The astrophysically important 3+ state in 18Ne and the 17F(p,γ)18Ne stellar rate -: art. no. 055804

Knowledge of the F-17(p, gamma)Ne-18 reaction rate is important for understanding stellar explosions, but it was uncertain because the properties of an expected but previously unobserved 3(+) state in Ne-18 were not known. This state would provide a strong s-wave resonance for the F-17+p system and, depending on its excitation energy, could dominate the stellar reaction rate at temperatures above 0.2 GK. We have observed this missing 3(+) state by measuring the H-1(F-17,p)F-17 excitation function with a radioactive F-17 beam at the ORNL Holifield Radioactive Ion Beam Facility (HRIBF). We find that the state lies at a center-of-mass energy of E-r=599.8. +/-1.5(stat)+/-2.0(sys) keV (E-x=4523.7+/-2.9 keV) and has a width of Gamma =18+/-2(stat)+/-1(sys) keV. The measured properties of the resonance are only consistent with a J(pi)=3(+) assignment.