rd ILIAS-GW annual general meeting 1 VIRGO Commissioning progress J. Marque (EGO)

rd ILIAS-GW annual general meeting 2 Status one year ago Run C7 duty cycle 64% 14 h lock C7 C6 Run C6 duty cycle 90% 40 h lock

rd ILIAS-GW annual general meeting 3 C7 noise budget Interferometer working with a reduced input power ~ 0.8 W (25 W on the beam splitter) High frequency sensitivity limited by shot noise Necessity to increase the stored power (input power and recycling factor )

rd ILIAS-GW annual general meeting 4 Absence of optical isolation Laser Frequency Noise (Hz) Power recycling aligned Power recycling misaligned Short term solution : attenuate the input beam Long term: install a Faraday isolator

rd ILIAS-GW annual general meeting 5 New Input Bench: optical layout Parabolic output telescope Faraday isolator Attenuation no more needed input power = 10W To interferometer Input Mode cleaner From laser

rd ILIAS-GW annual general meeting 6 New injection bench September 2006  Spring 2007 Installation and commissioning of the new injection bench Mode-cleaner restart Cavities re-lock New power recycling mirror Lock acquisition with high power and new power recycling mirror (higher reflectivity)

rd ILIAS-GW annual general meeting 7 Lock acquisition and thermal effects Interferometer locked with ~10 W input power and 300 W on the beam splitter (more than 10 times C7) Lock acquisition much more complicated than expected long work to improve locking robustness during the thermal transient Thermal lensing discovered Absorption input mirror 4-10 times higher than expected Thermal transient

rd ILIAS-GW annual general meeting 8 Automatic alignment 14 degrees of freedom controlled 7 full bandwidth (3Hz), no local controls 7 with low bandwith (10 mHz), local controls

rd ILIAS-GW annual general meeting 9 WSR-1: september 2006 Science mode: 88% 6 data taking segments, 10h average inspiral range for NS-NS optimally oriented ~ 2 Mpc (0.8 Mpc averaged) Interferometer internal power Inspiral range for NS-NS optimally oriented

rd ILIAS-GW annual general meeting 10 Sensitivity

rd ILIAS-GW annual general meeting 11 Noise budget Longitudinal noises (PR, BS) Actuators noise Frequency noise shot noise

rd ILIAS-GW annual general meeting 12 Next steps/1: robustness Red curve: 2.7 Mpc -(wind+sea) ~ wind ~ sea activity One mechanism: Seismic noise  alignment fluctuations  horizon decrease and unlocks Ideas to decrease the reintroduction of the seismic noise  better superattenuator control

rd ILIAS-GW annual general meeting 13 Next steps/2: noise Several hardware actions already performed after WSR1 Optimization of optical isolation of the Faraday isolator (x10) Acoustic enclosure laser laboratory Reduction of actuators noise Increase of the aperture of optical vacuum window Now post-intervention recovering Next sensitivity expected in a few weeks

rd ILIAS-GW annual general meeting 14 Conclusions New injection bench commissioned (x10 input power) Now interferometer works with 300 W of stored power (500 W design) Thermal lensing discovered, lock acquisition more complex, no thermal compensation needed so far New sensitivity curve: high-mid frequency improvements, 2.5 Mpc peak WSR-1 (56hours): 90% duty cycle and inspiral range ~ 2 Mpc Several actions in progress to improve the noise and the sensitivity to weather conditions

rd ILIAS-GW annual general meeting 15

rd ILIAS-GW annual general meeting 16 End

rd ILIAS-GW annual general meeting 17 Commisioning progress (1/2) Sept05 Oct05 Nov05 Dec05 Jan06 Feb06 Mar06 CommissioningCommissioning RunC7RunC7 New injection sytem integration (input power * 10, Faraday isolation, Parabolic Input telescope) PR mirror change Injection sytem realignment Local controls retuning Input Mode Cleaner relock Input Mode Cleaner automatic alignment Reference Cavity alignment ITF alignment Input Beam Control Integration Input Mode Cleaner matching Reference Cavity alignment Full ITF relock Full ITF automatic alignment Inertial damping upgrade Input Bench + Input Mode Cleaner automatic alignment Reference Cavity alignment and locking

rd ILIAS-GW annual general meeting 18 Commisioning progress (2/2) Apr06 May06 Jun06 Jul06 Aug06 Sep06 Oct06 WSR1WSR1 WSR2WSR2 WSR3WSR3 WSR4WSR4 Full ITF Locking / Output Mode Cleaner locking (Fabry Perrot input mirrors thermal lensing issue) Full ITF Automatic Alignment Full automation Wires heating compensation / Local controls optimization Beam centering on ITF core optics optimization / Input telescope tuning / matching Input Bench + Input Mode Cleaner Automatic Alignment Detection Bench seismic isolation upgrade Locking, Local Controls and Alignment loops fine tuning Noise Hunting Coil drivers optimization Faraday Isolator optimization Input telescope fine tuning Laser Acoustic enclosure installation Detection Brewster Window change

rd ILIAS-GW annual general meeting 19 New Power Recycling Mirror - Old - New PR mirror transfer function Old PR mirror: non-monolithic curved (part of beam matching telescope) R=95% 120 mm R=4100 mm 350 mm New PR mirror: monolithic: no nore internal resonance in the control band flat: no more lens effect, larger beam coming out of input bench, need for a parabolic telescope on input bench R=98%: recycling gain increased by 30% Old PR mirror mounting

rd ILIAS-GW annual general meeting 20 New injection bench (above)

rd ILIAS-GW annual general meeting 21 Reference cavity New injection bench (below)

rd ILIAS-GW annual general meeting 22 Faraday isolator performance Issue: Input Mode Cleaner diodes polluted by fringes between ITF reflection and backscattered light in IMC => laser frequency noise and alignment loops are affected, need for a Faraday isolator. Laser Frequency Noise Hz Time Power Recycling mirror misaligned Power Recycling mirror aligned The attenuation of the Faraday has been measured to be => Does not limit the ITF performance anymore. Before Now Light transmitted by IMC

rd ILIAS-GW annual general meeting 23 New input system alignment scheme control

rd ILIAS-GW annual general meeting 24 Mode matching and mirror centering Power transmitted by FP swinging cavity Before After BS mirror centering Tuning of parabolic input telescope: o Mode matching of the FP cavities (97%) o Beam positionning in ITF (clipping issue) TEM02 TEM01 2 techniques for mirror centering: o Direct imaging where possible (BS) o Mirror shaking at natural resonance => alignment/locking coupling minimization. All optics centered with 5mm accuracy.

rd ILIAS-GW annual general meeting 25 Suspension control upgrade Mirror excitation with bad weather => Changed suspension top stage control Noise introduced by DAC on the mirror => Rearrange forces going to suspension, Switch to low noise coil driver Emphasis-deemphasis filtering

rd ILIAS-GW annual general meeting 26 Locking acquisition suffers from thermal lensing transient Lock acquisition is delicate => Thermal lensing study o Compensation for gain change thermal drift, o Installed scanning Fabry Perrot to measure sidebands unbalance o Setup a mirror temperature monitoring (mirror drum modes frequency is shifting with temperature increase) o Started optical simulation effort o Phase camera preparation => Mirror coating absorption is 4 to 10 times higher than expected Sidebands evolution over 15mn

rd ILIAS-GW annual general meeting 27 Automatic alignment 14 degrees of freedom controled o 7 full bandwith (3Hz) o 7 low bandwith integrator (10mHz) + Local Controls