New insight into the N/Z and mass equilibration in heavy-ion collisions

TL;DR

This study uses an isospin-dependent quantum molecular dynamics model to reveal that N/Z and mass equilibration occur at different stages in heavy-ion collisions, with N/Z equilibrating early and mass later during separation.

Contribution

It provides the first detailed analysis showing that N/Z and mass equilibration happen at distinct collision phases, enhancing understanding of nuclear reaction dynamics.

Findings

N/Z equilibration occurs during the approaching phase.

Mass equilibration takes place during the separation phase.

Dynamical potential energy surface clarifies mass equilibration process.

Abstract

The dynamics of N/Z and mass equilibration are investigated in the reactions 112,124Sn + 239Pu by employing the isospin-dependent quantum molecular dynamics model. It is found that N/Z and mass equilibration take place at different collision stages. The N/Z relaxation is observed in the approaching phase (from first contact to deepest contact) with a very short time, whereas interestingly we find for the first time that mass equilibration only takes place in the separation phase (from the deepest contact to re-separation), which are explained by investigating the dynamical asymmetry between the approaching and separation phases. The mass equilibration also could be clarified with a dynamical potential energy surface. Our results provide a new insight into the equilibration dynamics of the quantum systems.