No Arabic abstract
The observation of high-energy extraterrestrial neutrinos is one of the most promising future options to increase our knowledge on non-thermal processes in the universe. Neutrinos are e.g. unavoidably produced in environments where high-energy hadrons collide; in particular this almost certainly must be true in the astrophysical accelerators of cosmic rays, which thus could be identified unambiguously by sky observations in neutrino light. To establish neutrino astronomy beyond the detection of single events, neutrino telescopes of km3 scale are needed. In order to obtain full sky coverage, a corresponding detector in the Mediterranean Sea is required to complement the IceCube experiment currently under construction at the South Pole. The groups pursuing the current neutrino telescope projects in the Mediterranean Sea, ANTARES, NEMO and NESTOR, have joined to prepare this future installation in a 3-year, EU-funded Design Study named KM3NeT. This report will highlight some of the physics issues to be addressed with the KM3NeT detector and will outline the path towards its realisation, with a focus on the upcoming Design Study.
KM3NeT is a new generation neutrino telescope currently under construction at two sites in the Mediterranean Sea. At the Capo Passero site, 100 km off-shore Sicily, Italy, a volume of more than one cubic kilometre of water will be instrumented with optical sensors. This instrument, called ARCA, is optimized for observing cosmic sources of TeV and PeV neutrinos. The other site, 40 km off-shore Toulon, France, will host a much denser array of optical sensors, ORCA. With an energy threshold of a few GeV, ORCA will be capable to determine the neutrino mass hierarchy through precision measurements of atmospheric neutrino oscillations. In this contribution, we review the scientific goals of KM3NeT and the status of its construction. We also discuss the scientific potential of a neutrino beam from Protvino, Russia to ORCA. We show that such an experiment would allow for a measurement of the CP-violating phase in the neutrino mixing matrix. To achieve a sensitivity competitive with that of the other planned long-baseline neutrino experiments such as DUNE and T2HK, an upgrade of the Protvino accelerator complex will be necessary.
A prototype string for the future km3-scale Baikal neutrino telescope has been deployed in April, 2008 and is fully integrated into the NT200+ telescope. All basic string elements - optical modules (with 12/13 hemispherical photomultipliers), 200MHz FADC readout and calibration system - have been redesigned following experience with NT200+. First results of in-situ operation of this prototype string are presented.
A study of the UHE nu_tau detection performances of a km^3 Neutrino Telescope sitting at the three proposed sites for ANTARES, NEMO and NESTOR in the Mediterranean sea is here performed. In particular, it is analyzed the effect of the underwater surface profile on the total amount of yearly expected tau crossing the fiducial volume in the limit of full detection efficiency and energy resolution.
KM3NeT will be a network of deep-sea neutrino telescopes in the Mediterranean Sea. The KM3NeT/ARCA detector, to be installed at the Capo Passero site (Italy), is optimised for the detection of high-energy neutrinos of cosmic origin. Thanks to its geographical location on the Northern hemisphere, KM3NeT/ARCA can observe upgoing neutrinos from most of the Galactic Plane, including the Galactic Centre. Given its effective area and excellent pointing resolution, KM3NeT/ARCA will measure or significantly constrain the neutrino flux from potential astrophysical neutrino sources. At the same time, it will test flux predictions based on gamma-ray measurements and the assumption that the gamma-ray flux is of hadronic origin. Assuming this scenario, discovery potentials and sensitivities for a selected list of Galactic sources and to generic point sources with an $E^{-2}$ spectrum are presented. These spectra are assumed to be time independent. The results indicate that an observation with $3sigma$ significance is possible in about six years of operation for the most intense sources, such as Supernovae Remnants RX,J1713.7-3946 and Vela Jr. If no signal will be found during this time, the fraction of the gamma-ray flux coming from hadronic processes can be constrained to be below 50% for these two objects.
The observation of high-energy neutrinos from astrophysical sources would substantially improve our knowledge and understanding of the non-thermal processes in these sources, and would in particular pinpoint the accelerators of cosmic rays. The sensitivity of different design options for a future cubic-kilometre scale neutrino telescope in the Mediterranean Sea is investigated for generic point sources and in particular for some of the galactic objects from which TeV gamma emmission has recently been observed by the H.E.S.S. atmospheric Cherenkov telescope. The effect of atmospheric background on the source detection probabilities has been taken into account through full simulation. The estimated event rates are compared to previous results and limits from present neutrino telescopes.