s-Process nucleosynthesis and the interior of Red Giants

Nucleosynthesis by the slow neutron capture process (s process) in the He burning zones of Red Giant stars contributes about half of the isotopic abundances in the mass region between Fe and Bi. Since these abundances are essentially determined by the respective neutron capture cross sections of stable and long-lived isotopes, the nuclear physics part of the s-process problem can be studied in laboratory experiments. The status of these data and the remaining experimental quests are briefly sketched in the light of recent achievements and future possibilities. Presently, s-process calculations are capable of providing a quantitative description of the observed abundances that can be attributed to an s-process origin. Moreover, these results can be interpreted as constraints for models of the red giant phase, an important feature for improving our understanding of persisting difficulties in stellar evolution.