IceCube Neutrinos: from Oscillations to PeV-Energy Events

Abstract

With IceCube and its low-energy extension DeepCore, a neutrino detector with an energy reach from tens of gigaelectronvolt to exaelectronvolt has been commissioned. It measures the atmospheric neutrino spectrum from the lower energies where neutrinos oscillate to energies as large as 100 TeV with a statistic of more than 100,000 events per year. The initial results suggest that IceCube can measure the oscillation parameters in an energy range that exceeds existing observations by 1 order of magnitude, thus opening a new window on neutrino physics. We emphasize the search for sterile neutrinos particularly relevant to cosmology. We also discuss the first observation of (PEV) petaelectronvolt-Energy events that cannot be accommodated by the flux anticipated by extrapolation of the present atmospheric neutrino measurements.