The IceCube Neutrino ObservatoryThe IceCube Neutrino ObservatoryTo Explore the EHE UniverseTo Explore the EHE Universe

Shigeru YoshidaThe Chiba University

The Baseline Performance

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 !

Baseline search policy

As Simple and Robust as possiblebecause….

• Must be clear demonstration to everybody outside the IceCube collaboration• Need not to rely on detailed (uncertain) detector response (ex. ice propagation)

main signalGZK neutrino induced leptonsGZK neutrino induced leptons

background Atmospheric muonAtmospheric muon

Background in EHE search

Fluxes at the IceCube depth

IC9 Data

log10(in-ice muon energy [GeV])

log

10(N

pe

)

IC9 data regionSee Aya’s talk this afternoon

Energy - Npe

IC9

Full IceCube

log10(in-ice muon energy [GeV])

log

10(N

pe

)

log10(in-ice tau energy [GeV])

Energy – Npe (BG – Signal)

e + +

log

10(N

pe

)

log

10(N

pe

)

log10(in-ice energy [GeV]) log10(in-ice energy [GeV])

Npe – Zenith Angle

e + +

log10(Npe) log10(Npe)

cos(first-guessed )

Npe & Zenith Angle

cos(first-guessed )log10(Npe)

Npe & Zenith Angle

cos(first-guessed )log10(Npe)

Npe – Zenith Cut

log10(Npe) log10(Npe)

cos(first-guessed ) cos(first-guessed )

Npe & Zenith Angle

cos(first-guessed )log10(Npe)

Npe & Zenith Angle

cos(first-guessed )log10(Npe)

Effective Area

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

Model-independent Sensitivity90 % C.L. based on dN/dLogE

srsecGeV/cm10x4E 282 @ 109 GeV

Muon Bundle?Survived BG events

IC9 data suggested…

GeV103E 10CR

For 1000 x rate ~ 1/year

GeV106E 8CR

50 times MORE Energy must be channeled into !

%20E

E

CR

TeV

!?

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)

Possible improvementsToward “background-free” event detection….

DOMs without photon signal

Distance [m]

log 1

0(N

umbe

r of

Ph

oto

elec

tron

)

Distance [m]

From the Mio’s talkin the cascade sessionAnd her TAUP2007 poster

ConclusionGZK physics is doable with IceCube

events

Robustness against the ice model

(Bulk Ice)

(L

ayer

ed I

ce)