In this paper, the definition of approximate XFDs based on value equality is proposed. Two metrics, sup port and strength, are presented for measuring the degree of approximate XFD. A basic algorithm is designed for e...In this paper, the definition of approximate XFDs based on value equality is proposed. Two metrics, sup port and strength, are presented for measuring the degree of approximate XFD. A basic algorithm is designed for extracting minimal set of approximate XFDs, and then two optimized strategies are proposed to improve the performance. Finally, the experimental results show that the optimized algorithms are correct and effective.展开更多
Key nuclear inputs for the astrophysical r-process simulations are the weak interaction rates.Consequently,the accuracy of these inputs directly affects the reliability of nucleosynthesis modeling.The majority of the ...Key nuclear inputs for the astrophysical r-process simulations are the weak interaction rates.Consequently,the accuracy of these inputs directly affects the reliability of nucleosynthesis modeling.The majority of the stellar rates,used in simulation studies are calculated by invoking the Brink-Axel(BA)hypothesis.The BA hypothesis assumes that the strength functions of all parent excited states are the same as for the ground state,only shifted in energies.However,the BA hypothesis has to be tested against microscopically calculated state-by-state rates.In this project,we study the impact of the BA hypothesis on calculated stellarβ^(-)-decay and electron capture rates.Our investigation include both unique first forbidden(U1F)and allowed transitions for 106 neutron-rich trans-iron nuclei([27,77]≤[Z,A]≤[82,208]).The calculations were performed using the deformed proton-neutron quasiparticle random-phase approximation(pn-QRPA)model with a simple plus quadrupole separable and schematic interaction.Waiting-point and several key r-process nuclei lie within the considered mass region of the nuclear chart.We computed electron capture andβ^(-)-decay rates using two different prescriptions for strength functions.One was based on invoking the BA hypothesis and the other was the state-by-state calculation of strength functions,under stellar density and temperature conditions([10,1]≤[ρYe(g/cm^(3)),T(GK)]≤[10^(11),30]).Our results show that the BA hypothesis invoked U1Fβ^(-)rates are overestimated by 4–5 orders of magnitude as compared to microscopic rates.For capture rates,more than two orders of magnitude differences were noted when applying the BA hypothesis.It was concluded that the BA hypothesis is not a reliable approximation,especially forβ^(-)-decay forbidden transitions.展开更多
基金Supported by the National Natural Science Foun-dation of China (60173051) , Teaching and Research Award Programfor Outstanding Young Teachers in Higher Education Institution ofthe Ministry of Education,the National Research Foundation for theDoctoral Programof Higher Education of China(20030145029) ,andthe Natural Science Foundationfor Doctoral Career Award of LiaoningProvince(20041016)
文摘In this paper, the definition of approximate XFDs based on value equality is proposed. Two metrics, sup port and strength, are presented for measuring the degree of approximate XFD. A basic algorithm is designed for extracting minimal set of approximate XFDs, and then two optimized strategies are proposed to improve the performance. Finally, the experimental results show that the optimized algorithms are correct and effective.
基金supported by the Higher Education Commission Pakistan through Project (0-15394/NRPU/R&D/HEC/2021)。
文摘Key nuclear inputs for the astrophysical r-process simulations are the weak interaction rates.Consequently,the accuracy of these inputs directly affects the reliability of nucleosynthesis modeling.The majority of the stellar rates,used in simulation studies are calculated by invoking the Brink-Axel(BA)hypothesis.The BA hypothesis assumes that the strength functions of all parent excited states are the same as for the ground state,only shifted in energies.However,the BA hypothesis has to be tested against microscopically calculated state-by-state rates.In this project,we study the impact of the BA hypothesis on calculated stellarβ^(-)-decay and electron capture rates.Our investigation include both unique first forbidden(U1F)and allowed transitions for 106 neutron-rich trans-iron nuclei([27,77]≤[Z,A]≤[82,208]).The calculations were performed using the deformed proton-neutron quasiparticle random-phase approximation(pn-QRPA)model with a simple plus quadrupole separable and schematic interaction.Waiting-point and several key r-process nuclei lie within the considered mass region of the nuclear chart.We computed electron capture andβ^(-)-decay rates using two different prescriptions for strength functions.One was based on invoking the BA hypothesis and the other was the state-by-state calculation of strength functions,under stellar density and temperature conditions([10,1]≤[ρYe(g/cm^(3)),T(GK)]≤[10^(11),30]).Our results show that the BA hypothesis invoked U1Fβ^(-)rates are overestimated by 4–5 orders of magnitude as compared to microscopic rates.For capture rates,more than two orders of magnitude differences were noted when applying the BA hypothesis.It was concluded that the BA hypothesis is not a reliable approximation,especially forβ^(-)-decay forbidden transitions.
