F. Käppeler

Kernforschungszentrum Karlsruhe, Institut für Kernphysik
D-7500 Karlsruhe, Federal Republic of Germany

The quantitative description of neutron capture nucleosynthesis requires the neutron capture cross sections of all involved isotopes. Only with this data base the observed abundances can be interpreted in terms of the physical conditions prevailing at the respective stellar sites. In this contribution, importance and status of stellar capture rates for the s- and r-process are outlined. The role of model calculations is emphasized as an essential complement to laboratory measurements, e.g. for determining the cross sections of short-lived isotopes that are not accessible to present experimental techniques as well as for describing the influence of temperature. The latter may cause the stellar rates to deviate significantly from laboratory values. Possible experimental improvements are discussed in connection with new developments in detector techniques and neutron sources.

KEYWORDS: nucleosynthesis, s- and r-process, neutron capture cross sections, 1 < En < 200 keV