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 HENAII. 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 hydrophonesIV. Portable submarine antenna of 132 hydrophones as a basic module of a deep-water acoustic neutrino telescope: status and prospects

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!

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.

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

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)

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)

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!)

II. HYDRO-ACOUSTICAL DETECTION of neutrino-induced cascades

SADCO in the MEDITERRANIEN.Acoustical backgroundmeasurements, 1991

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

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

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 theReal Ocean etc.

Table. Parameters of cascades in water with the LPM-effect

75.571014 1320 12 1021

21.361014 468 12 1020

5.681014 176 12 1019

1.511014 66 121018

Mean energy depo-sition

dE/dx, eV/cm

Length of cascade in water

L , m

Diameter of cascade

D, cm

Energy of electron

E0, eV

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

0

10x1012

20x1012

30x1012

40x1012

50x1012

12

34

5

1020

3040

5060

dE/dV , MeV/m3

r , cm

Z ,m

E0=10

18 eV

Comparison of distribution of energy depositions by 1019

and 1018 electrons in water (with the LPM-effect)

0

50x1012

100x1012

150x1012

12

34

5

20406080100120140160

dE/dV , MeV/m3

r , c

m

Z , m

E0=1019 eV

Comparison of distribution of energy depositions by 1020

and 1018 electrons in water (with the LPM-effect)

0

200x1012

400x1012

600x1012

800x1012

1x1015

12

34

50 100 200 300 400

dE/dV , MeV/m3

r , cm

Z ,m

E0=1020 eV

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

10-3 10-2 10-1

0.0

2.0x105

4.0x105

6.0x105

8.0x105

E0 = 1021 eV 0.4 km

1.0 km 3.0 km 10.0 km

P

/f (P

a/M

Hz)

f (MHz)

Distribution of energy deposition by 1021 eV electron in water with the LPM-effect

0.0

500.0x1012

1.0x1015

1.5x1015

2.0x1015

2.5x1015

23

45

0 200 400 600 800 1000 1200

dE/dV , MeV/m3

r , cm

Z ,m

E0=1021 eV

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

-40 -20 0 20 40 60 80 100 120 140 160 180 200

-500

0

500

1000

1500

2000

2500

E0 = 1019 eV

0.4 km 1.0 km 3.0 km 10.0 km

P

(P

a)

time (s)

Dependence of the peak value of acoustic signal on distances for various energies of cascades 1018–1021 eV in water with the LPM-effect

100 1000 1000010

100

1000

10000

1021 eV

1020 eV

1019 eV

1018 eV

Pm

ax (P

a)

R0 (m)

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

0 5 10 15 20 25 30

0

200

400

600

800

1000

E0 = 1018 eV

R0 = 400 m

Pm

ax (P

a)

R0 (m)

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!