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News from IceCube

News from IceCube. Marek Kowalski Physikalisches Institut University Bonn Calte ch , 15.5.2013. Cosmic Rays. Cosmic rays have been observed up to 10 20 eV ! What are the sources? How are particles accelerated?. High-energy neutrinos can be important messenger particles.

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News from IceCube

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  1. News from IceCube MarekKowalski PhysikalischesInstitutUniversity BonnCaltech, 15.5.2013

  2. Cosmic Rays • Cosmic rays have been observed up to 1020eV! • What are the sources? • How are particles accelerated? High-energy neutrinos can be important messenger particles. Spectrum of charged particles LHC

  3. Neutrino production in cosmic sources p   p  0 e  Inverse Compton (+Bremsstr.) Fermi shock acceleration of protons: dN/dE~E-2 radiation fields and matter protons/nuclei electrons/positrons

  4. Neutrino propagation Neutrino propagation Protonen AGN Neutrinos g - Radiation Neutrino oscillation length: l23 1011 (En/TeV)cm p + X+- + 0 + ...  n + m + ... Flavor ratio at the source ne : nm : nt 1 : 2 : 0 Flavor ratio at the Earth: ne : nm : nt 1 : 1 : 1

  5. The IceCube Detector Digital Optical Module

  6. The IceCube Detector Installation

  7. The IceCube Detector Installation

  8. Effective scattering coefficient l-1 [1/m] IceCube Coll, J. Geophys. Res. 111 (2006) D13203 Optical properties of the detection medium

  9. The IceCube Detector IceCubewith86 strings IC79

  10. Neutrino signatures signature of Muon-tracks + good pointing (~1 degree) + large event rates due long muon range 6 PeV 10 TeV

  11. Neutrino signatures signature of signature of e • Particle shower (cascade) • +ne,nt ,(nm ) • + good energy resolution (~0.2 in logE) + little background  +N+... ± (300 m track!) +hadrons 375 TeV Multi-PeV

  12. proton „atmospheric“ muon „atmospheric“ Neutrino proton

  13. Observation of moon shadow IceCube Pointing 0.5o Cosmic-ray protons Cosmic rays blocked by the moon lead to a point-like deficit in down-going muons

  14. Astrophysical neutrino search Point source

  15. Point Source Search: IceCube 40 & 59 Search for point sources Northern sky & Southern sky

  16. Point Source Search: IceCube 40 & 59 Search for point sources Northern sky & Southern sky Hottest spot: Post-trial p-value: ~67% No evidence for neutrino sources, yet

  17. Astrophysical neutrino search Sum of all point sources = isotropic/diffuse flux

  18. Diffuse flux Atmospheric Neutrinos primary cosmicray airshower D π K μ μ e νe νe νμ Waxman & Bahcallbound on astrophysicalneutrinos νμ prompt atmo. ν conventional atmo. ν

  19. Search forneutrino-inducedcascades, i.e. νe&ντ IC40 results: Events >100 TeV • 3 eventsobserved • 0.35 expected2.4 σ 220 TeV

  20. Next: pushingthe high energyfrontier

  21. Search for UHE neutrinosin IceCube (IC86) Diffuse flux Simple searchforultra high energyneutrino eventsbycut on # photoelectrons (NPE) cos(zenith angle) cos(zenith angle) Ernie (1.1±0.4) PeV Bert (1.3±0.5) PeV 670 daysofIC86 submittedto PRL

  22. Search for UHE neutrinosin IceCube (IC86) Diffuse flux Ernie (1.14 ± 0.14) PeV Bert (1.04 ± 0.14) PeV 2.8 σexcessoverbackgroundofatmosphericmuonsandneutrinos

  23. Search for UHE neutrinosin IceCube (IC86) Diffuse flux Ernie (1.14 ± 0.14) PeV Bert (1.04 ± 0.14) PeV 2.8 σexcessoverbackgroundofatmosphericmuonsandneutrinos

  24. digital optical module 44 on string 20

  25. „High EnergyStarting Event“ search

  26. Vetoingatmosphericmuonsandneutrinos primary cosmicray airshower Downgoingeventwithout Airshowerastro. neutrino! D π K μ e νe νe νμ μ νμ

  27. EffectiveVolume/Area

  28. High EnergyStarting Event Search - Results Expectadbackground: 12.1 ±3.4

  29. Event Distribution in theDetector Preliminary

  30. EnergyvsDeclinationofContained Vertex Events inconsistentwithbackground @ 4.3σ (includingdirectionandenergy)

  31. EnergySpectrum Harder thanatm. Background; potenticalcut-off at ~2 PeV

  32. Whatareweobserving? • Increasing evidence for high-energy component beyond the atmospheric spectrum (now 4.3 σ) • Hard spectral component might have a cut-off • Neutrino flavor ratio consistent with 1:1:1 • Directions consistent with being diffuse flux • Publication and more data coming soon

  33. End

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