gwdaw11, postdam 18th-21th december 2006 e. cuoco, on behalf of virgo collaboration 1 “data...
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GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
1
“Data quality studies for burst analysis of Virgo data acquired during Weekly
Science Runs “
E.Cuoco, EGO
on behalf of Virgo Collaboration
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
2
WSR goals
To ease the transition between commissioning to data taking 2.5 days during week-end, roughly one per month
Provide data sets taken in stationary condition for :Commissioning studiesSearch analysis (online, offline and noise studies)
WSR1 08/09-11/09 2006 : duty cycle 87.7%WSR2 22/09-25/09 2006 : duty cycle 71.2% WSR3 06/10-09/10 2006 (failed)WSR4 13/10-16/10 2006 (failed)WSR5 10/11-13/11 2006 : duty cycle 64.2%WSR6 01/12-04/12 2006 : duty cycle 80.5%
best sensitivity reached (4 Mpc NS-NS horizon for an optimally oriented source, SNR=8)
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
3
Goal of this study
Study the “quality” of the Virgo dataDetect all kinds of glitches in the data which may spoil a burst search (loudest events study)
Understand the origin of these glitches, when possible …
Study the stationarity of the burst trigger rate
Study possible vetoes strategy to suppress loud triggers
Set up “tools” and provide information for the burst searches (DataQuality flags and vetoes)
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
4
DataQuality & Vetoes
• DQ flags: list of periods during which the ITF is badly functioning (photodiodes saturation, no calibration, noisy Second Stage Frequency Stabilization loop (SSFS), DAQ problem…). • These periods can last from 1 second up to several hours. • They are applied a priori or a posteriori on the triggers list produced
by a burst pipeline.• For the moment they concern only “obvious” problems but may
concern in the future environmental condition (weather, …) if useful for the burst search
• Vetoes: list of short periods during which a fake burst signal could be visible in the Dark Fringe channel due to any cause
except a genuine GW. • They are applied on triggers’ lists.
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
5
Virgo burst pipelines
Time domainMean Filter (MF)
Excess of Mean
Estimation on different
window size
Time -FrequencyPower Filter (PF)
Wavelet Detection Filter (WDF)
CorrelatorPeak Correlator (PC)
Exponential Gaussian Correlator (EGC)
Time-Frequency map
with different window
Wavelet TransformCoefficient thresholdEnergy estimation
Wiener filtering with gaussian peak templates
Wiener filtering with exponential gaussian
templates
Wor
k on
whi
tene
d
data
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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Data Quality flags study
Few problems identified so far:Dark fringe outport photodiodes saturation
NE/WE/BS/PR mirror coil driver saturation
Second Stage Frequency Stabilization (SSFS) correction saturation
SSFS electronics problem
Timing problems (DAQ) (WSR5)
Photodiode shutter opening (WSR2)
Data quality segments given by the h reconstruction processingWhite noise injection segments
Bad quality when the lines are not high enough
It has been checked that all these problems create loud events in the dark fringe
Definition of Data Quality segments to flag these periods
Most of these flags can be applied a posteriori on trigger lists
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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DQ segments application on MF triggers: WSR1
WSR1
photodiode saturation
SSFS saturation
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
8
DQ segments application on MF triggers:WSR5
WSR5
timing
SSFS saturation
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
9
DQ segments application on MF triggers:WSR6
Coil drivers saturation
WSR6
The loudest events are suppressedby using these DQ flags
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
10
Loudest glitches study
We found only a few categories in WSR data:Oscillations in control loops (longitudinal and angular dof):
“z” events (low frequency events <100 Hz)
Noise increase on the full bandwidth due to laser frequency noise coupling temporary increase (duration <few seconds):
that generates some “Burst of Burst” events (“BOB” events)In C6/C7 data set, the origin of the laser frequency noise coupling
increase has been identified to be due to the residual angular motions of the mirrors which were too loose
SSFS electronics saturation events
Study of environmental channels (seismometers, magnetometers, acoustic probes …)
We did not find so far any loud glitches in the dark fringe due to environmental noise …
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
11
Events in the control signals
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
12
Example of a BOB event
• long duration events (up to few seconds),• large frequency band content• due to a coupling of the laser frequency noise and angular motion of the mirror
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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Example of a problem with the SSFS
2 seconds 2 seconds
Exclude 1 second before and 1 second after the event in the SSFS channel
Dark fringe
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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Veto for the SSFS saturation events WDF SNR of the triggers obtained
on the channel which “monitors” the SSFS
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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SSFS channel as Veto
SNR>85, Dt=0.1 More details in M.Delprete poster
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
16
Looking at the signal used to control the Power Recycling
cavity lengthz-events
Snr>30 ,Dt=0.1
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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WSR5:Dark fringe WDF events distribution
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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WSR5: Cleaning the Dark fringe
For SSFSSNR >85Dt=0.1
For z-events,SNR>30Dt=0.1
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
19
Enviromental channels: Magnetometers in North End
towerGlitches every 3-4secs
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
20
Glitches inWE-NE magnetometers
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
21
Lightning?
Dark fringe
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
22
Coalescing binaries horizon and seismic noise
Horizon fits quite well an empirical formula: 2.7 (4.3) Mpc – (wind+sea). “wind” is the North End tower top stage motion in the region 30-100 mHz, “sea” is the motion in the region 100 mHz-1 Hz
WSR1
WSR6
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
23
Burst trigger rate and weather condition ?
Study of the burst trigger rate as function of time (rate averaged on 10 minutes)
Horizon seems to follow the low frequency (<1Hz) seismic activity seen by the top of the suspensions
Comparison with the Common Mode Rejection Ratio which gives the coupling between the laser frequency noise and the dark fringe
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
24
Burst trigger rate and weather condition: WSR1
•The trigger rate follows the seismic noise <1Hz
•The trigger rate follows the evolution of the CMRR
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
25
Burst trigger rate and weather condition: WSR5
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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Burst trigger rate and weather condition: WSR6
•The trigger rate follows the seismic noise (<1Hz)
•The trigger rate does notfollows the evolution of the CMRR
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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Conclusions
WSR data sets have been analyzed offline using glitches finders algorithms to provide useful information for the burst searches
Identification of all problems generating huge glitches DataQuality flags defined to suppress a posteriori these periods
Identification of the loudest remaining glitches. A few categories have been identified
Setup of veto strategy for the identified sources of glitches
We found correlation between the transient trigger rate and the weather condition
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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Spare slides
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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Horizon vs weather conditionSeismic noise: quite quiet during the week-end!
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
30
A bob event
Fre
quen
cy (
Hz)
Dar
k fr
inge
(w
hite
n)
Time (s)
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
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BOB mechanism
Proposed Mechanism
• at high frequency, frequency noise dominates• Pr_B1_ACp = * related to Common Mode Rejection Ratio
varies with time by a significant amount (up to a factor 10) variations are mainly driven by angles
GWDAW11, Postdam 18th-21th December 2006
E. Cuoco, on behalf of Virgo collaboration
32
Dark fringe noise increase as function as the North End mirror θy angle
NE_ty
-2 -1 0 1 2
1.6
1.5
1.4
1.3
1.2
1.
1.1
0.9
0.8
0.7
x 10-8
Pr_B
1_A
Cp
RM
S
C7
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