2006/6/212006/6/21 11

IceCube EHE analysisIceCube EHE analysisOur findings and roadmap to analysisOur findings and roadmap to analysis

Shigeru YoshidaShigeru YoshidaFor the EHE working groupFor the EHE working group

2006/6/212006/6/21 22

DOM response to high NPEsDOM response to high NPEs

Log

10 (A

TW

D e

stim

ated

NP

E)

Estimated number of photo-electrons per DOM

ATWD or FADC?

Log

10 (F

AD

C b

ased

est

imat

ed N

PE

)

Log10 (ATWD based estimated NPE)

L

og10

(FA

DC

est

imat

ed N

PE

)

Log10 (MC Truth NPE) Log10 (MC Truth NPE)

Red: DOM of which ATWD charge is largerBlue: DOM FADC is larger

Npe saturation Npe saturation

“EHE specific” response!

2006/6/212006/6/21 33

NPE Energy DistributionNPE Energy Distribution

E-1 fluxes

containedcontained

GZK Atmospheric GZK

107 1010 [GeV] 107 1010 [GeV] 107 1010 [GeV]

Log

Np

e

2006/6/212006/6/21 44

NPE DistributionNPE Distribution

Distribution Distribution difference difference between the between the signals and signals and background! background!

GZKGZK

Atmospheric

2006/6/212006/6/21 55

Zenith Angle DistributionZenith Angle Distribution

Signals peak at Signals peak at horizontal horizontal directiondirection

Background Background distribute over distribute over down-going down-going regionregion

GZKGZK

Atmospheric

up down

2006/6/212006/6/21 66

Preliminary Event SelectionPreliminary Event Selection

GZK Atmospheric GZK

2006/6/212006/6/21 77

Event Rate with completed Event Rate with completed detectordetector

GZK 0.35 events/year

GZK 0.31 events/year

Atmospheric 0.033 events/year

GZKGZK

Atmospheric

GZKGZK

Atmospheric

GZK: S. Yoshida et. al. (1997) ApJ 479:547 (m=4, Zmax=4)

IceCube Preliminary

2006/6/212006/6/21 88

GZK Signal

Roadmap to analysisRoadmap to analysisAtmospheric BG

Standard CandleIn-Ice data9-strings unblinded data

Energy

Npe

Log(

Npe

)

NDOM

Cos(

zeni

th)

Log(Npe)

Cos(

zeni

th)

Log(Npe)

IceSim IceSim

))cos(,(

Ef

dE

dN

Tune

Energy

Eff.

Area

Extrapolate to signal domain

Empirical Model

2006/6/212006/6/21 99

9-strings working data9-strings working data

Npe>104Npe>104

NDOM >80NDOM >80

2006/6/212006/6/21 1010

9-strings working data9-strings working data

Npe>104

~ 500Events/yr

Needs statistics ! to understandIntensity(Npe, zenith), DOM response in EHE regime

2006/6/212006/6/21 1111

Muon bundlesMuon bundles1PeV bundle of 1000 muons (1TeV/muon)• Npe only would not be able to resolve tracks

• We do not know cosmic ray intensity in EHE

• We do not know cosmic ray composition in EHE

• Corsika has not reconstructed AGASA/Auger data9-strings “EHE” REAL DATA

Log(Npe)

Cos(

zeni

th)

Build Empirical Model

IceSim

))cos(,(

ENf

dE

dNm

2006/6/212006/6/21 1212

Why no problem in unblinding?Why no problem in unblinding?Signal stats in the following data is by far large.Almost independent confirmation!!

Expect

ed E

vent

Rate

[/y

ear]

This Year

Y2007

Y2008

x 2

x 1.5

2006/6/212006/6/21 1313

Why no problem in unblinding?Why no problem in unblinding?Background and Signals are so different inEnergies (Npe’s) and cos(1st-guess zenith)

This cut? This cut?Or this cut? Or this cut?

2006/6/212006/6/21 1414

Sensitivity/Bound Sensitivity/Bound Quasi-differential Quasi-differential methodmethod

S. Yoshida et. al. (2004)Phys. Rev. D 69 103004

Bound: energy dependent!!

][/3.2)( )( nobservatioevent TEdLogE

dJN

This is MODEL independent!!

2006/6/212006/6/21 1515

Beyond Npe and First-guessBeyond Npe and First-guessEnergy/Geometry recoEnergy/Geometry reco

e

NnNnP

Nn

k

i i

i

ii

i

!!!}){|}({

1

Waveform-based likelihood(proposed by Gary)

Utilize unscattered photon hits? (suggested by Lutz in 2004)

Including morenon-contained events

Log(Npe) Log(Energy)

cos(

1st g

uess

)

cos

(reco

)

2006/6/212006/6/21 1616

Our Bread and ButterOur Bread and Butter

Photo by David Boersma

Introducing “Yoshida” bottle(s)Your WG wins them if you publish your results earlier than anybody else!