17 research outputs found
New Seismic Attenuation System (SAS) for the Advanced LIGO Configurations (LIGO2)
A new passive seismic attenuation system is being developed to replace the current passive attenuation stacks in LIGO 2, it is expected to drive the seismic contribution to the interferometer noise below any other noise source. The SAS will be effective completely starting at about 5 Hz, well inside the (uncompensated) gravity gradient noise wall
Overview of Advanced LIGO Adaptive Optics
This is an overview of the adaptive optics used in Advanced LIGO (aLIGO),
known as the thermal compensation system (TCS). The thermal compensation system
was designed to minimize thermally-induced spatial distortions in the
interferometer optical modes and to provide some correction for static
curvature errors in the core optics of aLIGO. The TCS is comprised of ring
heater actuators, spatially tunable CO laser projectors and Hartmann
wavefront sensors. The system meets the requirements of correcting for nominal
distortion in Advanced LIGO to a maximum residual error of 5.4nm, weighted
across the laser beam, for up to 125W of laser input power into the
interferometer
Current status of Japanese detectors
Current status of TAMA and CLIO detectors in Japan is reported in this
article. These two interferometric gravitational-wave detectors are being
developed for the large cryogenic gravitational wave telescope (LCGT) which is
a future plan for detecting gravitational wave signals at least once per year.
TAMA300 is being upgraded to improve the sensitivity in low frequency region
after the last observation experiment in 2004. To reduce the seismic noises, we
are installing new seismic isolation system, which is called TAMA Seismic
Attenuation System, for the four test masses. We confirmed stable mass locks of
a cavity and improvements of length and angular fluctuations by using two SASs.
We are currently optimizing the performance of the third and fourth SASs. We
continue TAMA300 operation and R&D studies for LCGT. Next data taking in the
summer of 2007 is planned.
CLIO is a 100-m baseline length prototype detector for LCGT to investigate
interferometer performance in cryogenic condition. The key features of CLIO are
that it locates Kamioka underground site for low seismic noise level, and
adopts cryogenic Sapphire mirrors for low thermal noise level. The first
operation of the cryogenic interferometer was successfully demonstrated in
February of 2006. Current sensitivity at room temperature is close to the
target sensitivity within a factor of 4. Several observation experiments at
room temperature have been done. Once the displacement noise reaches at thermal
noise level of room temperature, its improvement by cooling test mass mirrors
should be demonstrated.Comment: 6 pages, 5 figures, Proceedings of GWDAW-1
Le système d'alignement du banc de détection de l'expérience VIRGO de recherche d'ondes gravitationnelles
LE BUT DE L'EXPERIENCE FRANCO-ITALIENNE VIRGO, EST LA DETECTION DES ONDES GRAVITATIONNELLES AVEC UN INTERFEROMETRE DE MICHELSON-MORLEY, AYANT DES BRAS DE 3 KM DE LONG. CETTE ETUDE EST FOCALISEE SUR LE BANC DE DETECTION DE VIRGO, DONT LES FONCTIONS PRINCIPALES SONT DE FOURNIR LE SIGNAL D'ONDE GRAVITATIONNELLE ET D'AMELIORER SON RAPPORT SIGNAL SUR BRUIT EN UTILISANT UNE CAVITE OPTIQUE RESONNANTE. C'EST UN ENSEMBLE FORME DE COMPOSANTS OPTIQUES (UN CAVITE OPTIQUE FABRY-PEROT), MECANIQUES (MOTEURS SOUS VIDE), ELECTRONIQUES (PHOTODIODES, AMPLIFICATEURS) ET INFORMATIQUES (LECTURE, CONTROLE). PLACE DANS UNE ENCEINTE A VIDE POUR L'ISOLER DU BRUIT ACOUSTIQUE, IL EST AUSSI ACCROCHE A UNE SUSPENSION QUI L'ISOLE DU BRUIT SISMIQUE. L'OBJET DE CETTE THESE, EST L'ETUDE, LA REALISATION ET LE TEST DES SYSTEMES DE CONTROLE AUTOMATIQUE DE POSITION DU BANC : LE SYSTEME DE POSITIONNEMENT LOCAL CONTROLE PAR UNE CAMERA CCD ET LE SYSTEME GLOBAL, COMPRENANT UNE OPTIQUE D'ADAPTATION (TELESCOPE), DES CAPTEURS DE POSITION INSTALLES SUR LE BANC, AINSI QUE L'ELECTRONIQUE ET L'INFORMATIQUE ASSOCIEES. LE BRUIT RESIDUEL DU SYSTEME LOCAL, QUI CONTROLE LES SIX DEGRES DE LIBERTE DU BANC, EST DE 5RAD#R#M#S EN ANGLE ET DE 4M#R#M#S EN POSITION. LE SYSTEME GLOBAL QUI SUIT UN DES DEUX FAISCEAUX DE SORTIE DE L'INTERFEROMETRE, REDUIT LE BRUIT ANGULAIRE D'UN ORDRE DE GRANDEUR, CE QUI EST SUFFISANT POUR L'ALIGNEMENT CORRECT DE LA CAVITE RESONNANTE. L'ENSEMBLE DU SYSTEME DE POSITIONNEMENT DU BANC DE DETECTION PRESENTE DANS CE MEMOIRE SERA INSTALLE SUR LE SITE AU DEBUT DE L'ANNEE 1999 EN MEME TEMPS QUE LE RESTE DE LA PARTIE CENTRALE DE L'EXPERIENCE VIRGO.NI