Influence of the symmetry energy on isospin ratios from projectile and target fragmentations in intermediate-energy heavy-ion collisions

Abstract

Using the isospin-dependent quantum molecular dynamics (IQMD) model, the sensitivity of isospin ratios from projectile and target fragmentation towards the density-dependent symmetry energy for the neutron-rich reaction systems Ca-40,Ca-48+ Ni-58,Ni-64 at 50 and 600 MeV/nucleon has been studied. The kinetic energy spectra of neutron-to-proton single and double ratios are elaborated in detail. The neutron-to-proton double ratio in neutron-rich projectile fragmentation is provided as a useful tool for the density dependence of symmetry energy near the subsaturation density. The sensitivity of the kinetic energy spectra of isospin ratios towards the isospin effect or symmetry energy reduces at suprasaturation density because of secondary nucleon-nucleon collisions.