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Status of VIRGO

Status of VIRGO. Lisa Barsotti - University and INFN Pisa – on behalf of the VIRGO collaboration. Status of the Commissioning Activity

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Status of VIRGO

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  1. Status of VIRGO Lisa Barsotti - University and INFN Pisa – on behalf of theVIRGO collaboration • Status of the Commissioning Activity • Status of Data Analysis - Agenda ANNECY - December 15th, 2004

  2. WI PR BS NI 3-km Fabry Perot cavities in the arms VIRGO Optical Scheme

  3. Commissioning Plan Steps of increasing complexity: Oct 2003 – Feb 2004 • A SINGLE FABRY-PEROT CAVITY PR misaligned

  4. Commissioning Plan Steps of increasing complexity: Oct 2003 – Feb 2004 • A SINGLE FABRY-PEROT CAVITY PR misaligned

  5. Commissioning Plan Steps of increasing complexity: Oct 2003 – Feb 2004 • A SINGLE FABRY-PEROT CAVITY Feb 2004 – Dec 2004 • ITF in RECOMBINED MODE PR misaligned

  6. Commissioning Plan Steps of increasing complexity: Oct 2003 – Feb 2004 • A SINGLE FABRY-PEROT CAVITY Feb 2004 – Dec 2004 • ITF in RECOMBINED MODE Sept 2004 • ITF in RECYCLED MODE • Final configuration PR aligned

  7. C3: Automatic alignmentand frequency servotested in a single arm configuration C4: Automatic alignmentand frequency servotested in recombined configuration Sensitivity Progress • From a single arm to the recombined mode C1 – November 2003 C4 – June 2004

  8. Commissioning Run C4- June 2004 • Recombined Data Taking Mode • ITF controlled with the reflected and the asymmetric beams • Automatic alignment of the cavities • Laser frequency stabilized to cavities common mode • Cavities common mode locked to reference cavity • Output Mode Cleaner locked on the dark fringe • Tidal control on both arms

  9. SPECIAL TESTS: Commissioning Run C4- June 2004 • 5 days of run • Lock losses understood • Longest lock ~ 28 h • h reconstruction on line • Acoustic noise injection in the laser and detection laboratory Session 7: Environmental noise studies in VIRGO - I. Fiori • Injection of inspiral events Session 9: Inspiral analysis of the VIRGO commissioning run 4– L. Bosi

  10. Michelson controller signal C4 After frequency modulation tuning Commissioning Run C4: Noise Characterization Coupling of IB resonances into the michelson controller signal due to a mismatch between modulation frequency and input mode-cleaner length (~ 70 Hz) Problem understood -> not final solution yet

  11. After C4 • July – August • Upgrade of the terminal benches -> Re-tuning and improvement of the linear automatic alignment • Suspension full hierarchical control started • Commissioning of the Recycled ITF started • Effect of the backscattered light in the IMC-> attenuator installed between the IMC and the ITF • Mid September: Re-Start • October – November: -> Recombined ITF locked with the full hierarchical control of the suspensions -> ITF locked in recycled mode

  12. marionette reference mass 103 y mirror z x z Suspension Hierarchical Control • Locking acquired and maintained acting at the level of the mirror • Reduce the strength of the mirror actuators by a few 103 to reach Virgo design sensitivity

  13. Corrections sent to the marionette TIDAL CONTROL DC-0.01 Hz Corrections sent to the mirror 0.01-8 Hz RE-ALLOCATION OF THE FORCE Force on the mirror reduced of a factor 20 • Switch to low noise coil drivers 8-50 Hz Suspension Hierarchical Control

  14. Suspension Hierarchical Control • SUMMARY • Single arm locked with the hierarchical control for the first time in July -> controllability of the superattenuator demonstrated • Last main result: hierarchical control of the recombined ITF in the C4 configuration, with automatic alignment and frequency servo engaged • Stable lock -> tested in the last commissioning run (C5, 2-6 December 2004)

  15. WE WI PR NI NE BS Half Fringe The Variable Finesse Locking Strategy “A recycled ITF with a low recycling factor is similar to a recombined ITF “ • Lock immediately the 4 degrees of freedom of the ITF on the half fringe: Low Recycling Factor • end photodiodes to acquire the lock of the long cavities • simple michelson locked on the half fringe with the asymmetric DC signal • 3f demodulated reflected signal to control the recycling cavity length

  16. POWER IN THE RECYCLING CAVITY The Variable Finesse Locking Strategy • With the ITF in a stable state, bring it adiabatically on the dark fringe evolving the control scheme Recycled interferometer (~ 17 W) • frequency servo (SSFS) engaged to control the common mode of the arms • from DC to demodulated signal to control the simple michelson length TPR=8% ->Recycling factor ~ 25 Recombined interferometer (~ 60 mW)

  17. The Variable Finesse Locking Strategy • SUMMARY • First lock of the recycled ITF on the end of last October • Stable lock of the recycled interferometer ~ 40-50 minutes • no linear automatic alignment yet  next step • Locking procedure tested several times • lock acquired in few minutes • New original lock acquisition procedure established, combining end photodiodes, frequency servo, 3f-demod signal, slightly misalignement of PR mirror, and lock on the half fringe  M. Evans (LIGO) and K. Arai (TAMA) present on Virgo site • 1 day and half of test in the last commissioning run C5

  18. 10 times more power than C5 Best VIRGO Sensitivity Commissioning Run C5- December 2004 • Injection of bursts and inspiral events during the run -> Analysis in progress

  19. Data Analysis Activity • h reconstruction (F. Marion - LAPP ) • Physics group activity: • Burst(P. Hello - LAL ) • Coalescent Binary(A. Vicerè – INFN Urbino) • Pulsar Source Software (S. Frasca – Roma University ) • Stochastic Background(G. Cella – INFN Pisa) • Noise Analysis(J. Y. Vinet – NICE) • Network analysis

  20. Agenda - I Burst and Inspiral Search • Injection of bursts and inspiral events in C4 Off–line analysis -> (see L.Bosi’s talk) • A new time-frequency tool: the S-Trasform Session 15: A burst search method based on the S-transform (A-C. Clapson – LAL ) • Network analysis of bursts Session 15: A couple of techniques to improve sensibility preserving robustness in gravitational wave's burst detection (G. Cella – INFN Pisa) • New algorithm for generic chirp Session 15: Chirplet chains: a quasi-physical model for near- optimal detection of gravitational wave chirps (Eric Chassande-Mottin– NICE ) POSTER: New definition of discrete time-frequency unitary Wigner-Ville distribution (A. Pai – Roma University)

  21. POSTER:Simulation of gravitational wave stochastic background (G. Cella – INFN Pisa) Agenda - II • Session 15: Pade and symmetrized Pade approximants in data processing (J. Fournier – CNRS) Periodic Sources • Session 12: Adaptive Hough transform for the search of periodic sources (C. Palomba – INFN Roma) • POSTER: Simulation of a population of gravitational wave-driven neutron stars (C. Palomba – INFN Roma) • POSTER: Evaluation of sensitivity and of computing power for the Virgo hierarchical search for periodic sources (S. Frasca – Roma University) Stochastic Background

  22. Agenda – III Noise Analysis • So far mainly carried out in the commissioning activity -> Peculiar tests performed to study the environmental noise and its coupling with the interferometer (see I. Fiori ‘s talk) • Line detection POSTER: A simple line detection algorithm applied to Virgo data (Eric Chassande-Mottin– I. Fiori) • Extended noise analysis to be added -> Software tool development: Noise Analysis Package POSTER: NAP: a tool for noise data analysis (E. Cuoco – EGO)

  23. Network Analysis • LSC – Virgo Collaboration - Joint working group for inspiral and burst search on simulated data Session 9: First comparison between the LIGO/Virgo inspiral search pipelines (F. Beauville – LAPP ) Session 13: Comparison of methods for gravitational wave burst search using simulated LIGO and VIRGO data (M. Zanolin – MIT)

  24. Conclusions • Well advanced status of the commissioning activity -> Suspension hierarchical control in recombined mode -> Lock of the recycled ITF • Next steps: -> Linear automatic alignment of the recycled ITF -> Frequency servo optimization • Last Commissioning Run Data -> analysis in progress • Data analysis main activities will be presented

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