Transcript Commissioning status of the Virgo interferometer

Status of the Virgo
interferometer
Enrico Calloni
Federico II Univ. - Naples
on behalf of the Virgo collaboration
E. Calloni – MG12 – July 13 2009 Paris
MG12, July 13 2009, Paris
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Commissioning timeline
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May '07 - Sep '07
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Oct '07 - May '08 Commissioning
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Scattered light mitigation: replaced brewster window by cryotrap
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TCS installation, mirror magnets strength reduction
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9 May '08
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May - Oct '08
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First Virgo Science Run (VSR1)
Vacuum viewport failure
Virgo+ shutdown
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Injection system, infrastructure and electronics upgrade
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NE payload recovery, replacement of all viewports
Oct '08 – July ‘09
Commissioning
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Remaining electronics upgrade
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Commissioning with more input power and TCS
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New Global Control
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7 Jul '09
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2010
This talk
Start Second Virgo Science Run (VSR2)
Monolithic suspension upgrade?
E. Calloni – MG12 – July 13 2009 Paris
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Incident recovery
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Caused by weak design of view-port, identified and tested safer model
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Replaced about 90 view-ports throughout whole interferometer
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Cleaned and tested North-End tower
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New payload at North-End: coating of already polished spare mirror
E. Calloni – MG12 – July 13 2009 Paris
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Virgo+ upgrade: infrastructure
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Replaced and doubled UPS
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Replaced 15 kV transformer
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New hot water pipes
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E. Calloni – MG12 – July 13 2009 Paris
Replaced complete wiring of
main power and grounding in
central building
Lowered speed of airconditioning
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Virgo+ upgrade: injection system
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New laser amplifier: up to 50 W (25 W at interferometer input)
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New pre-mode-cleaner
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Remotely tunable in-vacuum Faraday Isolator
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Heavier input-mode-cleaner end-mirror
E. Calloni – MG12 – July 13 2009 Paris
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Virgo+ upgrade: electronics
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Replaced real-time fiber links: more flexible signal routing
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Replaced old RIOs by real-time PC: much more computing power
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New ADCs: from 16 to 18 bit
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New quadrants read-out electronics for alignment
E. Calloni – MG12 – July 13 2009 Paris
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Interferometer restart
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Interferometer no longer showed bi-stability during lock acquisition
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Different working point: modulation frequency changed by 700 Hz
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Maybe caused by slightly different radius of curvature of new mirror
E. Calloni – MG12 – July 13 2009 Paris
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Thermal Compensation System
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Annulus and central spot from CO2 laser on both input mirrors
Essential for compensating thermal lensing in input mirrors when working with
high input powers
Not yet stabilized in amplitude, some evidence for introduced noise
E. Calloni – MG12 – July 13 2009 Paris
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Phase camera
field amplitude
phase between fields
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Beam scanned on pinhole detector, signal demodulated to separate carrier and
sidebands
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Located on dark fringe before output-mode-cleaner (B1p)
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Extensively used, but more as 'amplitude camera'
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TCS fine alignment, 'cold interferometer' experiments
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Mirror cool-down experiments to measure coating absorption
E. Calloni – MG12 – July 13 2009 Paris
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High power operation
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Power increased in steps from 8 W (VSR1) to 17 W now
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limited by thermal aberrations of input mode cleaner
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No major problems with interferometer stability
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Some alignments loops more critical
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Quadrature signals (B1_ACq or B5_ACq) kept close to zero using slow servos on
TCS power
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Currently about 1.5 W on both mirrors: interferometer similar to 8W
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'Cold interferometer' with about 2x 6W
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More optical gain, ideal frequency stabilization TF, but TCS too noisy
without TCS
E. Calloni – MG12 – July 13 2009 Paris
with TCS
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Sensitivity
May 2007: ~3 Mpc
July 2009: ~8 Mpc
Sensitivity at VSR1 start (black) and VSR2 start (red)
E. Calloni – MG12 – July 13 2009 Paris
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Noise budget
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Low frequency
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Some environmental
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Some scattering
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Laser bench resonances
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Actuator noise
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No control noise!
Medium frequency
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Mirror thermal noise
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Shot noise
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Detection bench
resonances
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TCS radiation pressure?
High frequency
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E. Calloni – MG12 – July 13 2009 Paris
Shot noise
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Robustness
Locking duty cycle : 97.4%
(update at July 12 )
Science Mode duty cycle:
94.9%
Interventions in “adjusting mode”
are visible
E. Calloni – MG12 – July 13 2009 Paris
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Future work
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During the run (commissioning breaks)
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Damp external bench resonance (sorbothane)
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TCS power stabilization?
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Replace detection output window, with AR coating?
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More noise hunting
Long term
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Monolithically suspended mirrors, finesse 50 -> 150
E. Calloni – MG12 – July 13 2009 Paris
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Concluding
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Robust interferometer
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95% Science Mode duty cycle
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Good sensitivity
Stable horizon:
8-8.5 Mpc (1.4-1.4 Ns-Ns) - averaged
42-44 Mpc (10-10 BH-BH) - averaged
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fluctuating with input mirror etalon effect
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Low glitch rate: factor 10 lower than VSR1
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Preparing for installation of monolithic suspensions
E. Calloni – MG12 – July 13 2009 Paris
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End
E. Calloni – MG12 – July 13 2009 Paris
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