Isospin Effects on Pre-Equilibrium Nucleon Emission in Heavy-Ion Collisions

Abstract：

The isospin-dependent symmetry energy, Coulomb energy, and N-N cross sections are considered in the quantum molecular dynamics model. The influence of isospin effects on the emission of nucleons is discussed in the head-on collisions of the system ⁴⁰Ar + ⁴⁰Ar at the incident energy of 25 MeV/u. It is observed that the ratio of neutron to proton of pre-equilibrium emission is higher than that of the reaction system. It is found that the symmetry energy enhances the emission of neutron but reduces the emission of proton and that the isospin-dependent N-N cross sections favor the emission of both proton and neutron, but they seem to be more beneficial to the emission of protons.