α -unbound levels in Ar 34 from Ar 36 (p,t) Ar 34 reaction measurements and implications for the astrophysical S 30 (α,p) Cl 33 reaction rate

The S30(α,p)Cl33 reaction has been identified in several type-1 x-ray burst (XRB) sensitivity studies as a significant reaction within the αp process, possibly influencing not only the abundances of burst ashes but also the bolometric shape of double-peaked light curves coming from certain XRB systems. Given the dearth of experimental data on the S30(α,p) Cl33 reaction at burst temperatures, we have performed high energy-resolution forward-angle Ar36(p,t)Ar34 measurements in order to identify levels in Ar34 that could appear as resonances in the S30(α,p)Cl33 reaction. Energies of levels identified in this work, along with model-based assumptions for spin assignments and spectroscopic factors, were then used to determine a rate for the S30(α,p)Cl33 reaction based on a narrow-resonance formalism. The rates determined in this work are then compared with two standard Hauser-Feshbach model predictions over a range of XRB temperatures.