Virgo commissioning status M.Barsuglia LAL Orsay

1
Virgo commissioning status M.BarsugliaLAL
Orsay
2
The central interferometer
Spring 2001- Summer 2002
BS
Test of the technical choices during end of the
construction
Acquire experience (no prototype in the Virgo
community)
3
Technical choice validation

• Suspensions
• long term operation, robustness.
• direct measurement of the attenuation at 4 Hz
• hierarchical control (top stage, reference mass)
• Digital controls
• local controls, control of SA resonances, lock
  acquisition, WFS
• Output mode-cleaner
• locking, contrast improvement
• Local controls

4
Suspension system
Top stage


Last stage
Seismic filters
5
Detection system

6
OMC locking
Transmitted power
TEM00
TEM00
TEM00
TEM00
c2 signal
7
CITF sensitivity during e-runs
Sept 2001
Alignment control
Frequency noise
July 2002
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Lock robustness during e-runs
Run losses duty cycle longest
lock
E0 1 98 51 h E1
1 85 27 h E2
3 98 41 h E3 4
98 40 h E4 4
73 14 h
ITF stored power
200 W
9

• July 2002 ? September 2003 Upgrade to Virgo
• mirrors installation
• arm completion, vacuum
• ITF upgrades (mode-cleaner, local controls, )
• September 2003 Virgo commissioning

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Commissioning plan

• North arm
• Lock acquisition
• output mode-cleaner
• 3-days engineering run
• frequency stabilization
• WFS
• hierarchical control (top stage, marionetta,
  reference mass)
• West arm
• Recombined ITF
• full ITF

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Interferometer operation shifts

• 2 8-hours shifts during commissioning

Morning Shift (8h-15h)
Evening Shift (16h-23h)
Task 2
Task 1
1 Interferometer operator
1 Interferometer operator
1 Interferometer coordinator
1 Computer operator
1-3 People working on commissioning task 1
1-3 People working on commissioning task 2
Daily meeting (15h-16h)

• 2 tasks in parallel

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North cavity locking scheme

• angular control (pitch, yaw)
• no longitudinal damping

6 W
50 Hz BW, digital control
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Signals and simulation
Lock acquisition speed threshold 10 mm/s
Linearized error signal
No Linearized error signal
Correction Transmitted P
Time domain Simulation (Siesta)
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locking

• Locking at the first trial
• first lock 1 hour
• frequency noise

Transmitted power
Frequency noise reduction
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Lock acquisition statistics

• with the linearized error signal

• 24 locking events collected locking and
  delocking the cavity
• 23 lock acquisition at the first attempt, only 1
  failed locking attempt

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Lock acquisition statistics

• Relative velocity between the mirrors computed
  for each locking attempt

2.5 mm/s mean value of the velocity

• 8 mm/s maximum velocity for the lock
  acquisition success
• 12.5 mm/s velocity of the failed event

Failed locking attempt v 12.5
8
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Output mode-cleaner locking
Reflected P
c 2
Transmitted P
2 min
State
Temperature
Error signal
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Output mode-cleaner locking -II
1. Cavity locked with 1 of the light
2. Mode-cleaner locked
3. Control transferred to this phd 99 of the
light
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North cavity noise budget
20
50 Hz
50 Hz

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Transmitted P during C1 run
3 days 14-17 november
Seismic Noise problem
2 Long locks
tests
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Seismic noise problem

• large seismic noise during the run _at_300 mHz
  (microseismic peak)
• new inertial control scheme less inertial
• marionetta roll resonance at 300 mHz excited
• new local controls sensing coupling roll?yaw

solution found? new inertial damping filter, in
test.
23
Tidals during C1 run
Correction sent to the end test mass
50 mm
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Commissioning plan

• North arm
• Lock acquisition
• output mode-cleaner
• 3-days engineering run
• frequency stabilization
• WFS
• hierarchical control
• West arm
• Recombined ITF
• full ITF

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Frequency stabilization
50 Hz
50 Hz

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Frequency stabilization

• 3 actions
• unlock reference cavity
• change IMC curved mirror locking point
• open second stage of frequency stabilization

50 Hz
50 Hz
10 kHz
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Frequency stabilization
Last step DC control of laser frequency
1 Hz
50 Hz
20 kHz.
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Frequency stabilization first tests
Cavity trans P
Test mass corr
Cavity err sig
2nd stage ON
2nd stage ON
Cavity corr OFF

• switch
• oscillations
• simulink model

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WFS control
matrix

• optical matrix measured
• filter ready

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WSF control
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WFS control
matrix

• optical matrix measured
• filter ready
• will be tested in early january
• transition from local controls ? WSF control

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2nd (west) arm locking
Error signal
Transmitted power

• cavity locked in a stable way yesterday
• same algorithm, same filter of north cavity
• preliminary analysis of 2 cavities optical
  properties

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Commissioning plan

• North arm
• lock acquisition
• output mode-cleaner
• 3-days engineering run
• frequency stabilization
• WFS
• hierarchical control (top stage, marionetta,
  reference mass)
• West arm
• Recombined ITF
• full ITF

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Hierarchical control 3 points

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Hierarchical control top stage
Slow corrections (f lt 70 mHz)
Done during the CITF commissioning
Fast corrections (f gt 70 mHz)
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Hierarchical control marionetta

• acquire the lock with the reference mass

• move the control to the marionetta?DAC noise
  reduction

• complicated transfer function ? simulations

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Commissioning plan

• North arm
• Lock acquisition
• output mode-cleaner
• 3-days engineering run
• frequency stabilization
• WFS
• hierarchical control
• West arm
• Recombined ITF (january)
• full ITF

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Recombined ITF
B8

• start noise analysis

west arm
250 mW
north arm
B7
B5
B1p
B2
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Lock acquisition
B8
Step 1 lock north arm using pick-off 5
Done
Step 2 lock west and mich
B7
B5
B1p
B2
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Recombined ITF simulation
north cavity locked
west cavity locked
mic locked
Acq_north ON
Acq_west_mic ON
Trigger westmic satisfied
Trigger north satisfied
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Commissioning plan

• North arm
• Locking, output mode-cleaner (done)
• 3-days engineering run
• frequency stabilization, WFS (in progress)
• hierarchical control (top stage, marionetta,
  reference mass)
• West arm (in progress)
• Recombined ITF (january)
• full ITF

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Lock acquisition for full ITF

• Lock acquisition LIGO method
• Time-Domain simulation (Siesta)
• Now transition 3?4

State 2 locked
State 3 locked
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Summary

• North arm
• Lock acquisition (done)
• output mode-cleaner (done)
• 3-days engineering run (done)
• frequency stabilization (in progress)
• WFS (in progress)
• hierarchical control (january)
• West arm (done)
• Recombined ITF (starts december 29th)
• full ITF (?)
• Science (?)