Eike Middell

Searches for diffuse neutrino fluxes with IceCubeReferent

One hundred years after their discovery much is known about cosmic rays
but there remain important unanswered questions, especially concerning
the astrophysical sources of the highest energy cosmic rays. Since in
the acceleration process of the highest energy cosmic rays also high
energy neutrinos should be created, the identification of astrophysical
neutrino sources is a crucial piece in the cosmic ray puzzle. But even
if no individual object can be resolved with current instruments, the
combined diffuse flux from all neutrino sources could be measurable.
Located at the geographic South Pole, the IceCube Neutrino Observatory,
is presently the world's largest detector to search for neutrinos in the
TeV to PeV range. A cubic kilometer volume deep in the glacial ice has
been instrumented with digital optical sensors in order to record
Cherenkov light emitted by charged secondaries that are generated in
neutrino interactions. The IceTop air shower array at the surface
complements the observatory. Throughout the years of construction the
detector was already taking data. This talk will present results from
searches for the diffuse neutrino flux in IceCube data taken in
different years. The analysis techniques as well as recent observations
will be discussed, including first evidence for the presence of high
energy (10^6 GeV) neutrinos of astrophysical origin.

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