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

WG1, Hannover, Jan 2007 1

Commissioning progress at Commissioning progress at GEO600GEO600

Martin Hewitson for the GEO teamMartin Hewitson for the GEO team

WG1, Hannover, Jan 2007WG1, Hannover, Jan 2007 22

Overview - plansOverview - plans

Ended full-time S5 15 Oct 2006Ended full-time S5 15 Oct 2006• Back to commissioning, overnight/weekend modeBack to commissioning, overnight/weekend mode

Planned work:Planned work:• Investigation periodInvestigation period

Power measurements, simulation improvements, etcPower measurements, simulation improvements, etc

• ESD AA for MIDESD AA for MID• Improve clean-room cleanlinessImprove clean-room cleanliness

New HEPA filters for ACNew HEPA filters for AC

• Fix various mains problemsFix various mains problems Filtering, ground loops, PE to neutral connectionsFiltering, ground loops, PE to neutral connections

• Open central clusterOpen central cluster Exchange HV feedthroughs for ESDs (corroded)Exchange HV feedthroughs for ESDs (corroded) Reposition beam block (scattering suspected)Reposition beam block (scattering suspected)


Since the last meeting…Since the last meeting…

Investigations:Investigations:• Power build-upPower build-up• Power increase - instability, PUGsPower increase - instability, PUGs• ‘‘Ripple’ noiseRipple’ noise

Commissioning:Commissioning:• MID AA ESDsMID AA ESDs• SR longitudinal loopSR longitudinal loop

Problems:Problems:• Significant series of power failuresSignificant series of power failures


Not in this talkNot in this talk

Power up stability, glitchesPower up stability, glitches• Detector not stable with full available input power Detector not stable with full available input power

HOT TOPICHOT 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 investigateNot observed recently so hard to investigate

Ripple noise investigationsRipple noise investigations• See Josh’s talkSee Josh’s talk

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.




Running performanceRunning performancePost S5 runningPost S5 running

Pow

er c

ut


PR build-upPR build-up

Two reliable methods used to determine Two reliable methods used to determine factor:factor:• PR cavity pole PR cavity pole • Direct measurement of power reflected from Direct measurement of power reflected from

BS AR coatingBS AR coating Additional measurements of power Additional measurements of power

transmitted at end mirrorstransmitted at end mirrors• Less reliable due to low light levelsLess reliable due to low light levels


PR cavity polePR cavity pole

Measurements of PR cavity pole giveMeasurements of PR cavity pole give






PR build-up - SummaryPR build-up - Summary

PR pole and BS-AR measurements agree within PR pole and BS-AR measurements agree within 10%10%• Yield a build-up factor of 840-920Yield a build-up factor of 840-920

Transmission at MFe gives build-up factor of Transmission at MFe gives build-up factor of 1410 (less confidence)1410 (less confidence)

Can be explained by 120-130 ppm/mirror


Site Power Failure - 02/12/06Site Power Failure - 02/12/06

3 power failures of increasing duration - last one around 3 power failures of increasing duration - last one around 40 minutes40 minutes

Various systems damagedVarious systems damaged• MC turbo pump, computers, ESDsMC turbo pump, computers, ESDs

North ESD damagedNorth ESD damaged• 2 pairs of wires shorted inside vacuum2 pairs of wires shorted inside vacuum

Diagnosed by current-limit of HVADiagnosed by current-limit of HVA Some external rewiring to bypass the problemSome external rewiring to bypass the problem

• Still less actuation after repairStill less actuation after repair 35% less on North drive, 65% less on East drive35% less on North drive, 65% less on East drive All quadrants on East are workingAll quadrants on East are working What else? Charges on test-mass counter-act the dielectric effect of What else? Charges on test-mass counter-act the dielectric effect of

ESD which means less forceESD which means less force


Charges on East test-massCharges on East test-mass

Lock with north onlyLock with north only Drive East drive with varying bias plus Drive East drive with varying bias plus

fixed ac (calibration) linefixed ac (calibration) line Measure line height in MID error-pointMeasure line height in MID error-point For un-charged test-mass line height For un-charged test-mass line height

should be zero for zero biasshould be zero for zero bias





Attempts to dischargeAttempts to discharge

UV attackUV attack• Shine UV into TCeShine UV into TCe

Knock of electrons from metal-workKnock of electrons from metal-work• neutralize test-massneutralize test-mass

Venting central cluster with argonVenting central cluster with argon• Vented to 1mbarVented to 1mbar

failedfailed

failedfailed




Going on after power cutGoing on after power cut

Decide to stick with lower strength ESDs Decide to stick with lower strength ESDs for now since we want to open vacuum for now since we want to open vacuum anyway soonanyway soon

Calibration adjusted to give old sensitivtyCalibration adjusted to give old sensitivty• Checked with PPDChecked with PPD

Loop gains adjusted for this stateLoop gains adjusted for this state So far seems not to cause too much So far seems not to cause too much

trouble for lockingtrouble for locking


Improving SR long lockImproving SR long lock



Motivation:Motivation:• Want to try PRAA for higher powerWant to try PRAA for higher power

PR long noise couples to SR cavityPR long noise couples to SR cavity• Want more SR long gainWant more SR long gain

Current SR long state:Current SR long state:• Loop bandwidth is limited by how much feedback Loop bandwidth is limited by how much feedback

noise we can toleratenoise we can tolerate• Feedback is shot-noise above 100HzFeedback is shot-noise above 100Hz• Previously using the AA quadrant diode for long error-Previously using the AA quadrant diode for long error-

signalsignal• Installed SED resonant for 9MHzInstalled SED resonant for 9MHz

Expect x2 lower shot-noiseExpect x2 lower shot-noise

Motivation:Motivation:• Want to try PRAA for higher powerWant to try PRAA for higher power

PR long noise couples to SR cavityPR long noise couples to SR cavity• Want more SR long gainWant more SR long gain

Current SR long state:Current SR long state:• Loop bandwidth is limited by how much feedback Loop bandwidth is limited by how much feedback

noise we can toleratenoise we can tolerate• Feedback is shot-noise above 100HzFeedback is shot-noise above 100Hz• Previously using the AA quadrant diode for long error-Previously using the AA quadrant diode for long error-

signalsignal• Installed SED resonant for 9MHzInstalled SED resonant for 9MHz

Expect x2 lower shot-noiseExpect x2 lower shot-noise


Further improvementsFurther improvements

Noticed coherence through dSPACE is not Noticed coherence through dSPACE is not 11

Limited by DAC noiseLimited by DAC noise• First tried flat gain factor for feedback First tried flat gain factor for feedback • Then added whitening at feedback outputThen added whitening at feedback output






Using new SED for SR longUsing new SED for SR long

Lowers MSR Lowers MSR feedback projection feedback projection to Hto H• We can use this We can use this

gain to improve the gain to improve the control loopcontrol loop




New SR run-loopNew SR run-loop

Relax feedback low-Relax feedback low-pass filtering allows pass filtering allows more low-frequency more low-frequency gain for similar loop-gain for similar loop-stability marginsstability margins






Cleaning up the clean-roomCleaning up the clean-room

Additional HEPA Additional HEPA filters installed for AC filters installed for AC systemsystem

We have additional We have additional particle leak from particle leak from pump-room due to pump-room due to over-pressure thereover-pressure there


Coming upComing up

Opening vacuum systemOpening vacuum system• Reposition beam dump(s) and install Reposition beam dump(s) and install

translation stage(s)translation stage(s)• Repair ESDsRepair ESDs

Fix wiring and install new HV feedthroughsFix wiring and install new HV feedthroughs Improvement of air-conditioning systemImprovement of air-conditioning system

• HEPA filters in clean room HEPA filters in clean room [done][done] Continue work on power increaseContinue work on power increase Continue commissioning of MID ESD AAContinue commissioning of MID ESD AA

Documents

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