Status of Virgo
B. Mours
September 21, 2005 Virgo Status – ESF Workshop 2
Main injection problem (2004)
Input Mode cleaner mirror back scattering:
IMC instability when Power Recycling mirror aligned
Solutions:
» Sort term: Factor 10 attenuation between IMC and PR mirror
–
Only 0.7W injected in the ITF
» Long term: add a Faraday isolator redesign the injection bench
IMC length control signal
Red: PR aligned Black: PR misaligned
With the factor 10 attenuation
Virgo Recent Progress
October 2004
First lock in recycled configuration.
C5 run: December 2004
Recycled and “Recombined” modes.
2005 Commissioning activities
Alignment:
» Drift controls using wavefront sensing now on all d.o.f.,
» Most loops are also closed.
Automation,
Control upgrades, robustness,
Noise hunting,
Commissioning slow down by instabilities (“jumps”) during the first semester,
C6 and C7 commissioning runs.
Summer shutdown preparation
New “injection” (bench, PR mirror, ISYS alignment).
Data analysis preparation
Study C-run data,
Collaborative data analysis (LIGO-Virgo, Bar-Virgo).
September 21, 2005 Virgo Status – ESF Workshop 4
Sensitivity evolution
C6 run
July 29 – August 13
Duty cycles:
Locking: 89%
Science mode: 86%
Daily Locking Performance
0 20 40 60 80 100
Day
Lock % %Science/Day
%Lock/Day
September 21, 2005 Virgo Status – ESF Workshop 6
C6 “Binaries Injections”
Inject NS-NS
Online Analysis
[1.2-1.6] Solar Mass
Injections seen on the
online SNR max plots
C6 “Burst Injections”
Strange periodicity
Inject Sine-Gausian
Central frequency: 460Hz
Nominal SNR: 15
Example of the third injection:
Power filter algorithm
Efficiency ~ 90%
False alarm rate ~.3 event/sec
Timing resolution: 1.3ms
Centering of the North Bench quadrant!
September 21, 2005 Virgo Status – ESF Workshop 8
C6 noise budget
Post C6 upgrades (I)
Sensitivity from Aug 12 (End of C6) Sensitivity from Aug 27
Improvement due to Linear Alignment (4 loops closed
instead of 2)
DAC noise reduction
PR z control noise reduction (Neo filter with roll-off
@ 100 Hz)
BS z control noise : alpha tuning
New optical setup for B5 Reduction of laser frequency noise
2kHz bump due to
detection tower
pump (exciting
external bench
resonances)
September 21, 2005 Virgo Status – ESF Workshop 10
Post C6 upgrades (II)
August 27
th(600kpc) with NEO2
September 12
th(850 kpc) without NEO2
Increase of modulation index => reduction of PR_zCorr impact
Diffused light dumped on WE => no more bump ~ 100-400 Hz
Modulation frequency tuning
BS coil driver upgrade
And LA tuning…
C7 run
September 14 - 19
Duty cycles:
Locking: 70%;
Science mode: 65%
Daily Locking Performance
0 20 40 60 80 100
Day
Lock % %Science/Day
%Lock/Day
