SUSY06, June 14th, 20061 The IceCube Neutrino Telescope and its capability to search for EHE neutrinos Shigeru Yoshida The Chiba University (for the IceCube

SUSY06, June 14th, 2006SUSY06, June 14th, 2006 11

The IceCube Neutrino TelescopeThe IceCube Neutrino Telescopeand its capability to search forand its capability to search for

EHE neutrinosEHE neutrinosShigeru Yoshida

The Chiba University(for the IceCube collaboration)


The IceCube DetectorThe IceCube Detector

IceTop

~1 km

60 DOMs

2450m

1450m

IceTop

AMANDA

Digital Optical Module

• 400ns/6.4s time range

• 400 photoelectron/15ns

• measure individual photon arrival time

• 1~2ns time resolution


The IceCube collaborationThe IceCube collaboration

Antarctica


This year’s strings deep in ice This year’s strings deep in ice

AMANDA

9 strings and 16 ice-top stations have been deployed

Toward 70 strings - km3 detector

and more and more

~125m


Where Are EHE Neutrinos From?Where Are EHE Neutrinos From?

seXp K '7.2 GZK neutrinoGZK neutrino

e

e

Beyond the Standard ModelBeyond the Standard Model

The standard scenarioThe standard scenarioEHE cosmic-ray induced neutrinos

The main energy range: E ~ 109-10 GeV

Exotic scenarios

Top-Down neutrinosdecays/interaction of massive particles

(topological defects, SUSY, micro black hole, …)

The main energy range: E ~ 1011-15 GeV

EHE-CR

XX


EHE Events in the EarthEHE Events in the Earth

General neutrino event ID through the Earth up-going events

Earth is opaque for EHE neutrino

EHE neutrino induced events are coming from above as down-going

North

North

down-going

up-goingup-going < 1PeV > PeV

EHE

CR

EHE neutrino mean free path ~ 100 km << REarth

cc ~ 10-6~-4 mb


EHE Spectrum in IceEHE Spectrum in Ice

EGZK >> EAtm

GZK neutrino induced lepton and GZK neutrino induced lepton and atmospheric muon fluxes at the IceCube atmospheric muon fluxes at the IceCube

depthdepth

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


EHE Track in Detection VolumeEHE Track in Detection Volume

and and tracks lose there energy by tracks lose there energy by ‘radiative processes’‘radiative processes’

e+e-

pair-creation

bremsstrahlung

photo-nuclear

e+e-Edx

dE


Muon EventsMuon Events

9 EeV100 TeV

~17m


NPENPENumber of photo-electrons (NPE) … an integrated Number of photo-electrons (NPE) … an integrated waveform charge divided by single pe chargewaveform charge divided by single pe charge

Correlated withCorrelated withnumber of photons at sourcenumber of photons at source

in-ice particle energyin-ice particle energy


Contained or UncontainedContained or UncontainedEvents with the same energy

containedcontainedHigh npe: 10High npe: 1077 npe npe

uncontaineduncontainedLow npe: 1000 npeLow npe: 1000 npe

~ 30PeV


NPE Energy DistributionNPE Energy Distribution

E-1 fluxes

containedcontained

GZK Atmospheric GZK

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

Log

Np

e


NPE DistributionNPE Distribution

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

GZKGZK

Atmospheric


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


Preliminary Event SelectionPreliminary Event Selection

GZK Atmospheric GZK


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


GZK 0.13 events/yearAtmospheric 0.009 events/year

Event Rate: 9 strings and moreEvent Rate: 9 strings and more

string number

s920406080

The same cut for all string

numbers

GZKGZK

Atmospheric

9 S 80 S

9 string event rate

event rate (integrated)

GZK GZKAtmospheric

107 109 [GeV] 107 109 [GeV]

Rat

e [/

year

]

IceCube Preliminary


Effective Area for Effective Area for EHE signalsEHE signals with completed detectorwith completed detector

80 S

up-goinghorizontal

down-going

Twice larger charged lepton effective area than physical area for >1010 GeV

IceCube Preliminary


How Many Photons Are We How Many Photons Are We Seeing?Seeing?

Standard-Candlee - Photon source with - Photon source with known absolute known absolute intensity for each intensity for each pulsepulse

Golden-DOMs

- Absolute calibrated - Absolute calibrated DOMs near SCDOMs near SC

SC ons40GD

ons39

The in-ice energy calibration


The Absolute Chain: The Absolute Chain: Standard Candle Standard Candle Golden DOMGolden DOM

SCSC Known position Known position

and shape and shape Nitrogen (337 Nitrogen (337

nm) pulsed lasernm) pulsed laser Cone reflected Cone reflected

resembles resembles cascadescascades

Pointing-upPointing-up 1-10 PeV n1-10 PeV nee

cascade equiv.cascade equiv.

GD GD Absolute calibrated Absolute calibrated

with nitrogen 337 with nitrogen 337 nm lasernm laser

distance from SC distance from SC

132, 233, 248 m132, 233, 248 m relative angle to SC relative angle to SC

-11.9, 56.2, 58.4 -11.9, 56.2, 58.4 degdeg

130.04m

GD

SC


IceTop: Background IceTop: Background TaggingTagging

Major background is atmospheric Major background is atmospheric (bundled) muons of which in-ice nature (bundled) muons of which in-ice nature still not well known at this energy regimestill not well known at this energy regime

Tagging on the surface muons with Tagging on the surface muons with surface array for an additional informationsurface array for an additional information

EHE CR

A real event example(E~ 100TeV-10 PeV)


Conclusion -outlook-Conclusion -outlook-

The largest multi-string neutrino detector!The largest multi-string neutrino detector! IceCube is capable of EHE neutrino search with IceCube is capable of EHE neutrino search with

this year’s configuration and the capability is this year’s configuration and the capability is growing with its string arraygrowing with its string array

The first-level EHE event selection from BG can be The first-level EHE event selection from BG can be achieved using measured number of photo-achieved using measured number of photo-electronselectrons

Energy and geometry reconstruction incl. that of Energy and geometry reconstruction incl. that of uncontained events, technique using photon uncontained events, technique using photon propagation information in ice (waveforms) to propagation information in ice (waveforms) to comecome

Power of subsystems – calibration and background Power of subsystems – calibration and background rejectionrejection


Backup slidesBackup slides


EExtremely xtremely HHigh igh EEnergy nergy Neutrino TargetsNeutrino Targets

benchmarking model

GZK: S. Yoshida et. al. (1997) ApJ 479:547 (m=4, Zmax=4)TD: Sigl et. al.(1999), UHE2K: S.Yoshida et al.(1998), AGN Jet: K.Mannheim (1995)


MC SetupMC Setup

Benchmarking modelsBenchmarking modelsGZK muon and tau signalsGZK muon and tau signalsAtmospheric muon background (no Atmospheric muon background (no

bundle)bundle)muon and tau propagation starts from muon and tau propagation starts from

outside of detection outside of detection volume volume Event energy range Event energy range 105 < < E < 1011 GeVGeV E-1 and E-2 fluxes (~10k events each)


Effective Area: toward 80 Effective Area: toward 80 stringsstrings

:1011 GeV

9 S 80 S

in-ice 108 GeV

up-goinghorizontaldown-going

in-ice 108 GeV

:1011 GeV

Effective area enlarged with string numbers for every

event direction

108 GeV 1011 GeV

0.2~0.4 km2 0.65~0.9 km2

0.02~0.15 km2

0.45~0.78 km2

9 string effective area

IceCube Preliminary

Documents

SUSY06, June 14th, 20061 The IceCube Neutrino Telescope and its capability to search for EHE neutrinos Shigeru Yoshida The Chiba University (for the IceCube