Download Virgo commissioning

VIRGO Commissioning progress
J. Marque (EGO)
26-10-06
3rd ILIAS-GW annual general meeting
1
Status one year ago
Run C7
duty cycle 64%
14 h lock
Run C6
C7
duty cycle 90%
40 h lock
C6
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3rd ILIAS-GW annual general meeting
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C7 noise budget
• Interferometer
working with a reduced
input power ~ 0.8 W
(25 W on the beam
splitter)
• High frequency
sensitivity limited by
shot noise
• Necessity to increase
the stored power (input
power and recycling
factor )
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3rd ILIAS-GW annual general meeting
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Absence of optical isolation
Laser Frequency Noise (Hz)
Power
recycling
aligned
Power
recycling
misaligned
• Short term solution : attenuate the
input beam
• Long term: install a Faraday
isolator
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3rd ILIAS-GW annual general meeting
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New Input Bench: optical layout
To interferometer
Parabolic
output
telescope
Faraday
isolator
Input Mode cleaner
Attenuation no more
needed
input power = 10W
From laser
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3rd ILIAS-GW annual general meeting
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September 2006Spring 2007
• Installation and commissioning of
the new injection bench
• Mode-cleaner restart
• Cavities re-lock
• New power recycling mirror
• Lock acquisition with high power
and new power recycling mirror
(higher reflectivity)
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3rd ILIAS-GW annual general meeting
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New injection bench
Lock acquisition and thermal effects
• Interferometer locked with ~10 W
input power and 300 W on the beam
splitter (more than 10 times C7)
Thermal transient
• Lock acquisition much more
complicated than expected
• long work to improve locking
robustness during the thermal
transient
• Thermal lensing discovered
• Absorption input mirror 4-10
times higher than expected
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3rd ILIAS-GW annual general meeting
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Automatic alignment
• 14 degrees of freedom controlled
• 7 full bandwidth (3Hz), no local
controls
• 7 with low bandwith
(10 mHz), local controls
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3rd ILIAS-GW annual general meeting
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WSR-1: september 2006
Interferometer
internal power
Inspiral range for
NS-NS optimally
oriented
• Science mode: 88%
• 6 data taking segments, 10h average
• inspiral range for NS-NS optimally oriented ~ 2 Mpc (0.8 Mpc averaged)
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3rd ILIAS-GW annual general meeting
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Sensitivity
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Noise budget
Longitudinal noises (PR, BS)
Actuators noise
Frequency noise
shot noise
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3rd ILIAS-GW annual general meeting
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Next steps/1: robustness
Red curve: 2.7 Mpc -(wind+sea)
~ wind
~ sea
activity
One mechanism: Seismic noise  alignment fluctuations horizon decrease and unlocks
Ideas to decrease the reintroduction of the seismic noise  better superattenuator control
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3rd ILIAS-GW annual general meeting
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Next steps/2: noise
• Several hardware actions already performed after
WSR1
• Optimization of optical isolation of the
Faraday isolator (x10)
• Acoustic enclosure laser laboratory
• Reduction of actuators noise
• Increase of the aperture of optical vacuum
window
Now post-intervention recovering
Next sensitivity expected in a few weeks
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3rd ILIAS-GW annual general meeting
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Conclusions
• New injection bench commissioned (x10 input power)
• Now interferometer works with 300 W of stored power (500 W design)
• Thermal lensing discovered, lock acquisition more complex, no thermal
compensation needed so far
• New sensitivity curve: high-mid frequency improvements, 2.5 Mpc peak
• WSR-1 (56hours): 90% duty cycle and inspiral range ~ 2 Mpc
• Several actions in progress to improve the noise and the sensitivity to
weather conditions
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End
End
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Commisioning progress (1/2)
Sept05
C
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m
m
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C
7
Oct05
Nov05
Dec05
Jan06
Injection sytem
realignment
ITF
alignment
Local controls
retuning
Input Beam
Control
Integration
Feb06
Mar06
Full ITF
relock
Full ITF
automatic alignment
Inertial damping
New injection sytem
upgrade
integration
Input Mode Cleaner
(input power * 10,
relock
Input Bench +
Input
Faraday isolation,
Mode Cleaner Input Mode Cleaner
Parabolic
Input Mode Cleaner matching
automatic alignment
Input telescope)
automatic alignment
Reference
Reference
PR mirror
Reference Cavity
Cavity
Cavity
change
alignment
alignment
alignment
and locking
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3rd ILIAS-GW annual general meeting
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Commisioning progress (2/2)
Apr06
May06
Jun06
Jul06
Aug06
Sep06
Full ITF Locking / Output Mode Cleaner locking
(Fabry Perrot input mirrors thermal lensing issue)
Full ITF Automatic Alignment
Locking,
Full automation
Local
Controls
Wires heating compensation /
and
Local controls optimization
Alignment
loops
Beam centering on ITF core optics optimization / fine
Input telescope tuning / matching
tuning
Input Bench + Input Mode Cleaner
Automatic Alignment
Noise
Hunting
Detection Bench seismic isolation upgrade
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3rd ILIAS-GW annual general meeting
W
S
R
1
Oct06
W
W W
S
S S
R
R R
2
3 4
Coil drivers
optimization
Faraday Isolator
optimization
Input telescope
fine tuning
Laser Acoustic
enclosure installation
Detection Brewster
Window change
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New Power Recycling Mirror
350 mm
Old PR mirror:
• non-monolithic
• curved (part of beam
matching telescope)
• R=95%
120 mm
R=4100 mm
New PR mirror:
• monolithic: no nore internal
resonance in the control band
• flat: no more lens effect, larger
beam coming out of input bench,
need for a parabolic telescope on
input bench
• R=98%: recycling gain increased
by 30%
26-10-06
Old PR mirror
mounting
- Old
- New
PR mirror transfer function
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26-10-06
New injection bench
(above)
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New injection bench (below)
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3rd ILIAS-GW annual general meeting
Reference
cavity21
Faraday isolator performance
Issue: Input Mode Cleaner diodes polluted
by fringes between ITF reflection and
backscattered light in IMC
=> laser frequency noise and alignment loops
are affected, need for a Faraday isolator.
Laser Frequency Noise
Hz
Power Recycling mirror misaligned
Power Recycling mirror aligned
Time
The attenuation of the Faraday
has been measured to be 1000.
=> Does not limit the ITF
performance anymore.
Before
Now
Light transmitted by IMC
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New input system alignment
scheme control
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Mode matching and
mirror centering
Tuning of parabolic input telescope:
o Mode matching of the FP cavities (97%)
o Beam positionning in ITF (clipping
issue)
2 techniques for mirror centering:
o Direct imaging where possible (BS)
o Mirror shaking at natural resonance
=> alignment/locking coupling
minimization.
TEM02
TEM01
Power transmitted by FP swinging cavity
All optics centered with 5mm accuracy.
Before After
BS mirror centering
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3rd ILIAS-GW annual general meeting
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Suspension control upgrade
Mirror excitation with bad weather
=> Changed suspension top stage control
Noise introduced by DAC on the mirror
=> Rearrange forces going to suspension,
Switch to low noise coil driver
Emphasis-deemphasis filtering
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3rd ILIAS-GW annual general meeting
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Locking acquisition suffers from
thermal lensing transient
Lock acquisition is delicate
=> Thermal lensing study
o Compensation for gain change thermal
drift,
o Installed scanning Fabry Perrot to
measure sidebands unbalance
o Setup a mirror temperature monitoring
(mirror drum modes frequency is shifting
with temperature increase)
o Started optical simulation effort
o Phase camera preparation
Sidebands evolution over 15mn
=> Mirror coating absorption is 4 to 10
times higher than expected
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3rd ILIAS-GW annual general meeting
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Automatic alignment
14 degrees of freedom controled
o 7 full bandwith (3Hz)
o 7 low bandwith integrator
(10mHz) + Local Controls
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