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Analysis methods of ITEP Baikal data

Berlin , May 200 5. Analysis methods of ITEP Baikal data. Dmitry Zaborov for the ITEP group. Scheme of the acoustic experiment. lake Baikal. scintillation detectors (EAS trigger). March 23 – April 4, 2003. energy up to ~ 10 17 eV. 50 m. 30 m. 50 m. H1 (4 m). B4 (4 m). B3 (4 m).

emmanuel-kline
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Analysis methods of ITEP Baikal data

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  1. Berlin, May 2005 Analysis methods of ITEP Baikal data Dmitry Zaborov for the ITEP group D. Zaborov, ARENA workshop

  2. Scheme of the acoustic experiment lake Baikal scintillation detectors (EAS trigger) March 23 – April 4, 2003 energy up to ~ 1017 eV 50 m 30 m 50 m H1 (4 m) B4 (4 m) B3 (4 m) G8 (9 m) G7 (9 m) B6 (4 m) H2 (9 m) H3 (14 m) H4 (19 m) hydrophones (name and depth shown) * For description of the hydrophones see V. Lyashuk’s presentation D. Zaborov, ARENA workshop

  3. Collected data • 3246 acoustic records x 9 hydrophones. • 1260 selected (low noise + EAS reconstructed) Noise level 1 week live time 1 ADC unit ~ 1 mPa ~ 7 mPa lowest noise March April D. Zaborov, ARENA workshop

  4. Statistical approach Example of real pulse Pulse duration 3ms typical * σ – noise RMS for the acoustic record D. Zaborov, ARENA workshop

  5. Antenna hydrophones 2-hydrophones correlation (H2-H3) Δt From surface H2 H3 H2 Horizontal propagation H3 ~8 degree from below horizon H2 H3 delay gives Θ day D. Zaborov, ARENA workshop

  6. 3 hydrophones in horizontal plane Distribution of the delays in the triangle of hydrophones located on a horizontal plane (H2-G7-G8) G8 G7 H2 The ellipse corresponds to real physical sounds propagated in horizontal plane φ Sounds coming from or through the center of the experimental setup * This figure is after some clean-up D. Zaborov, ARENA workshop

  7. Direction to source Using 6 hydrophones Angular distribution of sources as seen at the location of H2 hydrophone sin  3 “clusters”  = 90º surface noise  = 0º ice cracks far away?  = -8º ??? Not a point-like source noise channeling below ice due to temperature gradient ? t8-t2 = (r82/v)*cos *cos ( s- 82)  t7-t2 = (r72/v)*cos *cos ( s- 72) D. Zaborov, ARENA workshop

  8. Spherical wave fit Reconstructed sound source position 3D configuration Central scintillator Distance to source can be estimated from “non-sphericity” of the wave if the source is not too far away Pinger Antenna location Close sources + mis-reconstructed Well reconstructed sources (mostly) Works well for short pulses D. Zaborov, ARENA workshop

  9. Looking for sounds from “right” direction Time + direction to source 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 …) D. Zaborov, ARENA workshop

  10. A candidate event EAS gates D. Zaborov, ARENA workshop

  11. A candidate event (continued) E~ 1017eV r ~ 8 m 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. D. Zaborov, ARENA workshop

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