weekly meeting Cascina 28 Nov 2006 MSC recent activities weekly meeting Cascina 28 Nov 2006

MSC “activities” during last week : F7 damping Vertical control 11/11/2019 MSC “activities” during last week : F7 damping Vertical control MSC “activities” during this week : ALL long towers ALL long towers 4 towers (under study) GIPC Short towers Vertical control EM-MSC-281106 wwwwwww

F7 F7 damping ty implemented in 6 towers LC and AA filters can with 11/11/2019 F7 damping ty implemented in 6 towers LC and AA filters can with no compensation @ 16 mHz. handle to improve damping performance VS payload motion. other degrees of freedom ? EM-MSC-281106 wwwwwww

Vdamp vertical damping (y) implemented in 6 towers basically the same filter used for horizontal ID (@ 70 mHz). only top sensor used (F0) mseism rms reduction (NS-NS Horizon > 0 last stormy weather..). gain optimization under study short towers ? (this week) EM-MSC-281106

Vdamp vertical damping (y) implemented in 6 towers basically the same filter used for horizontal ID (@ 70 mHz). only top sensor used (F0) mseism rms budget reduction in critical weather conditions (lock during last night storm) short towers ? (next step, probably, urgent) EM-MSC-281106

GIPC Tested using all GC signals (PR,BS,NE,WE) at steps 1, 4, 12 yesterday night data under study > Mandatory issue: reduction of seismic (sea) re-injection > A shift is following EM-MSC-281106

step 11 V-damp ON/OFF: 6 suspensions EM-MSC-281106

step 11 V-damp ON/OFF one-by-one and OFF/ON All No crucial Improvement O-B-O OFF ALL OFF ALL ON No crucial Improvement during OBO Test. Clear Improvement All OFF/ON Relationship with Angular fluctuations EM-MSC-281106

step 11 V-damp ON/OFF one-by-one and OFF/ON All EM-MSC-281106

storm+GIPC step 12 Next improvements and studies A major effort necessary at LF during stormy weather! Note: preliminary version of GIPC And gain mistake Of IP reallocation @ WE. EM-MSC-281106

mseism VS tilt EM-MSC-281106

cavities locked independently mseism (300-600) mHz: relevant LVDTs seismic component in ID, blending must be accurate; => better lowering Acc/Pos cross-over frequency. cavities locked independently (correction signals) As expected Next slide Note: mseism produces excitation of payload pitch and yaw (qx,qz ). Notches implemented to reduce it. 30 mHz crossover N-arm 70 mHz crossover W-arm EM-MSC-281106

wind speed || LVDT_rms increase (observation); 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-281106

mandatory: reduction of rms displacement of IP at low frequency. GIPC mandatory: reduction of rms displacement of IP at low frequency. main benefits: wind disturbance rejection, lock acquisition, duty-cycle. Once the ITF is locked, the mirror position, provided by the Global control, can be used instead of Local LVDT. GC (reconstructed z) Tested at step 4 WI,NI fx=30 mHz WE,NE,BS,PR fx= 70 mHz WI,NI Tower frames (LVDT vs ground) EM-MSC-281106

BS,PR,NI under GIPC, fx =70 mHz all EM-MSC-281106