L. R. Hunter

Limit on the Electron Electric Dipole Moment in Gadolinium-Iron Garnet

A new method for the detection of the electron edm using a solid is described. The method involves the measurement of a voltage induced across the solid by the alignment of the samples magnetic dipoles in an applied magnetic field, H. A first application of the method to GdIG has resulted in a limit on the electron edm of 5E-24 e-cm, which is a factor of 40 below the limit obtained from the only previous solid-state edm experiment. The result is limited by the imperfect discrimination of an unexpectedly large voltage that is even upon the reversal of the sample magnetization.

Using the Earth as a Polarized Electron Source to Search for Long-Range Spin-Spin Interactions

In Search of Unparticles The standard model of particle physics, which describes the basic building blocks of the universe and the interactions among them, is incomplete. Numerous theoretical extensions have been proposed, some of which predict long-range, spin-spin interactions. To test whether such interactions exist, a laboratory spin source is normally used. Hunter et al. (p. 928) used Earth as a polarized spin source and looked for these interactions by changing the geographical position and the orientation of the measurement apparatus. The polarized spins mainly come from the electrons in iron-containing minerals of Earths mantle, which align in Earths magnetic field. The large numbers of such polarized electrons allowed the extraction of upper bounds on some of the exotic spin-spin interactions far lower than those obtained in the laboratory. Improved bounds on exotic spin-spin interactions were obtained from a study of polarized spins in Earths mantle. Many particle-physics models that extend the standard model predict the existence of long-range spin-spin interactions. We propose an approach that uses the Earth as a polarized spin source to investigate these interactions. Using recent deep-Earth geophysics and geochemistry results, we create a comprehensive map of electron polarization within the Earth induced by the geomagnetic field. We examine possible long-range interactions between these spin-polarized geoelectrons and the spin-polarized electrons and nucleons in three laboratory experiments. By combining our model and the results from these experiments, we establish bounds on torsion gravity and possible long-range spin-spin forces associated with the virtual exchange of either spin-one axial bosons or unparticles.

Measurement of the relativistic potential difference across a rotating magnetic dielectric cylinder

According to the Special Theory of Relativity, a rotating magnetic dielectric cylinder in an axial magnetic field should exhibit a contribution to the radial electric potential that is associated with the motion of the material’s magnetic dipoles. In 1913 Wilson and Wilson reported a measurement of the potential difference across a magnetic dielectric constructed from wax and steel balls. Their measurement has long been regarded as a verification of this prediction. In 1995 Pelligrini and Swift questioned the theoretical basis of the experiment. In particular, they pointed out that it is not obvious that a rotating medium may be treated as if each point in the medium is locally inertial. They calculated the effect in the rotating frame and predicted a potential different from both the Wilsons’ theory and experiment. Subsequent analysis of the experiment suggests that the Wilsons’ experiment does not distinguish between the two predictions due to the fact that their composite steel–wax cylinder is conductive in the regions of magnetization. We report measurements of the radial voltage difference across various rotating dielectric cylinders, including a homogeneous magnetic dielectric material (YIG), to unambiguously test the competing calculations. Our results are compatible with the traditional treatment of the effect using a co-moving locally inertial reference frame, and are incompatible with predictions based on the model of Pelligrini and Swift.

Limits on local Lorentz invariance in mercury and cesium

We report bounds on local Lorentz invariance (LLI) violation in Cs and Hg. The limits are obtained through the observation of the spin-precession frequencies of

Search for the electric dipole moment of the electron using metastable PbO

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Precise measurement of the Stark shift of the cesium D1 line

Hg and

Hyperfine structure of the B3Π1 state and predictions of optical cycling behavior in the X→B transition of TlF

{}^{133}

A review of the EDM of atoms and the neutron

Cs atoms in their ground states as a function of the orientation of an applied magnetic field with respect to the fixed stars. We measure the amplitudes of the dipole couplings to a preferred direction in the equatorial plane to be 19(11) nHz for Hg and 9(5) \ensuremath{\mu}Hz for Cs. The upper bounds established here improve upon previous bounds by about a factor of 4. The improvement is primarily due to mounting the apparatus on a rotating table. Bounds are established on several terms in the standard model extension including the first bounds on the spin couplings of the neutron and proton to the

New limits on the electron electric dipole moment from cesium.

z

Investigation of PbO as a system for measuring the electric dipole moment of the electron

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