Activation measurements of neutron capture cross sections at various temperatures

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 k_BT = 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 k_BT = 25 keV as well as for k_BT = 6 keV. To study the impact of isomeric states at higher energies, activations of ¹⁸¹Ta were performed using two different proton energies.