The search for a permanent electric dipole moment using 129Xe and 3He

Abstract

Time reversal and parity non‐invariant interactions within an atom naturally give rise to an atomic permanent electric dipole moment (PEDM). For noble gas atoms, the size of such a PEDM scales as Z2 and higher powers of Z depending on the actual manifestation of T non‐invariance, most importantly a distribution of electric dipole moment within the nucleus (Schiff Moment) and a T‐odd tensor interaction between the nucleus and atomic electrons. We have developed techniques to simultaneously measure the PEDMs of 129Xe and 3He in a single cell in order to mitigate systematic effects due to leakage currents and common mode problems such as magnetic field and time base noise. The philosophy of our approach is that the PEDM of 3He is negligible compared to that of 129Xe and thus we use the 3He as a ‘‘magnetometer’’ and monitor of systematic effects. Sensitivity of ≊10−25 e‐cm per day has been demonstrated in preliminary work using a free induction decay technique.