Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session X10: Tests of Relativity and Gravitation |
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Sponsoring Units: GGR Chair: Alan Kostelecky, University of Indiana Room: Marriott Tampa Waterside Room 6 |
Tuesday, April 19, 2005 10:45AM - 10:57AM |
X10.00001: Equivalence Principle Tests at the University of Washington Ki-Young Choi, Stephan Schlamminger, Eric Adelberger, Jens Gundlach, Blayne Heckel, Christopher Spitzer, Erik Swanson We are using a rotating torsion balance to test the equivalence principle for Yukawa ranges from 1 m to $\inf$ . A sensitive torsion balance is mounted on a turntable rotating with constant angular velocity. On the torsion pendulum beryllium and titanium test bodies are installed in a composition dipole configuration. A violation of the equivalence principle would yield to a differential acceleration of the two materials towards a source mass. In a three months long data run, we measured this acceleration with a sensitivity of $3 \times 10^{-15} m /s^2$. We analyzed the differential acceleration data for a variety of sources such as local topological features (a hill), the Earth, the Sun or the center of our galaxy. Since $25\%$ of the differential acceleration towards the center of our galaxy is caused by galactic dark matter, it allows us to test the equivalence principle for an ordinary matter falling towards galactic dark matter. [Preview Abstract] |
Tuesday, April 19, 2005 10:57AM - 11:09AM |
X10.00002: Searching for New Forces at Sub-Micron Separations using Casimir Force Experiments D.E. Krause, H.B. Chan, R.S. Decca, E. Fischbach, C.R. Jamel, G.L. Klimchitskaya , D. Lopez, V.M. Mostepanenko The search for new sub-micron-ranged forces predicted by extensions to the Standard Model is complicated by the existence of strong background effects like the Casimir force. This talk reviews progress in constraining new forces in the Casimir regime using a microelectromechanical torsion oscillator following two approaches: (1) directly measuring the Casimir force and comparing the result with theoretical predictions, and (2) implementing a ``Casimir-less'' approach using iso-electronically engineered samples to minimize the effects of the Casimir force. [Preview Abstract] |
Tuesday, April 19, 2005 11:09AM - 11:21AM |
X10.00003: Lorentz Violation and Post-Newtonian Gravity Quentin G. Bailey, V. Alan Kostelecky One possible experimental signature for Planck-scale physics is the discovery of Lorentz- and CPT-symmetry violation. The observable effects at low energies are described by the Standard-Model Extension (SME). This talk focuses on the Riemannian limit of the gravitational sector of the SME. We discuss some of the associated phenomenology in the post-Newtonian regime. [Preview Abstract] |
Tuesday, April 19, 2005 11:21AM - 11:33AM |
X10.00004: Short-Range Test of Newton's Inverse Square Law Daniel Kapner, Eric Adelberger, Ted Cook, Jens Gundlach, Blayne Heckel, C.D. Hoyle, Erik Swanson We present new results from our torsion pendulum tests of the Inverse-Square Law. Our sensitivity now probes gravity-strength force down to $\approx$70$\mu$m. These results represent a factor of 150 improvement in sensitivity over our published results at $\lambda = 50\mu$m. [Preview Abstract] |
Tuesday, April 19, 2005 11:33AM - 11:45AM |
X10.00005: Design of a New Eot-Wash Inverse Square Law Instrument Ted Cook, Dan Kapner, C.D. Hoyle, Eric Adelberger, Blayne Heckel, Jens Gundlach, Erik Swanson The Eot-Wash group has designed a new inverse square law torsion pendulum to replace the instrument described by Kapner et al. at this meeting. The new design employs a novel geometry that has been optimized to probe gravity at and below the 50-micron range by using much higher azimuthal symmetry and smaller scale features. This configuration also eliminates the need for Newtonian cancellation while increasing our sensitivity to new short-range physics by more than a factor of twenty. An overview of design, construction, and expected sensitivity will be discussed. [Preview Abstract] |
Tuesday, April 19, 2005 11:45AM - 11:57AM |
X10.00006: A new test of relativistic time dilation with laser spectroscopy of heavy ions in a storage ring Gerald Gwinner, Guido Saathoff, Sascha Reinhardt, Dirk Schwalm, Gerhard Huber, Sergej Karpuk, Christian Novotny We report on a new, improved test of time dilation in special relativity via the relativistic Doppler-effect. An optical transition with rest-frequency $\nu$ in $^7{\rm Li}^+$ ions, stored at a speed of $\beta=0.065$ in the TSR heavy-ion storage ring in Heidelberg, was used. The Doppler-shifted excitation frequencies $\nu_{\rm p}$ and $\nu_{\rm a}$ for laser beams travelling parallel and antiparallel with respect to the ions were measured simultaneously using saturation spectroscopy. The resonance conditions $\nu=\gamma (1-\beta)\nu_{\rm p}$ and $\nu=\gamma (1+\beta)\nu_{\rm a}$ yield the relation $\nu_{\rm p} \nu_{\rm a} = \nu ^2$, if $\gamma = \sqrt{1-\beta ^2}$, as predicted by SR. Deviations, e.g. caused by the existence of preferred frames, are parametrized by $\gamma = \gamma_{\rm SR} (1+\alpha \beta^2 + ...)$. We have determined a new limit of $\alpha < 2.2 \times 10^{-7}$, a $10\times$ improvement over other techniques. This result is limited by the knowledge of $\nu$, and not by the accuracy of our measurement. Our new measurement at $\beta = 0.025$ will serve as an improved rest-frequency measurement and will improve the limit on $\alpha$ further. [Preview Abstract] |
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