Effects of symmetry energy and momentum dependent interaction on low-energy reaction mechanisms

H Zheng,S Burrello,M Colonna,V Baran

doi:10.1051/epjconf/201611707026

Abstract

We study the dipole response associated with the Pygmy Dipole Resonance (PDR) and the Isovector Giant Dipole Resonance (IVGDR), in connection with specific properties of the nuclear effective interaction (symmetry energy and momentum dependence), in the neutron-rich systems $^{68}$Ni, $^{132}$Sn and $^{208}$Pb. We perform our investigation within a microscopic transport model based on the Landau-Vlasov kinetic equation. We observe that the peak energies of PDR and IVGDR are shifted to higher values when employing momentum dependent interactions, with respect to the results obtained neglecting momentum dependence. The calculated energies are close to the experimental values and similar to the results obtained in Hartree-Fock (HF) with Random Phase Approximation (RPA) calculations.

Highlights

The electric dipole (E1) response of nuclei, including exotic systems, was intensively explored during the last decade through a variety of experimental methods and probes [1]
With and without momentum dependent terms, in a semi-classical transport model, we investigate the isovector dipole response in the neutron-rich systems 68Ni, 132Sn and 208Pb
Our calculations indicate a clear dependence of the peak energy of the Isovector Giant Dipole Resonance (IVGDR) on the behavior of the symmetry energy below saturation density

Summary

Introduction

The electric dipole (E1) response of nuclei, including exotic systems, was intensively explored during the last decade through a variety of experimental methods and probes [1]. The role of the isovector sector of the nuclear effective interaction was explored, by considering three different parametrizations of the symmetry energy, but momentum dependent effects were neglected. In these calculations the peak energies, for the different exotic systems considered, were below the experimental values, especially in the case of the IVGDR mode. The SAMi27, SAMi31 and SAMi35 [10] are considered, in order to explore the impact of the symmetry energy on the properties of PDR and IVGDR

Theoretical framework

Results

Conclusion