1. SADCO Sea Acoustic Detector of Cosmic Objects: status of a pilot experiment in the Caspian Sea Igor Zheleznykh, INR, Moscow for SADCO collaboration John Learned reporting a Stanford, 14 Sept 2003 I.Introduction: Short history of HENA. Need in cubic km-size (KM3) detectors for HENA II.Hydro-acoustical method of UHE(EHE) cosmic neutrino detection: 30 years of its development for UHENA and EHENA III.Russian Navy stationary hydro-acoustical antennae for HENA: Kamchatka array AGAM of 2400 hydrophones IV.Portable submarine antenna of 132 hydrophones as a basic module of a deep-water acoustic neutrino telescope: status and prospects

3. I.Introduction. First estimations and comparison of atmospheric and astrophysical HE (E ~ 1-1000 GeV) neutrino fluxes had been carried out in 1958-1960 (Markov and Zh.) and Greisen (1960). Fluxes of HE atmospheric neutrinos are higher than astrophysical ones produced by standard Cosmic Rays. But: productive point astrophysical neutrino sources might exist!

4. So underground (underwater) HE neutrino experiments were suggested (M.A. Markov et al) for investigations of 2 problems: 1.-- High-Energy Neutrino Physics: Investigation of neutrino interactions with matter using available atmospheric neutrinos with energies 1-1000 GeV (energy growth of neutrino cross-sections, intermediate bosons etc); 2.-- High Energy Neutrino Astrophysics (HENA): Search for fluxes of HE cosmic neutrinos from astrophysical objects.

5. HE neutrino (gammas) sources discussed in 1958 – 1961** – Galaxy center, SN remnants (Crab Nebula); HE gammas (as well as HE neutrinos) are produced in the strong interactions: HEGA was suggested as complimentary to HENA HE cosmic neutrinos (as well as gammas) – indicator of the most energetic (strong) processes in hot places of the Universe; so detection of cosmic neutrinos might be a new branch of Astronomy which is complimentary to Electromagnetic Astronomies (optical, radio, X-ray…) ** M.A.Markov, Proc. Rochester Conf. (1960) p. 579; I.M.Zheleznykh, Diploma paper, Depart. of Phys., Moscow Univ., 1958 I.M.Zheleznykh and M.A.Markov. In: High-energy Neutrino Physics D-577, Dubna (1960); M.A.Markov and I.M.Zheleznykh, Nucl. Phys. 27 (1961) 385

6. In 70 th it was understood that kiloton HE neutrino telescopes which were under construction (Baksan et al) would not be able to register HE cosmic neutrinos. 1975: Fred Reines, John Learned, Arthur Roberts, Vic Stenger et al – idea of Gigaton underwater HE Neutrino Telescope (DUMAND). 1976 - 1979: Gurgen Askaryan et al, Ted Bowen, John Learned – idea of hydro-acoustic UHE neutrino detection. So KM3 – cubic km - scale detector for HE and UHE Neutrino Astrophysics (Astronomy) – is needed ! (M.Shapiro, Silverberg, Beresinsky et al)

7. New arguments to support construction of large-scale (DUMAND- type) NT for investigations of super GZK- particles were discussed in the end of 70th – begin of 80 th by M.A.Markov and his group: --the possibility of the existence of particles with energies 10 20 -10 28 eV originating in the decays of the Mini-Black Holes*; --maximons (particles with Plank mass) and EHE particles**; --neutrinos with energies above 10 20 eV as a result interactions (decays) of the hypothetical super heavy particles*** * M.Markov and I.Zheleznykh, Proc. DUMAND-1979, p.177 ** V.Maltsev and M.Markov (1980), V.Frolov and M.Markov, (1979) ***L.Dedenko, M.Markov and I.Zheleznykh, Proc. Neutrino-81, Maui, p.92 (in this paper the suggestion was also made to search for the electron-photon and hadron cascades produced by super-GZK neutrinos in the atmosphere by radio method)

8. Top–down models and possible EHE neutrino sources discussed last years: - decays of topological defects (see G.Sigl, 2002) - decays of long-living X-particles with masses 10 22 - 10 26 eV Kuzmin and Rubakov, 1997; Beresinsky et al., 1997 Such objects are objects of much interest for HENA (and hydro-acoustical UHE and EHE neutrino detection!)

9. II. HYDRO-ACOUSTICAL DETECTION of neutrino-induced cascades

10. SADCO in the MEDITERRANIEN. Acoustical background measurements, 1991

11. III. New Era of SADCO since 1997: to use Russian Navy stationary antennae for

16. IV. PORTABLE SUBMARINE ANTENNA MG-10M as a basic module of the deep-water Neutrino Telescope

20. SADCO collaboration have now: - one MG-10M antenna of 132 hydrophones, - Agreement with a plant in St.Petersburg to make necessary tests of this antenna, - Agreement with Azerbaijan Ac. Sci., - programs for simulations acoustic signals from cascades in water, transportation of the signals in the Real Ocean etc.

21. Table. Parameters of cascades in water with the LPM-effect 75.57  10 14 13201210 21 21.36  10 14 4681210 20 5.68  10 14 1761210 19 1.51  10 14 661210 18 Mean energy depo- sition dE/dx, eV/cm Length of cascade in water L, m Diameter of cascade D, cm Energy of electron E 0, eV

22. Distribution of energy deposition by10 18 electron in water with the LPM-effect

23. Comparison of distribution of energy depositions by 10 19 and 10 18 electrons in water (with the LPM-effect)

24. Comparison of distribution of energy depositions by 10 20 and 10 18 electrons in water (with the LPM-effect)

25. Distribution of frequencies of acoustic signals at 0.4; 1; 3; 10 km by the electron cascade of 10 21 eV in water with the LPM-effect

26. Distribution of energy deposition by 10 21 eV electron in water with the LPM-effect

27. Acoustic pulses at distances of 0.4; 1; 3: 10 km by the electron cascade of 10 19 eV in water with the LPM-effect

28. Dependence of the peak value of acoustic signal on distances for various energies of cascades 10 18 –10 21 eV in water with the LPM-effect

29. Dependence of the peak value of acoustic signal on shifting of the observation point along the cascade length for the 10 18 eV electron cascade at 400 m

31. Could Russian Navy help to HENA in searches for topological defects in our Universe? Yes, they could. USA Navy? We should ask G.Gratta. French Navy? We should ask L.Moscoso. It would be great if to cooperate!