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The origin of many p-nuclei remains an unsolved problem in nuclear astrophysics. While photo-dissociation reactions in the γ -process can explain the production of many p-nuclei, some, notably 92 , 94 Mo and 96 , 98 Ru are underproduced in network calculations. The 90 Zr(p, γ ) 91 Nb reaction is part of a possible (p, γ ) reaction chain for the production of the p-nucleus 92 Mo. Available data show a large disagreement between the different reported cross sections measurements for the 90 Zr(p, γ ) 91 Nb reaction. We measured proton capture cross sections with an enriched 90 Zr target using in-beam γ -ray spectroscopy for proton energies between 2.75 MeV and 5.1 MeV. The emitted γ -rays were detected using the HORUS (High efficiency Observatory for γ -Ray Unique Spectroscopy) detector array at the University of Cologne, Germany. To account for the possible contribution of the 91 Zr(p,n) reaction, an enriched 91 Zr was irradiated. We measured production cross sections for the ground and isomeric state of 91 Nb as well as partial cross section for up to ten high-energy primary transitions. The results are in good agreement with a former in-beam γ -ray spectroscopy measurement by Laird et al.. We provide a possible explanation for the discrepancies between our data and other available measurements. [ABSTRACT FROM AUTHOR]

Neutron capture cross sections are one of the most important nuclear inputs to models of stellar nucleosynthesis of the elements heavier than iron. The activation technique and the time-of-flight method are mostly used to determine the required data experimentally. Recent developments of experimental techniques allow for new experiments on radioactive isotopes. Monte Carlo based analysis methods give new insights into the systematic uncertainties of previous measurements. We present an overview over the state-of-the-art experimental techniques, a detailed new evaluation of the 197Au(n,) cross section in the keV-regime and the corresponding re-evaluation of 63 more isotopes, which have been measured in the past relative to the gold cross section. [ABSTRACT FROM AUTHOR]