Fusion and quasi-fission dynamics in nearly-symmetric reactions

TL;DR

This study uses an improved quantum molecular dynamics model to analyze fusion and quasi-fission processes in nearly-symmetric reactions, revealing insights into fusion probabilities, contact times, and neutron-rich fragment production.

Contribution

The paper introduces a modified ImQMD model with enhanced Fermi constraint to better simulate fusion and quasi-fission dynamics in nearly-symmetric nuclear reactions.

Findings

Fusion probability below 10^{-5} at energies above the Bass barrier.

Contact time generally less than 1500 fm/c.

Potential to produce neutron-rich heavy nuclei via quasi-fission.

Abstract

Some nearly-symmetric fusion reactions are systematically investigated with the improved quantum molecular dynamics (ImQMD) model. By introducing two-body inelastic scattering in the Fermi constraint procedure, the stability of an individual nucleus and the description of fusion cross sections at energies near the Coulomb barrier can be further improved. Simultaneously, the quasi-fission process in $^{154}$Sm+$^{160}$Gd is also investigated with the microscopic dynamics model for the first time. We find that at energies above the Bass barrier, the fusion probability is smaller than $10^{-5}$ for this reaction, and the nuclear contact-time is generally smaller than $1500$ fm/c. From the central collisions of Sm+Gd, the neutron-rich fragments such as $^{164,165}$Gd, $^{192}$W can be produced in the ImQMD simulations, which implies that the quasi-fission reaction could be an alternative way to synthesize new neutron-rich heavy nuclei.