Monday, May 28, 2012, 3:50PM – 5:40PM –

Session EOS + Cluster3 Equation of State of Neutron-Rich Nuclear Matter, Clusters in Nuclei and Nuclear Reactions III

Room: Pecos

Chair: B. A. Li

 

3:50PM

Three-body force effect on the properties of neutron-rich nuclear matter, W. Zuo, Institute of Modern Physics, Chinese Academy of Sciences, China − We shall report our investigation of the three-body force effect on the equation of state and the single particle properties of neutron-rich nuclear matter within the extended BHF approach.

 

4:20PM

Tensor force induced short-range nucleon-nucleon correlation and high-density behavior of nuclear symmetry energy, C. Xu, Nanjing University, China − The tensor force induced short-range nucleon-nucleon correlation on the Equations of State of nuclear matter as well as the nuclear symmetry energy are investigated.  It is found that the tensor force can influence significantly the nuclear symmetry energy especially at supra-saturation densities.  This finding confirms the critical role of the tensor force acting in neutron-proton isosinglet pairs in determining the high-density behavior of nuclear symmetry energy predicted by various microscopic and phenomenological nuclear many-body theories.

 

4:40PM

Nuclear symmetry energy and the role of the tensor force, I. Vidana, University of Coimbra, Portugal − Using the Hellmann--Feynman theorem we analyze the contribution of the different terms of the nucleon-nucleon interaction to the nuclear symmetry energy Esym and the slope parameter L.  The analysis is performed within the microscopic Brueckner--Hartree--Fock approach using the Argonne V18 potential plus the Urbana IX three-body force.  We find that the main contribution to Esym and L comes from the tensor component of the nuclear force.

 

5:00PM

The ASY-EOS experiment at GSI: investigating symmetry energy at supra-saturation densities, P. Russotto, INFN-LNS & Università di Catania, Italy − The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of neutron rich heavy-ions at intermediate energies is proposed as an observable sensitive to the strength of the symmetry term in the nuclear equation of state at supra-saturation densities.  The results obtained from the existing FOPI/LAND data for 197Au+197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model favours a moderately soft symmetry term but suffer from a considerable statistical uncertainty [1].  In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration in May 2011.  The flows of neutrons, protons and light complex particles were measured for 197Au+197Au, 96Ru+96Ru, and 96Zr+96Zr collisions at 400 MeV/nucleon using the LAND neutron detector, the forward part of CHIMERA device, the Aladin ToF-Wall, the Si-CsI Krakow Array and the Microball detector.  First results will be reported.

 

[1] P. Russotto et al., Phys. Lett. B 697 (2011) 471.

 

5:20PM

Isovector channel of quark-meson-coupling model and its effect on symmetry energy, X. Wang, State Key Laboratory of Nuclear Physics and Technology/School of Physics/Peking University, China − Both relativistic and non-relativistic energy density functional models have been widely used in describing the nuclear many-body system.  Systematical calculations show that both relativistic and non-relativistic models give quite similar results for the ground state properties and low-energy dynamics of stable nuclei.  However, significant differences are found when calculations go to the extreme cases of high isospin and high density.  The origin of these differences is still not clear.   The non-relativistic Skyrme-Hartree-Fock (SHF) model has been extensively employed in the investigation of nuclear structure since the first work of Vautherin and Brink.  In 1970s, almost at the same time as SHF, the Relativistic-Mean-Field (RMF) model was developed to give a competitive description of finite nuclei.  The relativistic Quark-Meson-Coupling model (QMC) was proposed by Guichon.  However, the Hartree approximation is usually used in both RMF and QMC models.  The real treatment of the Fock term remains interesting. Detailed comparisons between relativistic models within the non-relativistic Hartree-Fock approximation and the Skyrme model can be instructive in clearing the picture.  In this work, we compare the non-relativistic approximations of the QMC and RMF models and SHF models, with focusing on possible relationship.  We list the QMC energy density functional within the Hartree-Fock approximation and make comparison with RMF and Skyrme models.  We have paid special attention to the isovector channel of the nuclear energy density functionals.  The QMC and SHF models have a similar density dependence for the isoscalar channel, but have different forms for the isovector channel.  It is found that the Fock exchange leads to a nonlinear density-dependent isovector channel in the QMC model, which makes a soft symmetry energy.  The nonlinear density dependence is produced by the scalar field which is derived by considering subnucleonic freedoms.