Karlsruhe 2011 – scientific programme

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T: Fachverband Teilchenphysik

T 92: Neutrinoastronomie I

T 92.6: Talk

Monday, March 28, 2011, 18:00–18:15, 30.41: 105

Search for a diffuse extragalactic muon neutrino flux with IceCube — •Anne Schukraft, Marius Wallraff, and Christopher Wiebusch — III. Physikalisches Institut, RWTH Aachen, D-52056 Aachen

The neutrino detector IceCube at the South Pole is searching for sources of extraterrestrial neutrinos. If the neutrino flux from individual sources is too small to be detected as point sources, it is nevertheless possible that combined they produce a detectable diffuse signal. The experimental signature in this case is an excess of high energy neutrinos over the foreground of lower energetic neutrinos which are produced in the Earth’s atmosphere.

A likelihood ansatz is chosen to analyze the full shape of the distribution of neutrino energy and arrival direction, without the need to optimize a selection cut. The diffuse neutrino flux as well as nuisance parameters characterizing uncertainties in the atmospheric background and detector description are simultaneously constrained.

A good understanding of the detector systematics and uncertainties in the simulation of atmospheric background neutrinos is a prerequisite for such a neutrino search. Therefore, the optical properties and the propagation of photons in the South Pole ice are studied as well as the impact of uncertainties in the atmospheric neutrino flux prediction.

This analysis will be applied to the data which was measured with IceCube in its 59-string configuration from April 2009 to May 2010. The sensitivity will be substantially below the Waxmann-Bahcall diffuse neutrino flux prediction, allowing to test prevailing theories.