A six degree-of-freedom fused silica seismometer: Design and tests of a metal prototype

TL;DR

This paper presents the design and experimental testing of a compact six degree-of-freedom fused silica seismometer aimed at reducing low-frequency ground vibrations affecting gravitational wave detectors.

Contribution

It introduces a novel fused silica 6D seismometer prototype with experimental results demonstrating its potential for improving aLIGO sensitivity.

Findings

Fused silica prototype shows promise for low-frequency noise reduction

Interferometric readout effectively measures 6D motion

Limitations identified in metallic prototype suggest improvements with fused silica

Abstract

Ground vibrations couple to the longitudinal and angular motion of the aLIGO test masses and limit the observatory sensitivity below 30\,Hz. Novel inertial sensors have the potential to improve the aLIGO sensitivity in this band and simplify the lock acquisition of the detectors. In this paper, we experimentally study a compact 6D seismometer that consists of a mass suspended by a single wire. The position of the mass is interferometrically read out relative to the platform that supports the seismometer. We present the experimental results, discuss limitations of our metallic prototype, and show that a compact 6D seismometer made out of fused silica and suspended with a fused silica fibre has the potential to improve the aLIGO low frequency noise.