Measurement of Neutron Polarization and Transmission for the nEDM@SNS Experiment.

The neutron electric dipole moment experiment at the Spallation Neutron Source (nEDM@SNS) will implement a novel method, which utilizes polarized ultra-cold neutrons (UCN) and polarized $^3$He in a bath of superfluid $^4$He, to place a new limit on the nEDM down to 2-3×10$^{−28}$ e·cm. The experiment will employ a cryogenic magnet and magnetic shielding package to provide the required magnetic field environment to achieve the proposed sensitivity. This talk will describe the design and implementation of $^3$He polarimetry setup at the SNS to measure the neutron polarization and transmission losses resulting from passage through the magnetic shielding and cryogenic windows.