Search for astrophysically important ¹⁹Ne levels with a thick-target ¹⁸F(p,p)¹⁸F measurement

D. W. Bardayan, ORNL Physics Division
J. C. Blackmon, ORNL Physics Division
J. Gómez Del Campo, ORNL Physics Division
R. L. Kozub, Tennessee Technological University
J. F. Liang, ORNL Physics Division
Z. Ma, The University of Tennessee, Knoxville
L. Sahin, The University of North Carolina at Chapel Hill
D. Shapira, ORNL Physics Division
M. S. Smith, ORNL Physics Division

Abstract

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 eight levels in the mirror nucleus 19F for which analogs have not been observed in 19Ne in the excitation energy range Ex=6.4-7.6 MeV. These levels may significantly enhance the 18F+p reaction rates, and thus we have made a search for these levels by measuring the 1H( 18F,p)18F excitation function over the energy range E c.m.=0.3-1.3 MeV. We have identified and measured the properties of a newly observed level at Ex=7.420±0.014 MeV, which is most likely the mirror to the Jπ= 7/2+19F level at 7.56 MeV. We have additionally found a significant discrepancy with a recent compilation for the properties of a 19Ne state at Ex,=7.5 MeV and set upper limits on the proton widths of missing levels.