Measurement of the fusion excitation function for $^{19}$O + $^{12}$C at near barrier energies*

Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for $^{18}$O and $^{19}$O nuclei incident on a $^{12}$C target. A beam of $^{19}$O was produced by the $^{18}$O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting $^{19}$O beam bombarded a 100 $\mu$g/cm$^2$ $^{12}$C target at an intensity of 2-4 x 10$^{3}$ p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Using silicon detectors, micro-channel plate detectors, and an ionization chamber, evaporation residues were detected in the angular range $\theta_{lab}$ $\leq$ 23$^{\circ}$ with high efficiency. Initial experimental results including measurement of the fusion cross-section to approximately the 100 mb level will be presented. The measured excitation function will be compared to theoretical predictions.