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Scientific Report 2007-2009
Particle physics
P31. ANTARES: a Čerenkov Neutrino deep-sea detector.
The undisputed galactic origin of cosmic rays at energies
below the so-called knee implies an existence of
a non-thermal population of galactic sources which effectively
accelerate protons and nuclei to TeV-PeV energies.
The distinct signatures of these cosmic accelerators
are high energy neutrinos and gamma rays produced
through hadronic interactions with ambient gas or photoproduction
on intense photon fields near the source.
While gamma rays can be produced also by directly accelerated
electrons, high-energy neutrinos provide unambiguous
and unique information on the sites of the cosmic
accelerators and hadronic nature of the accelerated
particles. The original idea of a neutrino telescope based
on the detection of the secondary particles produced in
neutrino interactions is attributed to Markov [1] who
invoked the concept in the 1950’s. Events reconstruction
is possible through the Čerenkov light induced by
the path of the interaction products in transparent media.
The Antares neutrino telescope, operating at 2.5 km
depth in the Mediterranean Sea, 40 km off the Toulon
shore, represents the world’s largest operational underwater
neutrino telescope, optimized for the detection of
Čerenkov light produced by neutrino-induced muons. It
is equipped with 885 optical sensors arranged on 12 flexible
lines (Figure 1). Each line comprises up to 2 detection
storeys each equipped with three downward-looking
10-inch photo-multipliers (PMTs), orientated at 45 ◦ to
the line axis. The lines are maintained vertical by a
buoy at the top of the 450 m long line. The spacing
between storeys in 14.5 m and the lines are spaced by
60-70 m. An acoustic positioning system provides realtime
location of the detector elements to a precision of
a few centimeters. Antares is taking data in its full 12
lines configuration since May 2008.
cosmos; among them are Supernova Remnants, Pulsars
and Microquasars in the Galaxy. Possible extragalactic
sources include Active Galactic Nuclei and γ −ray burst
emitters. For such processes the neutrino energy scale is
10 12 to 10 16 eV . Another important objective of neutrino
telescopes like ANTARES is the search for dark matter
in the form of WIMPs (Weakly Interacting Massive Particles).
As an example in the case of supersymmetric
theories with R-parity conservation, the relic neutralinos
from the Big-Bang are predicted to concentrate in
massive bodies such as the centres of the Earth, the Sun
or the Galaxy. At these sites neutralino annihilations,
and the subsequent decays of the resulting particles, may
yield neutrinos with energies up to 10 10 - 10 12 eV . Additionally
the study of the diffuse neutrino flux, originating
from sources that cannot be individually resolved or from
interactions of cosmic rays with intergalactic matter or
radiation, may yield important cosmological clues. Such
measurements would be significant for neutrino energies
in excess of 10 15 eV . The apparatus is well performing
[2], [3], [4] and already allowed to reconstruct neutrino
events (Figure 2).
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ANTARES − Preliminary
Figure 2: Sky map, in equatorial coordinates, of 750 neutrino
candidates selected out of the 2007-2008 ANTARES data.
We participated to the construction of the detector
and to data analysis with a special interest for the
detection of ”Sources in the Super-Galactic Plane”.
References
1. M. A. Markov, in Proc. Int. Conf. on High Energy
Physics, Rochester, U.S.A., 1960 183, (1960).
2. J. A. Aguilar et al., Astropart. Phys., 33, 86,90 (2010).
3. M. Ageron et al., Astropart. Phys., 33, 277,283 (2009).
4. J. A. Aguilar et al., NIM-A 581, 695-708 (2007).
Authors
F. Ameli, A. Capone, T. Chiarusi, G. De Bonis, F. Lucarelli,
R. Masullo, F. Simeone, M. Vecchi
Figure 1: The layout of the completed ANTARES detector.
www.roma1.infn.it/people/capone/AHEN/index.htm
The main goal of Antares is the search of high energy
neutrinos from astrophysical point or transient sources.
There are numerous candidate neutrino sources in the
Sapienza Università di Roma 138 Dipartimento di Fisica