Measurement of the $^{18}$O($\alpha$,n)$^{21}$Ne reaction for nuclear astrophysics.

The formation of supernova carbonaceous dust is thought to originate from the inner He-rich zones of massive stars. We can study the isotopic abundances of these presolar grains to gain insight into explosive stellar nucleosynthesis. Analysis of presolar grains from the Orgueil meteorite found that $^{18}$O had an isotopic enrichment of up to 98,000% over terrestrial abundance, in addition to high spatial correlation with hotspots of $^{15}$N. A potential cause of this is that during explosive He-shell burning, the bulk of neutrons required for $^{15}$N production are sourced from the $^{18}$O($\alpha$,n)$^{21}$Ne reaction. Previous measurements of this reaction, performed almost 60 years ago, have varying levels of uncertainty and contain no branching ratio or partial cross section information. To address this, a high-resolution study of the $^{18}$O($\alpha$,n)$^{21}$Ne reaction was conducted at the University of Notre Dame over the energy range E$_{\alpha}$ = 2-8 MeV. Outgoing neutrons from this reaction were detected with ODeSA and secondary gamma rays were detected with 2 HPGe detectors from the LANL GEANIE array. Preliminary partial differential cross sections and neutron angular distributions will be presented.