A systematic study was conducted on the theoretical estimation of the nuclear cross sections of charged particle induced reactions on rare earth nuclei.The production cross sections of the ^(150,149,148,146,144,143,14...A systematic study was conducted on the theoretical estimation of the nuclear cross sections of charged particle induced reactions on rare earth nuclei.The production cross sections of the ^(150,149,148,146,144,143,141)Pm and ^(149,147)Nd nuclei were calculated theoretically via proton induced reactions on neodymium using TALYS(version 1.96)code in the default mode,with different combinations of nuclear models as well as adjusted nuclear model parameters from the reaction threshold up to a proton energy of 65 MeV.The theoretically computed results were compared with the experimental results taken from the EXFOR database and literature reported by various research groups.Moreover,the effects of various level density models,preequilibrium models,optical model potentials,and gamma strength functions on the cross section calculation were considered.This theoretical analysis will help elucidate the theory of nuclear reaction models and improve the evaluated nuclear data libraries.展开更多
The prediction of nuclear cross-section data is crucial, especially in the absence of experimental data or in the difficulty of these experimental data. Nickel(Ni) is an important material in fusion and fission reacto...The prediction of nuclear cross-section data is crucial, especially in the absence of experimental data or in the difficulty of these experimental data. Nickel(Ni) is an important material in fusion and fission reactor technologies, the production of radionuclides in nuclear medicine,and many other fields. In this study, the excitation functions for^(60,62) Ni(a,n),^(60,61) Ni(a,2 n),^(58,64) Ni(a,p), and ^(nat)Ni(a,x) reactions have been investigated by using preequilibrium reaction models. The calculations of the excitation functions for the reactions are used with the geometry-dependent hybrid model in ALICE/ASH code and the two-component exciton model in TALYS 1.8 code. The obtained results are compared to each other, and the experimental data are taken from the EXFOR database.展开更多
To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen s...To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen set of models accurately represents the‘true’distribution of considered observables.Furthermore,the models are chosen globally,indicating their applicability across the entire energy range of interest.However,this approach overlooks uncertainties inherent in the models themselves.In this work,we propose that instead of selecting globally a winning model set and proceeding with it as if it was the‘true’model set,we,instead,take a weighted average over multiple models within a Bayesian model averaging(BMA)framework,each weighted by its posterior probability.The method involves executing a set of TALYS calculations by randomly varying multiple nuclear physics models and their parameters to yield a vector of calculated observables.Next,computed likelihood function values at each incident energy point were then combined with the prior distributions to obtain updated posterior distributions for selected cross sections and the elastic angular distributions.As the cross sections and elastic angular distributions were updated locally on a per-energy-point basis,the approach typically results in discontinuities or“kinks”in the cross section curves,and these were addressed using spline interpolation.The proposed BMA method was applied to the evaluation of proton-induced reactions on ^(58)Ni between 1 and 100 MeV.The results demonstrated a favorable comparison with experimental data as well as with the TENDL-2023 evaluation.展开更多
The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was mea...The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured,most of the measured reactions have been carried out at the higher energy range from the astrophysical energies.Therefore, almost all cross sections needed for p process simulation have to be theoretically calculated or extrapolated to the astrophysical energies.^(112)Sn(α,γ)^(116)Te is an important reaction for the p process nucleosynthesis. The theoretical cross section of ^(112)Sn(α,γ)^(116)Te reaction was investigated for different global optical model potentials,level density, and strength function models at the astrophysically interested energies. Astrophysical S factors were calculated and compared with experimental data available in the EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and the back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at an astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the p process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.展开更多
The cross sections of the^(121)Sb(n,2n)^(120)Sb^(m) and ^(123)Sb(n,2n)^(122)Sb reactions were measured at 12.50,15.79 and 18.87 MeV neutron energies relative to the standard ^(27)Al(n,α)^(24)Na monitor reaction using...The cross sections of the^(121)Sb(n,2n)^(120)Sb^(m) and ^(123)Sb(n,2n)^(122)Sb reactions were measured at 12.50,15.79 and 18.87 MeV neutron energies relative to the standard ^(27)Al(n,α)^(24)Na monitor reaction using neutron activation and offline γ-ray spectrometry.Irradiation of the samples was performed at the BARC-TIFR Pelletron Linac Facility,Mumbai,India.The quasi-monoenergetic neutrons were generated via the ^(7)Li(p,n)reaction.Statistical model calculations were performed by nuclear reaction codes TALYS(ver.1.9)and EMPIRE(ver.3.2.2)using various input parameters and nuclear level density models.The cross sections of the ground and the isomeric state as well as the isomeric cross section ratio were studied theoretically from reaction threshold to 26 MeV energies.The effect of pre-equilibrium emission is also discussed in detail using different theoretical models.The present measured cross sections were discussed and compared with the reported experimental data and evaluation data of the JEFF-3.3,ENDF/B-VIII.0,JENDL/AD-2017 and TENDL-2019 libraries.A detailed analysis of the uncertainties in the measured cross section data was performed using the covariance analysis method.Furthermore,a systematic study of the(n,2n)reaction cross section for^(121)Sb and^(123)Sb isotopes was also performed within 14-15 MeV neutron energies using various systematic formulae.This work helps to overcome discrepancies in Sb data and illustrate a better understanding of pre-equilibrium emission in the(n,2n)reaction channel.展开更多
基金ICFAI University Tripura for all their help and support in carrying out the research
文摘A systematic study was conducted on the theoretical estimation of the nuclear cross sections of charged particle induced reactions on rare earth nuclei.The production cross sections of the ^(150,149,148,146,144,143,141)Pm and ^(149,147)Nd nuclei were calculated theoretically via proton induced reactions on neodymium using TALYS(version 1.96)code in the default mode,with different combinations of nuclear models as well as adjusted nuclear model parameters from the reaction threshold up to a proton energy of 65 MeV.The theoretically computed results were compared with the experimental results taken from the EXFOR database and literature reported by various research groups.Moreover,the effects of various level density models,preequilibrium models,optical model potentials,and gamma strength functions on the cross section calculation were considered.This theoretical analysis will help elucidate the theory of nuclear reaction models and improve the evaluated nuclear data libraries.
文摘The prediction of nuclear cross-section data is crucial, especially in the absence of experimental data or in the difficulty of these experimental data. Nickel(Ni) is an important material in fusion and fission reactor technologies, the production of radionuclides in nuclear medicine,and many other fields. In this study, the excitation functions for^(60,62) Ni(a,n),^(60,61) Ni(a,2 n),^(58,64) Ni(a,p), and ^(nat)Ni(a,x) reactions have been investigated by using preequilibrium reaction models. The calculations of the excitation functions for the reactions are used with the geometry-dependent hybrid model in ALICE/ASH code and the two-component exciton model in TALYS 1.8 code. The obtained results are compared to each other, and the experimental data are taken from the EXFOR database.
基金funding from the Paul ScherrerInstitute,Switzerland through the NES/GFA-ABE Cross Project。
文摘To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen set of models accurately represents the‘true’distribution of considered observables.Furthermore,the models are chosen globally,indicating their applicability across the entire energy range of interest.However,this approach overlooks uncertainties inherent in the models themselves.In this work,we propose that instead of selecting globally a winning model set and proceeding with it as if it was the‘true’model set,we,instead,take a weighted average over multiple models within a Bayesian model averaging(BMA)framework,each weighted by its posterior probability.The method involves executing a set of TALYS calculations by randomly varying multiple nuclear physics models and their parameters to yield a vector of calculated observables.Next,computed likelihood function values at each incident energy point were then combined with the prior distributions to obtain updated posterior distributions for selected cross sections and the elastic angular distributions.As the cross sections and elastic angular distributions were updated locally on a per-energy-point basis,the approach typically results in discontinuities or“kinks”in the cross section curves,and these were addressed using spline interpolation.The proposed BMA method was applied to the evaluation of proton-induced reactions on ^(58)Ni between 1 and 100 MeV.The results demonstrated a favorable comparison with experimental data as well as with the TENDL-2023 evaluation.
文摘The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured,most of the measured reactions have been carried out at the higher energy range from the astrophysical energies.Therefore, almost all cross sections needed for p process simulation have to be theoretically calculated or extrapolated to the astrophysical energies.^(112)Sn(α,γ)^(116)Te is an important reaction for the p process nucleosynthesis. The theoretical cross section of ^(112)Sn(α,γ)^(116)Te reaction was investigated for different global optical model potentials,level density, and strength function models at the astrophysically interested energies. Astrophysical S factors were calculated and compared with experimental data available in the EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and the back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at an astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the p process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.
基金IUAC New Delhi financial assistance through a research project (IUAC/XIII.7/UFR-60321)
文摘The cross sections of the^(121)Sb(n,2n)^(120)Sb^(m) and ^(123)Sb(n,2n)^(122)Sb reactions were measured at 12.50,15.79 and 18.87 MeV neutron energies relative to the standard ^(27)Al(n,α)^(24)Na monitor reaction using neutron activation and offline γ-ray spectrometry.Irradiation of the samples was performed at the BARC-TIFR Pelletron Linac Facility,Mumbai,India.The quasi-monoenergetic neutrons were generated via the ^(7)Li(p,n)reaction.Statistical model calculations were performed by nuclear reaction codes TALYS(ver.1.9)and EMPIRE(ver.3.2.2)using various input parameters and nuclear level density models.The cross sections of the ground and the isomeric state as well as the isomeric cross section ratio were studied theoretically from reaction threshold to 26 MeV energies.The effect of pre-equilibrium emission is also discussed in detail using different theoretical models.The present measured cross sections were discussed and compared with the reported experimental data and evaluation data of the JEFF-3.3,ENDF/B-VIII.0,JENDL/AD-2017 and TENDL-2019 libraries.A detailed analysis of the uncertainties in the measured cross section data was performed using the covariance analysis method.Furthermore,a systematic study of the(n,2n)reaction cross section for^(121)Sb and^(123)Sb isotopes was also performed within 14-15 MeV neutron energies using various systematic formulae.This work helps to overcome discrepancies in Sb data and illustrate a better understanding of pre-equilibrium emission in the(n,2n)reaction channel.
