Measurements of the $^{96}$Zr($\alpha$,n)$^{99}$Mo cross section for astrophysics and applications

TL;DR

This study measures the $^{96}$Zr($ ext{α}$,n)$^{99}$Mo reaction cross section, revealing higher values at low energies than previous data, which influences astrophysical models and medical isotope production.

Contribution

The paper provides new experimental cross section data for $^{96}$Zr($ ext{α}$,n)$^{99}$Mo and compares it with theoretical models, improving understanding of reaction rates relevant to astrophysics and medicine.

Findings

Larger cross section at low energies than previous measurements.

Implications for increased astrophysical reaction rates.

Phenomenological optical potentials may be adequate with adjustments.

Abstract

The reaction $^{96}$Zr($\alpha$,n)$^{99}$Mo plays an important role in $\nu$-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 $^{96}{\rm Zr}(\alpha,n)$ cross section and $^{96}{\rm Zr}(\alpha,\alpha)$ 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 $\nu$-driven wind nucleosynthesis calculations, but does not significantly alter prior conclusions about $^{99}{\rm Mo}$ 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 $\nu$-driven wind nucleosynthesis, albeit with regionally-adjusted model parameters.