analysis methods of itep baikal data
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May 17-19, 2005 D. Zaborov, ARENA workshop 1
Dmitry Zaborovfor the ITEP group
Berlin, May 2005
Analysis methods of ITEP Baikal data
May 17-19, 2005 D. Zaborov, ARENA workshop 2
Scheme of the acoustic experiment
H4 (19 m)
scintillation detectors (EAS trigger)
50 m
H3 (14 m)
H2 (9 m)
H1 (4 m)B3 (4 m)
B6 (4 m)
B4 (4 m)
lake Baikal
hydrophones (name and depth shown)
G7 (9 m)G8 (9 m)
March 23 – April 4, 2003
50 m30 m
* For description of the hydrophones see V. Lyashuk’s presentation
energy up to ~ 1017 eV
May 17-19, 2005 D. Zaborov, ARENA workshop 3
Collected data
1 ADC unit ~ 1 mPa
3246 acoustic records x 9 hydrophones. 1260 selected (low noise + EAS reconstructed)
~ 7 mPa lowest noise
Noise level1 week live time
March April
May 17-19, 2005 D. Zaborov, ARENA workshop 4
Statistical approach
* σ – noise RMS for the acoustic record
3 ms typicalPulse duration
Example of real pulse
May 17-19, 2005 D. Zaborov, ARENA workshop 5
Antenna hydrophones
Fromsurface
Horizontal propagation~8 degree from below horizon H3
H2
H3
H2
H3
H2
delay gives Θ
2-hydrophones correlation (H2-H3)
day
Δt
May 17-19, 2005 D. Zaborov, ARENA workshop 6
3 hydrophones in horizontal plane
The ellipse corresponds to real physical sounds propagated in horizontal plane
Sounds coming from or through the center of the experimental setup
φ
* This figure is after some clean-up
Distribution of the delays in the triangle of hydrophones located on a horizontal plane (H2-
G7-G8) G7G8 H2
May 17-19, 2005 D. Zaborov, ARENA workshop 7
Direction to source
sin 3 “clusters”
= 90º surface noise
= 0º ice cracks far away?
= -8º ???
Angular distribution of sourcesas seen at the location of H2 hydrophone
t7-t2 = (r72/v)*cos *cos ( s - 72)t8-t2 = (r82/v)*cos *cos ( s - 82)
noise channeling below ice due to temperature gradient ?
Not a point-like source
Using 6 hydrophones
May 17-19, 2005 D. Zaborov, ARENA workshop 8
Spherical wave fit
Close sources + mis-reconstructed
Pinger
Central scintillator
Antenna location
Distance to source can be estimated from “non-sphericity” of the wave if the source is not too far away
Well reconstructed sources (mostly)
3D configurationReconstructed sound source position
Works well for short pulses
May 17-19, 2005 D. Zaborov, ARENA workshop 9
Looking for sounds from “right” direction
2 events in the region:t: -3.5 .. 3.5 msφ: -7 .. 7 degreeBoth does not look
like signal from EAS(duration, distance …)
Time + direction to source
May 17-19, 2005 D. Zaborov, ARENA workshop 12
Conclusion
A large amount of acoustic Baikal data has been analyzed Special methods have been developed for the analysis of acoustic pulses The analysis reveals many interesting features of the under-ice acoustic noise 3D structure of the acoustic setup allows reliable acoustic wave reconstruction Present straightforward method does not allow to find acoustic signal from EAS. More sophisticated approach is needed.
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