Measurement of total and partial cross sections of the

The origin of many p-nuclei remains an unsolved problem in nuclear astrophysics. While photo-dissociation reactions in the $$\gamma $$-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,$$\gamma $$)$$^{91}$$Nb reaction is part of a possible (p,$$\gamma $$) 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,$$\gamma $$)$$^{91}$$Nb reaction. We measured proton capture cross sections with an enriched $$^{90}$$Zr target using in-beam $$\gamma $$-ray spectroscopy for proton energies between 2.75 MeV and 5.1 MeV. The emitted $$\gamma $$-rays were detected using the HORUS (High efficiency Observatory for $$\gamma $$-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 $$\gamma $$-ray spectroscopy measurement by Laird et al.. We provide a possible explanation for the discrepancies between our data and other available measurements