Underground Sagnac gyroscope with sub-prad/s rotation rate sensitivity: Toward general relativity tests on Earth

We review the current status of large ring laser gyroscopes having the potential to contributeto terrestrial measurements of general relativistic precessions. At this point in time, although thesedevices possess the raw sensitivity for such a measurement, they remain limited by long-term geometricinstability, detection noise and imperfections in the physical models required to isolate geophysicaleffects. Furthermore, minute non-reciprocal biases provide a null-shift error and therefore no currentlyconstructed laser system meets the requirement of absolute rotation rate sensing. Nevertheless, we are ofthe view that these are surmountable problems and the ability of ring laser gyroscopes to measure lowfrequency to DC signals has vastly increased in the last decade.

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An On-chip Optical Brillouin Gyroscope with Earth-Rotation-Rate Sensitivity

Conference on Lasers and Electro-Optics ◽

10.1364/cleo_qels.2019.ftu3b.1 ◽

2019 ◽

Author(s):

K. Vahala ◽

Y. H. Lai ◽

M. G. Suh

Keyword(s):

Rotation Rate ◽

Earth Rotation ◽

Rate Sensitivity ◽

On Chip

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Sensitivity limit investigation of a Sagnac gyroscope through linear regression analysis

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09199-1 ◽

2021 ◽

Vol 81 (5) ◽

Author(s):

Angela D. Di Virgilio ◽

Carlo Altucci ◽

Francesco Bajardi ◽

Andrea Basti ◽

Nicolò Beverini ◽

...

Keyword(s):

Rotation Rate ◽

Linear Regression Analysis ◽

Sensitivity Limit ◽

Angular Rotation ◽

Fundamental Physics ◽

Tests Of General Relativity ◽

The Earth ◽

Theoretical Investigations ◽

Sagnac Gyroscope

AbstractThe sensitivity to angular rotation of the top class Sagnac gyroscope GINGERINO is carefully investigated with standard statistical means, using 103 days of continuous operation and the available geodesic measurements of the Earth angular rotation rate. All features of the Earth rotation rate are correctly reproduced. The unprecedented sensitivity of fractions of frad/s is attained for long term runs. This excellent sensitivity and stability put Sagnac gyroscopes at the forefront for fundamental physics, in particular for tests of general relativity and Lorentz violation, where the sensitivity plays the key role to provide reliable data for deeper theoretical investigations.

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GINGER

International Journal of Modern Physics D ◽

10.1142/s0218271817410164 ◽

2017 ◽

Vol 26 (05) ◽

pp. 1741016

Author(s):

Angela D. V. Di Virgilio

Keyword(s):

General Relativity ◽

Rotation Rate ◽

Inertial Sensors ◽

Three Dimensional ◽

De Sitter ◽

Preliminary Results ◽

Large Size ◽

The Earth ◽

Ring Lasers ◽

Base Experiment

Gyroscopes IN General Relativity (GINGER) is a proposal of an Earth-base experiment to measure the Lense–Thirring effect. GINGER uses an array of ring lasers, which are the most sensitive inertial sensors to measure the rotation rate of the Earth. GINGER is based on a three-dimensional array of large size ring lasers, able to measure the de Sitter and Lense–Thirring effects. The instrument will be located in the INFN Gran Sasso underground laboratory, in Italy. We describe preliminary developments and measurements. Earlier prototypes based in Italy, GP2, GINGERino, and G-LAS are also described and their preliminary results reported.

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The effects of strain and strain rate on residual microstructures in copper

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143687 ◽

1986 ◽

Vol 44 ◽

pp. 420-421

Author(s):

M. F. Stevens ◽

P. S. Follansbee

Keyword(s):

Strain Rate ◽

Applied Stress ◽

Threshold Stress ◽

Rate Sensitivity ◽

Viscous Drag ◽

Strain Rates ◽

Strain And Strain Rate ◽

Threshold Strength ◽

Mechanism Transition ◽

Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

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