GZK ’s and their Detection with IceCube Interactions Interactions Results Results Implications for the IceCube Implications for the IceCube Summary Summary Shigeru Yoshida Dept. of Physics CHIBA Univ. CHIBA Univ. Chiba/Nagoya 2003

IceCube 1400 m 2400 m AMANDA South Pole IceTop Skiway 80 Strings 80 Strings 4800 PMT 4800 PMT Instrumented volume: 1 km3 (1 Gt) Instrumented volume: 1 km3 (1 Gt) IceCube is designed to detect neutrinos of all flavors at energies from 10 7 eV (SN) to eV IceCube is designed to detect neutrinos of all flavors at energies from 10 7 eV (SN) to eV

１．４ ｋｍ １ｋｍ Upward Ice Rock ν ± π γ ν + e － e １ｋｍ lepton ν

UHE (EeV or even higher) Neutrino Events Arriving Extremely Horizontally Needs Detailed Estimation Limited Solid Angle Window (  N A ) -1 ~ 600 (  / cm 2 ) -1 (  /2.6g cm -3 ) -1 [km] Involving the interactions generating electromagnetic/hadron cascades NN  X e + e - Chiba/Naoya 2003

e e      e/     Weak Incoming Products Weak Cascades Decay Weak Pair/decay Bremss Pair PhotoNucl. Decay Pair Pair Bremss Decay Weak Decay

Chiba/Nagoya 2003 Cross Sections and the Energy Loss Term CTEQ5 Parton Distribution for the evaluation

Chiba/Nagoya 2003

Muon(Neutrinos) from   Nadir Angle

e e      e/     Weak Incoming Products Weak Cascades Decay Weak Pair/decay Bremss Pair PhotoNucl. Decay Pair Pair Bremss Decay Weak Decay

Chiba/Nagoya 2003 Tau(Neutrinos) from    Suppression By  decay  pair contribution

GZK Neutrino Production K 411 photons / cm x cm 2 γ p n p π ＋ μ ＋ ν e ＋ ν γ E = eV E 0.8 x eV ~ Conventional Mechanism of EHE neutrinos!!

Chiba/Nagoya 2003

１．４ ｋｍ １ｋｍ Upward Ice Rock ν ± π γ ν + e － e １ｋｍ lepton ν

Chiba/Nagoya 2003 A factor of 2 enhancement Due to the heavier lepton production

Chiba/Nagoya 2003

e e      e/     Weak Incoming Products Weak Cascades Decay Weak Pair/decay Bremss Pair PhotoNucl. Decay Pair Pair Bremss Decay Weak Decay

Chiba/Nagoya 2003 Upward-going

Chiba/Nagoya 2003 Downward going!!

１．４ ｋｍ １ｋｍ Upward Ice Rock ν ± π γ ν + e － e １ｋｍ Downward ν γ γ + e － e lepton

Chiba/Nagoya 2003

Down-going events dominates… 1400 m 2800 m 11000m UpDown

１．４ ｋｍ １ｋｍ Downward Upward Ice Rock ν ν ± π γ γ γ ν + e － e １ｋｍ + e － e lepton EHE events!

Chiba/Nagoya 2003 Downward going!! 1 km 2 year

Energy Spectrum Diffuse Search Blue: after downgoing muon rejection Red: after cut on N hit to get ultimate sensitivity

Chiba/Nagoya 2003 Intensity of EHE  and  GZK model I  (E>10PeV) I  (E>10PeV) RATE [/yr/ km 2 ] m=4 Z max =4 Down Up m=7 Z max =5 Down Up [cm -2 sec -1 ]

Chiba/Nagoya 2003 GZK model dependence

Chiba/Nagoya 2003 Findings…  appeared in EeV-10EeV is our prime target on UHE detection. 1/100-1/500 of primary  intensity! Downward  and  make main contributions in EeV Energy Estimation would be a key for the bg reduction GZK is DETECTABLE by IceCube events/year

Chiba/Nagoya 2003 We still need… IceCube Sensitivity on energy-deposit basis -Simulation of the EHE energy deposit profile -Smart Background rejection