Speaker
Description
We present a study of scattered light noise in ground-based gravitational-wave detectors, based on advanced simulations for the Einstein Telescope (ET) and Virgo. Stray light mitigation remains a critical challenge for current interferometers, as the residual light can couple into the main beam and limit the sensitivity. For ET, we present updated noise estimations for both the high- and low-frequency interferometers, incorporating also the effect of beam misalignments, offsets and the presence of point absorbers. We additionally present the results for a 15 km arms L-shaped configuration. For the current generation of detectors, there is an active campaign to monitor and mitigate scattered light and, to this end, the installation of instrumented baffles is part of the Advanced Virgo Plus upgrade in time for the O5 observing run. They were originally envisaged to be suspended, mounted on new payloads and surrounding new larger end mirrors. We demonstrate using simulations that placing the instrumented baffles just beyond the cryotrap gate valve and in front of the end mirrors would be equally effective for monitoring scattered light inside the cavities, while minimizing contamination risks and potential interferences with the mirrors. Additionally, we provide a noise estimation that proves that these instrumented baffles will not compromise Virgo’s sensitivity. The installation of these instrumented baffles will serve as a technology demonstrator for an active monitoring strategy of scattered light for ET.
