Fusion dynamics of symmetric systems near barrier energies

TL;DR

This paper investigates how dynamical fusion barriers and neck nucleon transfer influence sub-barrier fusion cross sections in symmetric nuclear systems, using the ImIQMD model to compare with experimental data.

Contribution

It introduces detailed analysis of neck dynamics and fusion barrier distributions for symmetric systems near the Coulomb barrier, highlighting the role of neutron-richness.

Findings

Neutron-to-proton ratio in the neck increases for neutron-rich systems.

Dynamical fusion barriers are lowered in neutron-rich reactions.

Calculated fusion excitation functions agree with experimental data.

Abstract

The enhancement of the sub-barrier fusion cross sections was explained as the lowering of the dynamical fusion barriers within the framework of the improved isospin-dependent quantum molecular dynamics (ImIQMD) model. The numbers of nucleon transfer in the neck region are appreciably dependent on the incident energies, but strongly on the reaction systems. A comparison of the neck dynamics is performed for the symmetric reactions $^{58}$Ni+$^{58}$Ni and $^{64}$Ni+$^{64}$Ni at energies in the vicinity of the Coulomb barrier. An increase of the ratios of neutron to proton in the neck region at initial collision stage is observed and obvious for neutron-rich systems, which can reduce the interaction potential of two colliding nuclei. The distribution of the dynamical fusion barriers and the fusion excitation functions are calculated and compared them with the available experimental data.