Structure ofNe18and the breakout from the hot CNO cycle

We used the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ${(}^3$He,n${)}^{18}$Ne, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ${(}^{12}$C${,}^6$He${)}^{18}$Ne, and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$(p,t${)}^{18}$Ne reactions to study ${}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ states up to an excitation energy of 10 MeV, with emphasis on levels corresponding to ${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$(α,p${)}^{17}$F and ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$(p,γ${)}^{18}$Ne resonances that could strongly affect these reaction rates in hot stellar environments. Excitation energies, widths, absolute cross sections, and angular distributions were measured. We found previously unidentified states at ${\mathit{E}}_{\mathit{x}}$=6.15±0.01 MeV, 7.12±0.02 MeV, 7.35±0.02 MeV, 7.62±0.02 MeV, 8.30±0.02 MeV, (8.45±0.03 MeV), 8.55±0.03 MeV, 8.94±0.02 MeV, and 9.58±0.02 MeV. We combined level width, cross section, and angular distribution data to infer ${\mathit{J}}^{\mathrm{\pi }}$ values for a number of the new levels as well as for the previously known 5.1-MeV doublet. Using information from our experiments, we recalculated the ${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$(α,p${)}^{17}$F reaction rate, which constitutes a possible path out of the hot CNO cycle into the rp process and could play an important role in transforming nuclei involved in the hot CNO cycle into heavier nuclei with Z≥10. © 1996 The American Physical Society.