Comment on "Test of constancy of speed of light with rotating cryogenic optical resonators"

A recent experiment by Antonini et. al. [Phys. Rev. A {\bf 71}, 050101R 2005], set new limits on Lorentz violating parameters in the frame-work of the photon sector of the Standard Model Extension (SME), $\tilde{\kappa}_{e-}^{ZZ}$, and the Robertson-Mansouri-Sexl (RMS) framework, $\beta-\delta-1/2$. The experiment had significant systematic effects caused by the rotation of the apparatus which were only partly analysed and taken into account. We show that this is insufficient to put a bound on $\tilde{\kappa}_{e-}^{ZZ}$ and the bound on $\beta-\delta-1/2$ represents a five-fold improvement not a ten-fold improvement as claimed. (For reply see Phys. Rev. A 72, 066102 (2005) DOI: 10.1103/PhysRevA.72.066102)Comment: 2 page

Improved Constraints on Isotropic Shift and Anisotropies of the Speed of Light using Rotating Cryogenic Sapphire Oscillators

We demonstrate that Michelson-Morley tests, which detect direction-dependent anisotropies in the speed of light, can also be used to place limits upon isotropic deviations of the vacuum speed of light from $c$, as described by the photon sector Standard Model Extension (SME) parameter $\tilde{\kappa}_{tr}$. A shift in the speed of light that is isotropic in one inertial frame implies anisotropic shifts in others. Using observer Lorentz covariance, we derive the time-dependent variations in the relative resonance frequencies of a pair of electromagnetic resonators that would be generated by such a shift in the rest frame of the Sun. A new analysis of a recent experimental test of relativity using this result constrains $\tilde{\kappa}_{tr}$ with a precision of $7.4\times10^{-9}$. This represents the first constraint on $\tilde{\kappa}_{tr}$ by a Michelson-Morley experiment and the first analysis of a single experiment to simultaneously set limits on all nine non-birefringent terms in the photon sector of the SME

Improved test of Lorentz Invariance in Electrodynamics using Rotating Cryogenic Sapphire Oscillators

We present new results from our test of Lorentz invariance, which compares two orthogonal cryogenic sapphire microwave oscillators rotating in the lab. We have now acquired over 1 year of data, allowing us to avoid the short data set approximation (less than 1 year) that assumes no cancelation occurs between the $\tilde{\kappa}_{e-}$ and $\tilde{\kappa}_{o+}$ parameters from the photon sector of the standard model extension. Thus, we are able to place independent limits on all eight $\tilde{\kappa}_{e-}$ and $\tilde{\kappa}_{o+}$ parameters. Our results represents up to a factor of 10 improvement over previous non rotating measurements (which independently constrained 7 parameters), and is a slight improvement (except for $\tilde{\kappa}_{e-}^{ZZ}$) over results from previous rotating experiments that assumed the short data set approximation. Also, an analysis in the Robertson-Mansouri-Sexl framework allows us to place a new limit on the isotropy parameter $P_{MM}=\delta-\beta+{1/2}$ of $9.4(8.1)\times10^{-11}$, an improvement of a factor of 2.Comment: Accepted for publication in Phys. Rev.

Test of Lorentz Invariance in Electrodynamics Using Rotating Cryogenic Sapphire Microwave Oscillators

We present the first results from a rotating Michelson-Morley experiment that uses two orthogonally orientated cryogenic sapphire resonator-oscillators operating in whispering gallery modes near 10 GHz. The experiment is used to test for violations of Lorentz Invariance in the frame-work of the photon sector of the Standard Model Extension (SME), as well as the isotropy term of the Robertson-Mansouri-Sexl (RMS) framework. In the SME we set a new bound on the previously unmeasured $\tilde{\kappa}_{e-}^{ZZ}$ component of $2.1(5.7)\times10^{-14}$, and set more stringent bounds by up to a factor of 7 on seven other components. In the RMS a more stringent bound of $-0.9(2.0)\times 10^{-10}$ on the isotropy parameter, $P_{MM}=\delta - \beta + {1/2}$ is set, which is more than a factor of 7 improvement. More detailed description of the experiment and calculations can be found in: hep-ph/0506200Comment: Final published version, 4 pages, references adde

Rotating Odd-Parity Lorentz Invariance Test in Electrodynamics

We report the first operation of a rotating odd-parity Lorentz Invariance test in electrodynamics using a microwave Mach-Zehnder interferometer with permeable material in one arm. The experiment sets a direct bound to $\kappa_{tr}$ of $-0.3\pm 3\times10^{-7}$. Using new power recycled waveguide interferometer techniques (with the highest spectral resolution ever achieved of $2\times10^{-11} rad/\sqrt{Hz}$) we show an improvement of several orders of magnitude is attainable in the future

Capture of low grade methane from nitrogen gas using dual-reflux pressure swing adsorption

We report a dual-reflux pressure swing adsorption (DR-PSA) apparatus and cycle configuration to recover an enriched methane product from mixtures of methane and nitrogen containing between (2.4 and 49.6) mol% methane. This range of feed gas compositions is representative of some significant greenhouse gas emissions streams containing methane, including vent streams from liquefied natural gas production facilities and ventilation air from coal mining operations. The DR-PSA apparatus was demonstrated with activated carbon Norit RB3 as the adsorbent, operating with a low pressure step of 1.4 bar and a high pressure step of 5 bar. The effect of light reflux flowrate and heavy product draw on methane recovery and nitrogen vent purity were investigated. The DR-PSA experiment with 2.4 mol% methane in the feed produced a methane product containing 35.7 mol% methane, which is approximately a 15 times enrichment, and a clean nitrogen vent containing just 3000 ppmv methane. In another experiment an enrichment ratio of 21 was achieved for a feed containing 2.4 mol% CH4, which is significantly higher than the pressure ratio of 3.6 considered to be the theoretical enrichment limit of conventional PSA cycles. The capture of dilute methane with this DR-PSA process is energetically self-sustainable. (C) 2015 Elsevier B.V. All rights reserved

Testing for periodic changes in fundamental constants using long-term comparison of the SYRTE Cs fountains and H-masers

International audienceWe analyze data sets from three separate Cs Fountains compared to various Hydrogen Masers to search for periodic changes correlated with the changing gravitational potential and boost with respect to the Cosmic Microwave Background. Data sets begin at a Modified Julian Day of 52822 (July 2nd 2003) and continue to November 2nd 2011. The main source of long-term noise in such experiments is the offsets associated with the various H-masers used in the comparison combined with the linear drift. The drift can vary to nearly immeasurable to as high as 1.3×10^-15 per day. To circumvent this problem we use the derivative technique. This technique significantly reduces the standard error when searching for periodic signals from such data. Results determine a standard error of the LPI coefficient of 4.8×10^-6 , while boost sensitivity of fundamental constants was measured down to a precision in parts in 10^-11

Testing Lorentz invariance and fundamental constants with precision clocks and oscillators

International audienc