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 can not 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 , \gamma ) activation measurements , related by detailed balance to the respective photodisintegrations , were carried out at the Karlsruhe Van de Graaff accelerator using the ^ { 7 } Li ( p , n ) ^ { 7 } Be source for simulating a Maxwellian neutron distribution of kT = 25 keV .
First results for the experimental ( n , \gamma ) cross sections of the light p nuclei ^ { 74 } Se and ^ { 84 } Sr are reported .
These experimental values were used for an extrapolation to the Maxwellian averaged cross section at 30 keV , < \sigma > _ { 30 } , yielding 271 \pm 15 mb for ^ { 74 } Se , and 300 \pm 17 mb for the total capture cross section of ^ { 84 } Sr .
The partial cross section to the isomer in ^ { 85 } Sr was found to be 190 \pm 10 mb .