Towards an Apparatus for High-Precision Measurements of the Permanent Nuclear Electric Dipole Moment*

For decades, the study of electric dipole moments (EDMs) has probed symmetry-violating properties beyond the Standard Model of physics, with measurements of ³He and ¹²⁹Xe's nuclear EDMs (nEDMs) being particularly valuable. Although such measurements have been performed thoroughly by Oak Ridge National Laboratory and CERN, it is nevertheless beneficial to continue experimentation. Here we detail a simple experimental process implemented to calculate the nEDMs of ³He and ¹²⁹Xe. Using spin-exchange optical pumping, our gas samples were polarized to their theoretical maximums before being cooled and transferred to our experimental apparatus. This device was designed with separate electric and magnetic fields that were applied to induce and observe the free induction decays (FIDs) of the gases in various states. FID signals were recorded and analyzed for ³He through chi-squared minimization of the Breit-Wigner distribution and a dipole moment of d = (-0.4 ± 1.4) × 10^-17 e·cm was calculated with an established upper bound of d < 3.2 × 10^-18 e·cm at the 95% confidence level. Analogous measurements for ¹²⁹Xe were unsuccessful as its polarization could not be confirmed. Although our upper bound is roughly ten orders of magnitude higher than existing measurements, this work contributes to ongoing efforts investigating physics beyond the Standard Model.