Characterizing the AFP Spin Flipper for the Nab Experiment

The Nab experiment at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) aims to yield a precise measurement of the electron-neutrino correlation parameter, a, to ∆a/a ≈ 3×10^-4 from the β-decay of the free neutron. To achieve Nab’s precision goal, it is required that there is near-zero polarization of the neutron beam. A polarizer/analyzer combination, neutron monitors, and an Adiabatic Fast Passage (AFP) spin flipper will be used to determine a beam polarization effectively less than P_n = 2×10^-5. Here, I will discuss the initial characterization efforts of the Nab spin flipper as well as the plans for further testing and its ultimate role once installed on the Fundamental neutron Physics Beamline (FnPB).