The Cu(p,α)Ni cross section and heavy element nucleosynthesis in core collapse supernovae

In the research field of heavy element nucleosynthesis, the origin of p-nuclei has been a longstanding problem. They are thought to be produced in the hot environments such as supernovae via p-capture and γ-disintegration processes. But with these processes, most stellar models fail to reproduce the observed abundances of the lighter p-nuclei Mo and Ru [1]. In a study by Fröhlich et al., a new process called the νp-process was suggested as an explanation for the abundances of p-nuclei with A>64 [2]. However, the competition between (p,α) and (p,γ) reactions on Cu in an end-point cycle could hinder the reaction flow to the heavier elements by cycling the material back [3]. This competition is temperature sensitive and it is crucial to measure the Cu(p,α)Ni reaction cross section in order to obtain reliable modelling results. Additionally, this reaction is of key importance to the light curve of X-ray bursts and the ashes’ composition on the surface of the neutron star [4]. We have carried out the first direct measurement of the Cu(p,α)Ni reaction cross section. The experiment was performed at the recently upgraded HIE-ISOLDE facility at CERN in inverse kinematics bombarding a CH2 target with a high intensity radioactive Cu beam at beam energies between 3.6 5.0 MeV/u. I will present the experimental procedure, data analysis and first results.