The IceCube Neutrino Telescope and its capability to search for EHE neutrinos

1. The IceCube Neutrino Telescopeand its capability to search for EHE neutrinos Shigeru Yoshida The Chiba University (for the IceCube collaboration)

2. ~1 km Digital Optical Module IceTop IceTop AMANDA 1450m 60 DOMs • 400ns/6.4ms time range • 400 photoelectron/15ns • measure individual photon arrival time • 1~2ns time resolution 2450m The IceCube Detector

3. The IceCube collaboration Antarctica

4. and more This year’s strings deep in ice Toward 70 strings - km3 detector 9 strings and 16 ice-top stations have been deployed ~125m AMANDA

5. Where Are EHE Neutrinos From? GZK neutrino nm • The standard scenario m EHE-CR p • EHE cosmic-ray • induced neutrinos • The main energy range: En ~ 109-10 GeV nm ne e Beyond the Standard Model X • Exotic scenarios • Top-Down neutrinos • decays/interaction of massive particles • (topological defects, SUSY, micro black hole, …) • The main energy range: En ~ 1011-15 GeV

6. t t ng EHE Events in the Earth CR • General neutrino event ID a through the Earth up-going events • Earth is opaque for EHE neutrino • EHE neutrino induced events are coming from above as down-going 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

7. EHE Spectrum in Ice GZK neutrino induced lepton and atmospheric muon fluxes at the IceCube depth EGZK >> EAtmm S. Yoshida et. al. (2004) Phys. Rev. D 69 103004

8. e+e- p e+e- photo-nuclear m g pair-creation bremsstrahlung EHE Track in Detection Volume m and t tracks lose there energy by ‘radiative processes’

9. Muon Events m ~17m m m 9 EeV 100 TeV m

10. NPE Number of photo-electrons (NPE) … an integrated waveform charge divided by single pe charge Correlated with number of photons at source a in-ice particle energy

11. Contained or Uncontained Events with the same energy ~ 30PeV contained High npe: 107 npe uncontained Low npe: 1000 npe

12. t m contained contained Log Npe GZK m Atmospheric m GZK t E-1 fluxes 107 1010 [GeV] 107 1010 [GeV] 107 1010 [GeV] NPE Energy Distribution

13. NPE Distribution Distribution difference between the signals and background! GZK m GZK t Atmospheric m

14. Zenith Angle Distribution • Signals peak at horizontal direction • Background distribute over down-going region down up GZK m GZK t Atmospheric m

15. Preliminary Event Selection Atmospheric m GZK m GZK t

16. Event Rate with completed detector GZK m GZK t Atmospheric m GZK m GZK t Atmospheric m IceCube Preliminary GZK m0.35events/year GZK t0.31 events/year Atmospheric m0.033events/year GZK: S. Yoshida et. al. (1997) ApJ 479:547 (m=4, Zmax=4)

17. Event Rate: 9 strings and more GZK m Atmospheric m GZK t string numbers 9 20 40 60 80 Rate [/year] 107 109[GeV] 107 109[GeV] event rate (integrated) IceCube Preliminary 9 string event rate GZK m GZK t Atmospheric m GZK m+t0.13 events/year Atmospheric m 0.009 events/year The same cut for all string numbers 80 S 9 S

18. Effective Area for EHE signals with completed detector Twice larger charged lepton effective area than physical area for >1010 GeV m t 80 S IceCube Preliminary 0.5 < q < 1.0 -0.25 < q < 0.25 -1.0 < q < -0.5 up-going horizontal down-going

19. How Many Photons Are We Seeing? The in-ice energy calibration Standard-Candle - Photon source with known absolute intensity for each pulse Golden-DOMs - Absolute calibrated DOMs near SC SC on s40 GD on s39

20. The Absolute Chain: Standard Candle 4 Golden DOM SC • Known position and shape • Nitrogen (337 nm) pulsed laser • Cone reflected resembles cascades • Pointing-up • 1-10 PeV ne cascade equiv. GD GD • Absolute calibrated with nitrogen 337 nm laser • distance from SC 132, 233, 248 m • relative angle to SC -11.9, 56.2, 58.4 deg SC 130.04m

21. CR m m IceTop: Background Tagging A real event example (E~ 100TeV-10 PeV) • Major background is atmospheric (bundled) muons of which in-ice nature still not well known at this energy regime • Tagging on the surface muons with surface array for an additional information EHE n m,t

22. Conclusion -outlook- • The largest multi-string neutrino detector! • IceCube is capable of EHE neutrino search with this year’s configuration and the capability is growing with its string array • The first-level EHE event selection from BG can be achieved using measured number of photo-electrons • Energy and geometry reconstruction incl. that of uncontained events, technique using photon propagation information in ice (waveforms) to come • Power of subsystems – calibration and background rejection

23. Backup slides

24. benchmarking model Extremely High Energy Neutrino Targets GZK: S. Yoshida et. al. (1997) ApJ 479:547 (m=4, Zmax=4) TD: Sigl et. al.(1999), nUHEn2K: S.Yoshida et al.(1998), AGN Jet: K.Mannheim (1995)

25. MC Setup • Benchmarking models • GZK muon and tau signals • Atmospheric muon background (no bundle) • muon and tau propagation starts from outside of detection volume • Event energy range 105 < E < 1011 GeV • E-1 and E-2 fluxes(~10k events each)

26. Effective Area: toward 80 strings in-ice m:108 GeV in-ice t: 108 GeV up-going horizontal down-going Effective area enlarged with string numbers for every event direction IceCube Preliminary m:1011 GeV t:1011 GeV 9 string effective area 80 S 9 S