Bulletin of the American Physical Society
2005 36th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 17–21, 2005; Lincoln, Nebraska
Session E5: Precison Measurements, Fundamental Symmetries, & Structure |
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Chair: Harvey Gould, Lawrence Berkeley Laboratory Room: Burnham Yates Conference Center Arbor |
Thursday, May 19, 2005 8:00AM - 8:12AM |
E5.00001: Precision measurement and calculation of the 3d $^2$D-level lifetimes of $^{40}$Ca$^+$ Marianna Safronova, A. Kreuter, C. Becher, G.P.T Lancaster, A.B. Mundt, C. Russo, H. H\"affner, C. Roos, W. H\"ansel, F. Schmidt-Kaler, R. Blatt We report measurements of the lifetimes of the 3d $^2$D$_{5/2}$ and 3d $^2$D$_{3/2}$ metastable states of a single laser-cooled $^{40} $Ca$^+$ ion in a linear Paul trap. The result for the natural lifetime of the D$_{5/2}$ state of 1168(9)~ms agrees excellently with the most precise published value. The lifetime of the D$_{3/2}$ state is measured with a single ion for the first time and yields 1176(11)~ms which improves the statistical uncertainty of previous results by a factor of four. We perform high-precision {\it ab initio} all-order calculation of these lifetimes and conduct a detailed study of their accuracy. The resulting theoretical values (D$_{3/2}$ state: 1196(11)~ms, D$_{5/2}$ state: 1165(11)~ms) are in very good agreement with experimental values. These calculations represent an excellent test of high-precision atomic theory and will serve as a benchmark for the study of parity nonconservation in Ba$^+$ which has similar atomic structure. [Preview Abstract] |
Thursday, May 19, 2005 8:12AM - 8:24AM |
E5.00002: Precision Penning Trap Mass Spectrometry of $^{32}$S, $^{84,86}$Kr and $^{129,132}$Xe Matthew Redshaw, Wei Shi, Edmund Myers Using a phase coherent technique to measure the cyclotron frequency of single ions in a Penning trap [1], we have performed mass measurements on $^{32}$S and the two most abundant krypton and xenon isotopes $^{84}$Kr, $^{86}$Kr, $^ {129}$Xe and $^{132}$Xe, to relative precisions of 0.1 ppb. This is a factor of $\sim$10-100 improvement in precision over current values [2]. [1] M.P. Bradley, J.V. Porto, S. Rainville, J.K. Thompson, and D.E. Pritchard, PRL \textbf{83}, 4510 (1999). [2] G. Audi, A.H. Wapstra, and C. Thibault, Nucl Phys \textbf{A729}, 337 (2003). [Preview Abstract] |
Thursday, May 19, 2005 8:24AM - 8:36AM |
E5.00003: Novel absorption resonance for all-optical atomic clocks Irina Novikova, Sergei Zibrov, Chris Smallwood, Yanhong Xiao, David Phillips, Ronald Walsworth, Alexander Zibrov, Aleksei Taichenachev, Valeriy Yudin We report an experimental study of an all-optical three-photon- absorption resonance (N-resonance) and discuss its potential application as an alternative to atomic clocks based on coherent population trapping (CPT). We present measurements of the N- resonance contrast, width and light-shift for ${}^{87}$Rb under various experimental conditions, and find good agreement with an analytical model of this novel resonance. [Preview Abstract] |
Thursday, May 19, 2005 8:36AM - 8:48AM |
E5.00004: Relativistic calculations of Ba$^{+}$ atomic properties Eugeniya Iskrenova-Tchoukova, Marianna S. Safronova The interest in calculating the energy levels and transition rates of Ba$^{+}$ ion is motivated by the possibility to study the parity non-conservation (PNC) with a single trapped ion. The study of PNC in heavy atoms provides atomic-physics tests of the Standard Model and allows to measure nuclear anapole moment. There is an ongoing theoretical and experimental effort for precise calculations and measurements of the PNC transition amplitudes. We compute the energy levels and transition amplitudes of Ba$^{+}$ ion using the relativistic all-order method. The lifetimes of several excited states are calculated and the results are found to be in good agreement with the experimental values. The static electric-dipole and electric-quadrupole polarizabilities of the Ba$^{+}$ ion in its ground state are calculated and compared with recent experimental values. We investigate the significant disagreement between the theoretical and experimental values of the ground state quadrupole polarizability. A consistency study of the lifetime and polarizability measurements in Ba$^{+}$ is conducted. [Preview Abstract] |
Thursday, May 19, 2005 8:48AM - 9:00AM |
E5.00005: Progress towards the measurement of the electric dipole moment of $^{225}$Ra J. R. Guest, I. Ahmad, K. Bailey, D. Bowers, R. J. Holt, Z.-T. Lu, T. P. O'Connor, D. H. Potterveld, E. C. Schulte, N. D. Scielzo, H. Gould Ongoing searches in many laboratories for a permanent electric dipole moment (EDM) in the atom underscores the importance of this window into physics beyond the Standard Model. The lack of an observed EDM in $^{199}$Hg has set impressive limits on the strength of Parity (P)-and Time (T)-invariance violating interactions in the nucleus. We are in the process of developing a next generation experiment to search for an EDM in laser-cooled and trapped $^{225}$Ra. $^{225}$Ra is predicted to be more than two orders of magnitude more sensitive to these interactions than $^{199}$Hg due to a larger nuclear charge, the octupole deformation in the $^{225}$Ra nucleus, and the collective nature of (P,T)-odd nuclear moments. We will present the challenges associated with $^{225}$Ra, discuss our results from laser spectroscopy on a beam of $^{225}$Ra atoms, and report on our progress towards producing a laser-cooled and trapped sample of these atoms. We will also discuss measurements on the lifetime of the 7s7p $^{3}$P$_{1}$ state. [Preview Abstract] |
Thursday, May 19, 2005 9:00AM - 9:12AM |
E5.00006: Improved Measurement of the electron electric dipole moment using YbF B.E. Sauer, P.C. Condylis, J.J. Hudson, M.R. Tarbutt, E.A. Hinds A permanent electric dipole moment of an electron, $d_e$, violates time reversal symmetry. The current limit$^1$ on the size of $d_e$ is many orders of magnitude larger than the Standard Model prediction, but is in the range predicted by many extensions to the Standard Model. This makes improved experiments particularly exciting as a background-free search for physics beyond the Standard Model. We have previously published a limit on $d_e$ measured using a thermal beam of YbF molecules.$^2$ YbF is particularly sensitive to $d_e$ and is immune to some of the most troublesome systematic effects encountered in atomic experiments. We have improved our experimental apparatus by developing a pulsed supersonic source of YbF$^3$ which produces molecules with a rotational temperature of a few K. Using this new source, we are currently taking data with a statistical sensitivity of $1 \times 10^{-27}$e.cm in 24 hours of data collection. We will present our new results and discuss possible systematic effects in the experiment.\\ $^1$ B. C. Regan, et al., Phys. Rev. Lett. \textbf{88}, 071805 (2002).\\ $^2$ J. J. Hudson, et al., Phys. Rev. Lett. \textbf{89}, 023003 (2002).\\ $^3$ M. R. Tarbutt, et al., J. Phys. B At. Mol. Opt. Phys. \textbf{35}, 5013 (2002). [Preview Abstract] |
Thursday, May 19, 2005 9:12AM - 9:24AM |
E5.00007: Nature of chemical bond and EDM effects in molecular ions $\mathrm{HBr}^{+}$ and $\mathrm{HI}^{+}$ Boris Ravaine, Sergey Porsev, Andrei Derevianko Heavy polar molecules offer a great sensitivity to the electron Electric Dipole Moment(EDM). To guide emerging searches for EDMs with molecular ions, we estimate the EDM-induced energy corrections for hydrogen halide ions $\mathrm{HBr}^{+}$ and $\mathrm{HI}^{+}$ in their respective ground $X\,^2\!\Pi_{3/2}$ states. We find that the energy corrections due to EDM for the two ions differ by an unexpectedly large factor of fifteen. We demonstrate that a major part of this enhancement is due to a dissimilarity in the nature of the chemical bond for the two ions: the bond that is nearly of ionic character in $\mathrm{HBr}^{+}$ exhibits predominantly covalent nature in $\mathrm{HI}^{+}$. We conclude that because of this enhancement the HI$^+$ ion may be a potentially competitive candidate for the EDM search. [Preview Abstract] |
Thursday, May 19, 2005 9:24AM - 9:36AM |
E5.00008: Lorentz Violation, Gravity, and Atomic Physics Jay D. Tasson, V. Alan Kostelecky Lorentz violation offers a potential probe for new physics arising from a fundamental theory at the Planck scale. At our presently accessible energies, these violations are described by the Standard-Model Extension (SME). An outline of the fermion sector of the SME in the presence of gravity is given, and some phenomenological issues are considered. [Preview Abstract] |
Thursday, May 19, 2005 9:36AM - 9:48AM |
E5.00009: Excitation energies, hyperfine constants, E1, E2, M1 transition rates, and lifetimes of $6s^2nl$ states in Tl~I and Pb~II U.I. Safronova, M.S. Safronova, W.R. Johnson Energies of $6s^2np_j$ ($n$ = 6--9), $6s^2ns_{1/2}$ ($n$ = 7-- 9), $6s^2nd_j$ ($n$ = 6--8), and $6s^2nf_{5/2}$ ($n$ = 5--6) states in Tl~I and Pb~II are obtained using relativistic many-body perturbation theory. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the 72 possible $6s^2nl_j-6s^2n'l'_{j'}$ electric-dipole transitions. Electric-quadrupole and magnetic-dipole matrix elements are evaluated to obtain $6s^2np_{3/2} - 6s^2mp_{1/2}$ ($n,m=6,7$) transition rates. Hyperfine constants $A$ are evaluated for $6s^2np_j$ ($n$ = 6--9), $6s^2ns_{1/2}$ ($n$ = 7--9), and $6s^2nd_j$ ($n$ = 6--8) states in $^{205}$Tl. First-, second-, third-, and all-order corrections to the energies and matrix elements and first- and second-order Breit corrections to energies are calculated. In our implementation of the all-order method, single and double excitations of Dirac-Fock wave functions are included to all orders in perturbation theory. These calculations provide a theoretical benchmark for comparison with experiment and theory. Work was supported in part by National Science Foundation Grant No.\ PHY-01-39928 and DOE/NNSA under UNR grant DE-FC52- 01NV14050. [Preview Abstract] |
Thursday, May 19, 2005 9:48AM - 10:00AM |
E5.00010: New observation of outer well levels of the $B"\overline B { }^1\Sigma _u^+ $ state of molecular hydrogen R.C. Ekey, A. Marks, E.F. McCormack Double well states in the \textit{ungerade} manifold of molecular hydrogen are challenging to observe due to poor Franck-Condon overlap with the ground state. The large internuclear separation (R $>$ 7 a.u.) of the outer well, $\overline B { }^1\Sigma _u^+ $ state, in particular, must be excited in step-wise fashion to obtain appreciable excitation. The results reported here were achieved via two-color laser excitation through the double-well $E,F{ }^1\Sigma _g^+ (v=6,J)$ state. Levels were observed by detecting both molecular and atomic ion production as a function of laser wavelength using a time-of-flight mass spectrometer. Lineshapes in the molecular ion channel appear as window resonances, while in the atomic ion channel they appear as resonant peaks. Rovibrational energies of the outer well levels were measured, many for the first time. The newly observed levels were assigned using theoretical energy calculations incorporating the latest potential curves. In this energy region, the $B"\overline B $, ${ }^1\Sigma _u^+ $ state crosses the ionization threshold and should provide an interesting test for \textit{ab initio }and MQDT calculations of this fundamental system in a region of bound and continuum states. [Preview Abstract] |
Thursday, May 19, 2005 10:00AM - 10:12AM |
E5.00011: Precision measurement of light shifts in a single trapped Ba$^+$ ion as test of atomic theory Jeff Sherman, Timo Koerber, Warren Nagourney, Norval Fortson Using a single trapped barium ion we have developed an rf spectroscopy technique to measure the ratio of the off-resonant vector ac Stark effect (or light shift) in the $6S_{1/2}$ and $5D_{3/2}$ states to 0.1\% precision at the 514 nm argon-ion laser line. Our preliminary result\footnote{Sherman, J.A.\ et al., \emph{In preparation}.} of $R = -11.493(13)$ yields a new test of the theory of alkali-like atomic systems. Since the light shift ratio is expressible as sums of dipole matrix elements, our result also establishes a sum rule involving imprecisely known matrix elements, one of which is important for a proposed single-ion parity violation experiment\footnote{Koerber, T.W.\ et al., \emph{J.\ Phys.\ B} {\textbf{36}} (2003) 637--48.}. Along with these results we discuss analogous measurements at other wavelengths and future experimental plans. [Preview Abstract] |
Thursday, May 19, 2005 10:12AM - 10:24AM |
E5.00012: Measurement of a linear Stark effect on the 254-nm line of $^{199}$Hg M. D. Swallows, W. C. Griffith, L. K. Kogler, E. N. Fortson, M. V. Romalis We report a measurement of a linear Stark effect on the $6^{1}{S}_{0} \rightarrow 6^{3}{P}_{1}$ intercombination transition in $^{199}$Hg. This Stark interference effect occurs when a static electric field mixes magnetic dipole and electric quadrupole couplings into an allowed electric dipole transition. The effect can induce energy shifts linear in the applied electric field, and therefore could be a source of systematic error in the search for a permanent electric dipole moment (EDM) of $^{199}$Hg.\footnote {M. V. Romalis, W. C. Griffith, J. P. Jacobs, and E. N. Fortson, Phys. Rev. Lett. {\bf 86}, 2505 (2001).} The fractional change in the absorptivity of the 254-nm line has been calculated\footnote {S. K. Lamoreaux, E. N. Fortson, Phys. Rev. A. {\bf 46}, 7053 (1992).} to be $\delta \alpha/\alpha = -6.6 \times 10^{-8}\ (\textrm{kV/cm})^{-1}$. Our measurement (preliminary result: $\delta \alpha/\alpha = -6.0 \pm 0.8 \times 10^{-8}\ (\textrm{kV/cm})^{-1}$, error bar statistical only) of this effect allows us to assess its contribution to the systematic error of the EDM experiment, and provides a further test of the atomic theory involved in the interpretation of the limit on the $^{199}$Hg EDM. Current results will be reported. [Preview Abstract] |
Thursday, May 19, 2005 10:24AM - 10:36AM |
E5.00013: Modified Faddeev equation:frequently asked questions Chi Yu Hu, Zoltan Papp The modified Faddeev equation has a couple of unique charateristics that often concerned the atomic physics community. The effect of the Merkuriev-cut-off parameters on the calculated physical quantities, such as scattering cross sections,electron-positron annihilation in flight, Feshbach resonances will be demonstrated. Using large scale numerical experimentation, we will demonstrate that all these physical quantities are insensitive to the Merkuriev's cut-off parameters. [Preview Abstract] |
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