1. WG1, Hannover, Jan 2007 1 Commissioning progress at GEO600 Martin Hewitson for the GEO team

2. WG1, Hannover, Jan 2007 2 Overview - plans  Ended full-time S5 15 Oct 2006 Back to commissioning, overnight/weekend modeBack to commissioning, overnight/weekend mode  Planned work: Investigation periodInvestigation period  Power measurements, simulation improvements, etc ESD AA for MIDESD AA for MID Improve clean-room cleanlinessImprove clean-room cleanliness  New HEPA filters for AC Fix various mains problemsFix various mains problems  Filtering, ground loops, PE to neutral connections Open central clusterOpen central cluster  Exchange HV feedthroughs for ESDs (corroded)  Reposition beam block (scattering suspected)

3. WG1, Hannover, Jan 2007 3 Since the last meeting…  Investigations: Power build-upPower build-up Power increase - instability, PUGsPower increase - instability, PUGs ‘Ripple’ noise‘Ripple’ noise  Commissioning: MID AA ESDsMID AA ESDs SR longitudinal loopSR longitudinal loop  Problems: Significant series of power failuresSignificant series of power failures

4. WG1, Hannover, Jan 2007 4 Not in this talk  Power up stability, glitches Detector not stable with full available input powerDetector not stable with full available input power  HOT TOPIC Also observed large glitches in the past when at full powerAlso observed large glitches in the past when at full power  Not observed recently so hard to investigate  Ripple noise investigations See Josh’s talkSee Josh’s talk

5. WG1, Hannover, Jan 2007 5 Running performance Post S5 running Power cut

6. WG1, Hannover, Jan 2007 6 PR build-up  Two reliable methods used to determine factor: PR cavity polePR cavity pole Direct measurement of power reflected from BS AR coatingDirect measurement of power reflected from BS AR coating  Additional measurements of power transmitted at end mirrors Less reliable due to low light levelsLess reliable due to low light levels

7. WG1, Hannover, Jan 2007 7 PR cavity pole Measurements of PR cavity pole give

8. WG1, Hannover, Jan 2007 8 PR build-up - Summary  PR pole and BS-AR measurements agree within 10% Yield a build-up factor of 840-920Yield a build-up factor of 840-920  Transmission at MFe gives build-up factor of 1410 (less confidence) Can be explained by 120-130 ppm/mirror

9. WG1, Hannover, Jan 2007 9 Site Power Failure - 02/12/06  3 power failures of increasing duration - last one around 40 minutes  Various systems damaged MC turbo pump, computers, ESDsMC turbo pump, computers, ESDs  North ESD damaged 2 pairs of wires shorted inside vacuum2 pairs of wires shorted inside vacuum  Diagnosed by current-limit of HVA  Some external rewiring to bypass the problem Still less actuation after repairStill less actuation after repair  35% less on North drive, 65% less on East drive  All quadrants on East are working  What else? Charges on test-mass counter-act the dielectric effect of ESD which means less force

10. WG1, Hannover, Jan 2007 10 Charges on East test-mass  Lock with north only  Drive East drive with varying bias plus fixed ac (calibration) line  Measure line height in MID error-point  For un-charged test-mass line height should be zero for zero bias

11. WG1, Hannover, Jan 2007 11

12. WG1, Hannover, Jan 2007 12 Attempts to discharge  UV attack Shine UV into TCeShine UV into TCe  Knock of electrons from metal-work neutralize test-massneutralize test-mass  Venting central cluster with argon Vented to 1mbarVented to 1mbar failed failed

13. WG1, Hannover, Jan 2007 13 Going on after power cut  Decide to stick with lower strength ESDs for now since we want to open vacuum anyway soon  Calibration adjusted to give old sensitivty Checked with PPDChecked with PPD  Loop gains adjusted for this state  So far seems not to cause too much trouble for locking

14. WG1, Hannover, Jan 2007 14 Improving SR long lock  Motivation: Want to try PRAA for higher powerWant to try PRAA for higher power  PR long noise couples to SR cavity Want more SR long gainWant more SR long gain  Current SR long state: Loop bandwidth is limited by how much feedback noise we can tolerateLoop bandwidth is limited by how much feedback noise we can tolerate Feedback is shot-noise above 100HzFeedback is shot-noise above 100Hz Previously using the AA quadrant diode for long error- signalPreviously using the AA quadrant diode for long error- signal Installed SED resonant for 9MHzInstalled SED resonant for 9MHz  Expect x2 lower shot-noise  Motivation: Want to try PRAA for higher powerWant to try PRAA for higher power  PR long noise couples to SR cavity Want more SR long gainWant more SR long gain  Current SR long state: Loop bandwidth is limited by how much feedback noise we can tolerateLoop bandwidth is limited by how much feedback noise we can tolerate Feedback is shot-noise above 100HzFeedback is shot-noise above 100Hz Previously using the AA quadrant diode for long error- signalPreviously using the AA quadrant diode for long error- signal Installed SED resonant for 9MHzInstalled SED resonant for 9MHz  Expect x2 lower shot-noise

15. WG1, Hannover, Jan 2007 15 Further improvements  Noticed coherence through dSPACE is not 1  Limited by DAC noise First tried flat gain factor for feedbackFirst tried flat gain factor for feedback Then added whitening at feedback outputThen added whitening at feedback output

16. WG1, Hannover, Jan 2007 16 Using new SED for SR long  Lowers MSR feedback projection to H We can use this gain to improve the control loopWe can use this gain to improve the control loop

17. WG1, Hannover, Jan 2007 17 New SR run-loop Relax feedback low- pass filtering allows more low-frequency gain for similar loop- stability margins

18. WG1, Hannover, Jan 2007 18 Cleaning up the clean-room  Additional HEPA filters installed for AC system  We have additional particle leak from pump-room due to over-pressure there

19. WG1, Hannover, Jan 2007 19 Coming up  Opening vacuum system Reposition beam dump(s) and install translation stage(s)Reposition beam dump(s) and install translation stage(s) Repair ESDsRepair ESDs  Fix wiring and install new HV feedthroughs  Improvement of air-conditioning system HEPA filters in clean room [done]HEPA filters in clean room [done]  Continue work on power increase  Continue commissioning of MID ESD AA