Shell evolution is crucial for understanding nuclear structures across the nuclear chart.In this work,we employed the ab initio valence space in-medium similarity renormalization group with chiral nucleon-nucleon and ...Shell evolution is crucial for understanding nuclear structures across the nuclear chart.In this work,we employed the ab initio valence space in-medium similarity renormalization group with chiral nucleon-nucleon and three-nucleon interactions to study neutron-rich Si,S,Ar,and Ca isotopes,particularly focusing on nuclei near N=32,34.We systematically analyzed both neutron and proton shell evolutions by examining the excitation energies of the first 2^(+)states and the effective single-particle energies.Our calculations show that the N=32 sub-shell gradually weakens as protons are removed from the doubly magic nucleus^(52)Ca,eventually disappearing in 46si.Conversely,the strength of the N=34 sub-shell is enhanced with the removal of protons from^(54)Ca.Furthermore,our results indicate the existence of the proton Z=14 sub-shell in neutron-rich Si isotopes.These findings suggest that^(48)Si is a doubly magic nucleus,with the excitation energy of the first 2^(+)state around 2.49 MeV,which is approximately 400 keV higher than that of^(54)Ca.This value is comparable to those of other well-known exotic doubly magic nuclei,such as^(52)Ca and^(78)Ni,which is of great interest for further experiments at RIB facilities.In addition,we predicted the low-lying spectra of neutron-rich Si,S,and Ar isotopes,providing new insights for future experiments.展开更多
Bremsstrahlung photons emitted during nucleon-nucleus reactions in compact stars are investigated.The influence of stellar medium density on emission intensity is studied from a quantum perspective for the first time....Bremsstrahlung photons emitted during nucleon-nucleus reactions in compact stars are investigated.The influence of stellar medium density on emission intensity is studied from a quantum perspective for the first time.A bremsstrahlung model is generalized,where a new term describing the influence of the stellar medium is added to interactions between nucleons and nuclei(in the framework of a nuclear model of deformed oscillatoric shells).Polytropic EOS,Chandrasekar EOS,and Harrison-Wheeler EOS are employed for calculation.Haensel and Potekhin's unified EOS of neutron-star matter based on FPS and SLy EOSs are used for tests.Bremsstrahlung calculations are tested on existing measurements of bremsstrahlung in the scattering of protons off ^(197)Au nuclei at a proton beam energy of E_(p)=190 MeV.Many properties of bremsstrahlung emitted from nuclear processes in the stellar medium of compact stars are studied for the first time.In particular,the spectra of photons in the scattering of protons and neutrons off ^(4)He,^(8)Be,^(12)C,^(16O),^(24)Mg,40Ca,^(56)Fe are estimated based on stellar medium density.The medium of white dwarfs has a small influence on the bremsstrahlung emission from nuclear processes,while bremsstrahlung emission is intensive in neutron stars and it is changed in dependence on stellar medium and structure.展开更多
基金Supported by the National Key R&D Program of China(2024YFE0109800,2024YFE0109802,2023YFA1606403)the National Natural Science Foundation of China(12405141,12205340,12175281,12347106,12475128,12322507,12121005)+2 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2022423)the Gansu Natural Science Foundation(22JR5RA123,23JRRA614)the Natural Science Foundation of Henan Province(242300421048).
文摘Shell evolution is crucial for understanding nuclear structures across the nuclear chart.In this work,we employed the ab initio valence space in-medium similarity renormalization group with chiral nucleon-nucleon and three-nucleon interactions to study neutron-rich Si,S,Ar,and Ca isotopes,particularly focusing on nuclei near N=32,34.We systematically analyzed both neutron and proton shell evolutions by examining the excitation energies of the first 2^(+)states and the effective single-particle energies.Our calculations show that the N=32 sub-shell gradually weakens as protons are removed from the doubly magic nucleus^(52)Ca,eventually disappearing in 46si.Conversely,the strength of the N=34 sub-shell is enhanced with the removal of protons from^(54)Ca.Furthermore,our results indicate the existence of the proton Z=14 sub-shell in neutron-rich Si isotopes.These findings suggest that^(48)Si is a doubly magic nucleus,with the excitation energy of the first 2^(+)state around 2.49 MeV,which is approximately 400 keV higher than that of^(54)Ca.This value is comparable to those of other well-known exotic doubly magic nuclei,such as^(52)Ca and^(78)Ni,which is of great interest for further experiments at RIB facilities.In addition,we predicted the low-lying spectra of neutron-rich Si,S,and Ar isotopes,providing new insights for future experiments.
文摘Bremsstrahlung photons emitted during nucleon-nucleus reactions in compact stars are investigated.The influence of stellar medium density on emission intensity is studied from a quantum perspective for the first time.A bremsstrahlung model is generalized,where a new term describing the influence of the stellar medium is added to interactions between nucleons and nuclei(in the framework of a nuclear model of deformed oscillatoric shells).Polytropic EOS,Chandrasekar EOS,and Harrison-Wheeler EOS are employed for calculation.Haensel and Potekhin's unified EOS of neutron-star matter based on FPS and SLy EOSs are used for tests.Bremsstrahlung calculations are tested on existing measurements of bremsstrahlung in the scattering of protons off ^(197)Au nuclei at a proton beam energy of E_(p)=190 MeV.Many properties of bremsstrahlung emitted from nuclear processes in the stellar medium of compact stars are studied for the first time.In particular,the spectra of photons in the scattering of protons and neutrons off ^(4)He,^(8)Be,^(12)C,^(16O),^(24)Mg,40Ca,^(56)Fe are estimated based on stellar medium density.The medium of white dwarfs has a small influence on the bremsstrahlung emission from nuclear processes,while bremsstrahlung emission is intensive in neutron stars and it is changed in dependence on stellar medium and structure.
