MEASUREMENT OF THE SE-76(N,GAMMA) CAPTURE CROSS-SECTION AND PHENOMENOLOGICAL S-PROCESS STUDIES - THE WEAK COMPONENT

We have measured the excitation function of the reaction Se-76(n, gamma) in the energy range from 3 to 200 keV neutron energy. The Maxwellian-averaged capture cross section versus thermal energy kT has been calculated. For kT = 30 keV a value of 164 +/- 8 mbarn has been derived. The weak component s-process in the mass range A = 56 to 90 has been studied. Two models for the weak component, an s-process with an exponential exposure distribution and an s-process with a distinct single exposure, have been discussed. For a consistent description of the abundances of the weak component s-process under realistic stellar conditions a considerable part of the material produced during core He-burning in massive stars must be reprocessed by subsequent C-burning. The solar Kr-abundance was determined to be (47 +/- 5)/10(6) Si.