Freiburg 2008 – scientific programme
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T: Fachverband Teilchenphysik
T 79: Neutrinoastronomie III
T 79.8: Talk
Wednesday, March 5, 2008, 18:40–18:55, KGI-HS 1221
Search for a diffuse flux of extraterrestrial neutrinos in AMANDA using the cascade signature — •Oxana Actis for the IceCube collaboration — DESY, Platanenallee 6., D-15738 Zeuthen, Deutschland — Present address: III. Physikalisches Institut A, RWTH Aachen, D-52056 Aachen, Deutschland
The Antarctic Muon And Neutrino Detector Array (AMANDA) is a Cherenkov detector deployed in the Antarctic ice cap at the South Pole. The charged-current interaction of high-energy electron or tau neutrinos, as well as neutral-current interactions of neutrinos of any flavor, can produce isolated electromagnetic or hadronic cascades. There are several advantages associated with the cascade channel in the search for a "diffuse" flux of astrophysical neutrinos: a good energy resolution and a low background due to atmospheric electron neutrinos. In addition, the background from downward-going atmospheric muons can be suppressed due to their track-like topology which allows us to attain 4π acceptance above energies of ∼50 TeV.
In this talk we present a five years analysis of AMANDA data collected between 2000 and 2004. The analysis of the data does not reveal any excess of events over the expected background. Therefore, an upper limit of E2Φ90%CL ≤ 3.96· 10−7 GeV s−1 sr−1 cm−2 at 90% C.L. has been placed on the diffuse all-flavor neutrino flux with a Φ∝ E−2 energy spectrum in a range from 40 TeV to 9 PeV. This is currently the best upper limit on the diffuse all-flavor neutrino flux obtained analyzing cascade events.