Freiburg 2008 – scientific programme
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T: Fachverband Teilchenphysik
T 82: Kosmische Strahlung II
T 82.6: Talk
Tuesday, March 4, 2008, 18:10–18:25, KGI-HS 1199
Limit on the diffuse flux of tau neutrinos from the Pierre Auger Observatory — •Dariusz Gora1, Marko Haag1, Markus Roth2, and Alessio Tamburro1 for the Pierre Auger collaboration — 1Institut für Experimentelle Kernphysik, Universitat Karlsruhe — 2Institut für Kernphysik, Forschungszentrum Karlsruhe
The surface detector array of the Pierre Auger Observatory is sensitive to the Earth-skimming tau neutrinos. For an neutrino energy larger than 100 PeV the Earth is not transparent for tau neutrinos. They may interact therefore inside the Earth and produce tau leptons which can emerge from the Earth’s crust. Emerging leptons decay and produce extensive air showers (EAS) detectable by the ground detector of the Pierre Auger Observatory. The topological properties of such showers are quite different from the hadronic events. Neutrino-induced showers are characterized by very elongated and asymmetric footprints and a significant presence of electromagnetic component. The resulting neutrino induced shower would lead to broad timming signals, whereas hadronic showers show signals mostly due to the surviving secondary muons whose released signal is narrower in time than an electromagnetic signal. The data collected between 1st January 2004 until 31st December 2007 is used to place an upper limit on diffuse flux of tau neutrinos. Over this period there is not a single event that fulfills selection criteria. Based on that the limit for an E−2 differential energy spectrum at 90% C.L. is : Eν2dNντ/dEν <1.5−0.8+0.5 · 10 −7 GeVcm−2sr−1s−1.