1. MSC recent activities virgoweek Cascina 4 Dec 2006

2. EM-MSC-0412062 MSC activities during last month have been focused on - damping strategies (GIPC, new blending flts LVDT-vs-Accelerometers) - F7 damping - Vertical control long suspensions - Vertical control of short suspensions Completion of already-foreseen controls available without major HW changes Test of new strategies to face the winter (seism,mseism)

3. EM-MSC-0412063 MSC “open” issues - visual interface including F7 and V damping (this week design session) - x and tz local control damping (this week one shift on this topic) - “soft download” facility to allow quiet and repeatable swap between DSP implementations to cope with extreme environmental situations Development of better operation interfaces to facilitate more flexible tests of strategies and new implementations Performance weakness of some features

4. EM-MSC-0412064 MSC “open” issues - visual interface including F7 and V damping (this week design session) - x and tz local control damping (this week one shift on this topic) - “soft download” facility to allow quiet and repeatable swap between DSP implementations to cope with extreme environmental situations Development of better operation interfaces to facilitate more flexible tests of strategies and new implementations Performance weakness of some features

5. EM-MSC-0412065 DECISIONS TAKEN BEFORE THE RUN V-damp OFF for the run IB V-damp was implemented on Friday morning 50 mHz-peaked seismic bump was present in the afternoon Spikes related to V-damp at WE occurred the Thursday night V-damp long susp not tested under all  seismic conditions Operator-level switch for V-damp was not designed yet Signals flags to decide about V-damp ON/OFF not studied yet

6. EM-MSC-0412066 Implementation of V-damp for IB suspention

7. EM-MSC-0412067 Just before WSR6…

8. EM-MSC-0412068 Problem of WE V-damp before WSR6 Under investigation

9. EM-MSC-0412069 V-damp to be completed and interfaced with the operation Fight against wind and  seism going on (3 shifs/week rquested): measurements, modeling, tests. Software interfaces to facilitate operator and shifter actions under development Performance checkups and maintenance going on Conclusions

10. EM-MSC-04120610 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 ?

11. EM-MSC-04120611 vertical damping (y) implemented in 6 towers - basically the same filter used for horizontal ID (@ 70 mHz). - only top sensor used (F0) -  seism rms reduction (NS-NS Horizon > 0 last stormy weather..). - gain optimization under study - short towers ? (this week)

12. EM-MSC-04120612 vertical damping (y) implemented in 6 towers - basically the same filter used for horizontal ID (@ 70 mHz). - only top sensor used (F0) -  seism rms budget reduction in critical weather conditions (lock during last night storm) - short towers ? (next step, probably, urgent)

13. EM-MSC-04120613 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

14. EM-MSC-04120614 V-damp ON/OFF: 6 suspensions

15. EM-MSC-04120615 V-damp ON/OFF one-by-one and OFF/ON All ALL OFF ALL ON O-B-O OFF O-B-O OFF No crucial Improvement during OBO Test. Clear Improvement All OFF/ON Relationship with Angular fluctuations

16. EM-MSC-04120616 V-damp ON/OFF one-by-one and OFF/ON All

17. EM-MSC-04120617 A major effort necessary at LF during stormy weather! Note: preliminary version of GIPC And gain mistake Of IP reallocation @ WE. Next improvements and studies

18. EM-MSC-04120618  seism VS tilt

19. EM-MSC-04120619  seism (300-600) 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.

20. EM-MSC-04120620 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

21. EM-MSC-04120621 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. WI,NI Tower frames (LVDT vs ground) GC (reconstructed z) Tested at step 4 WI,NI fx=30 mHz WE,NE,BS,PR fx= 70 mHz

22. EM-MSC-04120622 BS,PR,NI under GIPC, fx =70 mHz all