MG 11 - Berlin Virgo status Marie-Anne Bizouard (LAL-Orsay) on behalf of the Virgo Collaboration

MG 11 - Berlin Ground based gravitational wave detectors Virgo detector commissioning – 2006 ( M. Barsuglia’s talk) Virgo data taking – 2005 Virgo data analysis – searches and detector characterization (E. Cuoco’s and C. Palomba’s talk) Virgo future preparation –Virgo++ (N. Man talk) –Advanced Virgo Short term planning Ground based gravitational wave detectors Virgo detector commissioning – 2006 ( M. Barsuglia’s talk) Virgo data taking – 2005 Virgo data analysis – searches and detector characterization (E. Cuoco’s and C. Palomba’s talk) Virgo future preparation –Virgo++ (N. Man talk) –Advanced Virgo Short term planning Outline

MG 11 - Berlin The Virgo Collaboration as in 2006 CNRS - LAPP - Annecy INFN - Firenze/Urbino CNRS - LMA/ESPCI – Lyon/Paris INFN – Napoli CNRS - OCA – Nice CNRS - LAL - Orsay INFN - Perugia INFN - Pisa INFN – Roma 2006: NIKHEF – Amsterdam (joining) + EGO (European Gravitational Observatory)  175 physicists / engineers

MG 11 - Berlin Growing ground based interferometers network 600 m 4 & 2 km 4 km 3 km AIGO ? km proposed + LCGT 3 km planned TAMA 300 m

MG 11 - Berlin Interferometers at a glance How to detect the path of a GW?  measure the displacement of the mirrors induced by the GW  light phase shift measurement But: GW amplitude is small h~ L=3km   L= m The laser has fluctuations in phase and amplitude External forces push the mirrors Seismic noise Thermal noise: vibration of bulk due to non null temperature Shot noise: quantum fluctuation in the number of detected photons

MG 11 - Berlin Virgo optical layout Laser Nd:YAG P=20 W Input Mode Cleaner Length = 144 m Recycling Output Mode Cleaner Length = 4 cm L=3km Finesse=50 L=3km Finesse=50 P=1kW A Michelson with 3 semi-transparent mirrors to form optical cavities to increase the power inside the arms

MG 11 - Berlin 1: longitudinal control Interferometer controls Keep the FP cavities in resonance (maximization of the phase response) Keep the PR cavity in resonance (minimization of the shot noise) Keep the output on the “dark fringe” (reduction of the dependence on power fluctuations) Keep the arms’ length constant within m

MG 11 - Berlin 2: angular control Interferometer controls Avoid high order mode generation (reduction of coupling dark fringe with frequency noise, power noise, input beam jitter, beam miscentering,..)  Reduction of the power fluctuation! Needs to control 12 degrees of freedom ITF power (a.u.) Auto-alignment ON

MG 11 - Berlin Interferometer controls Complicated scheme! Controls introduce noise in the dark fringe at low frequency (<100Hz)

MG 11 - Berlin

Free falling test masses … Thermal noise Multi stage pendulum ­ pre-isolator: inverted pendulum ­ cantilever springs for vertical isolation ­ cascade of six stages ­ height ~ 10 m

MG 11 - Berlin Foreseen sensitivity Seismic wall Thermal noise Shot noise

MG 11 - Berlin Ground based gravitational wave detectors Virgo detector commissioning – 2006 Virgo data taking – 2005 Virgo data analysis – searches and detector characterization Virgo future preparation –Virgo++ –Advanced Virgo Short term planning Outline

MG 11 - Berlin Virgo sensitivity curve progresses (as end of 2005) C7 run (sep. 2005): Best strain h ~ / Hz 1/2 NS/NS maximum range ~ 1.5 Mpc (optimal orientation)

MG 11 - Berlin Noise budget

MG 11 - Berlin Shutdown at end of 2005 – Why? Fringes due to backscattering in the Mode Cleaner  Increase a lot the frequency noise  Need to operate with reduced power 0.7 W instead of 7W !  Solution: Faraday isolator on the injection bench to attenuate the backscattering light a new injection bench Backscattering

MG 11 - Berlin Shutdown at end of 2005 – Why? Non-monolithic and curved Power Recycling mirror –Curved: because part of the output telescope to match the beam –Non-monolithic: lots of resonances  control problems and alignment drifts Solution: –Monolithic mirror –Flat mirror  No more lens effect: larger beam coming from the injection bench need of a telescope on the injection bench a new injection bench 120 mm R=4100 mm 350 mm Incident Beam Translations induce misalignment and jitter noise  flat mirror

MG 11 - Berlin New injection bench Faraday isolator New parabolic telescope

MG 11 - Berlin Virgo commissioning – new input bench Sep 2005 – April 2006 New scheme of the alignment wrt to the ITF Parabolic telescope alignment done Locking of the Mode Cleaner cavity Beam matching: 95% reached Faraday isolator tuned 7 W entering in the ITF 280 W on the BS (sep. 2005: 25W! ) Mode Cleaner transmitted power July 2004: before beam attenuation (.7W) March 2006: Concern: the Faraday isolator attenuation factor is only 100 instead of Under investigation while not yet a problem in the sensitivity curve!

MG 11 - Berlin Virgo commissioning – full power recycled interferometer Feb 2006 – until now We had few problems/difficulties: Beam matching Beam astigmatism Beam clipping on detection bench Oscillations in signals used for control  lock losses! Thermal effect in substrate (25W  280W on Beam Splitter mirror) ? Improvement of the beam matching and centering  increase the power inside the ITF by a factor 2  no more wire heating 10 hours Work done on: - demodulation phase tuning - more angular degrees of freedom controlled Lock stability improved a lot !

MG 11 - Berlin Virgo sensitivity – July 2006! High frequency: better than one year ago Low frequency: a lot of work to be done! The noise hunting period just restarted More details in M. Barsuglia’s talk Power Recycling mirror control noise

MG 11 - Berlin Ground based gravitational wave detectors Virgo detector commissioning – 2006 Virgo data taking – 2005 Virgo data analysis – searches and detector characterization Virgo future preparation –Virgo++ –Advanced Virgo Short term planning Outline

MG 11 - Berlin The last data taking periods Andromeda Horizon for SNR=8, optimally oriented 1.4/1.4 M NS-NS binary 14 days duty cycle: 86% in Science Mode 5 days duty cycle: 65% in Science Mode C6 July 2005 C7 Sep best NS-NS distance range: 1.5 Mpc

MG 11 - Berlin Ground based gravitational wave detectors Virgo detector commissioning – 2006 Virgo data taking – 2005 Virgo data analysis – searches and detector characterization Virgo future preparation –Virgo++ –Advanced Virgo Short term planning Outline

MG 11 - Berlin Data analysis in Virgo at a glance Group activities –Noise –Burst (SN, unmodelled short signal) –Binary inspiral –Pulsar –Stochastic background Collaborations –Auriga-RoG-Virgo –LIGO-Virgo Data taking: C6 & C7 More dealing with pipeline development detector characterization than with “physics” search or competitive upper limits More details in E. Cuoco and C. Palomba’s talks

MG 11 - Berlin Burst events search Burst studies on a single detector: hard! –Event distribution dramatically different from Gaussian –Vetoes based on auxiliary channels Understand the machine! Hardware injections to test veto safety Identification of the main source of excess noise for the burst search Excess noise above 100 Hz due to dark fringe coupling with the frequency noise when the North End is tilted  problem of mirror angular control (too loose during C6 &C7) Vetos definition: excess frequency noise environmental glitches (air conditioning for instance) air plane Nice reduction of the burst fake events … but huge dead time: >20% without veto with veto

MG 11 - Berlin Inspiral search Up to now focus only on NS-NS search (2 pipelines developed in Virgo) C6 & C7 analysis main concern: veto strategies set up use of “  2” methods to reject fake events The  2 checks the compatibility between the signal waveform and the recorded strain  2 2 bands < 40 Samples above threshold < 30  2 2 bands < 40 “hardware” injected events (equivalent force applied on mirror)

MG 11 - Berlin Continuous sources search All-sky search pipeline C6 & C7 work goal: –1kHz band considered –Production of bank of candidates for C6 and C7 and performance coincidence –Detection of detector related noise that could bias the analysis For more details: C. Palomba’s talk Example: 10 Hz disturbance : pulses caused by a video camera Number of candidates : excess for some frequencies! Sensitivity obtained : h~ Hz C6 Frequency (Hz)

MG 11 - Berlin Stochastic background search Search done by cross- correlated the output of 2 detectors The closer the detectors, the lower the frequencies that can be searched Virgo Ligo Hanford Virgo Ligo Livingston Virgo GEO Ligo Hanford Ligo Livingston Ligo Hanford GEO Ligo Livingston GEO Virgo does not have yet the sensitivity to constrain the SB but got prepared. Two collaborations: Auriga/Nautilus/Explorer/Virgo Limited by the bars sensitivity curve  GW < 2 x (Virgo design sensitivity) LSC-Virgo – Just starting project – Standard cosmological background (isotropic) search – Targeted search (sky map of gw)

MG 11 - Berlin International collaborations Auriga-RoG-Virgo –Burst search –Stochastic background search LSC-Virgo: joint GEO, LIGO and Virgo data analysis effort –Burst, inspiral : start working for 2 years! “Physics gain” to add a non aligned ITF to LIGO network: - reconstruction of the source location - detection efficiency enhanced by 50% (burst) or 30% (inspiral) –SB just joins –We are in the process of defining the data exchange agreement and how to work as a joint data analysis group. –Sketching a possible joint run planning (VERY PRELIMINARY) S5

MG 11 - Berlin Ground based gravitational wave detectors Virgo detector commissioning – 2006 Virgo data taking – 2005 Virgo data analysis – searches and detector characterization Virgo future preparation –Virgo++ –Advanced Virgo Short term planning Outline

MG 11 - Berlin Short –Acoustic isolation –Pre-Mode Cleaner –Upgrade of the quadrant diode front-end electronics –New coil drivers (R&D) Intermediate –Eddy current dissipation mitigation –New MC mirror payload –New DSP electronics (R&D) –Thermal compensation Virgo+ upgrades –High power laser amplifier –Monolithic payload –New DAQ electronics (R&D) Virgo upgrades planning 2008 Now “Standard” upgrades dedicated to reach the Virgo nominal sensitivity Short –Acoustic isolation –Pre-Mode Cleaner –Upgrade of the quadrant diode front-end electronics –New coil drivers (R&D) Intermediate –Eddy current dissipation mitigation –New MC mirror payload –New DSP electronics (R&D) –Thermal compensation Virgo+ upgrades –High power laser amplifier –Monolithic payload –New DAQ electronics (R&D) high freq. shot noise reduction! low and inter. freq. thermal noise reduction!

MG 11 - Berlin Virgo+ scientific outreach NS-NS signal detection benefits Of the sensitivity improvement at intermediate frequency Shot noise decrease Thermal noise decrease

MG 11 - Berlin Ground based gravitational wave detectors Virgo detector commissioning – 2006 Virgo data taking – 2005 Virgo data analysis – searches and detector characterization Virgo future preparation –Virgo++ –Advanced Virgo Short term planning Outline

MG 11 - Berlin Short term planning - Conclusions

MG 11 - Berlin