Rotating Resonator-Oscillator Experiments to Test Lorentz Invariance in Electrodynamics

In this work we outline the two most commonly used test theories (RMS and SME) for testing Local Lorentz Invariance (LLI) of the photon. Then we develop the general framework of applying these test theories to resonator experiments with an emphasis on rotating experiments in the laboratory. We compare the inherent sensitivity factors of common experiments and propose some new configurations. Finally we apply the test theories to the rotating cryogenic experiment at the University of Western Australia, which recently set new limits in both the RMS and SME frameworks [hep-ph/0506074].Comment: Submitted to Lecture Notes in Physics, 36 pages, minor modifications, updated list of reference

Optical frequency synthesis from a cryogenic microwave sapphire oscillator

We demonstrate an optical frequency comb with fractional frequency instability of </=2x10(-14) at measurement times near 1 s, when the 10th harmonic of the comb spacing is controlled by a liquid helium cooled microwave sapphire oscillator. The frequency instability of the comb is estimated by comparing it to a cavity-stabilized optical oscillator. The less conventional approach of synthesizing low-noise optical signals from a microwave source is relevant when a laboratory has microwave sources with frequency stability superior to their optical counterparts. We describe the influence of high frequency environmental noise and how it impacts the phase-stabilized frequency comb performance at integration times less than 1 s.J. J. McFerran, S. T. Dawkins, P. L. Stanwix, M. E. Tobar and A. N. Luite

Continuous operation of an odd parity Lorentz Invariance test in electrodynamics using a microwave interferometer

We present results from an odd parity test of Lorentz invariance in electrodynamics, based on a rotating microwave interferometer with permeable material in one arm. The experiment has been operating continuously since September 2007. Results set a limit on the standard model extension (SME) scalar Lorentz violating parameter, kappa(tr), of -0.8plusmn3.6times10⁻⁷.Michael E. Tobar, Eugene N. Ivanov, Paul L. Stanwix, Jean-Michel le Floch, John G. Hartnet

Rotating Michelson-Morley experiment based on a dual cavity cryogenic sapphire oscillator

Recent experiments based on cryogenic microwave oscillators [1,2,3] have tested the isotropy of the speed of light (Michelson-Morley experiment) at sensitivities of the order of a part in 1015, which is a similar sensitivity to other best tests [4,5]. Further improvements of the accuracy in this type of experiment are not expected due to the already long data set and the systematic error limit [3]. We have constructed a new rotating Michelson-Morley experiment consisting of two cylindrical cryogenic sapphire resonators. The temperature of the dual cavity is controlled at approximately 6 K where the beat frequency between two oscillators is independent on temperature. By rotating the experiment an improvement of several orders of magnitude in our sensitivity to light speed anisotropy is expected, as the relevant time variations will now be at the rotation frequency where the frequency stability of the cryogenic oscillators is the best.P.L. Stanwix, M.E. Tobar, M. Susli, C.R. Locke, E.N. Ivanov, J. Winterflood, J.G. Hartnett, F. van Kann, P. Wol

Gas hydrate formation probability distributions: The effect of shear and comparisons with Nucleation Theory

Gas hydrate formation is a stochastic phenomenon of considerable significance for any risk-based approach to flow assurance in the oil and gas industry. In principle, well-established results from nucleation theory offer the prospect of predictive models for hydrate formation probability in industrial production systems. In practice, however, heuristics are relied on when estimating formation risk for a given flowline subcooling or when quantifying kinetic hydrate inhibitor (KHI) performance. Here, we present statistically significant measurements of formation probability distributions for natural gas hydrate systems under shear, which are quantitatively compared with theoretical predictions. Distributions with over 100 points were generated using low-mass, Peltier-cooled pressure cells, cycled in temperature between 40 and −5 °C at up to 2 K·min–1 and analyzed with robust algorithms that automatically identify hydrate formation and initial growth rates from dynamic pressure data. The application of shear had a significant influence on the measured distributions: at 700 rpm mass-transfer limitations were minimal, as demonstrated by the kinetic growth rates observed. The formation probability distributions measured at this shear rate had mean subcoolings consistent with theoretical predictions and steel–hydrate–water contact angles of 14–26°. However, the experimental distributions were substantially wider than predicted, suggesting that phenomena acting on macroscopic length scales are responsible for much of the observed stochastic formation. Performance tests of a KHI provided new insights into how such chemicals can reduce the risk of hydrate blockage in flowlines. Our data demonstrate that the KHI not only reduces the probability of formation (by both shifting and sharpening the distribution) but also reduces hydrate growth rates by a factor of 2