First measurement of the Ru 96 (p,γ) Rh 97 cross section for the p process with a storage ring

This work presents a direct measurement of the Ru96(p,γ)Rh97 cross section via a novel technique using a storage ring, which opens opportunities for reaction measurements on unstable nuclei. A proof-of-principle experiment was performed at the storage ring ESR at GSI in Darmstadt, where circulating Ru96 ions interacted repeatedly with a hydrogen target. The Ru96(p,γ)Rh97 cross section between 9 and 11 MeV has been determined using two independent normalization methods. As key ingredients in Hauser-Feshbach calculations, the γ-ray strength function as well as the level density model can be pinned down with the measured (p,γ) cross section. Furthermore, the proton optical potential can be optimized after the uncertainties from the γ-ray strength function and the level density have been removed. As a result, a constrained Ru96(p,γ)Rh97 reaction rate over a wide temperature range is recommended for p-process network calculations.