We report on a new measurement of the CP-violating permanent Electric Dipole Moment (EDM) of the neutral 129 Xe atom. Our experimental approach is based on the detection of the free precession of co-located nuclear spin-polarized 3 He and 129 Xe samples. The EDM measurement sensitivity benefits strongly from long spin coherence times of several hours achieved in diluted gases and homogeneous weak magnetic fields of about 400 nT. A finite EDM is indicated by a change in the precession frequency, as an electric field is periodically reversed with respect to the magnetic guiding field. Our result, (−4.7 ± 6.4) · 10 −28 ecm, is consistent with zero and is used to place a new upper limit on the 129 Xe EDM: |dXe| < 1.5 · 10 −27 ecm (95% C.L.). We also discuss the implications of this result for various CP-violating observables as they relate to theories of physics beyond the standard model.

A simple compensation concept for eddy currents generated by additional gradient pulses is presented. Similar to other pre‐emphasis schemes, the gradient pulse shape is overemphasized in the opposite way of the effect of the eddy currents to compensate for the deviations from the anticipated (rectangular) shape. In difference to other schemes no extra hardware is required, but eddy currents have been tried to be cancelled simply by a few short extra gradient pulses. The compensation can be done either by cancelling the amplitude of the eddy currents or their effect on the phase of the NMR‐signal. For certain conditions even analytical solutions can be found. The general treatment is validated by simulations and experiments.

We report on the first preliminary result of our 129 Xe EDM measurement performed by the MIXed collaboration. The aim of this report is to demonstrate the feasibility of a new method to set limits on nuclear EDMs by investigating the EDM of the diamagnetic 129 Xe atoms. In our setup, hyperpolarized 3 He serves as a comagnetometer needed to suppress magnetic field fluctuations. The free induction decay of the two polarized spin species is directly measured by low noise DC SQUIDs, and the weighted phase difference extracted from these measurements is used to determine a preliminary upper limit on the 129 Xe EDM.

A sensor has been developed for low frequency and DC electric fields E. The device is capable of measuring fields with E = 4 (1) V/cm resolution. It is based on a Y-cut Z-propagation lithium niobate electro-optic crystal. For a particular commercially available bare crystal, we achieved an in air time constant c (air) = 6.4(1.8) h for the decay of the electro-optic signal. This enables field monitoring for several hours. As an application, we demonstrated that a constant electric field E ext = 640 V/cm applied via external electrodes to a particular spherical glass container holding an Xe/He gas mixture decays inside this cell with a time constant glass E = 2.5(5) h. This is sufficient for the needs of experiments searching for a permanent electric dipole moment in 129 Xe. An integrated electric field sensor has been constructed which is coupled to a light source and light detectors via optical fibers. The sensor head does not contain any electrically conducting material.