All-sky search for gravitational-wave bursts in the second joint LIGO-Virgo run

We present results from a search for gravitational-wave bursts in the data collected by the LIGO and Virgo detectors between July 7, 2009 and October 20, 2010: data are analyzed when at least two of the three LIGO-Virgo detectors are in coincident operation, with a total observation time of 207 days. The analysis searches for transients of duration < 1 s over the frequency band 64-5000 Hz, without other assumptions on the signal waveform, polarization, direction or occurrence time. All identified events are consistent with the expected accidental background. We set frequentist upper limits on the rate of gravitational-wave bursts by combining this search with the previous LIGO-Virgo search on the data collected between November 2005 and October 2007. The upper limit on the rate of strong gravitational-wave bursts at the Earth is 1.3 events per year at 90% confidence. We also present upper limits on source rate density per year and Mpc^3 for sample populations of standard-candle sources. As in the previous joint run, typical sensitivities of the search in terms of the root-sum-squared strain amplitude for these waveforms lie in the range 5 10^-22 Hz^-1/2 to 1 10^-20 Hz^-1/2. The combination of the two joint runs entails the most sensitive all-sky search for generic gravitational-wave bursts and synthesizes the results achieved by the initial generation of interferometric detectors.Comment: 15 pages, 7 figures: data for plots and archived public version at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=70814&version=19, see also the public announcement at http://www.ligo.org/science/Publication-S6BurstAllSky

Vacancy-oxygen defects in silicon: the impact of isovalent doping

Silicon is the mainstream material for many nanoelectronic and photovoltaic applications. The understanding of oxygen related defects at a fundamental level is essential to further improve devices, as vacancy-oxygen defects can have a negative impact on the properties of silicon. In the present review we mainly focus on the influence of isovalent doping on the properties of A-centers in silicon. Wherever possible, we make comparisons with related materials such as silicon germanium alloys and germanium. Recent advanced density functional theory studies that provide further insights on the charge state of the A-centers and the impact of isovalent doping are also discussed in detail

Einstein gravitational wave Telescope conceptual design study

This document describes the Conceptual Design of a third generation gravitational wave observatory named Einstein Telescope (“ET”). The design of this new research infrastructure has been realised with the support of the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n 211743. In this document are described the fundamental design options, the site requirements, the main technological solutions, a rough evaluation of the costs and a schematic time plan

Automatic Alignment for the first science run of the Virgo interferometer

During the past few years a network of large-scale laser interferometers, including the Virgo detector, has been developed with the aim of detecting gravitational waves. To properly operate the detectors, the longitudinal and angular positions of the suspended detector test masses, the interferometer mirrors, must be kept within a small range from the operating point. The design of the Virgo angular control system, called Automatic Alignment is based on a modified version of the Anderson-Giordano technique, a wave-front sensing scheme which uses the modulation-demodulation technique. This paper will present the theoretical background of the Virgo Automatic Alignment system, the implementation issues and the performances observed during the first Virgo science run (VSR1). A total RMS of 4 × 10−2 to 3 × 10−3 μrad for all angular degrees of freedom has been achieved

The seismic Superattenuators of the Virgo gravitational waves interferometer

The Virgo experiment, located near Pisa, Italy, is a large laser Michelson interferometer aiming at the first direct detection of gravitational waves. The interferometer monitors the relative distance of its mirrors placed at the ends of two 3 km-long perpendicular arms. The goal is to measure spectral differential variations of the arm lengths of 10(-18) m/Hz(1/2) in the frequency range from 10 Hz to 10 kHz. Avoiding spurious motions of the optical components is therefore essential to detect gravitational waves. Since the ground motion is 9 orders of magnitude larger than the arm length variations induced by gravitational waves, the seismic noise is the dominant low frequency noise source for terrestrial gravitational wave interferometers. The seismic isolation is obtained suspending the mirrors by an 8-meter tall chain of cascaded mechanical filters, called "Superattenuator" (SA). The Superattenuator is a passive device acting as a low pass filter in all six degrees of freedom, capable of attenuating the ground motion by more than 10 orders of magnitude, starting from a few Hz. To further reduce the seismic disturbances, the filter chain is suspended from an actively stabilized platform that compensates for low frequency and large amplitude oscillations caused by the mechanical resonances of the chain. In this article we describe the Superattenuator together with its control system, and we report about its performance

In-vacuum Faraday isolation remote tuning

none170sìIn-vacuum Faraday isolators (FIs) are used in gravitational wave interferometers to prevent the disturbance caused by light reflected back to the input port from the interferometer itself. The efficiency of the optical isolation is becoming more critical with the increase of laser input power. An in-vacuum FI, used in a gravitational wave experiment (Virgo), has a 20 mm clear aperture and is illuminated by an almost 20 W incoming beam, having a diameter of about 5 mm. When going in vacuum at 10−6 mbar, a degradation of the isolation exceeding 10 dB was observed. A remotely controlled system using a motorized λ=2 waveplate inserted between the first polarizer and the Faraday rotator has proven its capability to restore the optical isolation to a value close to the one set up in air.mixed Accadia T; Acernese F; Antonucci F; Aoudia S; Arun KG; Astone P; Ballardin G; Barone F; Barsuglia M; Bauer TS; Beker MG; Bigotta S; Birindelli S; Bitossi M; Bizouard MA; Blom M; Boccara C; Bondu F; Bonelli L; Bosi L; Braccini S; Bradaschia C; Brillet A; Brisson; Budzynski R; Bulik T; Bulten HJ; Buskulic D; Cagnoli G; Calloni E; Campagna E; Canuel B; Carbognani F; Cavalier F; Cavalieri R; Cella G; Cesarini E; Chassande-Mottin E; Chincarini A; Cleva F; Coccia E; Colacino CN; Colas J; Colla A; Colombini M; Corda C; Corsi A; Coulon JP; Cuoco E; D'Antonio S; Dari A; Dattilo V; Davier M; Day R; De Rosa R; del Prete M; Di Fiore L; Di Lieto A; Emilio MD; Di Virgilio A; Dietz A; Drago M; Fafone V; Ferrante I; Fidecaro F; Fiori I; Flaminio R; Fournier JD; Franc J; Frasca S; Frasconi F; Freise A; Gammaitoni L; Garufi F; Gemme G; Genin E; Gennai A; Giazotto A; Gouaty R; Granata M; Greverie C; Guidi GM; Heitmann H; Hello P; Hild S; Huet D; Jaranowski P; Kowalska I; Królak A; La Penna P; Leroy N; Letendre N; Li TG; Lorenzini M; Loriette V; Losurdo G; Mackowski JM; Majorana E; Man N; Mantovani M; Marchesoni F; Marion F; Marque J; Martelli F; Masserot A; Michel C; Milano L; Minenkov Y; Mohan M; Moreau J; Morgado N; Morgia A; Mosca S; Moscatelli V; Mours B; Neri I; Nocera F; Pagliaroli G; Palladino L; Palomba C; Paoletti F; Pardi S; Parisi M; Pasqualetti A; Passaquieti R; Passuello D; Persichetti G; Pichot M; Piergiovanni F; Pietka M; Pinard L; Poggiani R; Prato M; Prodi GA; Punturo M; Puppo P; Rabaste O; Rabeling DS; Rapagnani P; Re V; Regimbau T; Ricci F; Robinet F; Rocchi A; Rolland L; Romano R; Rosińska D; Ruggi P; Sassolas B; Sentenac D; Sturani R; Swinkels B; Toncelli A; Tonelli M; Tournefier E; Travasso F; Trummer J; Vajente G; van den Brand JF; van der Putten S; Vavoulidis M; Vedovato G; Verkindt D; Vetrano F; Viceré A; Vinet JY; Vocca H; Was M; Yvert M; Virgo C accadia, T;  acernese, F;  antonucci, F;  aoudia, S;  arun, Kg;  astone, P;  ballardin, G;  barone, F;  barsuglia, M;  bauer, Ts;  beker, Mg;  bigotta, S;  birindelli, S;  bitossi, M;  bizouard, Ma;  blom, M;  boccara, C;  bondu, F;  bonelli, L;  bosi, L;  braccini, S;  bradaschia, C;  brillet, A;  brisson, ;  budzynski, R;  bulik, T;  bulten, Hj;  buskulic, D;  cagnoli, G;  calloni, E;  campagna, E;  canuel, B;  carbognani, F;  cavalier, F;  cavalieri, R;  cella, G; Cesarini, Elisabetta;  Chassande Mottin, E;  chincarini, A;  cleva, F;  coccia, E;  colacino, Cn;  colas, J;  colla, A;  colombini, M;  corda, C;  corsi, A;  coulon, Jp;  cuoco, E;  d'Antonio, S;  dari, A;  dattilo, V;  davier, M;  day, R;  De Rosa, R;  del Prete, M;  Di Fiore, L;  Di Lieto, A;  emilio, Md;  Di Virgilio, A;  dietz, A;  drago, M;  fafone, V;  ferrante, I;  fidecaro, F;  fiori, I;  flaminio, R;  fournier, Jd;  franc, J;  frasca, S;  frasconi, F;  freise, A;  gammaitoni, L;  garufi, F;  gemme, G;  genin, E;  gennai, A;  giazotto, A;  gouaty, R;  granata, M;  greverie, C; Guidi, GIANLUCA MARIA;  heitmann, H;  hello, P;  hild, S;  huet, D;  jaranowski, P;  kowalska, I;  królak, A;  La Penna, P;  leroy, N;  letendre, N;  li, Tg;  lorenzini, M;  loriette, V;  losurdo, G;  mackowski, Jm;  majorana, E;  man, N;  mantovani, M;  marchesoni, F;  marion, F;  marque, J; Martelli, Filippo;  masserot, A;  michel, C;  milano, L;  minenkov, Y;  mohan, M;  moreau, J;  morgado, N;  morgia, A;  mosca, S;  moscatelli, V;  mours, B;  neri, I;  nocera, F;  pagliaroli, G;  palladino, L;  palomba, C;  paoletti, F;  pardi, S;  parisi, M;  pasqualetti, A;  passaquieti, R;  passuello, D;  persichetti, G;  pichot, M; Piergiovanni, Francesco;  pietka, M;  pinard, L;  poggiani, R;  prato, M;  prodi, Ga;  punturo, M;  puppo, P;  rabaste, O;  rabeling, Ds;  rapagnani, P;  re, V;  regimbau, T;  ricci, F;  robinet, F;  rocchi, A;  rolland, L;  romano, R;  rosińska, D;  ruggi, P;  sassolas, B;  sentenac, D; Sturani, Riccardo;  swinkels, B;  toncelli, A;  tonelli, M;  tournefier, E;  travasso, F;  trummer, J;  vajente, G;  van den Brand, Jf;  van der Putten, S;  vavoulidis, M;  vedovato, G;  verkindt, D; Vetrano, Flavio; Vicere', Andrea;  vinet, Jy;  vocca, H;  was, M;  yvert, M; Virgo, C

In-vacuum Faraday isolation remote tuning

In-vacuum Faraday isolators (FIs) are used in gravitational wave interferometers to prevent the disturbance caused by light reflected back to the input port from the interferometer itself. The efficiency of the optical isolation is becoming more critical with the increase of laser input power. An in-vacuum FI, used in a gravitational wave experiment (Virgo), has a 20 mm clear aperture and is illuminated by an almost 20 W incoming beam, having a diameter of about 5 mm. When going in vacuum at 10(-6) mbar, a degradation of the isolation exceeding 10 dB was observed. A remotely controlled system using a motorized lambda/2 waveplate inserted between the first polarizer and the Faraday rotator has proven its capability to restore the optical isolation to a value close to the one set up in air. c 2010 Optical Society of Americ