Measurement of 16O(n,n'γ) with CoGNAC at LANSCE and covariance reporting techniques*

Neutron transport codes like GEANT and MCNP rely on high-quality nuclear data. The Correlated Gamma-Neutron Array for sCattering (CoGNAC) project at Los Alamos National Laboratory is comprised by hemispheres of CLYC and liquid scintillator detectors to measure neutrons and gammas from MeV+ incident neutron scattering across much of the periodic table. Oxygen is common in the environment, increasing the importance of reliable 16O nuclear data. We will present a recent measurement of the 16O(n,n’γ) inelastic neutron scattering reaction in the range of 6.5-9.8 MeV, where (n,n’γ) reactions dominate the inelastic reaction channel, and a short discussion on data taken at higher energy, where (n,n’Z) reactions increasingly contribute.

Additionally, there is a strong need to improve nuclear data reporting. Nuclear data evaluations are filled with reasonable assumptions around measurements for which data and analyses are not available. The reliance on these assumptions can be reduced by reporting full and component-associated covariances that enable post-processing of results by evaluators. However, even modest datasets produce covariance matrices large enough to overwhelm print or digital databases such as EXFOR, and this problem will only grow with widespread adoption of covariance reporting. We will present work done to compress covariance matrices in a manner suitable for limited-space print and digital repositories.