High Sensitivity Torsion Balance Tests for LISA Proof Mass Modeling

TL;DR

This paper presents a highly sensitive torsion balance designed to measure small forces between gold surfaces, aiming to better understand and quantify noise sources affecting the LISA gravitational wave observatory.

Contribution

The study introduces a novel torsion balance setup for measuring surface forces relevant to LISA, providing initial data on surface potential fluctuations affecting low-frequency noise.

Findings

Surface potential fluctuations contribute significantly to LISA noise.

The torsion balance achieves high sensitivity in force measurements.

Initial measurements reveal key noise sources for LISA.

Abstract

We have built a highly sensitive torsion balance to investigate small forces between closely spaced gold coated surfaces. Such forces will occur between the LISA proof mass and its housing. These forces are not well understood and experimental investigations are imperative. We describe our torsion balance and present the noise of the system. A significant contribution to the LISA noise budget at low frequencies is the fluctuation in the surface potential difference between the proof mass and its housing. We present first results of these measurements with our apparatus.