Limit on the diffuse flux of ultrahigh energy tau neutrinos with the surface detector of the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION (T. TARUTINA PERTENECE A LA COLABORACION - ORDEN ALFABETICO)

PHYSICAL REVIEW D - PARTICLE AND FILDS

The American physical society

Año: 2009 vol. 79 p. 10200101 - 10200115

0556-2821

Data collected at the Pierre Auger Observatory are used to establish an upper limit on the diffuse flux of tau neutrinos in the cosmic radiation. Earth-skimming ντ may interact in the Earth’s crust and produce a τ lepton by means of charged-current interactions. The τ lepton may emerge from the Earth and decay in the atmosphere to produce a nearly horizontal shower with a typical signature, a persistent electromagnetic component even at very large atmospheric depths. The search procedure to select events induced by τ decays against the background of normal showers induced by cosmic rays is described. The method used to compute the exposure for a detector continuously growing with time is detailed. Systematic uncertainties in the exposure from the detector, the analysis, and the involved physics are discussed. No τ neutrino candidates have been found. For neutrinos in the energy range 2×1017  eV<Eν<2×1019  eV, assuming a diffuse spectrum of the form Eν-2, data collected between 1 January 2004 and 30 April 2008 yield a 90% confidence-level upper limit of Eν2dNντ/dEν<9×10-8  GeV  cm-2 s-1  sr-1.