Atomic Electric Dipole Moment Measurement Using Spin Exchange Pumped Masers of129Xeand3He

We have measured the $T$-odd permanent electric dipole moment of ${}^{129}\mathrm{Xe}$ with spin exchange pumped masers and a ${}^3\mathrm{He}$ comagnetometer. The comagnetometer provides a direct measure of several systematic effects that may limit electric dipole moment sensitivity, and we have directly measured the effects of changes in leakage current that result when the applied electric field is changed. Our result, $d{(}^{129}\mathrm{Xe})=0.7\mathrm{}\pm 3.3(\mathrm{stat})\pm 0.1(\mathrm{syst})\times {10}^{-27\mathrm{}}e\mathrm{cm}$, is a fourfold improvement in sensitivity.