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

2. 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
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3. 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 16 mHz.
handle to improve damping
performance VS payload
motion.
other degrees of freedom ?
EM-MSC
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4. 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

5. 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

6. 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

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

8. 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

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

10. 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

11. mseism VS tilt
EM-MSC

12. cavities locked independently
mseism ( ) 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

13. 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

14. 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

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