The "missing" 3(+) state of 18Ne and explosive 17F(p, gamma ) burning.

Abstract

Wiescher, G\orres, and Thielemann suggested that a missing ${J}^{\ensuremath{\pi}}={3}^{+}$ level in $^{18}\mathrm{Ne}$ should occur at ${E}_{x}\ensuremath{\approx}4.33$ MeV, only \ensuremath{\approx}410 keV above the $^{17}\mathrm{F}$+$p$ threshold. They noted that this level would provide an $s$-wave resonance in the $^{17}\mathrm{F}(p, \ensuremath{\gamma})$ reaction, greatly increasing its thermonuclear reaction rate. This, in turn, would have a pronounced effect on the production of $^{17}\mathrm{O}$ and $^{18}\mathrm{O}$ in explosive stellar environments. We have searched for this level using the $^{16}\mathrm{O}(^{3}\mathrm{He}, n)$ reaction. High-resolution time-of-flight spectra show that the ${3}^{+}$ level occurs at ${E}_{x}=4.561\ifmmode\pm\else\textpm\fi{}0.009$ MeV, \ensuremath{\approx}230 keV higher than suggested. The astrophysical consequences of this result are discussed.