Passive Newtonian noise suppression for gravitational-wave observatories based on shaping of the local topography

TL;DR

This paper proposes a novel method to reduce Newtonian noise in gravitational-wave detectors by excavating recesses around test masses, showing potential for significant noise suppression through finite element simulations.

Contribution

It introduces a new passive topography shaping technique using ground recesses to mitigate Newtonian noise in gravitational-wave observatories.

Findings

Recesses of 4m depth can achieve a noise suppression factor of 2 to 4.

Finite element simulations validate the effectiveness of the recess design.

The method is more feasible for future detector infrastructure upgrades.

Abstract

In this article we propose a new method for reducing Newtonian noise in laser-interferometric gravitational-wave detectors located on the Earth's surface. We show that by excavating meter-scale recesses in the ground around the main test masses of a gravitational wave detector it is possible to reduce the coupling of Rayleigh wave driven seismic disturbances to test mass displacement. A discussion of the optimal recess shape is given and we use finite element simulations to derive the scaling of the Newtonian noise suppression with the parameters of the recess as well as the frequency of the seismic excitation. Considering an interferometer similar to an Advance LIGO configuration, our simulations indicate a frequency dependent Newtonian noise suppression factor of 2 to 4 in the relevant frequency range for a recesses of 4m depth and a width and length of 11m and 5m, respectively. Though a retrofit to existing interferometers seems not impossible, the application of our concept to future infrastructures seems to provide a better benefit/cost ratio and therefore a higher feasibility.