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symmetry energy and experimentally observed cold fragments in intermediate heavy-ion collisions

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Chinese Physics C 2017年第4期41卷 50-55页

作者：张苏雅拉吐黄美容 R.Wada 刘星泉林炜平王建松 College of Physics and Electronics Information Inner Mongolia University for Nationalities Cyclotron Institute Texas A&M UniversityCollege Station Institute of Modern Physics Chinese Academy of Sciences

An attempt is made to study the symmetry energy at the time of primary fragment formation from the experimentally observed cold fragments for a neutron-rich system of ^64Ni ＋ ^9Be at 140 MeV/nucleon,utilizing the recent finding that the excitation energy becomes lower for more neutron-rich isotopes with a given Z *** extracted α（sym）/T values from the cold fragments,based on the Modified Fisher Model（MFM）,are compared to those from the primary fragments of the antisymmetrized molecular dynamics（AMD） simulation and become consistent with the simulation when the I = N —Z value becomes larger,indicating that the excitation energy of these neutron-rich isotopes is indeed lower.

关键词： symmetry energy modified Fisher model antisymmetrized molecular dynamics simulations

symmetry energy of strange quark matter and tidal deformability of strange quark stars

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Nuclear Science and Techniques 2022年第11期33卷 89-100页

作者： Jian-Feng Xu Cheng-Jun Xia Zhen-Yan Lu Guang-Xiong Peng Ya-Peng Zhao College of Information Engineering Suqian UniversitySuqian 223800China School of Physics and Electrical Engineering AnYang Normal UniversityAnyang 455000China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Institute of High-energy Physics Chinese Academy of SciencesBeijing 100049China School of Mathematics and Physics Henan Urban Construction UniversityPingdingshan 467036China

Research performed during the past decade revealed an important role of symmetry energy in the equation of state(EOS)of strange quark matter(SQM).By introducing an isospin-dependent term into the quark mass scaling,the SQM stability window in the equivparticle model was *** results show that a sufficiently strong isospin dependence C_(I)can significantly widen the SQM region of absolute stability,yielding results that simultaneously satisfy the constraints of the astrophysical observations of PSR J1614-2230 with 1.928±0.017 Mand tidal deformability 70≤Λ_(1:4)≤580 measured in the event *** increasing C_(I),the difference between the u,d,and s quark fractions for the SQM inβ-equilibrium becomes inconspicuous for C>0,leading to small isospin asymmetryδ,and further resulting in similar EOS and structures of strange quark stars(SQSs).Moreover,unlike the behavior of the maximum mass of ud QSs,which varies with C_(I)depending on the sign of the parameter C,the maximum mass of the SQSs decreases monotonously with increasing CI.

关键词： symmetry energy Strange quark matter Strange stars Tidal deformability

symmetry energy from neutron-rich fragments in heavy-ion collisions,and its dependence on incident energy,and impact parameters

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Chinese Physics C 2013年第2期37卷 19-25页

作者：马春旺宋恒利普洁张同林张莎王闪闪赵新丽陈丽 Department of Physics Henan Normal University Department of Nuclear Physics Shanghai Institute of Applied Physics

The yields of fragments produced in the ^60Ni＋ ^12C reactions at 80 A and 140 A MeV, and with maximum impact parameters of 1.5, 2 and 7.3 fm at 80 A MeV are calculated by the statistical abrasion-ablation model. The yields of fragments are analyzed by the isobaric yield ratio （IYR） method to extract the coefficient of symmetry energy to temperature （asym/T ）. The incident energy is found to influence asym/T very little. It’s found that asym/T of fragments with the same neutron-excess I = N-Z increases when A increases, while asym/T of isobars decreases when A increases. The asym/T of prefragments is rather smaller than that of the final fragments, and the asym/T of fragments in small impact parameters is smaller than that of the larger impact parameters, which both indicate that asym/T decreases when the temperature increases. The choice of the reference IYRs is found to have influence on the extracted a sym /T of fragments, especially on the results of the more neutron-rich fragments. The surface-symmetry energy coefficient （bs/T ） and the volume-symmetry energy coefficient （bv/T） are also extracted, and the bs/bv is found to coincide with the theoretical results.

关键词： symmetry energy isobaric yield ratio neutron-rich nucleus heavy-ion collisions

Deformation dependence of symmetry energy coefficients of nuclei

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Science China(Physics,Mechanics & Astronomy) 2015年第8期58卷 33-38页

作者： MO QiuHong LIU Min CHENG LiChun WANG Ning Department of Physics Guangxi Normal University School of Material Science and Engineering Guilin University of Electronic Technology

Based on the semi-classical Thomas-Fermi approximation together with the Skyrme energy-density functional, we study the deformation dependence of symmetry energy coefficients of finite nuclei. The symmetry energy coefficients of nuclei with mass number A = 40, 100, 150, 208 are extracted from two-parameter parabola fitting to the calculated energy per particle. We find that the symmetry energy coefficients decrease with the increase of nuclear quadrupole deformations, which is mainly due to the isospin dependence of the difference between the proton and neutron surface diffuseness. Large deformations of nuclei can cause the change of the symmetry energy coefficient by about 0.5 Me V and the influence of nuclear deformations on the symmetry energy coefficients is more evident for light and intermediate nuclei.

关键词： symmetry energy Skyrme energy-density functional nuclear deformation Thomas-Fermi

Effect of tensor force on the density dependence of symmetry energy within the BHF framework

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Chinese Physics C 2015年第1期39卷 31-36页

作者：王培左维 Institute of Modern Physics Chinese Academy of Sciences School of Physical Science and Technology Lanzhou University University of Chinese Academy of Sciences State Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of Sciences

The effect of tensor force on the density dependence of nuclear symmetry energy has been investigated within the framework of the Brueckner-Hartree-Fock （BHF） approach. It is shown that the tensor force manifests its effect via the tensor 3SD1 channel. The density dependence of symmetry energy Esym turns out to be determined essentially by the tensor force from the π meson and p meson exchanges via the 3SD1 coupled channel. Increasing the strength of the tensor component due to the p-meson exchange tends to enhance the repulsion of the equation of state of symmetric nuclear matter and leads to the reduction of symmetry energy. The present results confirm the dominant role played by the tensor force in determining nuclear symmetry energy and its density dependence within the microscopic BHF framework.

关键词： symmetry energy asymmetric nuclear matter tensor force Brueckner-Hartree-Fock approach

Constraining nuclear symmetry energy with the charge radii of mirror-pair nuclei

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Nuclear Science and Techniques 2023年第8期34卷 154-163页

作者： Rong An Shuai Sun Li-Gang Cao Feng-Shou Zhang Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Key Laboratory of Beam Technology of Ministry of Education Institute of Radiation TechnologyBeijing Academy of Science and TechnologyBeijing 100875China CAS Key Laboratory of High Precision Nuclear Spectroscopy Institute of Modern PhysicsChinese Academy of SciencesLanzhou 730000China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of LanzhouLanzhou 730000China

The nuclear charge radius plays a vital role in determining the equation of state of isospin asymmetric nuclear *** on the correlation between the differences in charge radii of mirror-partner nuclei and the slope parameter(L)of symmetry energy at the nuclear saturation density,an analysis of the calibrated slope parameter L was performed in finite *** this study,relativistic and nonrelativistic energy density functionals were employed to constrain the nuclear symmetry energy through the available databases of the mirror-pair nuclei^(36)Ca–^(36)S,^(38)Ca–^(38)Ar,and ^(54)Ni–^(54)*** deduced nuclear symmetry energy was located in the range 29.89–31.85 MeV,and L of the symmetry energy essentially covered the range 22.50–51.55 MeV at the saturation ***,the extracted L_(s) at the sensitivity density p_(s)=0.10 fm^(-3) was located in the interval range 30.52–39.76 MeV.

关键词： symmetry energy Charge radii Mirror nuclei

Isospin splitting of nucleon effective mass and symmetry energy in isotopic nuclear reactions

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Chinese Physics C 2017年第10期41卷 103-109页

作者：郭亚飞陈鹏辉牛菲张鸿飞靳根明冯兆庆 School of Nuclear Science and Technology Lanzhou University Institute of Modern Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Institute of Particle and Nuclear Physics Henan Normal University

Within an isospin and momentum dependent transport model, the dynamics of isospin particles（nucleons and light clusters） in Fermi-energy heavy-ion collisions are investigated for constraining the isospin splitting of nucleon effective mass and the symmetry energy at subsaturation densities. The impacts of the isoscalar and isovector parts of the momentum dependent interaction on the emissions of isospin particles are explored, i.e., the mass splittings of m_n^＊=m_p^＊ and m_n^＊〉 m_p^＊（m_n^＊〈 m_p^＊）. The single and double neutron to proton ratios of free nucleons and light particles are thoroughly investigated in the isotopic nuclear reactions of ^112Sn＋^112Sn and ^124Sn＋^124Sn at incident energies of 50 and 120 MeV/nucleon, respectively. It is found that both the effective mass splitting and symmetry energy impact the kinetic energy spectra of the single ratios, in particular at the high energy tail（larger than 20 Me V）. The isospin splitting of nucleon effective mass slightly impacts the double ratio spectra at the energy of 50 MeV/nucleon. A soft symmetry energy with stiffness coefficient of γ_s =0.5 is constrained from the experimental data with the Fermi-energy heavy-ion collisions.

关键词： isotopic reactions isospin and momentum dependent transport model symmetry energy effective mass splitting

Investigation of the symmetry energy of nuclear matter using isospin-dependent quantum molecular dynamics

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Nuclear Science and Techniques 2020年第6期31卷 83-89页

作者： Hao Yu De-Qing Fang Yu-Gang Ma Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of the Chinese Academy of Sciences Beijing 100080China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China

Simulations of infinite nuclear matter at different densities,isospin asymmetries and temperatures are performed using the isospin-dependent quantum molecular dynamics(IQMD)model to study the equation of state and symmetry energy.A rigorous periodic boundary condition is used in the *** energies are extracted from the binding energies under different conditions and compared to the classical molecular dynamics(CMD)model using the same *** results show that both models can reproduce the experimental results for the symmetry energies at low densities,but IQMD is more appropriate than CMD for nuclear matter above the saturation *** indicates that IQMD may be a reliable model for the study of the properties of infinite nuclear matter.

关键词： Infinite nuclear matter symmetry energy IQMD model

Deexcitation energy of Superdeformed Secondary Minima as a Probe to Density Dependence of symmetry energy

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Communications in Theoretical Physics 2010年第10期54卷 715-722页

作者：蒋维洲陆幸陈云鹏 Department of Physics Southeast University Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator

Deexcitation energies of superdeformed secondary minima of odd-odd A u and T1 isotopes are investigated with the relativistic mean field （RMF） model where the isoscalar-isovector coupling is included to change the symmetry energy. It is verified by the theoretical analysis and numerical results that the deexcitation energies of superdeformed secondary minima relative to the ground states in these heavy nuclei are sensitive to differences in the symmetry energy. In particular, the linear correlation between the deexeitation energies of odd-odd Au and T1 isotopes and the neutron skin thickness in 208Pb is established. Moreover, explorations are extended to superdeformed candidates of other mass regions. It is found that the linear correlation can even be established between the deexcitation energies and the symmetry pressure at subsaturation density. These indicate that deexcitation energies can serve as a probe to the density dependence of the symmetry energy.

关键词： symmetry energy superdeformation relativistic mean-field models