New

The rates of the 18F(p,α) 15O and 18F(p,γ) 19Ne reactions in astrophysical environments depend on the properties of 19Ne levels above the 18F + p threshold. There are at least 8 levels in the mirror nucleus 19F for which analogs have not been observed in 19Ne in the excitation energy range E x = 6.4-7.6MeV. We have made a search for these levels by measuring the 1H( 18F, p) 18F excitation function over the energy range E c.m. = 0.3-1.3MeV. We have identified and measured the properties of a newly observed level at E x = 7.420±0.014MeV, which is most likely the mirror to the J π = 7/2+ 19F level at 7.56MeV. This new level is found to increase the calculated 18F(p,α) 15O reaction rate by 16%, 63%, and 106% at T = 1, 2, and 3GK, respectively