Timing and Energy Calibrations for Systematic Studies in Nab

Neutron beta-decay provides crucial information towards testing the unitarity of the CKM matrix through the parameter $V_{ud}$. Nab's overarching goal is to determine $`a`$- the angular correlation between the electron and the antineutrino- and $`b`$ the electron energy spectrum. Timing and energy calibrations are essential for minimizing systematic effects in the Nab experiment. One strategy to accomplish this is by using radioactive sources with electron-gamma ray coincidences to calibrate a CeBr3 scintillator which will be used as a stopwatch for the Nab detectors. In this presentation we will show how we calibrate the CeBr3 detector to less than a nanosecond, the analyses performed,

and outline future work at Oak Ridge National Lab.