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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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