37 research outputs found
The Virgo data acquisition system
International audienc
The gravitational wave detector VIRGO
International audienc
Search for non-Gaussian events in the data of the VIRGO E4 engineering run
International audienc
ÉTUDE DE L'EFFET FARADAY DANS QUELQUES CRISTAUX ET VERRES DOPÉS AUX TERRES RARES
La variation du pouvoir rotatoire magnétique de verres dopés avec de l'holmium, de l'erbium, du néodyme, ou de fluorine dopée avec du néodyme, du samarium ou de l'oxyde d'uranium (U2 O8) a été déterminée entre 3 000 ou 3 600 Å et 6 000 Å, dans les régions de transparence comme dans celles d'absorption des ions d'addition. Les spectres présentés ont été obtenus à l'aide du spectro-polarimètre photoélectrique mis au point au laboratoire
The Virgo Suspensions
The VIRGO suspensions are chains of passive mechanical filters designed to isolate the interferometer mirrors from seismic noise starting from a few Hz. In order to reduce the low-frequency swing of the mirror along the beam, an
active control system, acting at the level of the suspension point, damps the main resonant modes of the system (all below 2.5 Hz). Another control loop, at the level of the optical payload, makes use of a digital camera monitoring the mirror position in all six degrees of freedom. Its main goal is to decrease the rms angular displacements of the mirror, on a time scale of several minutes, down to less than 1 ÎĽrad. All the seven suspensions of the VIRGO central interferometer are presently in operation, while the assembly of the last two,
for the terminal mirrors, is in progress. The design andperformance of the system are described in this paper