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VIRGO Commissioning progress J. Marque (EGO) 26-10-06 3rd ILIAS-GW annual general meeting 1 Status one year ago Run C7 duty cycle 64% 14 h lock Run C6 C7 duty cycle 90% 40 h lock C6 26-10-06 3rd ILIAS-GW annual general meeting 2 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 ) 26-10-06 3rd ILIAS-GW annual general meeting 3 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 26-10-06 3rd ILIAS-GW annual general meeting 4 New Input Bench: optical layout To interferometer Parabolic output telescope Faraday isolator Input Mode cleaner Attenuation no more needed input power = 10W From laser 26-10-06 3rd ILIAS-GW annual general meeting 5 September 2006Spring 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) 26-10-06 3rd ILIAS-GW annual general meeting 6 New injection bench Lock acquisition and thermal effects • Interferometer locked with ~10 W input power and 300 W on the beam splitter (more than 10 times C7) Thermal transient • 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 26-10-06 3rd ILIAS-GW annual general meeting 7 Automatic alignment • 14 degrees of freedom controlled • 7 full bandwidth (3Hz), no local controls • 7 with low bandwith (10 mHz), local controls 26-10-06 3rd ILIAS-GW annual general meeting 8 WSR-1: september 2006 Interferometer internal power Inspiral range for NS-NS optimally oriented • Science mode: 88% • 6 data taking segments, 10h average • inspiral range for NS-NS optimally oriented ~ 2 Mpc (0.8 Mpc averaged) 26-10-06 3rd ILIAS-GW annual general meeting 9 Sensitivity 26-10-06 3rd ILIAS-GW annual general meeting 10 Noise budget Longitudinal noises (PR, BS) Actuators noise Frequency noise shot noise 26-10-06 3rd ILIAS-GW annual general meeting 11 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 26-10-06 3rd ILIAS-GW annual general meeting 12 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 26-10-06 3rd ILIAS-GW annual general meeting 13 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 26-10-06 3rd ILIAS-GW annual general meeting 14 26-10-06 3rd ILIAS-GW annual general meeting 15 End End 26-10-06 3rd ILIAS-GW annual general meeting 16 Commisioning progress (1/2) Sept05 C o m m i s s i o n i n g R u n C 7 Oct05 Nov05 Dec05 Jan06 Injection sytem realignment ITF alignment Local controls retuning Input Beam Control Integration Feb06 Mar06 Full ITF relock Full ITF automatic alignment Inertial damping New injection sytem upgrade integration Input Mode Cleaner (input power * 10, relock Input Bench + Input Faraday isolation, Mode Cleaner Input Mode Cleaner Parabolic Input Mode Cleaner matching automatic alignment Input telescope) automatic alignment Reference Reference PR mirror Reference Cavity Cavity Cavity change alignment alignment alignment and locking 26-10-06 3rd ILIAS-GW annual general meeting 17 Commisioning progress (2/2) Apr06 May06 Jun06 Jul06 Aug06 Sep06 Full ITF Locking / Output Mode Cleaner locking (Fabry Perrot input mirrors thermal lensing issue) Full ITF Automatic Alignment Locking, Full automation Local Controls Wires heating compensation / and Local controls optimization Alignment loops Beam centering on ITF core optics optimization / fine Input telescope tuning / matching tuning Input Bench + Input Mode Cleaner Automatic Alignment Noise Hunting Detection Bench seismic isolation upgrade 26-10-06 3rd ILIAS-GW annual general meeting W S R 1 Oct06 W W W S S S R R R 2 3 4 Coil drivers optimization Faraday Isolator optimization Input telescope fine tuning Laser Acoustic enclosure installation Detection Brewster Window change 18 New Power Recycling Mirror 350 mm Old PR mirror: • non-monolithic • curved (part of beam matching telescope) • R=95% 120 mm R=4100 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% 26-10-06 Old PR mirror mounting - Old - New PR mirror transfer function 3rd ILIAS-GW annual general meeting 19 26-10-06 New injection bench (above) 3rd ILIAS-GW annual general meeting 20 New injection bench (below) 26-10-06 3rd ILIAS-GW annual general meeting Reference cavity21 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 Power Recycling mirror misaligned Power Recycling mirror aligned Time The attenuation of the Faraday has been measured to be 1000. => Does not limit the ITF performance anymore. Before Now Light transmitted by IMC 26-10-06 3rd ILIAS-GW annual general meeting 22 New input system alignment scheme control 26-10-06 3rd ILIAS-GW annual general meeting 23 Mode matching and mirror centering Tuning of parabolic input telescope: o Mode matching of the FP cavities (97%) o Beam positionning in ITF (clipping issue) 2 techniques for mirror centering: o Direct imaging where possible (BS) o Mirror shaking at natural resonance => alignment/locking coupling minimization. TEM02 TEM01 Power transmitted by FP swinging cavity All optics centered with 5mm accuracy. Before After BS mirror centering 26-10-06 3rd ILIAS-GW annual general meeting 24 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 26-10-06 3rd ILIAS-GW annual general meeting 25 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 Sidebands evolution over 15mn => Mirror coating absorption is 4 to 10 times higher than expected 26-10-06 3rd ILIAS-GW annual general meeting 26 Automatic alignment 14 degrees of freedom controled o 7 full bandwith (3Hz) o 7 low bandwith integrator (10mHz) + Local Controls 26-10-06 3rd ILIAS-GW annual general meeting 27