Reduced Limit on the Permanent Electric Dipole Moment of 199 Hg

Abstract

This thesis describes an experiment to measure the permanent electric dipole moment (EDM) of 199Hg. The EDM is manifested as a small perturbation to the Larmor precession frequency due to the interaction energy of the electric dipole with a static electric field. The atoms are prepared in four separate glass vapor cells using optical pumping with resonant 254 nm laser light and allowed to precess in a common magnetic field and oppositely-directed electric fields. The precession frequency difference in a pair of cells is derived from the accumulated phase difference between two probe periods separated in time. Using this technique, we find the 199 Hg EDM projection onto the nuclear spin axis d Hg = (2.20±2.75 stat ±1.48 syst )·10 −30 e·cm. While consistent with zero, this result places a new upper limit on the 199 Hg EDM |d Hg | < 7.4 · 10 −30 e · cm (95% C.L.), improving the previous best limit by a factor of > 4. The new limit places stringent constraints on theories of physics beyond the Standard Model which incorporate new sources of time-reversal or CP symmetry violation. This work was supported by NSF Grant No. 1306743 and the U.S. Department of Energy Office of Science, Office of Nuclear Physics under Award No. DE-FG02-97ER41020.