1. MSC report
14-20 September
weekly meeting
EM-MSC

2. VSR1 breaks Mantenance GIPC, SFR implementations
e.m. noise investigations
Commissioning
Beam Centring on BS
Etalon
EM-MSC

3. reconstructed by local DSP
GIPC (Global IP Control) + SFR (SeismFreeReconstruction)
GIPC:
zGC is not crucially affected by Seism (its reference is a suspended mirror)
SFR:
Sseism is coherent in the central area and reconstructed signals are free from it.
deduced from GC zCorr
reconstructed by local DSP GC
done !
Fabry-Perot cavtiy input mirrors as reference
EM-MSC

4. Top-stage control strategies involving suspension operation as-a-whole
The strategy.
Top-stage control strategies involving suspension operation as-a-whole
improve disturbance rejection capability.
EQ GUARD used in monitor mode.
SFR
(Central Area)
GIPC
(ARMs)
higher cross-over f
(lower wind noise
without seism re-injection)
&
Coherent response to EQs
ENV-TUNED
GUARD
Next !
EM-MSC

5. Performance (in quiet environmental conditions)
Spectral check as the new scheme was implemented
In quiet conditions
no change at the mirror level
EM-MSC

6. A lucky occurrence ! Comparison of two events with similar
local amplitude.
A lucky occurrence !
40 m peak
Previously we got
saturation as the
amplitude was
less than 20 m
MARIO:
small residual
correction (~7 m)
The system
is much more
robust
Dynamics more
than doubled
EM-MSC

7. Beam vs BS (centring investigations)
Motivated by: control noise coupling, actual BS position ..)
STD method: tx,ty 10Hz from RM; x,y slow translation from
suspension top; BS tracked keeping aligned the ITF. x B5 B1 W
Large H
translation
z (locked)
interesting
evidence:
B5 changes
EM-MSC

8. Tilt transfer function ty => z vs horizontal positionx m m
Coupling ty z
worse (170%) B5
better 3 %
The system was left at m
according to this procedure the beam is off-centred by 15 mm
tx vs z checked also the beam results to be almost centred (1.5 mm)
EM-MSC

9. Etalon
Known relationship among PRCL_NEWE subtraction (beta) and Fabry-Perot finesse asymmetry between Virgo arms (Vajente).
Known relationship
among beta
subtraction and
NS-NS Horizon
(Tournefier).
EM-MSC

10. Etalon Beta vs asymmetry (B8-B7) Known relationship
between the temperature in the ovens, finesse asymmetry and Etalon effect
(Punturo).
14/09/07
T_NI B7
Beta too large
T_WI
Thermal drift into the
ovens of NI and WI B8
EM-MSC

11. Etalon Beta vs asymmetry (B8-B7) Known relationship
between the temperature in the ovens, finesse asymmetry and Etalon effect
(Punturo).
14/09/07
T_NI B7
Beta decreases
T_WI
Cm control to GxServer
to provide a small heating
through LC illuminators
(few Watts !!!) B8
EM-MSC

12. Etalon
a simple check to verify that we are actually actuating on Etalon
Mirror temperature
checked through drum mode freq. vs temperature change
driven by LC coarse
illuminator.
T [C] WI NI
Beta can be
remotely driven
(in simple way ?)
21/09/07
17/09/07
1.5 V
1.3 V
e.m. noise investigations into the ovens
EM-MSC