The rates of the 18 F͑p , ␣͒ 15 O and 18 F͑p , ␥͒ 19 Ne reactions in astrophysical environments depend on the properties of 19 Ne levels above the 18 F+ p threshold. There are at least eight levels in the mirror nucleus 19 F for which analogs have not been observed in 19 Ne in the excitation energy range E x = 6.4-7.6 MeV. These levels may significantly enhance the 18 F+ p reaction rates, and thus we have made a search for these levels by measuring the 1 H͑ 18 F, p͒ 18 F excitation function over the energy range E c.m. = 0.3-1.3 MeV. We have identified and measured the properties of a newly observed level at E x = 7.420± 0.014 MeV, which is most likely the mirror to the J = 7 2 + 19 F level at 7.56 MeV. We have additionally found a significant discrepancy with a recent compilation for the properties of a 19 Ne state at E x = 7.5 MeV and set upper limits on the proton widths of missing levels.

The degree to which the (p, γ) and (p, α) reactions destroy 18 F at temperatures 1-4×10 8 K is important for understanding the synthesis of nuclei in nova explosions and for using the long-lived radionuclide 18 F, a target of γ-ray astronomy, as a diagnostic of nova mechanisms. The reactions are dominated by low-lying proton resonances near the 18 F+p threshold (E x =6.411 MeV in 19 Ne).

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