Neutron reactions in massive stars and the origin of 60 Fe

Slow neutron capture reactions in massive stars are substantially contributing to the abundances of the elements between Fe and Zr, producing the so-called weak s component. The weak s process is characterized by a low neutron exposure, where the reaction flow does not reach equilibrium conditions. As a consequence, uncertainties in the stellar (n,γ) rates give rise to large propagation effects. This is illustrated by the impact of recently improved experimental cross sections. Massive stars are also the main production site of the unstable isotope 60Fe, which provides an important chronometer for the early solar system. The successful measurement of the stellar (n,γ) cross section of 60Fe represents an important step towards a quantitative determination of the s-process origin of 60Fe in massive stars.