Telescopes neutrino

Fiber optic data cable will stretch from the shore for 30 km to a connector box some 4800 meters below the ocean surface. Strings of nine separate cables will rise vertically about 280 meters above the ocean floor. Each cable, held up by a float, will contain 24 detectors. The apparatus, referred to as a neutrino telescope, will have to pick up at least ten muon events per year from any given 1° patch of sky for the DUMAND scientists to be confident that they have a significant neutrino source, not just a few background pulses from non-ncutrino cosmic rays,... 

Figure 16.17. Complementarity of direct and indirect neutralino dark matter searches. The figure shows that several supersymmetric models that are within the (expected) reach of a big neutrino telescope of 10 km2 yr exposure are beyond the reach of current and future direct detection experiments. The vertical axis is the product of the neutralino-proton spin-independent scattering cross section

This limit has been discussed and recalculated by Mannheim, Protheroe, Rachen [26] and, again, by Waxman and Mannheim [27], taking into account the effect of propagation of CR and of cosmological evolution of the source distribution. However equation 4 limit sets a strong reference value for the discussions on the dimensions of future neutrino telescopes. 

As shown in the previous section, light and neutral neutrinos are optimal probes for high energy astronomy, i.e. for the identification of astrophysical sources of UHE particles.To fulfill this task neutrino detectors must be design to optimise reconstruction of particle direction and energy, thus they are commonly referred as neutrino telescopes (for a clear review see [31]). 

Figure 2. Detection principle of an underwater neutrino telescope. Astrophysical neutrinos can reach the Earth and interact in water or in rocks generating an upgoing muon. An array of 5000 optical detectors tracks Cerenkov photons generated along the muon track. A water shielding > 3000 m is effective to reduce the atmospheric fi background, allowing the reconstruction of upgoing muon tracks.

The contemporary observation of the full sky with at least two neutrino telescopes in opposite Earth Hemispheres is an important issue for the study of transient phenomena. Moreover v events detection from the Northern Hemisphere is required to observe the Galactic Centre region (not seen by ICECUBE), already observed by HESS as an intense TeV gamma source. In the Norther Hemisphere a favourable region is offered by the Mediterranean Sea, where several abyssal sites (> 3000 m) close to the coast are present and where it is possible to install the detector near scientific and industrial infrastructures. 

Research and development for the km3 NEMO. The construction of km3 scale neutrino telescopes requires detailed preliminary studies the choice of the underwater installation site must be carefully investigated to optimise detector performance the readout electronics must have a very low power consumption the data transmission system must allow data flow transmission, as high as 100 Gbps, to shore the mechanical design must allow easy detector deployment and recovery operations, moreover the deployed structures must be reliable over more than 10 years the position monitoring system has to determine the position of OM within 10 cm accuracy. In order to propose feasible and reliable solutions for the km3 installation the NEMO (NEutrino Mediterranean Observatory) Collaboration has been conducting an intense R D activity on all the above subjects since 1998 [53],... 

The forthcoming km3 neutrino telescopes are discovery detectors that could widen the knowledge of the Universe. These detectors have high potential to solve questions as the detection of UHECR sources, the investigation of hadronic processes in astrophysical environments or massive dark matter. Strong scientific motivations suggest the construction of two km3 scale detectors in the Northern and the Southern Hemisphere. 

In the South Pole the ICECUBE detector is extending AMANDA to the km3 size and it is planned to be completed within year 2010, being probably the fist km3 telescope running. In the Mediterranean Sea ANTARES is going to install a 0.1 km2 neutrino telescope demonstrator, NESTOR has deployed... 

Keywords Neutrino Detector, Neutrino Telescopes, Neutrino Astronomy, Antarctic Ice, Ul-... 

AMANDA has yet to observe an extraterrestrial neutrino source, but she has demonstrated the cost-effectiveness and robustness of the technique. The detector is very versatile it addresses many different neutrino physics subjects and sets the most stringent upper limits on Galactic and extragalactic neutrino fluxes. The improved search for diffuse fluxes, which has ruled out several predictions, along with the extended four-year search for point sources has started to constrain the enormous parameter space that exist in many models of neutrino production. The reported experimental limits on the diffuse neutrino flux are less than an order of magnitude above the Waxman-Bahcall bound ( Waxman and Bahcall, 1999). As more of the data on tape is analyzed, AMANDA sensitivities will continue to improve. This is a very exciting time in neutrino astronomy and we look forward to neutrino astrophysics with next generation of neutrino telescopes. 

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