Pre-equilibrium effects in charge-asymmetric low-energy reactions

Abstract

We study the pre-equilibrium dipole response in the charge-asymmetric reaction ${}^{132}$Sn+${}^{58}$Ni at $E_{lab}=10$ MeV/A, within a semi-classical transport model employing effective interactions for the nuclear mean-field. In particular, we adopt the recently introduced SAMi-J Skyrme interactions, whose parameters are specifically tuned to improve the description of spin-isospin properties of nuclei. Within the same framework, we also discuss pre-equilibrium nucleon emission. Our results show that both mechanisms, i.e., pre-equilibrium dipole oscillations and nucleon emission, are sensitive to the symmetry energy below the saturation density $\ddot{I}{}_0$ (in the range $0.6\ddot{I}{}_0-\ddot{I}{}_0$), to the effective mass and to the nucleon-nucleon cross section. Finally, a covariant analysis is applied to study the correlations between the model parameters and observables of experimental interest.

6 pages, 4 figures