1. May 17-19, 2005D. Zaborov, ARENA workshop1 Dmitry Zaborov for the ITEP group Berlin, May 2005 Analysis methods of ITEP Baikal data

2. May 17-19, 2005D. Zaborov, ARENA workshop2 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 ~ 10 17 eV

3. May 17-19, 2005D. Zaborov, ARENA workshop3 Collected data 1 ADC unit ~ 1 mPa  3246 acoustic records x 9 hydrophones.  1260 selected (low noise + EAS reconstructed) ~ 7 mPa lowest noise Noise level 1 week live time MarchApril

4. May 17-19, 2005D. Zaborov, ARENA workshop4 Statistical approach * σ – noise RMS for the acoustic record 3 ms typical Pulse duration Example of real pulse

5. May 17-19, 2005D. Zaborov, ARENA workshop5 Antenna hydrophones From surface Horizontal propagation ~8 degree from below horizon H3 H2 H3 H2 H3 H2 delay gives Θ 2-hydrophones correlation (H2-H3) day ΔtΔt

6. May 17-19, 2005D. Zaborov, ARENA workshop6 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

7. May 17-19, 2005D. Zaborov, ARENA workshop7 Direction to source  sin  3 “clusters”  = 90º surface noise  = 0º ice cracks far away?  = -8º ??? Angular distribution of sources as seen at the location of H2 hydrophone t 7 -t 2 = (r 72 /v)*cos  *cos (  s -  72 ) t 8 -t 2 = (r 82 /v)*cos  *cos (  s -  82 ) noise channeling below ice due to temperature gradient ? Not a point-like source Using 6 hydrophones

8. May 17-19, 2005D. Zaborov, ARENA workshop8 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 configuration Reconstructed sound source position Works well for short pulses

9. May 17-19, 2005D. Zaborov, ARENA workshop9 Looking for sounds from “right” direction 2 events in the region: t: -3.5.. 3.5 ms φ: -7.. 7 degree Both does not look like signal from EAS (duration, distance …) Time + direction to source

10. May 17-19, 2005D. Zaborov, ARENA workshop10 A candidate event EAS gates

11. May 17-19, 2005D. Zaborov, ARENA workshop11 A candidate event (continued) E ~ 10 17 eV r ~ 8 m

12. May 17-19, 2005D. Zaborov, ARENA workshop12 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.