Measurement of total and partial cross sections of the $$^{90}$$Zr(p,$$\gamma $$)$$^{91}$$Nb reaction with in-beam $$\gamma $$-ray spectroscopy

Abstract

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