The self-attraction correction for the FG5X absolute gravity meter

Abstract

The gravitational attraction of the body of a gravity meter upon its own proof mass is sometimes called the self-attraction. The self-attraction is a source of systematic error for absolute measurements of g, the acceleration of an object due to Earth's gravity. While the effect is typically small-of the order of one part per billion of the Earth's gravitational attraction-it is significant at the current level of accuracy of absolute gravity meters. In the past, a self-attraction correction for the FG5 gravity meter has been estimated by considering a rather coarse description of the instrument using simple geometrical shapes (spheres and cylinders). This paper describes a more complete calculation using a CAD-based digitized model of the newest FG5X instrument. We have also included the attraction of the co-moving drag-free chamber as well as the self-attraction of the counterweights used in the FG5X to reduce recoil. The results are also applicable to older style FG5 instruments with a fibre-optic interferometer base. The correction found with this new approach agrees with previous estimates but is now based upon a more complete and accurate model.

Geophysics From Terrestrial Time‐Variable Gravity Measurements

“…This induces transients in the time series ( Figure A7), which should be minimized and carefully reported in a logbook. Self-attraction of absolute gravimeters must also be considered (Biolcati et al, 2012;Niebauer et al, 2013). Hence, activities that are part of the measuring process do influence the measurand, that is, here, the high-precision gravity measurements.…”

Precision measurement of the relativistic Doppler shift of an accelerated system

“…Since the gravimeter itself has mass and thus produces a perturbing attraction on the freely falling mirror, the data had to also be corrected for this self attraction [7]. Next the drop length was shortened using the same data set by selectively removing data from the least-squares fit.…”

Measuring the Newtonian constant of gravitation with a differential free-fall gradiometer: A feasibility study

“…γ = 2α then represents the intersection angle between both beams. This is equivalent to the case when the angle between the test beam and the plumb line equals ϕ = γ/2, thus we obtain (19). For a gravimeter the alignment along the plumb line has to be done to better than 6 × 10 −5 radians, in order to reach the aimed relative uncertainty of 10 −9 .…”

“…This is done with classical free fall absolute gravimeters 19-21 as well as with cold atom gravimeters 22 . The parts of the gravimeters are then either roughly estimated by measuring them and building a simple model [19][20][21] (e.g. rods, tubes, blocks etc.)…”