Differential cross sections of the ${}_{16}O(n,\alpha )$ reaction at neutron energies from 3.8 to 15 MeV

The importance of studying the ${}_{16}O(n,\alpha )$ reaction is motivated by multiple nuclear applications which rely on an accurate nuclear reaction data library for oxygen. Discrepancies between past experimental data on the ${}_{16}O(n,\alpha ){}_{13}C$ reaction and its time-reverse ${}_{13}C(\alpha ,n){}_{16}O$ reaction have led to various different nuclear data evaluations. We have measured ${}_{16}O(n,\alpha )$ reaction cross sections using the LENZ instrument with the unmoderated white neutron source at LANSCE. Results from 2016/2017 data are discussed and used to benchmark the mcnp and geant simulations of the LENZ experimental setup. We report partial differential cross sections of ${}_{16}O(n,{\alpha }_0)$ at $E_n=3.8–15$ MeV and ${}_{16}O(n,{\alpha }_1+{\alpha }_2+{\alpha }_3)$ at $E_n=9–15$ MeV, based on the new measurement in 2021. The resonances that we observed are in good agreement with the levels in ${}_{17}O$ that were previously measured. The LENZ cross sections are in better agreement with the ENDF/B-VIII.0 evaluation than the with reduced cross section found in ENDF/B-VII.1 up to 6 MeV. However, the current results for ${}_{16}O(n,{\alpha }_0){}_{13}C_{g.s.}$ appear to be in the best agreement over the entire energy range with that of JENDL/AN-2005 (ENDF/B-VI.0).