Upper limits on stray force noise for LISA

TL;DR

This paper describes a sensitive torsion pendulum setup designed to measure and limit stray force noise on test masses for the LISA gravitational wave observatory, providing crucial data for its noise mitigation.

Contribution

It introduces a novel ground testing facility and measurement techniques that achieve high sensitivity in detecting residual forces relevant to LISA's performance.

Findings

Achieved torque sensitivity below 20 fNm/√Hz from 0.3 to 10 mHz

Set upper limits on stray force noise for LISA-like sensors

Characterized specific disturbance sources affecting test masses

Abstract

We have developed a torsion pendulum facility for LISA gravitational reference sensor ground testing that allows us to put significant upper limits on residual stray forces exerted by LISA-like position sensors on a representative test mass and to characterize specific sources of disturbances for LISA. We present here the details of the facility, the experimental procedures used to maximize its sensitivity, and the techniques used to characterize the pendulum itself that allowed us to reach a torque sensitivity below 20 fNm /sqrt{Hz} from 0.3 to 10 mHz. We also discuss the implications of the obtained results for LISA.