Investigation of a $^{129}$Xe magnetometer for the Neutron Electric Dipole Moment Experiment at TRIUMF

A non-zero neutron electric dipole moment (nEDM) would signify a previously unknown source of CP (or T) violation. New sources of CP violation are believed to be required to explain the baryon asymmetry of the universe. Employing a newly developed high-density UCN source, an experiment at TRIUMF aims to measure the nEDM to the level of $10^{-27}~e\cdot$cm in its initial phase. Precession frequency differences for UCN stored in a bottle subject to parallel and anti-parallel E and B fields signify a permanent nEDM. Magnetic field instability and inhomogeneity, as well as field changes resulting from leakage currents (correlated with E fields) are the dominant systematic effects in nEDM measurements. To address this, passive and active magnetic shielding are in development along with a dual species ($^{129}$Xe and $^{199}$Hg) atomic comagnetometer. Simultaneously introducing both atomic species into the UCN cell, the comagnetometer can mitigate false EDMs. $^{199}$Hg precession will be detected by Faraday rotation spectroscopy, and $^{129}$Xe precession will measured via two-photon excitation and emission. The present comagnetometer progress will be discussed, with focus on polarized $^{129}$Xe production and delivery.