Limits on the diffuse flux of ultra high energy neutrinos set using the Pierre Auger Observatory

PIERRE AUGER COLLABORATION (J. ABRAHAM, ... , A. MARIAZZI, ET AL)

Lodz, Polonia

Conferencia; 31th International Cosmic Ray Conference; 2009

The array of water-Cherenkov detectorsof the Pierre Auger Observatory is sensitive toneutrinos of > 1 EeV of all flavours. These interactthrough charged and neutral currents in the atmosphere(down-going) and, for tau neutrinos, throughthe ”Earth skimming” mechanism (up-going). Bothtypes of neutrinos can be identified by the presenceof a broad time structure of signals in the water-Cherenkov detectors in the inclined showers thatthey induce when interacting close to ground. Usingdata collected from 1 January 2004 to 28 February2009, we present for the first time an analysis basedon down-going neutrinos and place a competitivelimit on the all-flavour diffuse neutrino flux. We alsoupdate the previous limit for up-going tau neutrinos.Sources of possible backgrounds and systematicuncertainties are discussed.