GEO 600 and the GEO-HF upgrade program: successes and challenges

TL;DR

The GEO 600 gravitational wave detector's GEO-HF upgrade program successfully enhanced high-frequency sensitivity by up to four times, demonstrating technological advancements and ongoing challenges in gravitational wave detection.

Contribution

This paper reports on the successful implementation of the GEO-HF upgrade program, achieving significant sensitivity improvements and providing insights into future detector technologies.

Findings

Sensitivity improved by up to a factor of four at high frequencies

All planned upgrades completed by early 2014

Ongoing efforts to further enhance detector performance

Abstract

The German-British laser-interferometric gravitational wave detector GEO 600 is in its 14th year of operation since its first lock in 2001. After GEO 600 participated in science runs with other first-generation detectors, a program known as GEO-HF began in 2009. The goal was to improve the detector sensitivity at high frequencies, around 1 kHz and above, with technologically advanced yet minimally invasive upgrades. Simultaneously, the detector would record science quality data in between commissioning activities. As of early 2014, all of the planned upgrades have been carried out and sensitivity improvements of up to a factor of four at the high-frequency end of the observation band have been achieved. Besides science data collection, an experimental program is ongoing with the goal to further improve the sensitivity and evaluate future detector technologies. We summarize the results of the GEO-HF program to date and discuss its successes and challenges.