Search for neutrino-induced particle showers with IceCube-40

Abstract

We report on the search for neutrino-induced particle-showers, so-called cascades, in the IceCube-40 detector. The data for this search was collected between April 2008 and May 2009 when the first 40 IceCube strings were deployed and operational. Three complementary searches were performed, each optimized for different energy regimes. The analysis with the lowest energy threshold (2 TeV) targeted atmospheric neutrinos. A total of 67 events were found, consistent with the expectation of 41 atmospheric muons and 30 atmospheric neutrino events. The two other analyses targeted a harder, astrophysical neutrino flux. The analysis with an intermediate threshold of 25 TeV lead to the observation of 14 cascade-like events, again consistent with the prediction of 3.0 atmospheric neutrino and 7.7 atmospheric muon events. We hence set an upper limit of $E^2{\Phi }_{lim}\le 7.46\times 10^{-8}\mathrm{GeVs}{\mathrm{r}}^{-1}{\mathrm{s}}^{-1}\mathrm{c}{\mathrm{m}}^{-2}$ (90% C.L.) on the diffuse flux from astrophysical neutrinos of all neutrino flavors, applicable to the energy range 25 TeV to 5 PeV, assuming an $E_{\nu }^{-2}$ spectrum and a neutrino flavor ratio of 1:1:1 at the Earth. The third analysis utilized a larger and optimized sample of atmospheric muon background simulation, leading to a higher energy threshold of 100 TeV. Three events were found over a background prediction of 0.04 atmospheric muon events and 0.21 events from the flux of conventional and prompt atmospheric neutrinos. Including systematic errors this corresponds to a $2.7\sigma$ excess with respect to the background-only hypothesis. Our observation of neutrino event candidates above 100 TeV complements IceCube's recently observed evidence for high-energy astrophysical neutrinos.

19 pages, 13 figures, submitted to Phys. Rev. D

References in corpus (13)

• Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector
• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• Calculation of atmospheric neutrino flux using the interaction model calibrated with atmospheric muon data
• Prompt neutrino fluxes from atmospheric charm
• Measurement of the atmospheric neutrino energy spectrum from 100 GeV to 400 TeV with IceCube
• Measurement of the Atmospheric ${\nu }_e$ flux in IceCube
• Light tracking through ice and water -- Scattering and absorption in heterogeneous media with Photonics
• Determination of the Atmospheric Neutrino Fluxes from Atmospheric Neutrino Data
• Cosmic Rays: Recent Progress and some Current Questions
• Electron and Photon Interactions in the Regime of Strong LPM Suppression
• Calculation of the Cherenkov light yield from electromagnetic cascades in ice with Geant4
• Fluxes of Atmospheric Leptons at 600 GeV - 60 TeV
• First Evidence For Atmospheric Neutrino-Induced Cascades with the IceCube Detector

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• Characteristics of the diffuse astrophysical electron and tau neutrino flux with six years of IceCube high energy cascade data
• (In)direct Detection of Boosted Dark Matter
• An All-Sky Search for Three Flavors of Neutrinos from Gamma-Ray Bursts with the IceCube Neutrino Observatory
• Measurement of the Atmospheric ${\nu }_e$ Spectrum with IceCube
• Boosted Self-interacting Dark Matter in a Multi-component Dark Matter Model
• Status of High-Energy Neutrino Astronomy
• Constraining the Violation of Equivalence Principle with IceCube Atmospheric Neutrino Data
• Measurement of the atmospheric ${\nu }_e$ and ${\nu }_{\mu }$ energy spectra with the ANTARES neutrino telescope
• A new contribution to the conventional atmospheric neutrino flux
• Hadronic supercriticality as a trigger for GRB emission
• (In)Direct Detection of Boosted Dark Matter
• The Observation of High-Energy Neutrinos from the Cosmos: Lessons Learned for Multimessenger Astronomy
• IceCube - status and recent results
• Probing new physics with high-multiplicity events: UHE neutrinos at air-shower detector arrays
• Very High Energy Antineutrinos from Photo-disintegration of Cosmic Ray Nuclei
• Neutrino Astronomy at High Energies - An Experimental Review
• Boosting (In)direct Detection of Dark Matter