Global Feed-Forward Vibration Isolation in a km scale Interferometer

TL;DR

This paper presents a feed-forward vibration isolation method using seismometer networks and optimal filtering to enhance the stability and data quality of km-scale gravitational wave interferometers.

Contribution

It introduces a novel control technique employing Wiener filters derived via Levinson-Durbin recursion for seismic noise reduction in large-scale interferometers.

Findings

Reduced RMS of feedback signals below 10 Hz

Improved interferometer stability and duty cycle

Significant decrease in non-Gaussian transients

Abstract

Using a network of seismometers and sets of optimal filters, we implemented a feed-forward control technique to minimize the seismic contribution to multiple interferometric degrees of freedom of the LIGO interferometers. The filters are constructed by using the Levinson-Durbin recursion relation to approximate the optimal Wiener filter. By reducing the RMS of the interferometer feedback signals below \sim10 Hz, we have improved the stability and duty cycle of the joint network of gravitational wave detectors. By suppressing the large control forces and mirror motions, we have dramatically reduced the rate of non-Gaussian transients in the gravitational wave signal stream.