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