The R&D activities of
VIRGO can be separately described as in the following:
UVVV (Ultra Violet Vacuum Virgo) is aiming to monitoring 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 H2molecules;
sensitivity of this probe is of about 103 molecules/cm3,
which is good enough to satisfy requirements by Virgo. This activity is
approaching its end.
CRYSTAL is a logical development of the previous Low Dissipation Suspension Wires
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. After analysis of PSD from physical data,
this complex device will remain as a stable, available facility for Virgo (and
related) groups.
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 results in a more efficient way to obtain a
sharp TEM00 mode.
ViC represents a first approach for a feasibility study for future cryogenic
Virgo-like suspension (at 4 K temperature).