37 research outputs found
The archiving system of the Virgo antenna for gravitational wave detection
No full textIn this article we describe the hardware and software architecture of the prototypes of the archiving system of the very long base line interferometric Virgo antenna for gravitational wave detection. The characteristics which make this system very interesting and innovative are not only its performances but also the modularity of the architecture which makes it easier to both follow the progress of the technology without dramatic changes of the hardware and software architecture and to match the requirements according to the Virgo needs. This prototype has been tested in the data acquisition of the 3 m pendularly suspended and evacuated Michelson interferometer prototype which is operational in Naples and in the monitoring of physical environmental quantities, like electromagnetic noise, acoustic noise, etc., necessary for the correlation of the output of the interferometer with the environmen
Production de dimuons dans les interactions pi- W a 200GeV/c : comparaison aux predictions QCD et determination des fonctions de structure du pi-
No full textSIGLECNRS T 56477 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Predicting electromagnetic counterparts using low-latency gravitational-wave data products
No full textSearches for gravitational-wave counterparts have been going in earnest since GW170817 and the discovery of AT2017gfo. Since then, the lack of detection of other optical counterparts connected to binary neutron star or black hole–neutron star candidates has highlighted the need for a better discrimination criterion to support this effort. At the moment, low-latency gravitational-wave alerts contain preliminary information about binary properties and hence whether a detected binary might have an electromagnetic counterpart. The current alert method is a classifier that estimates the probability that there is a debris disc outside the black hole created during the merger as well as the probability of a signal being a binary neutron star, a black hole–neutron star, a binary black hole, or of terrestrial origin. In this work, we expand upon this approach to both predict the ejecta properties and provide contours of potential light curves for these events, in order to improve the follow-up observation strategy. The various sources of uncertainty are discussed, and we conclude that our ignorance about the ejecta composition and the insufficient constraint of the binary parameters by low-latency pipelines represent the main limitations. To validate the method, we test our approach on real events from the second and third Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)–Virgo observing runs
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B physics at the Z sup 0 pole
No full textThe SLC has been running at SLAC since April, and more than 100 Z{sup 0} events have been reconstructed. Shortly the new European facility at CERN-LEP-will also turn on, and by the end of the year we anticipate that more than 10,000 Z{sup 0} events will have been registered by each of the four LEP detectors. Most of the experimental facilities at these two machines are equipped with excellent particle tracking and identification. Some have close-in tracking devices which will provide unparalleled precision in trajectory reconstruction, and lead to the possibility of identifying a large proportion of the charmed and beauty particles. Not only does the Z{sup 0} pole offer a relatively large production cross section for e{sup +}e{sup {minus}} machines, but a large proportion of the events are b{bar b} pairs. One sees from this figure that a gain of six or more is obtained from running at the Z{sup 0}. An SLC producing 10{sup 5} events per year yields 20,000 b{bar b} events. Similarly, for LEP, over 200,000 b{bar b} events will become available per year. In addition, the planned upgrade for LEP will increase its luminosity by about an order of magnitude, and the SLC will run with polarized electron beams. The physics that may be studies from these event samples fall into two general categories: tests of the Standard Model; and studies of B mesons and B baryons, including lifetimes, mixing, spectroscopy, and CP violation. 8 refs., 8 figs., 1 tab
Placement of templates technique in a 2D parameter space for binary inspiral searches
No full text25 pages, 28 figures - VIRGOIn the search for binary systems inspiral signal in interferometric gravitational waves detectors, one needs the generation and placement of a grid of templates. We present an original technique for the placement in the associated parameter space, that makes use of the variation of size of the isomatch ellipses in order to reduce the number of templates necessary to cover the parameter space. A study of the covering efficiency, as well as a comparison with a very simple regular tiling using a single ellipse is made
Le système d'alignement du banc de détection de l'expérience VIRGO de recherche d'ondes gravitationnelles
No full textLE 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
From the Virgo interferometer calibration to the bias and uncertainty of the h(t) detector strain during the O4 run
No full textInternational audienceSince the first gravitational wave detection in 2015, ground-based interferometer sensitivities have significantly improved, requiring highly precise calibration to ensure accurate reconstruction of the h(t) strain signal. In this talk we will outline the Virgo interferometer calibration steps performed in preparation of the O4b run started in April 2024. We will first describe the Photon Calibrator power devices intercalibration allowing for a 0.48% precision on mirror displacement. Before explaining how the Photon Calibrator is used to calibrate every Virgo mirror actuators. We will also discuss the monitoring of the h(t) strain reconstruction during the run showing that, on the 10 Hz to 2 kHz band, the reconstructed strain achieves a precision of 2% in modulus and 30 mrad in phase. Special emphasis will be given on the newly developed frequency-dependent bias and uncertainty computation method and the resulting online unbiasing of the h(t) strain
From the Virgo interferometer calibration to the bias and uncertainty of the h(t) detector strain during the O4 run
No full textInternational audienceSince the first gravitational wave detection in 2015, ground-based interferometer sensitivities have significantly improved, requiring highly precise calibration to ensure accurate reconstruction of the h(t) strain signal. In this talk we will outline the Virgo interferometer calibration steps performed in preparation of the O4b run started in April 2024. We will first describe the Photon Calibrator power devices intercalibration allowing for a 0.48% precision on mirror displacement. Before explaining how the Photon Calibrator is used to calibrate every Virgo mirror actuators. We will also discuss the monitoring of the h(t) strain reconstruction during the run showing that, on the 10 Hz to 2 kHz band, the reconstructed strain achieves a precision of 2% in modulus and 30 mrad in phase. Special emphasis will be given on the newly developed frequency-dependent bias and uncertainty computation method and the resulting online unbiasing of the h(t) strain
Etude de méthodes pour la recherche avec le détecteur VIRGO d'ondes gravitationnelles émises par des étoiles à neutrons
No full textLe but de l'expérience Virgo est la détection des ondes gravitationnelles. L'objet de cette thèse est l'étude de méthodes pour la recherche de signaux émis par des étoiles à neutrons ainsi que l'étalonnage du détecteur. Dans une première partie, l'étoile à neutrons et son émission d'ondes gravitationnelles, sont présentées. Ensuite le détecteur, les principales sources de bruits, ainsi que la solution adoptée pour l'étalonnage sont décrits. Puis dans une seconde partie la modélisation des effets dus aux mouvements de la terre (effet Doppler, modulation d'amplitude) est décrite. Leurs conséquences sur le rapport signal sur bruit sont déterminées. Les deux derniers chapitres sont consacrés aux algorithmes de recherche de signaux périodiques. Tout d'abord le cas où la position de la source est connue est présenté. Le ralentissement de la rotation de la source et la correction de cet effet sont décrits. La correction de l'effet Doppler est aussi détaillée. De même, le problème de la gestion du gigantesque flot de données à traiter est abordé, et une solution y est apportée. Finalement la difficulté de recherche multidirectionnelle est présentée. Des prototypes d'algorithmes hiérarchiques sont aussi évalués.NI
