1. The IceCube Neutrino Observatory To Explore the EHE Universe Shigeru Yoshida The Chiba University The Baseline Performance

2. Let me acknowledge you first MC data production/debugging Juan Carlos, Keiichi, Mio, Paolo, Xianwu,…. Weighting/IC-9 analysis/Filtering Aya, Carsten, Dusan Offline software coordination David B. Atmospheric Muon modeling Francis, Gary, Tom G., … PMT saturation Chris, Kotoyo, Mina Many IceCubers !

3. Our Target GZK neutrino  e  e Beyond the Standard Model The standard scenario The standard scenario EHE cosmic-ray induced neutrinos The main energy range: E ~ 10 9-10 GeV  Exotic scenarios Top-Down neutrinos decays/interaction of massive particles (topological defects, SUSY, micro black hole, …) The main energy range: E ~ 10 11-15 GeV  EHE-CR X

4. Baseline search policy As Simple and Robust as possible because…. Must be clear demonstration to everybody outside the IceCube collaboration Need not to rely on detailed (uncertain) detector response (ex. ice propagation)

5. main signal GZK neutrino induced leptons background Atmospheric muon Background in EHE search Fluxes at the IceCube depth IC9 Data log10(in-ice muon energy [GeV]) log10(Npe) IC9 data region See Aya’s talk this afternoon

6. Energy - Npe     IC9 Full IceCube log10(in-ice muon energy [GeV]) log10(Npe) log10(in-ice tau energy [GeV])

7. Energy – Npe (BG – Signal)  e +  +  log10(Npe) log10(in-ice energy [GeV])

8. Npe – Zenith Angle  e +  +  log10(Npe) cos(first-guessed  )

9. Npe & Zenith Angle cos(first-guessed  ) log10(Npe)

10. Npe & Zenith Angle cos(first-guessed  ) log10(Npe)

11. Npe – Zenith Cut log10(Npe) cos(first-guessed  )

12. Npe & Zenith Angle cos(first-guessed  ) log10(Npe)

13. Npe & Zenith Angle cos(first-guessed  ) log10(Npe)

14. Effective Area

15. Baseline Event Rate GZK Yoshida-Teshima (m, Zmax) = (4,4) 0.70 GZK Klashev et al (m, Zmax) = (3,5) 1.10 Top Down Sigl et al SUSY 6.73 Atmospheric Muon (Elbert-IceCube9 extension) ~0.000187 Number of Events/365 day

16. Model-independent Sensitivity 90 % C.L. based on dN/dLogE @ 10 9 GeV

17. Muon Bundle? Survived BG events IC9 data suggested… For 1000 x rate ~ 1/year 50 times MORE Energy must be channeled into  ! !?

18. Possible improvements Toward more GZK event rate…. Better zenith angle reconstruction  x 1.1 With IceTop veto  x 1.3 cos(first-guessed  ) log10(Npe)

19. Possible improvements Toward “background-free” event detection….   DOMs without photon signal Distance [m] log 10 (Number of Photoelectron) Distance [m] From the Mio’s talk in the cascade session And her TAUP2007 poster

20. Conclusion GZK physics is doable with IceCube events

21. Robustness against the ice model (Bulk Ice) (Layered Ice)