1. Search for Extremely-high Energy Cosmic Neutrino with IceCube Chiba Univ. Mio Ono

2. Contents High energy neutrino astrophysics The IceCube neutrino observation 2007 analysis at extremely-high energies Future work

3. Contents High energy neutrino astrophysics The IceCube neutrino observation 2007 analysis at extremely-high energies Future work

4. Origin of Highest Energy Cosmic-ray Cosmic-rays > 10 20 eV observed by AGASA, HiRes, Auger. Their origin has been a long-standing puzzle in particle astrophysics. No accelerator can reach the energy region. 10 20 eV10 9 eV Flux [ / m 2 sr sec GeV] 1/ m 2 yr 1/ km 2 yr

5. gammas 10 15 eV neutrinos protons E>10 19 eV (<30 Mpc) protons E<10 19 eV Straight line propagation to point back to sources Small absorption in sources and during propagation Neutrinos as a Messenger of Deep Universe

6. 6 Neutrino Fluxes High energy neutrino astronomy: Small fluxes, Need large detectors, GRB AGN Solar SN C B, GZK

8. Extremely High Energy Neutrinos GZK neutrino EHE cosmic-ray induced neutrinos E ~ EeV(10 18 eV) Highest energy cosmic-ray

9. Contents High energy neutrino astrophysics The IceCube neutrino observation 2007 analysis at extremely-high energies Future work

10. Photon Detector Cherenkov light emitted from relativistic charged particles Concept of Neutrino detector  u d W  Weak Interaction with Nucleons

11. THE ICECUBE COLLABORATION about 30 institutions and 250 members http://icecube.wisc.edu USA: Bartol Research Institute, Delaware Pennsylvania State University UC Berkeley UC Irvine Clark-Atlanta University University of Maryland 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 Sweden: Uppsala Universitet Stockholm Universitet UK: Oxford University Belgium: Université Libre de Bruxelles Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut Germany: Universität Mainz DESY-Zeuthen Universität Dortmund Universität Wuppertal Humboldt Universität MPI Heidelberg RWTH Aachen Japan: Chiba university New Zealand: University of Canterbury Netherlands: Utrecht University Switzerland: EPFL,

12. IceCube Skiway Amundsen-Scott South Pole Station Drill Site IceCube at the South Pole Geographic South Pole

13. The IceCube Detector InIce 80 strings, each with 60 digital optical modules (DOM) 13 IceCube will detect neutrinos 10 11 eV to 10 18 eV. Digital Optical Module (DOM) PMT ~1 km 2006-2007: 13 Strings 2005-2006: 8 Strings 2004-2005 : 1 String 2007-2008: 18 Strings 2008-2009: 18+1 Strings Total of 58+1 Strings 1450 m 2450 m

14. Low Energy Extension: Deep Core

15. Contents High energy neutrino astrophysics The IceCube neutrino observation 2007 analysis at extremely-high energies Future work

16. Neutrino Events in IceCube Back grounds  Cosmic ray induced atmospheric muons down-going events North down-going up-going  < 1PeV  CR        Up-going Main Signal  Neutrino induced muons up-going events

17. Atmospheric Muon Background Main background is … Muon bundles in air shower produced by cosmic-rays 10 ～ 10,000 muons with GeV-TeV E EHE >> E Atm 

18. EHE Neutrino Events in IceCube Horizontal && Bright Main Signal  Neutrino-induced energetic muons E EHE >> E Atm   e+e-e+e-  ’s hadrons e+e-e+e- NPE = Number of Photoelectrons log(NPE) log(Muon Energy [GeV]) 明 暗

19. Empirical Background Model Muon Bundles Unknown Cosmic Ray Composition Possible Prompt Muon production from Charm slope Min. energy in a bundle E CR EBEB Fit with data

20. Empirical Background Model 2007 data - Data - Background MC (Empirical model) - Other BG model 1 - Other BG model 2 - Signal Fit in background dominated region ↓ Extrapolate the model to signal region ∝ Energy

21. Cut Optimization Preliminary

22. Sensitivity GZK neutrino events /242.1 days: 0.155 Backgrounds: 6.32x10 -4 By Keiichi Mase Preliminary

23. Contents High energy neutrino astrophysics The IceCube neutrino observation 2007 analysis at extremely-high energies Future work

24. Neutrino Starting Event  IceCube  Cosmic-ray Atmospheric    NPE Event Topology   DOM Hit Disappearance Starting Events Through-going Events EHE

25. Future Work Channel-wise analysis (Starting event analysis) Improve the ice model (LED/N 2 laser) Single/bundle muon effect

26. Thanks!

27. Back Up

28. Empirical Background Model By K. Mase By A. Ishihara, 30 th ICRC - Data - MC 2007 data

29. Sensitivity events / yr Total GZK 1.03 GZK strong evol1.62 TD10.56 Z-Burst1.70 Background3.26x10 -5 Full 5 year : E 2  10 9  ~ 3.16x10 -8 [GeV cm -2 sr -1 sec -1 ] IC9(2006) :    x10 -6 [GeV cm -2 sr -1 sec -1 ] By Aya Ishihara and Shigeru Yoshida