MSC winter, short-term schedule Commissioning meeting Cascina 2 Oct 2006

EM-MSC MSC “activities” are: - Inertial damping - Local control - Tide control - Locking re-allocation to marionette - F7 control - Vertical control

EM-MSC The “objects” that allow these activities are: - SA-Suspension mechanics (ground-F7) - LastStage-Suspension Mechanics (F7-Mirror) - STD digital control electronics - STD analogic crate (actuation driving) - STD SA-suspension sensors/actuators - F7-ground sensors/actuators - STD local control sensors/actuators - STD interface with GC - SW to deal with all the systems above…. Maintenance and performance (awards!) of each item used by MSC concern object responsible/developer.

EM-MSC Virgo sensitivity (at LF !)Virgo duty-cycle MSC is the direct product of the work done by each responsible of any object or activity. MSC people are involved to efficiently contribute to the achievement of two main tasks: Example, last week:

EM-MSC  seism VS tilt

EM-MSC  seism ( ) mHz: relevant LVDTs seismic component in ID, blending must be accurate; => better lowering Acc/Pos cross-over frequency. 30 mHz crossover N-arm 70 mHz crossover W-arm cavities locked independently (correction signals) As expected Next slide Note:  seism produces excitation of payload pitch and yaw (  x,  z ). Notches implemented to reduce it.

EM-MSC Tilt (f< 100 mHz): - wind speed || LVDT_rms increase (observation); - tilt causes fake acceleration (Losurdo, Passuello, Ruggi); => ID causes LVDT_rms increase through in-loop accel. signal. wind speed susp displacement X crossover f = 30 mHz; Z crossover f = 50 mHz

EM-MSC From the WSR2 run summary Actual configuration arisen through trials and tests during short periods of bad weather. Need of experience during long runs !

EM-MSC Next months (no tiltmeters) mandatory: reduction of rms displacement of IP due to  seism/tilt (Note: large force re-allocation to marionette (zMcorr) during IP oscillation is harmful, causes payload tilts) Difficult using only: 1)ID cross-over frequency tuning (to optimize acc/pos components) 2)notch patches (not to excite payload tilt modes) A proposal arisen during MSC-Losurdo is to “extend and generalize” the tide control. Namely, it means to use mirror level signals derived from the ITF signal to keep IP position instead of LVDT (once locked, science mode etc…). A third handle…

EM-MSC Question marks (several, at least two): - reduction by a factor ~100 in IP rms is enough to ensure decoupling from  seism increase ? - how to deal with x IP d.o.f. (no global signal)? “extended and generalized tide control” (global IP control?) seism attenuated at the mirror level by HTF 100 mHz)  higher ID z cross-over freq. (lesser  seism re-injection without LVDT)  lesser tilt re-injection through accelerometers.

EM-MSC Readout upgrade & microseism Causes a roll about z Roll motion read-out as yaw  y 10 o Motion along x A remarkably useful mistake in optical lever design To the top stage x? Flt Roll notched in  y LC

EM-MSC “global IP control” schedule Step 2) IP control using mirror sensing signal: preliminary test by means of z LC signal, done. Step 1) position control of 4 IPs using standard narrow bandwidth: PR ready to be tested. Step 3) study and test of suitable filters to swap LVDT/mirror-sensing.

EM-MSC Locking force re-allocation

EM-MSC From the WSR2 run summary BS marionette re-allocation ready to be implemented. PR force re-allocation need under study. Test with emphasis-deemphasis (further improvement by a factor 6, D. Huet’s talk).

EM-MSC Further features needed to accomplish the main tasks

EM-MSC F7 damping from ground: Useful in presence of marionette lock re-allocation (actually on NE WE) and, in general, to damp SA Yaw recoil. - BS ready to be implemented - Other installations scheduled (PR,WI,NI)

EM-MSC Vertical damping: Vertical seismic excitation is coupled with payload tilts (  x,  z ), critical in the range Hz. A campaign of tests using the ITF has to be scheduled to better asses the need and specifications of vertical damping.

EM-MSC Interface with Alignment:

EM-MSC LC versus AA: Actual and near-future setup WSR1 - Steep noise re-injection roll-off tested at NI LC  y WI-C7-like  x on both WI and NI - Overall improvement on both LC and AA for all-but-NI  y.

EM-MSC LC versus AA: Actual and near-future setup WSR2 short-term prospective of leaving WI,NI, BS  y under LC+DrCo, aggressive roll-off also in WI

EM-MSC LC versus AA: before WSR3 ? Logbook 11:46, Tuesday 19 September 2006 (13415) IP motion during wind Large lock correction on marionette Driving coupling with  z non-negligible LC  y mario readout coupled to  z Wrong LC driving hardly compensated by Drift Ctrl WSR1 Unlock! Full BW AA recommended on NE.

EM-MSC Conclusions -Assistance to commissioning ITF (performance monitoring and response to commissioning issues) -Effort to develop noise budget tools within MSC - scheduling improvements by merging commissioning requests and the expertise of suspension and LC groups. Konogurai kakakimaska ? The time schedule has to be coordinated with AA setup completion. Two months ?

EM-MSC