COSMO/CosPA 2010 Searches for the Highest Energy Neutrino with IceCube Searches for the Highest...

COSMO/CosPA 2010COSMO/CosPA 2010

Searches for the Highest Searches for the Highest Energy Neutrino with IceCubeEnergy Neutrino with IceCube

Aya IshiharaAya Ishihara((JSPS Research Fellow) Fellow)

Chiba UniversityChiba UniversityCOSMO/CosPA 2010September 27, 2010

IceCube at South Pole

1km3 volume 80+6 Holes 60 Optical Modules 17 m between modules 125 m between holes

construction>90% finished

7 more holesto completethis winter

COSMO/CosPA 2010COSMO/CosPA 2010 neutrino

muon or tau by track/cascade

electron neutrino via cascade

Cerenkov

light cone Detector

Detection Principle

Neutrino In the Earth…Neutrino In the Earth…

GeneralGenerallyly neutrino neutrino identified identified asas “ “through the Earth” through the Earth” up-up-going eventsgoing events

Earth is opaque for EHE Earth is opaque for EHE neutrinoneutrino

EHE neutrino induced events EHE neutrino induced events are coming from above and are coming from above and near horizontal directionnear horizontal direction

North

North

down-going

up-goingup-going < 1PeV > PeV

EHE

CR

EHE neutrino mean free path ~ 100 km << REarth

cc ~ 10-6~-4 mb


seXp K '7.2

The main energy range: E ~ 109-10 GeV

2.725 K

411 photons / cm3

EHE cosmic-ray and CMB induce neutrinos

+

+

e+

e

p >1EeV

Diffusive Highest Energy NeutrinosDiffusive Highest Energy Neutrinos

Gorham

COSMO/CosPA 2010

Energy Estimation

e+e-

pair-creation

bremsstrahlung

photo-nuclear

e+e-

100 TeV

and tracks loose their energy by

radiative processes.const

dx

dE

9 EeVE

dx

dE


EExtremely xtremely HHigh igh EEnergy nergy Neutrino Signals in IceCubeNeutrino Signals in IceCube

Vertical atmospheric BG

　⇒ Near horizontal signal

GZK signal

Atmospheric background (CORSIKA)

Soft atmospheric m BG

⇒ Hard signal spectra

Basic InformationBasic Information

Half IceCube data (2400 optical modules 0.5Km3) Data from 2008/4/17~2009/5/20Data from 2008/4/17~2009/5/20 EffectiveEffective 　　 live timelive time 　　 370days370days

Background MC CORSIKA SIBYLL iron data Background MC CORSIKA SIBYLL iron data Systematic study with proton, QGSJET-IISystematic study with proton, QGSJET-II

Blind analysisBlind analysis MC and partial data samples are compared in detail and MC and partial data samples are compared in detail and

final selection criteria is determined without looking at final selection criteria is determined without looking at full samplefull sample


Data MC comparisonsData MC comparisons 10% of sample is used for MC applicability10% of sample is used for MC applicability

• Energy loss brightness = NPE

• Signal is harder than atmospheric muon background


Full Event Distributions on the planes of Full Event Distributions on the planes of the final variablesthe final variables

log (NPE BTW)

shallow SIGNAL shallow BG

deep SIGNAL deep BG

Cuts are decided without looking at data sample

BG 0.11 per

full livetime


Null Result…Null Result…

Error BudgetError Budget

Err. Sources Signal (GZK model)

statistical error 0.8 %

NPE measurementin-situ calib. -18.5% in-lab calib. 10.1%)

+3.89 / -7.22 %

neutrino cross section

9.0 %

photo-nuclear interaction

+10.0 %

LPM effect 1.0 %

Err. Sources Background

statistical error 17.0 %

Composition -83.86%

interaction model +36.1%

Coincident event (cos theta>0.2)

+29.4%

Coincident event (cos theta<0.2)

+10.5%

ice property +30.2% / - 22.2%

NPE measurements

+37.1% / -46.7%

Signal (GZK1)0.8 %(stat.)

+14.0 -11.6 %(sys.)

Background17.0% (stat.)

+60.4 % -96.0%(sys.)

http://www.ppl.phys.chiba-u.jp/research/IceCube/pmt/GoldenPMT/error_summary/

http://www.ppl.phys.chiba-u.jp/research/IceCube/pmt/GoldenPMT/error_summary/


Upperlimit and SensitivityUpperlimit and SensitivityE-2 flux upperlimit: 106.3 < Energy/GeV < 109.8 E2dN/dE = 4.23 x 10-8 [GeV cm2 s-1 sr -1]

333.4 days upperlimit with only the half detector

IceCube Upperlimit ~2009/5

Full scale sensitivity(MC)

Preliminary


Expected EHE signal eventsExpected EHE signal eventsModels

The half IceCube# of events

The full IceCube# of events(3 years)

　GZK1 (Yoshida et al) * 0.57 3.13.1

　 GZK2 Strong Evol. (Sigl) ** 0.91 (C.L 53.4%) 4.9

　GZK3 (ESS with WL=0.0) ***

0.29 1.51.5

　GZK4 (ESS with WL=0.7) ***

0.47 2.52.5

　 GZK5 (Ahlers max) **** 0.89 (C.L 52.8%) 4.8

　 GZK6 (Ahlers best fit) **** 0.43 2.32.3

　 Z-Burst # 1.03 (C.L 55.7%) 5.1

　 Top Down(SUSY) ## 5.68 (C.L 99.6%) 31.6

　 Top Down(QCD) ### 1.19 (C.L 66.4%) 6.3

　 W&B(evol) ^ 3.7 24.524.5

　 W&B(no evol) ^ 1.1 5.55.5*Yoshida et al The ApJ 479 547-559 (1997), **Kalahsev et al , Phys.Rev.Rev. D 66 063004 (2002), ***Engel et al, Phys. Rev. D, 64(9):093010, 2001, ****Ahlers et al, Astropart. Phys. 34 106-115 (2010) #Yoshida et al, Phys.Rev.Lett. 81 5505 (1998),##Sigl et al , Phys.Rev.Rev. D 59 043504 (1998), ^Razzaque et al(2003)


IceCube’s Wide View in Energy IceCube’s Wide View in Energy

By IceCube 2008-2009


Data MC comparison Data MC comparison with the full samplewith the full sample

deep BG

log (NPE BTW)

deep SIGNAL

shallow data

deep data

shallow BG

0.75 < cos theta < 0.8

0.95 < cos theta < 1.0

0.35 < cos theta < 0.4

MCdata


The highest NPE event in half IC dataThe highest NPE event in half IC data

>10 PeV muon

SummarySummary

IceCube is sensitive to neutrino with energies from TeIceCube is sensitive to neutrino with energies from TeV upto 100EeV V upto 100EeV

Search 3 flavor neutrinos with energy exceeding PeV Search 3 flavor neutrinos with energy exceeding PeV IceCube from 2008/04 to 2009/05 , the half IceCube cIceCube from 2008/04 to 2009/05 , the half IceCube c

onfiguration (~0.5kmonfiguration (~0.5km33)) Null results has set the world’s best 3 flavor Null results has set the world’s best 3 flavor upperli upperli

mit to date from 10mit to date from 1066 to 10 to 101010 GeV GeV Can constrain to hadronic component of the extragarCan constrain to hadronic component of the extragar

actic Universeactic Universe


Diffusive High Energy LightsDiffusive High Energy Lights

ee+

Extragaractic-diffuseVHE

p VHE

What’s making the extragaractic Universe so bright?

unknownIR/UV background

Fermi LAT

COSMO/CosPA 2010

USA: Bartol Research Institute, Delaware University of California, Berkeley University of California, Irvine Pennsylvania State University Clark-Atlanta University Ohio State University Georgia Tech University of Maryland University of Alabama, Tuscaloosa University of Wisconsin-Madison University of Wisconsin-River Falls Lawrence Berkeley National Lab. University of Kansas Southern University and A&M

College, Baton Rouge University of Alaska, Anchorage

Sweden: Uppsala Universitet Stockholm Universitet

UK: Oxford University

Belgium: Université Libre de Bruxelles Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut

Germany: DESY-Zeuthen Universität Mainz Universität Dortmund Universität Wuppertal Humboldt Universität MPI Heidelberg RWTH Aachen

Japan: Chiba University

New Zealand: University of Canterbury

33 institutions, ~250 members http://icecube.wisc.edu

Switzerland: EPFL

The IceCube Collaboration


Different Windows to the Different Windows to the high energy neutrinoshigh energy neutrinos

Optimized for <106GeV neutrinosOptimized for >106GeV neutrinos

(This Talk)

Signal Event DistributionsSignal Event Distributions

x

=

E2dN/dE Exposure/E

IC40


Agreement between Data/MC with full Agreement between Data/MC with full data sampledata sample

shallow

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