1. Stefan Hild 1GWDAW 10, Brownsville, December 2005 Status of GEO 600 Stefan Hild, AEI Hannover for the GEO-team

2. Stefan Hild 2GWDAW 10, Brownsville, December 2005 Overview Some examples from commissioning work - increasing circulating power - radiation pressure compensation - reduction of feedback noise Calibration Data quality Detector characterization, stationarity Sensitivity progress

3. Stefan Hild 3GWDAW 10, Brownsville, December 2005 GEO 600 layout 3 kW 0.09 9 W 4 W 5 kW Increased to full input power Still not the full power build-up IFO due to unexplained power losses

4. Stefan Hild 4GWDAW 10, Brownsville, December 2005 Radiation pressure compensation High power inside the modecleaners in combination with low weight suspended mirrors causes strong radiation pressure effects Right after lock acquisition mirrors are pushed by RP  Saturation of the actuator (Laser PZT) Solution: Apply a bias force to the mirrors for acquisition and reduce this force in lock corresponding to the power build-up.

5. Stefan Hild 5GWDAW 10, Brownsville, December 2005 Optical transfer function Signal Recycling provides an adjustable optical response Lock acquistion at 2.5 kHz, OPERATION NOW at 350 Hz.

6. Stefan Hild 6GWDAW 10, Brownsville, December 2005 Noise projections / instrumental vetoes Useful tool for commissioning Can be used for instrumental vetoes

7. Stefan Hild 7GWDAW 10, Brownsville, December 2005 Noise hunting example 1: Reduction of feedback noise in SR-loop FB noise in Signal Recycling loop: Shot noise from camera causes FB noise in detection band Solution: Using a digital loop with strong filtering above unity gain. Improved sensitivity below 500 Hz

8. Stefan Hild 8GWDAW 10, Brownsville, December 2005 Noise hunting example 2: Reduction of feedback noise in MI-loop Noise mainly caused in HVA for ESD Due to dynamic range constraints use whitening-dewhitenig Passive dewhitening done in HV path (0-1kV) Improved sensitivity from 50 to 600 Hz

9. Stefan Hild 9GWDAW 10, Brownsville, December 2005 Noise hunting example 3: Attacking Phase noise Indication that Phase noise is nearly limiting Implementation of a new RF- setup for Michelson modulation (higher signal levels, higher quality components) Increased robustness of the detector, but no sensitivity improvement.

10. Stefan Hild 10GWDAW 10, Brownsville, December 2005 Calibration of GEO600 2 main outputs (each containing GW signal) both calibrated to strain using time-domain method making an optimal combination Calibration quality can be judged by chi^2 value (data quality flag)

11. Stefan Hild 11GWDAW 10, Brownsville, December 2005 Null-Stream Veto

12. Stefan Hild 12GWDAW 10, Brownsville, December 2005 Independent check of calibration using: Wavelength: 1035 nm Max. power: 1.4 W Photon pressure calibrator Good agreement with ESD.

13. Stefan Hild 13GWDAW 10, Brownsville, December 2005 Sensitivity improvement of GEO Peak sensitivity = 4e-22 @ 550 Hz

14. Stefan Hild 14GWDAW 10, Brownsville, December 2005 Inspiral range Optimal orientation Detector characterization information available on daily basis: www.geo600.uni-hannover.de/georeports/

15. Stefan Hild 15GWDAW 10, Brownsville, December 2005 Noise stationarity / BLRMS of h(t)

16. Stefan Hild 16GWDAW 10, Brownsville, December 2005 Future plans No hardware changes foreseen Continue intense noise hunting Overnight and weekend runs Best guess: start around Christmas Provide a well-calibrated detector output Join S5 When additional improvements will take too long or are too risky to implement

17. Stefan Hild 17GWDAW 10, Brownsville, December 2005 E n d

18. Stefan Hild 18GWDAW 10, Brownsville, December 2005 Sensitivity improvement of GEO Peak sensitivity = 4e-22 @ 550 Hz

19. Stefan Hild 19GWDAW 10, Brownsville, December 2005 Instrumental vetos

20. Stefan Hild 20GWDAW 10, Brownsville, December 2005 CHI^2 data quality flag HACRmon h(t) @ 1kHz chi 2 Example: MU3-Glitches (Problem was fixed during S4)

21. Stefan Hild 21GWDAW 10, Brownsville, December 2005 S4 duty cycle (chi^2 cutoff dependent)