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T: Fachverband Teilchenphysik

T 88: Neutrinoastronomie 3

T 88.6: Talk

Tuesday, March 5, 2013, 18:00–18:15, HSZ-E03

Results of the search for a diffuse astrophysical muon neutrino flux with IceCube — •Anne Schukraft, Leif Rädel, Sebastian Schoenen, Marius Wallraff, Christopher Wiebusch, and Anne Zilles — III. Physikalisches Institut, RWTH Aachen, D-52056 Aachen

High-energy neutrinos propagate unaffected through the universe and are therefore ideal messenger particles to discover the sources and acceleration mechanisms of cosmic rays. The IceCube experiment has been constructed to measure neutrinos of TeV energies and above. A promising approach is the search for a high-energy diffuse muon neutrino flux. This method is directionally independent and therefore sensitive to the cumulative flux from all potential neutrino sources, e.g. Active Galactic Nuclei. The experimental signature is an excess of high-energy neutrinos over the foreground of lower-energetic atmospheric neutrinos. Data, measured between May 2009 and May 2010, has been analyzed with a two-dimensional likelihood approach taking full advantage of the information of neutrino energies and arrival directions with a consistent treatment of systematic uncertainties. This analysis achieves a superior sensitivity compared to previous searches, which is for the first time below the Waxman-Bahcall upper bound. The result is a non-zero astrophysical neutrino flux, which is consistent with zero at the level of less than 2σ. This is interpreted in context of other diffuse neutrino searches and implications for astrophysical neutrino predictions are discussed.