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Searches for the Highest Energy Neutrino with IceCube

Searches for the Highest Energy Neutrino with IceCube. Aya Ishihara ( JSPS Research Fellow) Chiba University. COSMO/CosPA 2010 September 27, 2010. IceCube at South Pole. 1km 3 volume 80 +6 Holes 60 Optical Modules 17 m between m odules 125 m between holes. construction

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Searches for the Highest Energy Neutrino with IceCube

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  1. Searches for the Highest Energy Neutrino with IceCube Aya Ishihara (JSPS Research Fellow) Chiba University COSMO/CosPA 2010 September 27, 2010

  2. IceCube at South Pole • 1km3 volume • 80+6Holes • 60 Optical Modules • 17 m between modules • 125 m between holes construction >90% finished 7 more holes to complete this winter

  3. Detection Principle Cerenkov light cone Detector muon or tau by track/cascade electron neutrino via cascade neutrino

  4. t t ng Neutrino In the Earth… CR • Generallyneutrino identified as “through the Earth” up-going events • Earth is opaque for EHE neutrino • EHE neutrino induced events are coming from above and near horizontal direction down-going m EHE n m m,t m,t m North ng m EHE neutrino mean free path ln ~ 100 km << REarth sccnN ~ 10-6~-4 mb up-going nm nm < 1PeV > PeV

  5. nm p >1EeV nm + ne m+ 0 e+ 2.725 K 411 photons / cm3 Diffusive Highest Energy Neutrinos EHE cosmic-ray and CMB induce neutrinos • The main energy range: En ~ 109-10 GeV Gorham

  6. 9 EeV Energy Estimation mandttracks loose their energy by radiative processes 100 TeV pair-creation e+e- m p photo-nuclear e+e- m g bremsstrahlung

  7. Extremely High Energy Neutrino Signals in IceCube Soft atmospheric m BG ⇒ Hard signal spectra GZK signal Vertical atmospheric m BG 　⇒ Near horizontal signal m Atmospheric background (CORSIKA)

  8. Basic Information • Half IceCube data (2400 optical modules 0.5Km3) • Data from 2008/4/17~2009/5/20 • Effectivelive time370days • Background MC CORSIKA SIBYLL iron data • Systematic study with proton, QGSJET-II • Blind analysis • MC and partial data samples are compared in detail and final selection criteria is determined without looking at full sample

  9. Data MC comparisons • 10% of sample is used for MC applicability • Energy loss ~ brightness = NPE • Signal is harder than atmospheric • muon background

  10. Full Event Distributions on the planes of the final variables shallow BG shallow SIGNAL log (NPE BTW) deep SIGNAL deep BG BG 0.11 per full livetime Cuts are decided without looking at data sample

  11. Null Result…

  12. Error Budget Background 17.0% (stat.) +60.4 % -96.0%(sys.) Signal (GZK1) 0.8 %(stat.) +14.0 -11.6 %(sys.)

  13. Upperlimit and Sensitivity 333.4 days upperlimit with only the half detector E-2 flux upperlimit: 106.3 < Energy/GeV < 109.8 E2dN/dE = 4.23 x 10-8 [GeV cm2 s-1 sr -1] Preliminary IceCube Upperlimit ~2009/5 Full scale sensitivity (MC)

  14. Expected EHE signal events *Yoshida et al The ApJ 479 547-559 (1997), **Kalahsev et al , Phys.Rev.Rev. D 66 063004 (2002), ***Engel et al, Phys. Rev. D, 64(9):093010, 2001, ****Ahlers et al, Astropart. Phys. 34 106-115 (2010)#Yoshida et al, Phys.Rev.Lett. 81 5505 (1998),##Sigl et al , Phys.Rev.Rev. D 59 043504 (1998), ^Razzaque et al(2003)

  15. IceCube’s Wide View in Energy By IceCube 2008-2009

  16. 0.95 < cos theta < 1.0 0.75 < cos theta < 0.8 shallow data shallow BG 0.35 < cos theta < 0.4 log (NPE BTW) deep SIGNAL deep data Data MC comparison with the full sample MC data deep BG

  17. >10 PeV muon The highest NPE event in half IC data

  18. Summary • IceCube is sensitive to neutrino with energies from TeV upto 100EeV • Search 3 flavor neutrinos with energy exceeding PeV • IceCube from 2008/04 to 2009/05 , the half IceCube configuration (~0.5km3) • Null results has set the world’s best 3 flavor n upperlimit to date from 106 to 1010 GeV • Can constrain to hadronic component of the extragaractic Universe

  19. gVHE p0 p g gExtragaractic-diffuse gVHE g g e e+ Diffusive High Energy Lights Fermi LAT What’s making the extragaractic Universe so bright? unknown IR/UV background

  20. The IceCube Collaboration Germany: DESY-Zeuthen Universität Mainz Universität Dortmund Universität Wuppertal Humboldt Universität MPI Heidelberg RWTH Aachen Sweden: Uppsala Universitet Stockholm Universitet USA: Bartol Research Institute, Delaware University of California, Berkeley University of California, Irvine Pennsylvania State University Clark-Atlanta University Ohio State University Georgia Tech University of Maryland University of Alabama, Tuscaloosa University of Wisconsin-Madison University of Wisconsin-River Falls Lawrence Berkeley National Lab. University of Kansas Southern University and A&M College, Baton Rouge University of Alaska, Anchorage UK: Oxford University Belgium: Université Libre de Bruxelles Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut Japan: Chiba University Switzerland: EPFL New Zealand: University of Canterbury 33 institutions, ~250 members http://icecube.wisc.edu

  21. Different Windows to the high energy neutrinos Optimized for >106GeV neutrinos (This Talk) Optimized for <106GeV neutrinos

  22. Signal Event Distributions IC40 x Exposure/E E2dN/dE =

  23. Agreement between Data/MC with full data sample shallow

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