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

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, ${(N/Z)}_{\mathrm{CN}}$, have allowed for the dependence of quasifission on the ${(N/Z)}_{\mathrm{CN}}$ 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 ${(N/Z)}_{\mathrm{CN}}$, 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.