The nucleosynthesis of elements beyond iron is dominated by the s and r processes. However, a small amount of stable isotopes on the proton-rich side cannot be made by neutron capture and are thought to be produced by photodisintegration reactions on existing seed nuclei in the so-called "p process". So far most of the p-process reactions are not yet accessible by experimental techniques and have to be inferred from statistical Hauser-Feshbach model calculations. The parametrization of these models has to be constrained by measurements on stable proton-rich nuclei. A series of (n,γ) activation measurements, related by detailed balance to the respective photodisintegrations, were carried out at the Karlsruhe Van de Graaff accelerator using the 7Li(p,n)7Be source for simulating a Maxwellian neutron distribution of kT= 25 keV. First results for the experimental (n,γ) cross sections of the light p nuclei 74Se and 84Sr are reported. These experimental values were used for an extrapolation to the Maxwellian averaged cross section at 30 keV, <σ>30, yielding 271±15 mb for 74Se, and 300±17 mb for the total capture cross section of 84Sr. The partial cross section to the isomer in 85Sr was found to be 190±10 mb.
@article{arxiv.0805.4747,
title = {Experimental (n,$\gamma$) cross sections of the p-process nuclei $^{74}$Se and $^{84}$Sr},
author = {I. Dillmann and M. Heil and F. Käppeler and T. Rauscher and F. -K. Thielemann},
journal= {arXiv preprint arXiv:0805.4747},
year = {2009}
}