Status of VIRGOLisa Barsotti - University and INFN Pisa –

on behalf of the VIRGO collaboration

ANNECY - December 15th, 2004

Status of the Commissioning Activity

Status of Data Analysis - Agenda

VIRGO Optical Scheme

BS NIWIPR

3-km Fabry Perot cavities in the arms

Commissioning PlanSteps of increasing complexity:Steps of increasing complexity:

Oct 2003 – Feb 2004Oct 2003 – Feb 2004

A SINGLE FABRY-PEROT CAVITY

PR misaligned

Commissioning PlanSteps of increasing complexity:Steps of increasing complexity:

Oct 2003 – Feb 2004Oct 2003 – Feb 2004

A SINGLE FABRY-PEROT CAVITY

PR misaligned

Commissioning PlanSteps of increasing complexity:Steps of increasing complexity:

Oct 2003 – Feb 2004Oct 2003 – Feb 2004

A SINGLE FABRY-PEROT CAVITY

Feb 2004 – Dec 2004Feb 2004 – Dec 2004

ITF in RECOMBINED MODE

PR misaligned

Commissioning PlanSteps of increasing complexity:Steps of increasing complexity:

Oct 2003 – Feb 2004Oct 2003 – Feb 2004

A SINGLE FABRY-PEROT CAVITY

Feb 2004 – Dec 2004Feb 2004 – Dec 2004

ITF in RECOMBINED MODE Sept 2004 Sept 2004

ITF in RECYCLED MODE Final configuration

PR aligned

Sensitivity Progress From a single arm to the recombined mode

C3: Automatic alignment and frequency servo tested in a

single arm configuration

C4: Automatic alignment and frequency servo tested in recombined configuration

C1 – November 2003

C4 – June 2004

Commissioning Run C4 - June 2004

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

Recombined Data Taking Mode

Commissioning Run C4 - June 2004

5 days of run

Lock losses understood

Longest lock ~ 28 h

h reconstruction on line

SPECIAL TESTS:

Acoustic noise injection in the laser and detection laboratorySession 7: Environmental noise studies in VIRGO - I. Fiori

Injection of inspiral events

Session 9: Inspiral analysis of the VIRGO commissioning run 4 – L. Bosi

Commissioning Run C4: Noise

CharacterizationCoupling of IB resonances into the

michelson controller signal due to a mismatch between modulation

frequency and input mode-cleaner length (~ 70 Hz)

C4

After frequency modulation tuning

Michelson controller signalProblem understood -> not final solution yet

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

Suspension Hierarchical Control

10-1

100

101

102

103

10-20

10-15

10-10

10-5

Actuators noise: current status

Frequency (Hz)

m/H

z1/2

Reference Mass - Mirror Actuators NoiseFilter #7 - Marionetta Actuators NoiseVIRGO Sentivity

103

Locking acquired and maintained acting at the level of the mirror

zz

x

y

marionette

reference mass

mirror Reduce the strength of the mirror actuators by a few 103 to reach

Virgo design sensitivity

Suspension Hierarchical Control

DC-0.01 Hz

0.01-8 Hz

8-50 Hz

Corrections sent to the marionette

Corrections sent to the mirror

Force on the mirror reduced of a factor 20

Switch to low noise coil drivers

TIDAL CONTROL

RE-ALLOCATION OF THE FORCE

Suspension Hierarchical Control

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)

SUMMARY

The Variable Finesse Locking Strategy“A recycled ITF with a low recycling factor is

similar to a recombined ITF “

NI NE

WE

WI

BSPR

Low Recycling Factor

Half Fringe

Lock immediately the 4 degrees of freedom of the ITF on the half fringe:

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

POWER IN THE RECYCLING CAVITY

With the ITF in a stable state, bring it adiabatically on the dark fringe evolving the control scheme

Recombined interferometer (~ 60 mW)

Recycled interferometer (~ 17 W)

TPR=8% -> Recycling factor ~ 25

frequency servo (SSFS) engaged to control the common mode of the arms

from DC to demodulated signal to control the simple michelson length

The Variable Finesse Locking Strategy

The Variable Finesse Locking Strategy

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

SUMMARY

Commissioning Run C5 - December 2004

Best VIRGO Sensitivity

Injection of bursts and inspiral events during the run -> Analysis in progress

10 times more power than C5

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

Agenda - I

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 burstsSession 15: A couple of techniques to improve sensibility preserving robustness in gravitational wave's burst detection

(G. Cella – INFN Pisa)

Injection of bursts and inspiral events in C4 Off–line analysis -> (see L.Bosi’s talk)

Session 15: Chirplet chains: a quasi-physical model for near- optimal detection of gravitational wave chirps

New algorithm for generic chirp

(Eric Chassande-Mottin – NICE )

Burst and Inspiral Search

POSTER: New definition of discrete time-frequency unitary Wigner-Ville distribution

(A. Pai – Roma University)

Agenda - II

POSTER: Simulation of gravitational wave stochastic background

(G. Cella – INFN Pisa)

Session 12: Adaptive Hough transform for the search of periodic sources (C. Palomba – INFN Roma)

Periodic Sources

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

Session 15: Pade and symmetrized Pade approximants in data processing (J. Fournier – CNRS)

Agenda – III

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: NAP: a tool for noise data analysis (E. Cuoco – EGO)

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

Noise Analysis

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)

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