pNAB: A Polarized Neutron Beta Decay Correlation Experiment

pNAB aims to measure the A and B correlation parameters in free neutron beta decay, requiring a polarized beam of cold neutrons. The collaboration will use the existing Nab spectrometer at the Fundamental Neutron Physics Beamline of the Spallation Neutron Source at Oak Ridge National Laboratory to perform this high precision measurement. In combination with others, this measurement will shed light on recent hints for a violation of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix. Motivation for and design of the experiment, with a particular focus on the methods planned to provide very high polarization of cold neutrons to minimize systematic uncertainty, will be presented.