Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session K5: Tests of Fundamental Symmetries |
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Chair: Protik K. Majumder, Williams College Room: Clark Hall 107 |
Thursday, May 21, 2009 10:30AM - 10:42AM |
K5.00001: Recent Results from the PbO Electron EDM Experiment Paul Hamilton, Hunter Smith, David DeMille Observation of an electric dipole moment (EDM) of the electron would imply CP violation beyond the Standard Model. This experiment searches for the electron EDM using a metastable state of the PbO molecule. Several unique properties of this state, including closely spaced levels of opposite parity and a long coherence time, make it suitable for use in a vapor cell, which in turn enables high counting rates. The closely spaced levels of opposite parity are due to omega-doubling. Roughly speaking this doubling leads to states with oppositely directed internal electric fields but otherwise nearly identical properties. This reversal along with those of the lab electric and magnetic fields allow us to greatly reduce most systematics. We will discuss the statistical and systematic limits from a recent EDM data run as well as progress towards improving both our state preparation and detection schemes. [Preview Abstract] |
Thursday, May 21, 2009 10:42AM - 10:54AM |
K5.00002: Progress Toward Measurement of the Electron's Electric Dipole Moment Using the PbF Molecule Neil Shafer-Ray, Christopher McRaven, Poopalasingam Sivakumar, Milinda Rupasinghe The PbF molecule is particularly suited to a search for the electron's electric dipole moment ($e$-EDM.) In addition to its sensitivity to an $e$-EDM, its $^2\Pi_{1/2}$ ground state provides for a small magnetic moment. Furthermore, this small magnetic moment vanishes at a magic value of electric field. This vanishing point has an experimentally observable signature: When a beam of suitably aligned ground state PbF molecules is allowed to traverse a region of electric and magnetic fields, the polarization is conserved when the electric field matches this magic value. By measuring the (molecular-frame)magnitude of this magic electric field for the case that the electric field is parallel or antiparallel to the magnetic field, sensitivity to the $e$-EDM is achieved. Progress toward this measurement, including the development of a continuous molecular beam source of PbF, characterization of the electronic, rotational, and hyperfine structure of the molecule, the achievement of an ultra-sensitive continuous ionization detection scheme, and the construction of a Ramsey- resonance machine are briefly summarized. [Preview Abstract] |
Thursday, May 21, 2009 10:54AM - 11:06AM |
K5.00003: An Electron Electric Dipole Moment Search in the $^3\Delta_1$ Ground State of Tungsten Carbide Molecules Jeongwon Lee, Aaron Leanhardt We report on progress towards constructing and characterizing a continuous tungsten carbide (WC) molecular beam for an electron electric dipole moment (EDM) search\footnote{J.\ Lee et al., Atomic Physics \textbf{XXI}, 190 (2008).}. Tungsten atoms are evaporated from a resistively heated filament and tungsten carbide molecules are formed through a reaction with methane: $\textrm{W}+\textrm{CH}_4 \rightarrow \textrm{WC} + 2\textrm{H}_2$. WC has a $^3\Delta_1$ ground state with its two valance electrons in a $\sigma\delta$ molecular orbital configuration\footnote{K.\ Balasubramanian, J.\ Chem.Phys.\textbf{112}, 7425 (2000).}$^,$\footnote{S.\ M.\ Sickafoose et al., J.\ Chem.\ Phys.\ \textbf{116}, 993 (2002).}$^,$\footnote{D.\ Rothgeb et al., J.\ Chem.Phys.\textbf{129}, 114304 (2008).}. This molecular structure has several unique advantages for an electron EDM search and arises in other diatomic species such as HfF$^+$\footnote{\texttt{http://jilawww.colorado.edu/bec/CornellGroup/}.}$^,$\footnote{E.R.Meyer et al., Phys.\ Rev.\ A \textbf{73}, 062108 (2006).}, ThF$^+$$^{5,}$\footnote{E.\ R.\ Meyer et al., Phys.\ Rev.\ A \textbf{78}, 010502 (2008).}, and ThO$^{7,}$\footnote{A.\ C.Vutha et al., Atomic Physics \textbf{XXI}, 191 (2008).}. [Preview Abstract] |
Thursday, May 21, 2009 11:06AM - 11:18AM |
K5.00004: Progress towards an electric dipole moment measurement in radium-225 I.A. Sulai, W. Trimble, I. Ahmad, K. Bailey, H.A. Gould, B. Graner, J.P. Greene, R.J. Holt, W. Korsch, Z.-T. Lu, P. Mueller, T.P. O'Connor The search for a permanent electric dipole moment (EDM) in an atom is a sensitive test of time-reversal symmetry violation. In the nuclear sector, the best limit for T-violation through EDMs is set by measurements of the EDM of the neutron and of the diamagnetic atom Hg-199. Collective and mean field calculations suggest that because of the octupole deformation of its nucleus, Ra-225 (a spin $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ diamagnetic atom with a half life of 15 days) would be two to three orders of magnitude more sensitive to underlying T-violating interactions in the nucleus than Hg-199. Our search for a permanent EDM in Ra-225 involves measuring the nuclear spin precession of polarized Ra-225 atoms held in an optical dipole trap. We will report on recent measurements of atomic properties in Ra as well as progress in the construction of the experiment. This work is supported by DOE, Office of Nuclear Physics, under contract No. DE-AC02-06CH11357. [Preview Abstract] |
Thursday, May 21, 2009 11:18AM - 11:30AM |
K5.00005: Improved test of the standard model of elementary particles with atomic parity violation Andrei Derevianko, Sergey Porsev, Kyle Beloy Atomic parity violation places powerful constraints on new physics beyond the Standard Model (SM) of elementary particles. The measurements are interpreted in terms of the nuclear weak charge, quantifying the strength of the electroweak coupling between atomic electrons and quarks of the nucleus. We report the most accurate to-date determination of this coupling strength by combining previous measurements by the Boulder group with our high-precision calculations in cesium atom. Our result is in a perfect agreement with the prediction of the SM. In combination with the results of high-energy collider experiments, our work confirms the predicted energy dependence (or ``running'') of the electroweak interaction over an energy range spanning four orders of magnitude (from $\sim 10$ MeV to $\sim 100$ GeV) and places new limits on the masses of extra $Z$ bosons ($Z^\prime$). Our raised bound on the $Z^\prime$ masses carves out a lower-energy part of the discovery reach of the Large Hadron Collider. At the same time, a major goal of the LHC is to find evidence for supersymmetry (SUSY), one of the basic, yet experimentally unproven, concepts of particle physics. Our result is consistent with the R-parity conserving SUSY with relatively light (sub-TeV) superpartners. This raises additional hopes of discovering SUSY at the LHC. [Preview Abstract] |
Thursday, May 21, 2009 11:30AM - 11:42AM |
K5.00006: Nuclear Spin-Dependent Parity Nonconservation in Diatomic Molecules David Rahmlow, David Demille, Sidney Cahn, Dennis Murphree, John Barry, Matthew Steinecker, Christopher Yale, Edward Deveney, Richard Paolino, Mikhail Kozolv Nuclear spin-dependent parity nonconservation (NSD-PNC) effects arise from couplings of the $Z_{0}$ boson (parameterized by the electroweak coupling constants $C_{2P,N}$) and from the interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The latter scales with the nucleon number $A$ of the nucleus as $A^{2/3}$, while the $Z_{0}$ coupling is independent of $A$; the former will be the dominant source of NSD-PNC in nuclei with $A>20$. The most precise result on NSD-PNC to date comes from a measurement of the hyperfine dependence of atomic PNC in $^{133}Cs$, but this effect can be dramatically enhanced in diatomic molecules. We outline an experimental program to take advantage of this enhancement with over ten suitable molecules with which we can extract the relative contributions of the anapole moment and the electroweak $Z_{0}$ couplings. This will increase the available data on nuclear anapole moments, as well as reduce the uncertainties in current measurements of $C_{2N}$ and $C_{2P}$. We report on improvements in the design of our pulsed molecular beam experiment and the current status of our efforts. [Preview Abstract] |
Thursday, May 21, 2009 11:42AM - 11:54AM |
K5.00007: Calculation of parity nonconserving amplitude and other properties of Ra$^+$ Marianna Safronova, Rupsi Pal, Dansha Jiang, Ulyana Safronova We have calculated parity nonconserving $7s - 6d_{3/2}$ amplitude $E1_{PNC}$ in Ra$^+$ using high-precision relativistic all-order method where all single and double excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Detailed study of the uncertainty of the parity nonconserving (PNC) amplitude is carried out; additional calculations are performed to estimate some of the missing correlation corrections. A systematic study of the parity conserving atomic properties, including the calculation of the energies, transition matrix elements, lifetimes, hyperfine constants, quadrupole moments of the $6d$ states, as well as dipole and quadrupole ground state polarizabilities, is carried out. The results are compared with other theoretical calculations and available experimental values. [Preview Abstract] |
Thursday, May 21, 2009 11:54AM - 12:06PM |
K5.00008: Data tables for Lorentz and CPT Violation Neil Russell, Alan Kostelecky We discuss the content of the 2009 edition of the Data Tables for Lorentz and CPT violation, arXiv:0801.0287v2. Emphasis will be placed on results from experiments in atomic, molecular, and optical physics. [Preview Abstract] |
Thursday, May 21, 2009 12:06PM - 12:18PM |
K5.00009: Quantization of Lorentz Symmetry Violating Electromagnetism Michael Hohensee, David Phillips, Ronald Walsworth We present the non-relativistic quantization of light in the context of the Standard Model Extension. Deriving the single-quantum dispersion relation permits us to determine the recoil associated with transitions between atomic states. This may allow atom interferometer experiments to act as sensitive probes of Lorentz symmetry violation in QED. The formalism may also simplify theoretical studies of general Lorentz violation in more complicated systems. [Preview Abstract] |
Thursday, May 21, 2009 12:18PM - 12:30PM |
K5.00010: Multiply charged ionic crystals for nuclear laser spectroscopy Corey J. Campbell, Adam V. Steele, Layne R. Churchill, Michael V. DePalatis, Dave E. Naylor, Dzmitry N. Matsukevich, Michael S. Chapman, Alex Kuzmich Coherent excitation of the electronic states of atoms and molecules with lasers is at the heart of modern spectroscopy and metrology. To extend these techniques to nuclear states would be a tremendous advance. However, the typical excitation energies for nuclear matter are in the keV to MeV energy range, where coherent radiation sources are lacking. In the remarkable case of the $^{229}$Th~nucleus, the energy splitting of the ground state doublet is only several eV $^{1}$, which may be within the reach of coherent table-top UV lasers. ~We have produced laser-cooled crystals of the more abundant $^{232}$Th$^{3+}$~in an rf Paul trap. This is the first time that a multiply charged ion has been laser cooled.~ Our work opens an avenue for excitation of the nuclear transition in a trapped, cold $^{229}$Th$^{3+}$ ion. Laser excitation of nuclear states would establish a new bridge between atomic and nuclear physics, with the promise of new levels of metrological precision. $^{1}$ Kroger, L. A. {\&} Reich, C. W. Features of Low-Energy Level Scheme of Th-229 as Observed in Alpha-Decay of U-233. \textit{Nucl Phys A} \textbf{259}, 29 (1976). [Preview Abstract] |
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