New Astrophysical Reaction Rates for 18F(p, α) 15O and 18F(p, γ)19Ne

Neng Chuan Shu, China Institute of Atomic Energy
D. W. Bardayan, ORNL Physics Division
J. C. Blackmon, ORNL Physics Division
Yong Shou Chen, China Institute of Atomic Energy
R. L. Kozub, Tennessee Technological University
P. D. Parker, Yale University
M. S. Smith, ORNL Physics Division


The rates of the thermonuclear 18F(p, α)15O and 18F(p, γ)19Ne reactions in hot astrophysical environments are needed to understand gamma-ray emission from nova explosions. The rates for these reactions have been uncertain due to discrepancies in recent measurements, as well as to a lack of a comprehensive examination of the available structure information in the compound nucleus 19Ne. We have examined the latest experimental measurements with radioactive and stable beams, and made estimates of the unmeasured 19Ne nuclear level parameters, to generate new rates with uncertainties for these reactions. The rates are expressed as numerical values over the temperature range relevant for stellar explosions, as well as analytical expressions as functions of temperature in a format suitable for use in astrophysical simulations. Comparisons with the previous rate calculations are carried out, and the astrophysical implications are briefly discussed.