VIRGO R&D

The R&D activities of VIRGO can be separately described:

UVVV (Ultra Violet Vacuum Virgo) is aiming to monitori the vacuum level of Virgo arms by a coherent UV beam generated by a pulsed high-power Nd-YAG laser entering a narrow tube filled by Ar gas. Suitable UV harmonic is extracted and used, by absorption and/or fluorescence, as probe for H2 molecules; sensitivity of this probe is of about 103 molecules/cm3, which is good enough to satisfy requirements by Virgo.

LDSW (Low Dissipation Suspension Wires) is an experimental study of the quality factor of the wire suspensions of Virgo mirrors for improving Virgo sensitivity in the frequency band from 10 to some hundreds Hz. Many materials have been tested in order to determine the best solution.

CRYSTAL is a logical development of the LDSW activity, aiming at producing and testing new (monocrystalline) material in order to improve performances (against thermal noise) in the field of cryogenic approach to new interferometric detectors.

LFF (Low Frequency Facility) is a facility working in S.Piero (INFN Lab of Pisa Section). The idea is to suspend an optical resonant cavity (Fabry-Pèrot cavity) to the last stage of a Virgo-like Superattenuator. This cavity results in an optical very-sensitive displacement sensor, which is able (for instance) to determine thermal noise spectra in a large band, out of resonance too. Its performance is good enough for studying phenomena at very small distances, new inertial accelerometric sensors etc.

ElPu (Electrostatic Pushers) is a preliminary study of the possibility to use electrostatic pushers as actuators for the control of Virgo mirrors in the loop at the last stage of Superattenuator: this can result in eliminating the presently used electromagnetic actuators, potential sources of (even very small) electromagnetic noise.

AOC (Adaptive Optics Control) has been proposed as a strategy for better cleaning of laser beam (after the Mode Cleaner stage working in Virgo) through a new loop by adaptive optics, which result in a more efficient way to obtain a sharp TEM00 mode.