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The slow neutron capture process produces heavy elements in different stellar sites at different temperatures. Neutron capture cross sections for stellar temperatures between kBT = 5 keV and kBT = 100 keV are crucial for a quantitative understanding of the s-process abundance distribution. Over the last decade activation measurements were performed at the Goethe University Frankfurt to study cross sections at a temperature of kBT = 25 keV. We developed a new method to measure neutron capture cross sections at kBT = 6 keV.

About 50% of the elements heavier than iron are produced during the slow neutron capture process. This process occurs in different stellar sites at various energies. To understand the ongoing nucleosynthesis, the probability of a neutron capture for different temperatures and therefore for different stellar sites is essential. Activation experiments using the 7Li(p,n) reaction as neutron source were performed. At a temperature of kBT = 25 keV the cross sections were determined for 27Al, 37Cl and 41K. A new method was developed to perform activation experiments at even lower temperatures. For a proof of principle, the cross section for 64Ni was measured at kBT = 25 keV as well as for kBT = 6 keV. To study the impact of isomeric states at higher energies, activations of 181Ta were performed using two different proton energies.