Detection of high energy neutrinos

High energy muon neutrinos can be detected by observing long range muons produced in charged current neutrino nucleon interactions in the matter surrounding the detector. Due to the increase of the #tex2html_wrap_inline504# cross-section with the neutrino energy and to the increase of the muon path-length with the muon energy the ratio of the event rate to the neutrino flux #tex2html_wrap_inline506# is an increasing function of the neutrino energy #tex2html_wrap_inline508#. This means that high energy neutrinos will be statistically enhanced. The higher the energy of the neutrino, the lower the scattering angle between the neutrino and the produced muon is. At energies above 1TeV the average of this angle is lower than 1#tex2html_wrap_inline510#. So, the direction of the parent neutrino is well determined. Despite its increase with the neutrino energy the #tex2html_wrap_inline512# cross-section remains small. So, the detector area must be large enough to provide a sufficient sensitivity in any direction. For this reason a volume of 1km#tex2html_wrap_inline514# is needed. The main source of background is the flux of neutrinos produced in the cascades initiated by primary cosmic rays in the atmosphere. This is a physical unavoidable background. The flux of downward-going atmospheric muons is about 10 order of magnitude higher than the flux of muons induced by atmospheric neutrinos. In order to suppress this high flux the detector must be well shielded. The most economic way to realize a km-scale well shielded detector is to build a 3-D array of optical modules in ocean deep or under the polar ice. High energy muons crossing the detector medium will produce Cerenkov light at an angle #tex2html_wrap_inline516#. The reconstrucion of the muon direction is performed by using the informations on the arrival times of the photons recorded by the optical modules. All simulations show that an angular resolution of #tex2html_wrap_inline518# is easily reachable. To avoid the high flux of atmospheric muons only upward-going muons will be considered.