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Searches for the Highest Energy Neutrino with IceCube. Aya Ishihara ( JSPS Research Fellow) Chiba University. COSMO/CosPA 2010 September 27, 2010. IceCube at South Pole. 1km 3 volume 80 +6 Holes 60 Optical Modules 17 m between m odules 125 m between holes. construction - PowerPoint PPT Presentation
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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
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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.)
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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)
COSMO/CosPA 2010COSMO/CosPA 2010
IceCube’s Wide View in Energy IceCube’s Wide View in Energy
By IceCube 2008-2009
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
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
COSMO/CosPA 2010COSMO/CosPA 2010
Agreement between Data/MC with full Agreement between Data/MC with full data sampledata sample
shallow
COSMO/CosPA 2010COSMO/CosPA 2010