Reduced quasifission competition in fusion reactions forming neutron-rich heavy elements

TL;DR

This study investigates how neutron-rich conditions influence quasifission in fusion reactions, showing increased fusion probability with higher neutron-to-proton ratios, supported by experimental measurements and microscopic calculations.

Contribution

It provides the first model-independent experimental evidence linking neutron richness to reduced quasifission in heavy element formation.

Findings

Increased contact time with higher (N/Z)CN

Enhanced mass evolution of quasifission fragments

Agreement with microscopic Hartree-Fock calculations

Abstract

Measurements of mass-angle distributions (MADs) for Cr + W reactions, providing a wide range in the neutron-to-proton ratio of the compound system, (N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be determined in a model-independent way. Previous experimental and theoretical studies had produced conflicting conclusions. The experimental MADs reveal an increase in contact time and mass evolution of the quasifission fragments with increasing (N/Z)CN, which is indicative of an increase in the fusion probability. The experimental results are in agreement with microscopic time-dependent Hartree-Fock calculations of the quasifission process. The experimental and theoretical results favor the use of the most neutron-rich projectiles and targets for the production of heavy and superheavy nuclei.