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.
Limited resolution in indirect detected frequency dimensions (evolution periods) in multidimensional spectroscopy is a common problem, especially in the carbon dimension of heteronuclear experiments. Folding of signals in empty regions can overcome these problems. To record the spectra in a pure phase certain conditions have to be fulfilled to account for unavoidable deviations from zero time of the zero increment. A new sligbt variation of inverse heteronuclear correlation pulse sequences is proposed to allow pure phase spectra. Practical applications are given.
We report on precise measurements of magnetic field gradients extracted from transverse relaxation rates of precessing spin samples. The experimental approach is based on the free precession of gaseous, nuclear spin polarized 3 He and 129 Xe atoms in a spherical cell inside a magnetic guiding field of about 400 nT using LTC SQUIDs as low-noise magnetic flux detectors. The transverse relaxation rates of both spin species are simultaneously monitored as magnetic field gradients are varied. For transverse relaxation times reaching 100 h, the residual longitudinal field gradient across the spin sample could be deduced to be|∇Bz| = (5.6 ± 0.4) pT/cm. The method takes advantage of the high signal-to-noise ratio with which the decaying spin precession signal can be monitored that finally leads to the exceptional accuracy to determine magnetic field gradients at the sub pT/cm scale.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.