Cascina, January 24, 2005 Status of GEO600 Joshua Smith for the GEO600 team

Joshua Smith, Cascina, January 24, 2005 Optical Layout

Joshua Smith, Cascina, January 24, 2005 Since Last Meeting Sept-Jan Sensitivity improvement Better grasp of noise sources Maturing detector characterization and noise analysis programs Transition to observatory operation Mehr platz…

Joshua Smith, Cascina, January 24, 2005 “GEO City” Workshop Central Building Bathrooms Offices Control Room / Visitor Center

Joshua Smith, Cascina, January 24, 2005 Scattered Light Sept 27-Nov16 – Various experiments to identify excess noise Mirror misalignment, different DC alignments Tapping of optics, bellows, tubes Acoustically “quiet run” Bellow damping Output beam through spatial filters and optical fiber Output optics in vacuum Filter experiments* Nov 17-Nov 29 – Reducing scattering* * talk by S. Hild

Joshua Smith, Cascina, January 24, 2005 Post-scattering Noise Hunting Dec 4-Dec 12 – Noise projections, noise hunting reveal limiting noise sources Detection + shot noise Dark port ampl. Noise Projections to hQ(t)

Joshua Smith, Cascina, January 24, 2005 Increased Laser Power Dec – 0.57 transmission filters in front of all photo-diodes – Increase injected laser power 3  5 W into first Modecleaner 1  1.7 W into Power Recycling Cavity 270  450 W at the Beamsplitter 30  50 mW at the detector output –?% MI sideband –?% SR sideband –?% Carrier Naïve Picture: 2 Power(carrier) = sqrt(2) Amp(carrier & MI SB ) Signal = Amp(carrier)*amp(MIsb) = 2 Power on HPD = 2 Shot = sqrt(2) Dark = 1 Win sqrt(2) with shot Win 2 with dark noise

Joshua Smith, Cascina, January 24, 2005 Dark Port Amplitude Noise Dec 23-Jan 17 – Dominant noise coupled via MI modulation path Decreased modulation depth 2x Amplitude stabilized 15MHz F MI Better gain distribution, cabling reduced pickup on 10m sending path P Q Moving RF Amplifier

Joshua Smith, Cascina, January 24, 2005 Decreased MI Mod. Depth Dec 29 – Factor 2 Naïve Picture: 0.5 Power(MI SB ) = 0.7 Amp(MI SB ) Signal = Amp(carrier)*Amp(MI SB ) = 0.7 Power on output diode = 0.5 (Mostly MI SB ) Shot = 0.7 Dark = 1 Pickup = 1 Ideas: - Nonlinear dependence of EOM or RF amplifier noise on signal size?

Joshua Smith, Cascina, January 24, 2005 Michelson Feedback Noise Jan 5-8 – Problems addressed: Square-root circuit ESD Bias voltage Gain distribution Pickup – Slight improvement around 100 Hz – Problems remaining: Further reduction of bias to reach design sensitivity –Will increase bilinear upconversion and beats

Joshua Smith, Cascina, January 24, 2005 Crossing /rt(Hz)

Joshua Smith, Cascina, January 24, 2005 Decreased SR Mod. Depth Jan 19 – Factor 3 – SR control loop noise not limiting – F SR AM coupling to the carrier or F MI due to the “noisy” removal of light at the Signal Recycling EOM?

Joshua Smith, Cascina, January 24, 2005 GEO Sensitivity History

Joshua Smith, Cascina, January 24, 2005 Jan 14 `05 vs. 1kHz Design

Joshua Smith, Cascina, January 24, 2005 GEO Summary Reports Lock List Duty Cycle Sensitivity Calibration Stationarity Glitches Lines Data Quality

Joshua Smith, Cascina, January 24, 2005 Overnight & Weekend Runs Consist of 1500 Hours total, during which >93% Duty Cycle Inspiral Range History

Joshua Smith, Cascina, January 24, 2005 Noise Projection Automation Semi-automatic Projections – Measure “snapshot” transfer functions – Measure noise FFTs live and simultaneously – TF amplitude and phase checks at noise calibration lines During measurement Long-term

Joshua Smith, Cascina, January 24, 2005 Noise Projections  Vetoes

Joshua Smith, Cascina, January 24, 2005 Future Plans Near term – Install crystal oscillators Oscillator amplitude + phase noise – Increase to full laser power Shot noise + detection noise – Hardware freeze mid Feb. Monitors, alarms Channel quality Noise projections – Join LSC S4 Medium term – Install final PR mirror – Reach design sensitivity

Joshua Smith, Cascina, January 24, 2005 Injected Sideband Power Normalized: C = 1 MI =.035 .017 SR =.044 .015 PR =.006