2011, 28(4): 377-395.
doi: 10.11804/NuclPhysRev.28.04.377
Published：2011-12-20
Nuclear symmetry energy plays an important role in the properties of nuclei and neutron stars. Since theoretical predictions of the density dependence of symmetry energy S(ρ) from microscopic nucleonnucleon interactions show large uncertainties, especially in the region of suprasaturation density, constraining the density dependence of symmetry energy has become one of the main goals in nuclear physics and has stimulated many theoretical and experimental studies. In this paper, we have reviewed the ImQMD05 code and its description on charge distribution, collective flow and nuclearnuclear stopping. By comparing ImQMD05 prediction with data, the isoscalar part of nucleonic mean field, the energy and density dependence of inmedium NN cross sectoin in the ImQMD05 were determined. In order to extracting the symmetry energy information by comparing the ImQMD05 calculations with the data for 112, 124Sn+112, 124 Sn at Ebeam=50 MeV/u, the influence of symmetry potential and inmedium NN cross section on the isospin sensitive observables of intermediateenergy heavyion collisions was investigated. Focusing on the region above the Fermi energy, our results show that the symmetry potential plays a more important role in the experimental observables, such as double neutron to proton ratio and the isospin transport ratio Ri, than that the inmedium nucleonnucleon cross section does. Since the copious production of intermediate mass fragments is a distinguishing feature of intermediateenergy heavyion collisions, we also examined the influence of cluster emission on the isospin transport ratio using different isospin tracers. The values of the isospin transport ratios with the tracer defined by the isospin asymmetry of the heaviest fragments with Z≥20 in the projectile region is greater than those obtained from projectile residues (emitting source). This phenomenon can be tested experimentally. By comparing the ImQMD05 predictions with the data for three observables, the selfconsistent constraints on the symmetry energy at subsaturation density were obtained.
甘公网安备 62010202000723号