First Observation of PeV-Energy Neutrinos with IceCube

• Published in: Physical Review Letters
• Main Authors: Aartsen, M. G., Besson, David Zeke, IceCube Collaboration
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Physical Society 2014
• Subjects: Canada; National Science Foundation Office of Polar Programs; Swedish Polar Research Secretariat
• Online Access: http://hdl.handle.net/1808/15830; https://doi.org/10.1103/PhysRevLett.111.021103

We report on the observation of two neutrino-induced events which have an estimated deposited energy in the IceCube detector of 1.04±0.16 and 1.14±0.17 PeV, respectively, the highest neutrino energies observed so far. These events are consistent with fully contained particle showers induced by neutral-current νe,μ,τ (ν¯e,μ,τ) or charged-current νe (ν¯e) interactions within the IceCube detector. The events were discovered in a search for ultrahigh energy neutrinos using data corresponding to 615.9 days effective live time. The expected number of atmospheric background is 0.082±0.004(stat)+0.041−0.057(syst). The probability of observing two or more candidate events under the atmospheric background-only hypothesis is 2.9×10−3 (2.8σ) taking into account the uncertainty on the expected number of background events. These two events could be a first indication of an astrophysical neutrino flux; the moderate significance, however, does not permit a definitive conclusion at this time. We acknowledge the support from the following agencies: U.S. National Science Foundation-Office of Polar Programs, U.S. National Science Foundation-Physics Division, University of Wisconsin Alumni Research Foundation, the Grid Laboratory Of Wisconsin (GLOW) grid infrastructure at the University of Wisconsin—Madison, the Open Science Grid (OSG) grid infrastructure; U.S. Department of Energy, and National Energy Research Scientific Computing Center, the Louisiana Optical Network Initiative (LONI) grid computing resources; Natural Sciences and Engineering Research Council of Canada, Compute Canada, and Compute West High Performance Computing; Swedish Research Council, Swedish Polar Research Secretariat, Swedish National Infrastructure for Computing (SNIC), and Knut and Alice Wallenberg Foundation, Sweden; German Ministry for Education and Research (BMBF), Deutsche Forschungsgemeinschaft (DFG), Helmholtz Alliance for Astroparticle Physics (HAP), Research Department of Plasmas with Complex Interactions (Bochum), Germany; Fund for Scientific ...