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 10

A candidate event

EAS gates

May 17-19, 2005 D. Zaborov, ARENA workshop 11

A candidate event (continued)

E ~ 1017 eVr ~ 8 m

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.