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Hydro-Acoustic Method of EHE Neutrino Detection in the Mediterranean Sea

This study explores the development of a hydro-acoustic method for detecting ultra-high-energy cosmic neutrinos in the Mediterranean Sea. It discusses deep hydro-acoustic measurements, attempts to use converted hydro-acoustic arrays, and proposals for joint research.

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Hydro-Acoustic Method of EHE Neutrino Detection in the Mediterranean Sea

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  1. Development of Hydro-Acoustic Method of EHE Neutrino Detection in the Mediterranean Sea I. Zheleznykh and S. Karaevsky (INR, Moscow) P. Korotin (IAP, Nizhnii Novgorod) L. Dedenko (Moscow University) • Deep hydro-acoustic measurements during “Vityaz”-1991 cruise in the Mediterranean Sea • Attempts to use Converted Hydro-Acoustic Arrays: - Kamchatka array of 2400 hydrophones (BW up to 1.5 kHz), - Submarine array of 132 hydrophones – MG-10M (BW up to 25 kHz).

  2. III. Proposals INR and IAP to use their equipment for joint research in the Mediterranean: - measurement of characteristics of acoustic noise in the water area (level, anisotropy, spectral composition, statistical characteristics, etc.) for determining the detection threshold of cosmic neutrinos, - measurement of the Gruneisen coefficient in marine conditions. IV. The IAP proposal: The use of new technologies to reduce the detection threshold. The creation of an autonomous station for a long-term study of the dynamics of the marine environment, including a development hydro-acoustic method for detecting ultrahigh-energy cosmic neutrinos.

  3. 1. Deep hydro-acoustic measurements during “Vityaz”-1991 cruise in the Mediterranean Sea Two scientific cruises (Vityaz - 1991, Keldysh -1992) were undertaken jointly by Russian and Greek sides to study the acoustic, optical and hydrological conditions in the Ionian Sea near the town of Pylos. The important results were obtained for the acoustic background. Two array of hydrophones were employed: a large aperture (25m) 8-element array and 12-element nonuniform array of closely spaced sensors. The threshold sensitivity of the hydrophones was around 5x10-6 Pa/Hz -0.5 in the 15-30 kHz band. The minimal level we observed (1.2x10-5 Pa/Hz -0.5) exceeds the minimum Wenz level by 2 to 3 times.

  4. 1991Deployment of SADCO module for measurement of acoustic BG at 4 km depths

  5. 2. Attempts to use Converted Hydro-Acoustic Arrays • In 1997 Karlik, Learned, Svet and Zheleznykh suggested to use the Russian Navy stationary hydro-acoustical Kamchatka array AGAM of 2400 hydrophones for goals of the extremely high-energy Neutrino Astronomy (Proc. XXXII-nd Rencontres de Moriond)

  6. Kamchatka array of 2400 hydrophones (BW up to 1.5 kHz),

  7. Neutrino registration with an array AGAM

  8. In 2000 the same authors (+L. Dedenko) considered possibilities of using for goals of EHE Neutrino Astronomy a portable hydro-acoustic system designated MG-10M, formerly used by the USSR Navy which was withdrawed from service.

  9. PORTABLE SUBMARINE ANTENNA MG-10M Submarine array of 132 hydrophones – MG-10M (BW up to 25 kHz) as a possible basic module of the deep-water Neutrino Telescope

  10. We believed that the system MG-10M was the most suitable array to start the first ocean long-term experimental researches. This system has high enough factor of amplification (more than 1700) in a frequency band of 10-25 kHz, is capable to work on depths up to 400 meters, is compact and possesses a high degree of reliability (~10 years)

  11. Acoustic pulses at distances of 0.4; 1; 3: 10 km produced by the electron cascade of 1019 eV in water with the LPM-effect

  12. 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

  13. Profile of the vertical velocity of sound, adopted in the calculations of the field.

  14. The length of the cascade is 10 m. The angle of inclination is 0 deg. Depth of the source is 50 m.

  15. The length of the cascade is 10 m. The angle of inclination is 0 deg. Depth of the source is 100 m.

  16. The length of the cascade is 10 m. The angle of inclination is 0 deg. Depth of the source is 150 m.

  17. The length of the cascade is 10 m. The angle of inclination is 30 degrees. Depth of the source is 150 m.

  18. III. Suggestion of INR RAS and IAP RAS to use their equipment for joint investigations in the Mediterranean Sea: - measurements of acoustical noises, - measurements of Gruneisen coefficient etc. • The region of the Mediterranean Sea near Greece is good one for the location of a neutrino detector. Great depth, up to 5 km, sufficient distance from sea routes and a large number of windless days per year provide a rather low level of acoustic noise. The relatively high temperature of sea water (up to +14 deg) provides a higher level of acoustic signal generated by the cascade from the neutrino

  19. The amplitude of the acoustic signal from the neutrino cascade is proportional to the energy of the cascade and the thermoelastic properties of water (Grüneisen coefficient)The value of the Grüneisen coefficient depends on the temperature, salinity and depth of the measurement site. The measurement of this coefficient under the conditions of operation of a real acoustic neutrino detector will make it possible to refine its values necessary for calculating the fundamental characteristics of an acoustic neutrino detector. For full-scale studies, a deep-sea measuring module is being developed that allows one to estimate the spatial spectrum of acoustic noise and the Grüneisen coefficient at various depths

  20. Temperature profile in the sea near Pylos and the calculated value of the Grüneisen coefficient in places of different projects

  21. In the Institute for Nuclear Research of the Russian Academy of Sciences laboratory studies have been carried out on the possibility of using a low-power solid-state pulsed laser to excite a thermo-acoustic pulse in water. The results of the studies confirmed the possibility of using a compact laser based on erbium-doped aluminum garnet to simulate the neutrino cascade and to measure the Grüneisen coefficient in marine conditions.

  22. Deep-water titanium container with a diameter of 150 mm, length of 560 mm with a high-sensitivity hydroacoustic antenna operating up to 25 kHz

  23. Deep underwater bottom titanium station (diameter 1m) with a set of equipment for autonomous operation at depths of up to 6 km .

  24. The IAP proposal. Employees of the Institute of Applied Physics of the Russian Academy of Sciences have developed a whole set of measuring instruments and methods for acoustic measurements. Digital hydro-acoustic receivers with integrated signal processing and antennas based on them are successfully used in marine experiments.

  25. Hydroacoustic system can consist of a few vertical array of such monoblocs

  26. A monoblock for depths up to one km can be manufactured and installed in the course of the project. The equipment will be able to read the processed data (not raw data) via satellite communication. At the end of the project the monoblock can be given to you for the data accumulation and processing. If it is necessary, a monoblock for depths of a few km can be manufactured for the bottom mounting. But this option is more complicated and will require additional approvals for auxiliary devices. In its most complete form, the hydro-acoustic system can consist of a few vertical array of such monoblocs.

  27. Calculations of cascades and acoustical signals produced by them

  28. Calculations of cascades and acoustical signals produced by them • Figure 1.The longitudinal distributions of the energy deposition dE/dZ in cascades induced in water by gammas with energies of 0,1;1;101;102 and 103GeV

  29. Figure 2. The longitudinal distributions of the energy deposition dE/dZ in cascades induced in water by gammas with energies 104;105;106 GeV

  30. Figure 3. The longitudinal distributions of the energy deposition dE/dZ in cascades induced in water by gammas with energies 107;108;109;1010 and 1011GeV.

  31. Figure 4. The longitudinal distributions of the energy deposition dE/dZ in cascades induced in water by gammas with energies 1010 and 1011 GeV

  32. Figure 5. The position Zmax of the maximum of the longitudinal distributions of the energy deposition dE/dZ in cascades induced in water by gammas with energies in the range of 0,1-1011 GeV.

  33. Figure 7. The average lateral spread of an energy deposition in a cascade induced by gammas with the energy of 10 GeV.

  34. Figure 6. The longitudinal distributions of the energy deposition dE/dZ in cascades induced in water by gammas with energy of 1011GeV: (a) the average distribution for 10 events, (b, c, d, e, f) – examples of individual distributions.

  35. Conclusion The most suitable place for development of Hydro-Acoustic Method of EHE Cosmic Neutrino Detection as well for applied investigations is the Mediterranean Sea. • The most constructive way for realization of the suggested investigations is an international collaboration.

  36. REFERENCES • 1. Sea Acoustic Detection of Cosmic Objects ( SADCO), I.M. Zheleznykh, S.Kh. Karaevsky, M.A. Markov, A.V. Trenikhin. L.Dedenko, E.G.Anassntzis, P.Ioannou, L.K.Resvanis, V.Albul, A.Kurchanov, A.Sinitsky, A.Rupalev , 1993. Published in 23rd Int. Cosmic Ray Conference: proceedings. Calgary, Edited by R.B. Hicks, D.A. •  2. G. A. Askaryan (1979), “Acoustic Radiation by Charged Atomic Particles in Liquids”, Nucl. Inst. Meth., 164, 267. •  3. SADCO: Hydroacoustic Detection of Superhigh Energy Cosmic Neutrinos. L.G. Dedenko (Moscow, INR), A.V. Furduev (Andreev Acoustic Inst., Moscow), Ya.S. Karlik, I.M. Zheleznykh, A.A. Mironovich (Moscow, INR), J.G. Learned ,V.D. Svet , 1997 Published in Proc. 25th ICRC, Durban, South Africa, vol. 7, p.89, 1997, also in e-Print Archive: astro-ph/9705189. •  4. Sea Acoustic Detector of Cosmic Objects – SADCO. (Status of SADCO-92 Collaboration). A.V. Butkevich, S.Kh. Karaevsky, M.A.Markov, I.M. Zheleznykh, A.V. Trenikhin et al., Trends in Astro-particle Physics, Proc. 2nd Int. Conf., Aachen, 1991 Published in Teubner Texte zur Physik, Leipzig, ed. P.Bosetti, pp.128-131, 1994 • 5. Acoustic signal from neutrinos of ultrahigh-energy and background conditions for an acoustic neutrino telescope in the Ionian Sea. L.G. Dedenko, I.V. Denisov, I.M. Zheleznykh, S.Kh. Karaevsky, A.A. Mironovich, A.V. Trenikhin (Moscow, INR), 1994. Published in Bull.Russ.Acad.Sci.Phys. vol.58, pp. 2075-2077, 1994 • 6. Hydroacoustic detection of ultra-high energy cosmic neutrinos. I.M. Zheleznykh (Moscow, INR), Ya.S. Karlik , J.G. Learned , V.D. Svet , 1997. Prepared for 32nd Rencontres de Moriond: High-Energy Phenomena in Astrophysics, Les Arcs, France, 18-25 Jan., 1997. • 7. Prospects for deep-sea acoustic detection of neutrinos. L.G. Dedenko, I.M. Zheleznykh, S.Kh. Karaevsky, A.A. Mironovich (Moscow, INR), V.D. Svet, A.V. Furduev (Andreev Acoustic Inst., Moscow), 1997. • Published in Bull.Russ.Acad.Sci.Phys. vol. 61, pp. 469-471, 1997. • 8. Data from an INSU sea campaign at the ANTARES site Aug. 2007, V. Bertin, private communication (Aug. 2009). • 9. The International Association for the Properties of Water and Steam (IAPWS), Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (Aug. 2007), Release on the IAPWS Formulation 2008 for the Thermodynamic Properties of Seawater (Sept. 2008), http://www.iapws.org/.

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