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Virgo Commissioning progress and plans
ILIAS, Jan 23rd 2007
Matteo Barsuglia on behalf of the Commissioning Team
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Outline
Status at the last meeting, November 13th
Commissioning progress during last 2 months
Future steps
Related talks:
Noise hunting issues in Virgo (Gabriele)
Use of a second modulation (Maddalena, Henrich)
Some considerations on Virgo design sensitivity (Matt)
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Thermal lensing: power decrease needed
Laser power reduction
(25%)
Stored power reduction ~ 10%
wrs WSR-1
20 min100 sec
Matching activity: 10% power
increase
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WSR5 noise budget
Unknown noise in the 100 Hz region (suspect: diffused light)
Longitudinal control near the sensitivity – sometimes limiting
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Sensitivity to weather conditions
Red curve: 2.7 Mpc -(wind+sea)
Red curve = 2.7 Mpc-(wind+sea)
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Progress since last meeting
Calibration uncertainty fixed
Noise hunting
Diffused light investigations
Longitudinal control noise
Increase ITF robustness
Automatic alignment
Mirror suspension control
2 WSR’s performed
WSR-6 in December
WSR-7+ commissioning run in January
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Calibration fixed – end of November
Discrepancy of 40% between calibrations with north-end and west-end
Conservative value taken so far
Problem discovered in a DAC of one of the end test masses
New value gives “improvement” in sensitivity
1.4 above 100 Hz
Present uncertainty ~ 10%
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Diffused light investigations
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Detection port
Dump spurious beam on vacuum (half of December)
Simplify optical scheme of the external bench (beginning of January)
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B1b
B5b
Optics centering checks:- Realignment of M9 (on B1s)
In vacuum beam dumps
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In vacuum beam dumps/2
No significant results from the mitigations in and out vacuum
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Big work on alignment
Increase the gain in the alignment filters, in order to:
Improve the quality of the data
Increase ITF robustness
deal with bad weather conditions
Gain increase already done, further increase planned
Re-design of the alignment control chain
Filters migration to the global control (not the DSP) more flexible
Possibility to change between acquisition/detection filters
Possibility to inject noise on error points and measure open loop TF
Second modulation at 8 Hz, control the “common-end” mode
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New alignment filters
ty (yaw)
tx (pitch)
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Quality of the data: WSR5 vs WSR7
WSR5
(nov 10-13)
WSR7
(Jan 12-15)
Coalescing binaries analysis
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WSR’s program
1 (Sept 8th-11th) ~ 90% duty cycle
2 (Sept 22nd-25th), ~ 65% due to infrastructure failure, >90% after
3 (Oct 6th-9th) - cancelled
4 (Oct 13th-16th) – cancelled
5 (Nov 10th-13th), ~ 65%
6 (Dec 1st -4th), ~ 80%
7 (Jan 12th-15th), ~ 76% + commissioning run 2.5 days
Tests (noise injections, change of some parameters,…) in stable and homogeneous conditions
8 (Feb 9th-12th) planned
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Earthquake during WSR7
From Hanford e-log
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Noise budget – WSR7
Unknown noise in the 100 Hz region (suspect: diffused light)
Power recycling control near the sensitivity – sometimes limiting
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Structures around 100 Hz
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Longitudinal control noise
Switch to B2
“Beta” technique
Change completely control scheme
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Locking scheme
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Switch to B2
PR is currently controlled with B2_3f (third harmonics)
B2 (first harmonics) gives better SNR, about 1 order of mag
Transition B2_3f B2 works
B2 contains an offset
Not understood
Manually compensated
ITF controlled with B2 works for hours but still not convincing (instabilities), more test are needed
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Noise budget – B2
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Beta technique
MICH and PRCL corrections sent to the end mirrors to subtract the noise
reintroduced by these loops to the dark fringe
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Change the control strategy
beta technique is not sufficient to decrease enough the control noise
Fluctuations of the coupling
Second modulation (not resonant in the recycling cavity) already in preparation to control the angular common end mode
If transition to B2 does not work ina reliable way
Lock the SSFS with the second modulation
Move the power recycling control from B2_3f to B5 (pick-off)
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Plans before next meeting
Noise hunting
Diffused light investigations
Control noise
SSFS new board
Continue work on alignment
Increase filter gain
Second modulation – common end
Continue work on mirror suspension control
WSR8 (mid February) + 1-2 WSR’s to be decided
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Noise hunting: terminal benches
Diffused light mitigation end benches (next week)
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Noise hunting: detection port
Further diffused light mitigation suspended injection bench (half February)
Further diffused light mitigation external injection bench (February)
Acoustic mitigation detection laboratory (end of March)
New (larger) Brewster (April?)
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