KM3NeT: Study of the angular acceptance for a high energy neutrino telescope in the Mediterranean Sea

Simulations for the study of the angular acceptance for a high energy neutrino telescope in the Mediterranean Sea are performed in the frame of the KM3NeT Design Study. In particular we have investigated how the PMT orientation can affect the performance of a km3 detector based on towers with a pair of Optical Modules equipped with 10 in. PMTs at each edge of the storey. Some preliminary results for three different PMT orientations are presented and the expected effect on the detection of point-sources and a diffuse flux of very energetic neutrinos is discussed. Moreover, a first attempt to study the response to atmospheric muons for different PMT orientations was also undertaken aiming both at the rejection of the atmospheric muons mis-reconstructed as up-going and the detection of the Moon shadow. However, due to the large detector volume, a huge statistics is needed to achieve an adequate live-time. For this reason we started a mass production of atmospheric muons at several detector depths.