Transcript M.Barsuglia: Virgo progress and plans

Virgo Commissioning progress and plans
ILIAS, Jan 23rd 2007
Matteo Barsuglia
on behalf of the Commissioning Team
1
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)
2
Thermal lensing: power decrease needed
Stored power
reduction ~ 10%
Matching activity:
10% power
increase
wrs WSR-1
Laser power
reduction
(25%)
100 sec
20 min
3
WSR5 noise budget

Unknown noise in the 100 Hz
region (suspect: diffused light)

Longitudinal control near the
sensitivity – sometimes limiting
4
Sensitivity to weather conditions
Red curve: 2.7 Mpc -(wind+sea)
Red curve = 2.7 Mpc-(wind+sea)
5
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
6
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%
7
Diffused light investigations
8
Detection port

Dump spurious beam on vacuum
(half of December)

Simplify optical scheme of the
external bench (beginning of
January)
9
In vacuum beam dumps
Optics centering checks:
- Realignment of M9 (on B1s)
B1b
B5b
10
In vacuum beam dumps/2
No significant results from the mitigations in and out vacuum
11
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
12
New alignment filters
ty (yaw)
tx (pitch)
13
Quality of the data: WSR5 vs WSR7
WSR7
WSR5
(Jan 12-15)
(nov 10-13)
Coalescing binaries
analysis
14
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
15
Earthquake during WSR7
From Hanford e-log
16
Noise budget – WSR7

Unknown noise in the 100 Hz
region (suspect: diffused light)

Power recycling control near the
sensitivity – sometimes limiting
17
Structures around 100 Hz
18
Longitudinal control noise

Switch to B2

“Beta” technique

Change completely control scheme
19
Locking scheme
20
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
21
Noise budget – B2
22
Beta technique
MICH and PRCL corrections sent to the
end mirrors to subtract the noise
reintroduced by these loops
23
to the dark fringe
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)
24
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
25
Noise hunting: terminal benches

Diffused light mitigation end benches (next week)
26
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?)
27
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