An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.B...An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.By taking several forms of nuclear symmetry energy,we calculate the time evolutions of neutron over proton ratio,π multiplicity and π-/π+ ratio,and the kinetic energy and transverse momentum spectra of π-/π+ ratio in the heavy ion collisions at 400A MeV.It is found that the neutron over proton ratio and π-/π+ ratio are very sensitive to the nuclear symmetry energy,and the π-is more sensitive to the nuclear symmetry energy than the π+.A supersoft symmetry energy results in a larger π-/π+ ratio.展开更多
Isospin-dependent Quantum Molecular Dynamics model (IQMD) has been applied to investigate the Pygmy Dipole Resonance (PDR) and Giant Dipole Resonance (GDR) in Ni isotopes by Coulomb excitation. By Gaussian fitting to ...Isospin-dependent Quantum Molecular Dynamics model (IQMD) has been applied to investigate the Pygmy Dipole Resonance (PDR) and Giant Dipole Resonance (GDR) in Ni isotopes by Coulomb excitation. By Gaussian fitting to the photon emission spectra, the peak energies and strengths of PDR and GDR are extracted. Their sensitivities to impact parameter, incident energy and the symmetry energy are discussed. By the comparison of energy-weighted sum rule (EWSR) with the data and other calculations for 68 Ni, the parameters of density-dependence of symmetry energy in the IQMD are constrained. In addition, the N/Z dependence of PDR and GDR parameters of Ni isotopes are investigated, and the results that the EWSR increases linearly with the N/Z are obtained.展开更多
Two different isospin splittings of nucleon effective mass in nuclear medium as the form of mn*>mp* and mn*<mp* have been implemented in an isospin and momentum dependent transport model.Their impacts on the iso...Two different isospin splittings of nucleon effective mass in nuclear medium as the form of mn*>mp* and mn*<mp* have been implemented in an isospin and momentum dependent transport model.Their impacts on the isospin emission in heavy-ion collisions is investigated thoroughly.It is found that the yield ratios of energetic neutrons to protons squeezed out during the compression stage of two colliding nuclides are sensitive to the isospin splitting.The elliptic flows of free nucleons are also to be promising observables for extracting the nucleon effective mass splitting.Further experimental measurements are being expected,in particular at the CSR-CEE platform in Lanzhou.Several observables are proposed for constraining the density dependence of symmetry energy,such as the transverse flow difference of neutrons and protons,double ratios of n/p and π-/π+,excitation functions of π-/π+ and K0/K+.展开更多
This paper reports my recent study[1]on the shear viscosity of neutron-rich nuclear matter from a relaxation time approach.An isospin- and momentum-dependent interaction is used in the study.Dependence of density,temp...This paper reports my recent study[1]on the shear viscosity of neutron-rich nuclear matter from a relaxation time approach.An isospin- and momentum-dependent interaction is used in the study.Dependence of density,temperature,and isospin asymmetry of nuclear matter on its shear viscosity have been discussed.Similar to the symmetry energy,the symmetry shear viscosity is defined and its density and temperature dependence are studied.展开更多
We studied the role that electron gas has on the formation of nuclear structures at subsaturation densities and low temperatures(T<1 Me V).Using a classical molecular dynamics model we studied isospin symmetric and...We studied the role that electron gas has on the formation of nuclear structures at subsaturation densities and low temperatures(T<1 Me V).Using a classical molecular dynamics model we studied isospin symmetric and asymmetric matter at subsaturation densities and low temperatures varying the Coulomb interaction strength.The effect of such variation was quantified on the fragment size multiplicity,the inter-particle distance,the isospin content of the clusters,the nucleon mobility and cluster persistence,and on the nuclear structure shapes.We found that the presence of an electron gas distributes matter more evenly,disrupts the formation of larger objects,reduces the isospin content,and modifies the nucleon average displacement,but does not affect the inter-nucleon distance in clusters.The nuclear structures are also found to change shapes by different degrees depending on their isospin content,temperature and density.展开更多
The hadron-quark phase transition is studied with the newly constructed Hadron-Poyakov-Nambu- Jona-Lasinio(PNJL) model.Particularly,in the description of quark matter,we include the isoscalar-vector interaction.With t...The hadron-quark phase transition is studied with the newly constructed Hadron-Poyakov-Nambu- Jona-Lasinio(PNJL) model.Particularly,in the description of quark matter,we include the isoscalar-vector interaction.With the constraints of neutron star observations,our calculation shows the isoscalar-vector interaction between quarks is indispensable if massive hybrids star exist in the universe.Its strength determines the onset density of quark matter,and the mass-radius relations of hybrid stars.Also,as a connection with heavy-ion-collision experiments,we discuss the strength of isoscalar-vector interaction and its effect on the signals of hadron-quark phase transition in heavy-ion collisions,such as NICA at JINR-Dubna and FAIR at GSI-Darmstadt.展开更多
By extending the minimum spanning tree(MST)clusterization algorithm for the binding energy cut,the isospin asymmetry dependence of directed flow for isospin sensitive isobar pairs(neutrons-protons,3H-3He) is studied f...By extending the minimum spanning tree(MST)clusterization algorithm for the binding energy cut,the isospin asymmetry dependence of directed flow for isospin sensitive isobar pairs(neutrons-protons,3H-3He) is studied from low towards high incident energies.The modified clusterization method(MSTB) has the advantage to identify the fragments at quite early time.It enhances(reduces) the production of free nucleons(fragments) over MST method.The directed flow of isobaric pair3H-3He is more sensitive towards isospin asymmetry caused by MSTB than isobaric pair n-p.This sensitivity becomes quite strong towards the high incident energy and neutron-rich reaction system.In conclusion,the inclusion of binding energy in clusterization method for the flow studies has been uniquely important for understanding the isospin physics,especially for high density behavior of symmetry energy.展开更多
The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI.Fi...The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI.Five different nuclear thermometers are used to extract nuclear temperature.We find that the He and Li isotope temperature reaches a plateau at about 70-100 MeV/nucleon of beam energy.The slope temperature and the quadrupole fluctuation temperature give high values.The quantum slope temperature and the quantum quadrupole fluctuation temperature are more close to the He and Li isotope temperatures.展开更多
基金Supported by National Natural Science Foundation of China(NSFC) projects (Nos.11025524 and 11161130520)National Basic Research Program of China(No.2010CB832903)
文摘An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.By taking several forms of nuclear symmetry energy,we calculate the time evolutions of neutron over proton ratio,π multiplicity and π-/π+ ratio,and the kinetic energy and transverse momentum spectra of π-/π+ ratio in the heavy ion collisions at 400A MeV.It is found that the neutron over proton ratio and π-/π+ ratio are very sensitive to the nuclear symmetry energy,and the π-is more sensitive to the nuclear symmetry energy than the π+.A supersoft symmetry energy results in a larger π-/π+ ratio.
基金Supported by the National Natural Science Foundation of China(Nos.11220101005,11035009,10979074 and 11205230)Major State Basic Research Development Program in China(No.2013CB834405)
文摘Isospin-dependent Quantum Molecular Dynamics model (IQMD) has been applied to investigate the Pygmy Dipole Resonance (PDR) and Giant Dipole Resonance (GDR) in Ni isotopes by Coulomb excitation. By Gaussian fitting to the photon emission spectra, the peak energies and strengths of PDR and GDR are extracted. Their sensitivities to impact parameter, incident energy and the symmetry energy are discussed. By the comparison of energy-weighted sum rule (EWSR) with the data and other calculations for 68 Ni, the parameters of density-dependence of symmetry energy in the IQMD are constrained. In addition, the N/Z dependence of PDR and GDR parameters of Ni isotopes are investigated, and the results that the EWSR increases linearly with the N/Z are obtained.
基金Supported by National Natural Science Foundation of China(NSFC) projects (No.11175218)the Advancement Society of Young Innovation of Chinese Academy of Sciences
文摘Two different isospin splittings of nucleon effective mass in nuclear medium as the form of mn*>mp* and mn*<mp* have been implemented in an isospin and momentum dependent transport model.Their impacts on the isospin emission in heavy-ion collisions is investigated thoroughly.It is found that the yield ratios of energetic neutrons to protons squeezed out during the compression stage of two colliding nuclides are sensitive to the isospin splitting.The elliptic flows of free nucleons are also to be promising observables for extracting the nucleon effective mass splitting.Further experimental measurements are being expected,in particular at the CSR-CEE platform in Lanzhou.Several observables are proposed for constraining the density dependence of symmetry energy,such as the transverse flow difference of neutrons and protons,double ratios of n/p and π-/π+,excitation functions of π-/π+ and K0/K+.
基金Suppprted by "100-talent plan" of Shanghai Institute of Applied Physics from the Chinese Academy of Sciences(No.Y290061011)
文摘This paper reports my recent study[1]on the shear viscosity of neutron-rich nuclear matter from a relaxation time approach.An isospin- and momentum-dependent interaction is used in the study.Dependence of density,temperature,and isospin asymmetry of nuclear matter on its shear viscosity have been discussed.Similar to the symmetry energy,the symmetry shear viscosity is defined and its density and temperature dependence are studied.
基金Supported by National Science Foundation-Physics(No.1066031)the China-US Theory Institute for Physics with Exotic Nuclei
文摘We studied the role that electron gas has on the formation of nuclear structures at subsaturation densities and low temperatures(T<1 Me V).Using a classical molecular dynamics model we studied isospin symmetric and asymmetric matter at subsaturation densities and low temperatures varying the Coulomb interaction strength.The effect of such variation was quantified on the fragment size multiplicity,the inter-particle distance,the isospin content of the clusters,the nucleon mobility and cluster persistence,and on the nuclear structure shapes.We found that the presence of an electron gas distributes matter more evenly,disrupts the formation of larger objects,reduces the isospin content,and modifies the nucleon average displacement,but does not affect the inter-nucleon distance in clusters.The nuclear structures are also found to change shapes by different degrees depending on their isospin content,temperature and density.
基金Supported by National Natural Science Foundation of China(NSFC) projects (Nos.11147144 and 11305121)
文摘The hadron-quark phase transition is studied with the newly constructed Hadron-Poyakov-Nambu- Jona-Lasinio(PNJL) model.Particularly,in the description of quark matter,we include the isoscalar-vector interaction.With the constraints of neutron star observations,our calculation shows the isoscalar-vector interaction between quarks is indispensable if massive hybrids star exist in the universe.Its strength determines the onset density of quark matter,and the mass-radius relations of hybrid stars.Also,as a connection with heavy-ion-collision experiments,we discuss the strength of isoscalar-vector interaction and its effect on the signals of hadron-quark phase transition in heavy-ion collisions,such as NICA at JINR-Dubna and FAIR at GSI-Darmstadt.
基金Supported by the Chinese Academy of Sciences Support program for young international scientists(No.2010Y2JB02)National Natural Science Foundation of China(NSFC) projects (Nos.11220101005,11035009 and 10979074)the Knowledge Innovation project of the Chinese Academy of Sciences(No.KJCX2-EW-N01)
文摘By extending the minimum spanning tree(MST)clusterization algorithm for the binding energy cut,the isospin asymmetry dependence of directed flow for isospin sensitive isobar pairs(neutrons-protons,3H-3He) is studied from low towards high incident energies.The modified clusterization method(MSTB) has the advantage to identify the fragments at quite early time.It enhances(reduces) the production of free nucleons(fragments) over MST method.The directed flow of isobaric pair3H-3He is more sensitive towards isospin asymmetry caused by MSTB than isobaric pair n-p.This sensitivity becomes quite strong towards the high incident energy and neutron-rich reaction system.In conclusion,the inclusion of binding energy in clusterization method for the flow studies has been uniquely important for understanding the isospin physics,especially for high density behavior of symmetry energy.
基金Supported by National Natural Science Foundation of China(Grant Nos.11025524 and 11161130520)National Basic Research Program of China(Grant No.2010CB832903)
文摘The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI.Five different nuclear thermometers are used to extract nuclear temperature.We find that the He and Li isotope temperature reaches a plateau at about 70-100 MeV/nucleon of beam energy.The slope temperature and the quadrupole fluctuation temperature give high values.The quantum slope temperature and the quantum quadrupole fluctuation temperature are more close to the He and Li isotope temperatures.
