SADCO Sea Acoustic Detector of Cosmic Objects: status of a pilot experiment in the Caspian Sea

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 • Introduction: • Short history of HENA. • Need in cubic km-size (KM3) detectors for HENA • Hydro-acoustical method of UHE(EHE) cosmic neutrino detection: • 30 years of its development for UHENA and EHENA • Russian Navy stationary hydro-acoustical antennae for HENA: Kamchatka array AGAM of 2400 hydrophones • Portable submarine antenna of 132 hydrophones as a basic module • of a deep-water acoustic neutrino telescope: status and prospects

3. 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: • -- 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); • -- 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 70th 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 80th by M.A.Markov and his group: --the possibility of the existence of particles with energies 1020-1028 eV originating in the decays of the Mini-Black Holes*; --maximons (particles with Plank mass) and EHE particles**; --neutrinos with energies above 1020 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 1022 - 1026 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. Energy of electron E0, eV Diameter of cascade D, cm Length of cascade in water L , m Mean energy depo-sition dE/dx, eV/cm 1018 12 66 1.511014 1019 12 176 5.681014 1020 12 468 21.361014 1021 12 1320 75.571014 Table.Parameters of cascades in water with the LPM-effect

22. Distribution of energy deposition by1018 electron in water with the LPM-effect

23. Comparison of distribution of energy depositions by 1019 and1018electrons in water (with the LPM-effect)

24. Comparison of distribution of energy depositions by 1020 and1018electrons 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 1021 eV in water with the LPM-effect

26. Distribution of energy deposition by 1021 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 1019 eV in water with the LPM-effect

28. Dependence of the peak value of acoustic signal on distances for various energies of cascades 1018–1021 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 1018 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!