| Summary: | The IceCube neutrino detector at the South Pole is sensitive to atmospheric muons produced by primary cosmic rays in the TeV energy range. The high rate of events (about 2 kHz in the full 86-string detector) allows for searches of anisotropy in the arrival direction distribution of cosmic rays at the level of a few parts per mille. Using the muon data recorded with IceCube between 2007 and 2010, we show that the cosmic ray flux in the southern hemisphere is not isotropic, but exhibits significant structure on multiple angular scales. In addition to large-scale features in the form of strong dipole and quadrupole moments, the data include several localized regions of excess and deficit on scales between 10° and 30°. These features are statistically significant. The origin of the features is currently unknown. info:eu-repo/semantics/published
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