybrid model have been used to calculate the pre-equilibrium neutron-production cross sections. The mean free path parameter’s effect for (α, xn) neutron-production cross section has been examined. The obtained results have been discussed and compared with the available experimental data.     

Prompt fission neutron multiplicity and spectrum evaluations for n+238U reaction

The prompt fission neutron multiplicity and spectra for n+²³⁸U reaction are calculated using an improved Los Alamos model which includes the linear relation between the average prompt gamma ray energy and the prompt neutron multiplicity and also the average fission fragment kinetic energy dependence on the incident neutron energy. The coefficients describing the quadratic variation of the fission fragment kinetic energy versus the incident energy are obtained by extrapolation of the data and procedure used for n+²³⁵U reaction. The inverse process compound nucleus cross-section of the fissioning nucleus is calculated using the coupled channel method. In the incident energy range where only the first fission chance is involved the comparison of present spectrum evaluation with spectrum calculation using multi-modal model is made too. The calculated prompt neutron multiplicity and spectra of ²³⁸U neutron induced fission are in good agreement with the experimental data for the entire incident energy range required in evaluations, proving the validity of the used procedure.     

p+~(59)Co原子核反应的理论计算

基于光学模型势方法,依据p+59Co反应的总截面和弹性散射角分布的实验数据,利用APMN.FOR程序,给出1套与实验数据符合很好的光学势参数。将光学势参数应用于质子与59Co的邻近核56Fe、58Ni、63Cu的核反应理论计算,质子入射能量小于200MeV时,该光学势参数有很好的普适性。