Bonn 2010 – wissenschaftliches Programm
HK 55.1: Gruppenbericht
Donnerstag, 18. März 2010, 16:30–17:00, HG VI
Experimental constraints on the stellar 63Ni(n,γ)64Ni cross section — •Iris Dillmann — Physik Department E12 und Excellence Cluster Universe, TU München
63Ni (t1/2=101 y) is an important branching point in the weak s-process flow, but experimental information is still missing for the 63Ni(n,γ) as well as for the inverse 64Ni(γ,n) reaction. We have measured the 64Ni(γ,n)63Ni cross section via photoactivation using bremsstrahlung at end-point energies of 10.3, 11.5, and 13.4 MeV from the ELBE facility in Dresden-Rossendorf followed by Accelerator Mass Spectrometry (AMS) at the MLL accelerator in Garching [1,2]. The irradiation at 13.4 MeV revealed a cross section which is lower by a factor of 2 compared to NON-SMOKER predictions. Calculations of s-process nucleosynthesis in massive stars showed that this change has no influence during core He burning and 63Ni can decay to 63Cu. However, with the higher temperatures and neutron densities during convective shell C burning this lower cross section will change strongly the final abundances of 63Cu (+30%) and 64Ni (−20%).
This research is supported by the DFG cluster of excellence "Origin and Structure of the Universe"
 Stephan Walter, Ph. D. thesis (Universität Karlsruhe) 2008.
 I. Dillmann et al., Nucl. Instr. and Meth. B (2009), doi: 10.1016/j.nimb.2009.10.153