Proposed large scale monolithic fused silica mirror suspension for 3rd generation gravitational wave detectors

TL;DR

This paper proposes and experimentally demonstrates a large-scale fused silica suspension design capable of supporting 160 kg, aiming to reduce thermal noise in future third-generation gravitational wave detectors.

Contribution

It introduces a novel large-scale fused silica suspension design and provides experimental validation for its suitability in high-mass gravitational wave detectors.

Findings

Demonstrated support for 160 kg mass with fused silica suspension

Achieved thermal noise performance meeting ET-HF requirements

Approaching Cosmic Explorer thermal noise specifications

Abstract

Thermal noise from the suspension fibres used in the mirror pendulums in current gravitational wave detectors is a critical noise source. Future detectors will require improved suspension performance with the specific ability to suspend much heavier masses to reduce radiation pressure noise, whilst retaining good thermal noise performance. In this letter, we propose and experimentally demonstrate a design for a large-scale fused silica suspension, demonstrating its suitability for holding an increased mass of 160 kg. We demonstrate the concepts for improving thermal noise via longer suspension fibres supporting a higher static stress. We present a full thermal noise analysis of our prototype, meeting requirements for conceptual 3rd generation detector designs such as the high frequency interferometer of the Einstein Telescope (ET-HF), and closely approaching that required for Cosmic Explorer (CE).