Enhancement of fusion at near and sub-barrier energies for neutron-rich light nuclei

TL;DR

This study measures fusion cross-sections of neutron-rich 19O with 12C at near-barrier energies, revealing a significant enhancement over 18O, suggesting dynamic effects influence fusion in neutron-rich light nuclei relevant to neutron star crusts.

Contribution

First experimental measurement of 19O + 12C fusion cross-sections at near-barrier energies, highlighting the importance of dynamic effects in fusion of neutron-rich light nuclei.

Findings

Significant fusion enhancement for 19O + 12C compared to 18O + 12C.

Static models do not predict the observed enhancement.

Dynamic effects are crucial in understanding fusion of neutron-rich nuclei.

Abstract

Measurement of the fusion cross-section for neutron-rich light nuclei is crucial in ascertaining if fusion of these nuclei occurs in the outer crust of a neutron star. We have therefore measured the fusion excitation function at near-barrier energies for the 19O + 12C system and compared the experimental results with the fusion excitation function of 18O + 12C and 16O + 12C. In the experiment a beam of 19O, produced via the 18O(d,p) reaction, was incident on a 12C target at energies near the Coulomb barrier. Evaporation residues produced in fusion of 18,19O ions with 12C target nuclei were detected with good geometric efficiency and identified by measuring their energy and time-of-flight. A significant enhancement in the fusion probability of 19O ions with a 12C target as compared to 18O ions is observed. The significantly larger cross-sections observed at near barrier energies are not predicted by a static model of fusion for 19O + 12C indicating that dynamics play an important role in the fusion of neutron-rich light nuclei.