Isospin dependence of fragment yields in peripheral heavy ion collisions

Abstract

We have theoretically investigated isospin dependence in peripheral isospin asymmetric $^{112}$Sn + $^{124}$Sn and $^{124}$Sn + $^{112}$Sn reaction systems at 50 MeV/nucleon projectile energy. Mass, charge and isotope yields emitted from the excited quasiprojectile sources are obtained within a statistical approach. In order to interpret the experimental data, the N/Z ratio, isotope yield, and isoscaling analyses were carried out for light intermediate mass fragments (with $Z\le 8$, at available data range). We show that predicted results produced for fragment yields, are consistent with the experimental data for peripheral isospin asymmetric reaction systems. From the comparison of the statistical model predictions with experimental data, it is concluded that a lower value of the effective symmetry-term coefficient $\gamma$ must be considered at low density freeze-out. Statistical analysis of isoscaling shows that the isoscaling parameter $\alpha$ is very sensitive to the isospin composition (N/Z ratio) of the the sources, and it is proportional to the strength of the symmetry-term coefficient.