Astrophysics studies relevant to stellar x-ray bursts

Two reactions of 14O(α,p)17F and 18Ne(α,p)21Na provide the pathways for breakout from the hot CNO cycles to the rp-process in type I X-ray bursts. To better determine their astrophysical reaction rates, resonance parameters of the compound nuclei 18Ne and 22Mg have been investigated by the resonant elastic scattering of 17F+p and 21Na+p, respectively. The 17F and 21Na radioactive ion beams were produced at the CNS Radioactive Ion Beam Separator and impinged on the thick proton targets. The excitation functions were obtained with a thick-target method over a wide excitation energy range. The resonance parameters in the compound nuclei 18Ne and 22Mg have been determined through an R-matrix analysis. New reaction rates of these two (α,p) reactions are recalculated. The astrophysical impact for the 18Ne(α,p)21Na reaction has been investigated through one-zone postprocessing X-ray burst calculations.