Fusion Enhancement for Neutron-Rich Light Nuclei

TL;DR

This study measures fusion cross-sections of neutron-rich light nuclei, revealing a significant enhancement in fusion probability for $^{19}$O compared to $^{18}$O, which has implications for neutron star crust composition.

Contribution

It provides new experimental data on fusion excitation functions for neutron-rich nuclei near the Coulomb barrier, highlighting fusion enhancement mechanisms.

Findings

Significant fusion enhancement for $^{19}$O + $^{12}$C compared to $^{18}$O + $^{12}$C.

Observation of narrowing of the fusion barrier at near-barrier energies.

Larger tunneling probability for neutron-rich $^{19}$O 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. The fusion excitation function at near-barrier energies for the $^{19}$O + $^{12}$C system was measured and the experimental results are compared to the fusion excitation function of $^{18}$O + $^{12}$C and $^{16}$O + $^{12}$C. The experiment was performed by utilizing a beam of $^{19}$O, produced via the $^{18}$O(d,p) reaction, to bombard a $^{12}$C target at energies near the Coulomb barrier. Evaporation residues produced in fusion of $^{18,19}$O ions with $^{12}$C target nuclei were detected with good geometric efficiency and identified by measuring their energy and time-of-flight. A significant enhancement is observed in the fusion probability of $^{19}$O ions with a $^{12}$C target as compared to $^{18}$O ions. The larger cross-sections observed at near barrier energies is related to significant narrowing of the fusion barrier indicating a larger tunneling probability for the fusion process.