Characterization of disturbance sources for LISA: torsion pendulum results

TL;DR

This paper reports on improved torsion pendulum experiments that enhance sensitivity and enable detailed characterization of various acceleration noise sources affecting LISA test masses, crucial for space-based gravitational wave detection.

Contribution

The paper introduces advanced measurement techniques and provides new insights into the forces affecting LISA test masses, including electrostatic and thermal effects.

Findings

Improved upper limit on sensor-induced force noise

Characterization of electrostatic and dielectric loss forces

Preliminary results on temperature gradient effects

Abstract

A torsion pendulum allows ground-based investigation of the purity of free-fall for the LISA test masses inside their capacitive position sensor. This paper presents recent improvements in our torsion pendulum facility that have both increased the pendulum sensitivity and allowed detailed characterization of several important sources of acceleration noise for the LISA test masses. We discuss here an improved upper limit on random force noise originating in the sensor. Additionally, we present new measurement techniques and preliminary results for characterizing the forces caused by the sensor's residual electrostatic fields, dielectric losses, residual spring-like coupling, and temperature gradients.