Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session H6: Symmetry Tests and Electric Dipole Moment Measurements |
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Chair: David Weiss, Pennsylvania State University Room: Garden 4 |
Wednesday, June 6, 2012 10:30AM - 10:42AM |
H6.00001: ABSTRACT MOVED TO U1.00004 |
Wednesday, June 6, 2012 10:42AM - 10:54AM |
H6.00002: ABSTRACT WITHDRAWN |
Wednesday, June 6, 2012 10:54AM - 11:06AM |
H6.00003: Electric dipole moment enhancement factor of thallium Sergey Porsev, Marianna Safronova, Mikhail Kozlov A number of extensions of the standard model of particle physics predict electric dipole moments (EDM) of particles that may be observable with the present state-of-the art experiments. The EDMs arise from the violations of both parity and time-reversal invariance. The electron EDM is enhanced in certain atomic and molecular systems. One of the most stringent limits on the electron EDM $d_e$ was obtained from the experiments with $^{205}$Tl: $d_e<1.6\ 10^{-27}e$~cm [Regan {\it et al.}, PRL {\bf 88}, 071805 (2002)]. This result crucially depend on the calculated value of the effective electric field on the valence electron. In the case of Tl this effective field is proportional to the applied field $E_0$, $E_{\rm eff}= {\rm K}\, E_0$. The goal of this work is to resolve the present controversy in the value of the EDM enhancement factor K in Tl. We have carried out several calculations by different high-precision methods, studied previously omitted corrections, as well as tested our methodology on other parity conserving quantities. We find the EDM enhancement factor of Tl to be equal to $-$573(20). This value is 20\% larger than the recently published result of Nataraj {\it et al.} [PRL {\bf 106}, 200403 (2011)] but agrees very well with several earlier results. [Preview Abstract] |
Wednesday, June 6, 2012 11:06AM - 11:18AM |
H6.00004: Spectroscopic approach for an electron EDM measurement using neutral cesium atoms Kunyan Zhu, Neal Solmeyer, David S. Weiss Observation of a permanent electric dipole moment of the electron (eEDM) would imply CP violating effects not contained in the Standard Model. We describe the state preparation and spectroscopy that will be used to measure the eEDM. Cesium atoms are guided into a measurement chamber, where they are laser-cooled and trapped in a pair of parallel one-dimensional optical lattices. The lattices thread three specially coated glass electric field plates. The measurement chamber is surrounded by a four layer magnetic shield inside of which eight magnetic field coils control the bias and gradient magnetic fields. A series of microwave and low frequency magnetic field pulses transfer the atoms into a superposition state that is sensitive to the eEDM signal. A measurement of the eEDM using neutral cesium atoms can obtain an ultimate shot noise limit of $3\times10^{-30}$ e-cm. [Preview Abstract] |
Wednesday, June 6, 2012 11:18AM - 11:30AM |
H6.00005: New spectroscopic constants from high-resolution Stark spectroscopy of the PbF molecule: Implications for state-selection in an e-EDM measurement Tao Yang, James Coker, John Furneaux, Neil Shafer-Ray Lead mono-fluoride (PbF) is ideally suited to carry out a search for an e-EDM: PbF has relatively large molecular dipole moment (making it easy to polarize), a strong effective internal field (making it sensitive to an e-EDM), ground-state sensitivity to the e-EDM (allowing for long coherence time), a small magnetic moment (making it less sensitive to stray magnetic fields) and convenient optical spectroscopy. Here we use a sensitive multi-photon ionization technique (pseudo-continuous-REMPI) to carry out A$\leftarrow $X$_{1}$ spectroscopic measurements. New dipole moments and spectroscopic constants for the A state are presented. With these new data we have isolated an e-EDM sensitive Stark transition at a magic electric field that both polarizes the molecule and allows for sharp transitions that are immune to variations in electric field. [Preview Abstract] |
Wednesday, June 6, 2012 11:30AM - 11:42AM |
H6.00006: Design and Construction of an Electron Electric Dipole Moment Experiment Using Thorium Monoxide Benjamin Spaun, Paul Hess, Nick Hutzler, Elizabeth Petrik, John Doyle, Gerald Gabrielse, Cheong Chan, Emil Kirilov, Brendon O'Leary, David DeMille Observation of an electron electric dipole moment (eEDM) would imply new sources of CP violation beyond the Standard Model. By measuring spin precession signals on a cryogenic molecular beam, the ACME collaboration is searching for the eEDM in the metastable H $^3\Delta_1$ state of thorium monoxide. We discuss the design and completed assembly of the first generation of this experiment. Precise electric and magnetic field sources, magnetic shields, and a fluorescence collection system have been constructed and installed, and the molecule beam source has been optimized.\footnote{N.R.~Hutzler \textit{et al.}, Phys. Chem. Chem. Phys., 13, 18976-18985 (2011)} With this system we have begun collecting and analyzing eEDM data. [Preview Abstract] |
Wednesday, June 6, 2012 11:42AM - 11:54AM |
H6.00007: Towards Improvements to the Statistical Sensitivity of the ACME Electron EDM Experiment Nicholas Hutzler, Paul Hess, Emil Kirilov, Brendon O'Leary, Elizabeth Petrik, Benjamin Spaun, David DeMille, Gerald Gabrielse, John Doyle Construction of the first generation ACME experiment [A. C. Vutha et al., J. Phys. B 43, 074007 (2010)] to measure the electron electric dipole moment (eEDM) has been completed, and data acquisition and analysis are currently underway. In order to further increase our statistical sensitivity, several improvements are being developed and implemented. We report on: progress towards increasing our total molecule flux with a new beam source; utilizing microwaves, optical pumping, and electrostatic beam focusing to increase the molecule flux in a single state; efficient state preparation via STIRAP; improving detection efficiency by photon cycling; and apparatus redesign to allow more efficient fluorescence collection. [Preview Abstract] |
Wednesday, June 6, 2012 11:54AM - 12:06PM |
H6.00008: Optical Spectroscopy of Tungsten Carbide Molecules for Permanent Electron Electric Dipole Moment Search Jeongwon Lee, Jinhai Chen, Aaron Leanhardt Searching for a permanent electron electric dipole moment (EDM) is a powerful tool to probe for physics beyond the Standard Model. We identify the $X^3\Delta_1$ ground state of tungsten carbide molecules as a candidate system for the electron EDM search. We have developed a molecular beam source from pulse supersonic expansion technique and used laser induced fluorescence spectroscopy to detect the molecules through $[20.6]\Omega=2, v'=4 \leftarrow X^3\Delta_1,v"=0$ transition. The beam properties, including the flux and internal temperature, are characterized. The hyperfine structure and the lambda doublet of the transition are measured and the implications related to the EDM experiment are revealed. [Preview Abstract] |
Wednesday, June 6, 2012 12:06PM - 12:18PM |
H6.00009: Towards an EDM Measurement in Radium-225 Matthew Dietrich, K. Bailey, J. Greene, R. Holt, M. Kalita, W. Korsch, Z.-T. Lu, P. Mueller, T. O'Connor, R. Parker, J. Singh The existence of an atomic electric dipole moment (EDM) would violate both the time and parity symmetries of nature, and so the measurement of one would give a valuable window into physics beyond the standard model. Here we describe recent progress towards measurement of the EDM of radium-225, which is expected to be abnormally large compared to other species. Neutral cold radium atoms are loaded from a magneto-optic trap into an optical dipole trap (ODT), which is mechanically translated to move the radium into the science region. We then transfer the atoms to a second, standing wave ODT suitable for the EDM measurement. In the near future, we plan to optically pump and observe nuclear spin precession. This research is supported by DOE, Office of Nuclear Physics contract No. DE-AC02-06CH11357. [Preview Abstract] |
Wednesday, June 6, 2012 12:18PM - 12:30PM |
H6.00010: Progress towards an electron electric dipole moment search in Europium-Barium Titanates Stephen Eckel, Alexander Sushkov, Steven Lamoreaux We report on recent progress on a search for the electron's electric dipole moment (eEDM) using solid- state Eu$_{0.5}$Ba$_{0.5}$TiO$_3$. This material has many desirable properties including ferroelectricity below $200\mbox{ K}$ and paramagnetism above $1.8\mbox{ K}$. When the sample has a non-zero electric polarization, the seven unpaired $4f$ electrons of the Eu$^{2+}$ ions in the lattice feel a large effective electric field of order $10\mbox{ MV/cm}$ in the direction of the polarization. This causes the electron spins to align with the electric polarization and generate a magnetization, which is measured using DC SQUID magnetometers. We will detail measurements of systematic effects along with recent results toward a measurement of the eEDM. [Preview Abstract] |
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