The European Gravitational wave Observatory Virgo is undergoing an upgrade to increase its strain sensitivity to about 3 x 10(-24) 1/root Hz in the detection band of 10 Hz-10 kHz. The upgrade for this detector necessitates seismically isolating sensing optics in a vacuum environment that were on an optical bench outside vacuum in previous Virgo configurations. For this purpose, Nikhef has designed and built the five compact isolators, called MultiSAS. To measure the residual motion of the optical components and the transfer function of the isolator in full assembly, no (commercial) sensor is available that has sufficient sensitivity. A novel vibration sensor has been built at Nikhef that features an interferometric readout for a horizontal monolithic accelerometer. It will be able to measure in the vicinity of the fm/Hz regime from 10 Hz onwards. Current results show unprecedented (self) noise levels around 35 fm/Hz from 25 Hz onwards. In spite of these excellent results, it is still higher than the modeled noises. Several possible unmodeled noise sources and possible solutions have been identified. (C) 2015 Elsevier B.V. All rights reserved.
|Number of pages||5|
|Journal||Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors and Associated Equipment|
|Publication status||Published - 11 Jul 2016|
- Gravitational waves
- Seismic attenuation
- Shot-noise limited