Bochum 2009 – scientific programme
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HK: Fachverband Hadronen und Kerne
HK 60: Nuclear Astrophysics
HK 60.2: Group Report
Wednesday, March 18, 2009, 17:00–17:30, H-ZO 60
Neutron-capture cross sections of Fe-peak seed nuclei — •I Dillmann1, T Faestermann1, G Korschinek1, J Lachner1, M Poutivtsev1, G Rugel1, F Käppeler2, S Walter2, C Domingo-Pardo3, M Heil3, R Reifarth3, L Coquard4, A Wallner5, K Buczak5, and C Lederer5 — 1Physik-Department and Excellence Cluster Universe, Technische Universität München — 2Forschungszentrum Karlsruhe — 3Gesellschaft für Schwerionenforschung — 4Technische Universität Darmstadt — 5VERA, Fakultät für Physik, Universität Wien
About 50% of the elements beyond iron are produced via the s process. In the vicinity of the Fe seed the resulting abundances are dominated by the weak s-process component. The neutron exposure here is not strong enough that the so-called local equilibrium is reached. Accordingly, the neutron capture rate of a nucleus, which experiences the entire mass flow, will affect also the abundances of all isotopes in the following reaction chain and hence the overall s-process efficiency as well.
Recently the neutron-capture cross sections of 54,58,60Fe and 58,62,64Ni were measured with the activation technique at kT= 25 keV. The number of produced 55Fe, 59Ni, and 63Ni atoms were then determined with accelerator mass spectrometry.
For extrapolation to higher and lower temperatures an accurate knowledge of the energy dependence is required. A campaign to measure these cross sections with the time-of-flight technique is scheduled for 2009/10 at the CERN/n_TOF facility.