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

TL;DR

This paper investigates how pre-equilibrium dipole oscillations and nucleon emission in charge-asymmetric nuclear reactions are influenced by symmetry energy, effective mass, and nucleon-nucleon interactions using a semi-classical transport model.

Contribution

It introduces a detailed analysis of pre-equilibrium effects in charge-asymmetric reactions using SAMi-J Skyrme interactions, highlighting sensitivities to nuclear matter properties.

Findings

Pre-equilibrium dipole response is sensitive to symmetry energy below saturation density.

Nucleon emission is affected by effective mass and nucleon-nucleon cross section.

Correlations between model parameters and experimental observables are identified.

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 $\rho_0$ (in the range $0.6\rho_0-\rho_0$), 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.