GINGER: A feasibility study

Abstract

Abstract. GINGER (Gyroscopes IN General Relativity) is a proposal for an Earth-based experiment to measure the Lense-Thirring (LT) and de Sitter effects. GINGER is based on ring lasers, which are the most sensitive inertial sensors to measure the rotation rate of the Earth. We show that two ring lasers, one at maximum signal and the other horizontal, would be the simplest configuration able to retrieve the GR effects. Here, we discuss this configuration in detail showing that it would have the capability to test LT effect at 1%, provided the accuracy of the scale factor of the instrument at the level of 1 part in 10 12 is reached. In principle, one single ring laser could do the test, but the combination of the two ring lasers gives the necessary redundancy and the possibility to verify that the systematics of the lasers are sufficiently small. The discussion can be generalised to seismology and geodesy and it is possible to say that signals 10-12 orders of magnitude below the Earth rotation rate can be studied; the proposed array can be seen as the basic element of multi-axial systems, and the generalisation to three dimensions is feasible adding one or two devices and monitoring the relative angles between different ring lasers. This simple array can be used to measure with very high precision the amplitude of angular rotation rate (the length of the day, LOD), its short term variations, and the angle between the angular rotation vector and the horizontal ring laser. Finally this experiment could be useful to probe gravity at fundamental level giving indications on violations of Einstein Equivalence Principle and Lorenz Invariance and possible chiral effects in the gravitational field.

Evolution of the electric field along null rays for arbitrary observers and spacetimes

“…The results derived here might be relevant whenever we want to infer or estimate intrinsic properties of an object with unknown motion by observing its light intensity and polarization. That is the case for the many probes of state-of-the-art cosmology and astrophysics, such as: the polarization field of the cosmic microwave background (CMB), whose B modes carry information on the existence of primordial gravitational waves generated by inflation [15,16], that may be affected by gravitational lensing [17][18][19]; the polarization of light coming from supernovae, giving clues of a possible anisotropy in the explosion events [20][21][22]; the accurate determination of black hole masses by means of signatures in the polarization of light emitted by their accretion discs [23]; the study of standard sirens as detected by laser interferometry [24] and their optical counterpart [25]; the description of light traveling through Sagnac interferometers [26][27][28].…”

Gravito-electromagnetic approach for the space-time of a plane gravitational wave

“…[11]) that Einstein equations, in weak-field approximation (small masses, low velocities), can be written in analogy with Maxwell equations for the electromagnetic field, where the mass density and current play the role of the charge density and current, respectively. Actually, these effects are very small, but there were many proposals in the past (see the review paper [11]) and also more recently to test them, such as the LAGEOS tests around the Earth [12], the Gravity Probe B mission [13], the LARES mission [14][15][16][17], the GINGER project [18][19][20][21][22][23], the LAGRANGE proposal [24] and other space-based tests [25]. Actually, it is possible to introduce a space-time curvature approach to gravito-electromagnetism [10] , which allows to express the curvature effects in analogy to classical electromagnetism, and this approach can be used in arbitrary curved space-time (see also [26,27]).…”

Identification and correction of Sagnac frequency variations: an implementation for the GINGERINO data analysis

“…They are largely used for inertial navigation, and applications in geodesy, geophysics and even for General Relativity, where tests are foreseen [4]. Since 2011 we are studying the feasibility of the test of Lense-Thirring dragging of the rotating Earth at the level of 1% with an array of large frame RLGs [5][6][7]. For that purpose it a e-mail: angela.divirgilio@pi.infn.it (corresponding author) is necessary to push the relative accuracy of the Earth rotation rate Ω ⊕ measurement in the range from 1 part in 10 9 up to 1 part in 10 12 .…”