Measurements of the Zr-96(a, n) Mo-99 cross section for astrophysics and applications

The reaction Zr-96(alpha, n) Mo-99 plays an important role in v-driven wind nucleosynthesis in core-collapse supernovae and is a possible avenue for medical isotope production. Cross-section measurements were performed using the activation technique at the Edwards Accelerator Laboratory. Results were analyzed along with world data on the Zr-96(alpha, n) cross section and Zr-96(alpha, alpha) differential cross section using large-scale Hauser-Feshbach calculations. We compare our data, previous measurements, and a statistical description of the reaction. We find a larger cross section at low energies compared to prior experimental results, allowing for a larger astrophysical reaction rate. This may impact results of core-collapse supernova v-driven wind nucleosynthesis calculations but does not significantly alter prior conclusions about Mo-99 production for medical physics applications. The results from our large-scale Hauser-Feshbach calculations demonstrate that phenomenological optical potentials may yet be adequate to describe (alpha, n) reactions of interest for v-driven wind nucleosynthesis, albeit with regionally adjusted model parameters.