New Ne-19 resonance observed using an exotic F-18 beam

Abstract

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