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HK: Fachverband Hadronen und Kerne

HK 28: Nuclear Astrophysics

HK 28.3: Talk

Tuesday, March 17, 2009, 15:00–15:15, H-ZO 60

In-beam experiments on (p,γ) and(α,γ) reactions for the astrophysical p process — •Jens Hasper, Marc Büssing, Michael Elvers, Janis Endres, and Andreas Zilges — Institut für Kernphysik, Universität zu Köln

Whereas most nuclei heavier than iron can be produced by neutron-capture processes, 35 proton-rich nuclei are believed to be synthesized exclusively by the p process in the explosive scenario of supernovae type II. This process involves an extensive reaction network consisting of about ten thousand (γ,n), (γ,p) and (γ,α) reactions on more than thousand nuclei. Due to the absence of experimental data, p-process network calculations are based almost completely on theoretically predicted reaction rates, which are subject to rather large uncertainties. A comprehensive experimental data base for these reaction rates is strongly required to improve the accuracy of p-process models. In the last decade increasing effort has been made to provide experimental data on (p,γ) and (α,γ) reactions at astrophysically relevant energies. Most of these experiments have been based on the activation technique which is restricted to the investigation of a very limited number of nuclei. This limitation can be overcome by measuring (p,γ) and (α,γ) reactions directly in in-beam experiments. A particularly suited experimental tool for these measurements is provided by the highly-efficient HPGe detector array HORUS at the ion TANDEM accelerator at the University of Cologne. We will present first results of experiments performed at HORUS on (p,γ) reactions of relevance for the p process.

This project is supported by the DFG under contract ZI 510/5-1.