Precision Polarization of Neutrons

Determining polarization of a cold neutron beam to high precision is required for the next generation neutron decay correlation experiments at the SNS, such as the proposed abBA and PANDA experiments. Precision polarimetry measurements were conducted at Los Alamos National Laboratory with the goal of determining the beam polarization to the level of 10$^{-3}$ or better. The cold neutrons from FP12 were polarized using optically polarized ${}^{3}$He gas as a spin filter, which has a highly spin-dependent absorption cross section. A second ${}^ {3}$He spin filter was used to analyze the neutron polarization after passing through a resonant RF spin rotator. A discussion of the experiment and results will be given.