GZK GZK ’s and their Detection with Ic’s and their Detection with IceCubeeCube

InteractionsInteractionsResults Results Implications for the IceCubeImplications for the IceCubeSummarySummary

Shigeru YoshidaShigeru YoshidaDept. of PhysicsDept. of Physics

CHIBA Univ.CHIBA Univ.

Chiba/Nagoya 2003

IceCubeIceCube

1400 m

2400 m

AMANDA

South Pole

IceTop

Skiway

80 Strings80 Strings 4800 PMT 4800 PMT Instrumented volume: Instrumented volume:

1 km3 (1 Gt)1 km3 (1 Gt) IceCube is designed to IceCube is designed to

detect neutrinos of all fldetect neutrinos of all flavors at energies from avors at energies from 101077 eV (SN) to 10 eV (SN) to 102020 eV eV

１．４ｋｍ

１ｋｍ

Upward

Ice

Rock ν

±πγ

ν

+e －e１ｋｍ lepton

ν

UHE (EeV or even higher) Neutrino EventsArriving Extremely Horizontally

• Needs Detailed Estimation• Limited Solid Angle Window

(NA)-1 ~ 600 (/10-32cm2) -1(/2.6g cm-3) -1 [km]

Involving the interactions generating electromagnetic/hadron cascades

N X e+e-

Chiba/Naoya 2003

e

e

e/

e/

Weak

Weak

Weak

Inco

min

gProducts

Weak

Weak

Weak

Cascades

Cascades

Decay DecayWeak

Pair/decayBremss Pair Pair PhotoNucl.

PhotoNucl.DecayPair Pair

PairBremssDecay

DecayWeak

Decay

Chiba/Nagoya 2003

Cross Sections and the Energy Loss Term

CTEQ5 Parton Distribution for the evaluation

Chiba/Nagoya 2003

Chiba/Nagoya 2003

Chiba/Nagoya 2003

Muon(Neutrinos) from

Nadir Angle

e

e

e/

e/

Weak

Weak

Weak

Inco

min

gProducts

Weak

Weak

Weak

Cascades

Cascades

Decay DecayWeak

Pair/decayBremss Pair Pair PhotoNucl.

PhotoNucl.DecayPair Pair

PairBremssDecay

DecayWeak

Decay

Decay

Chiba/Nagoya 2003

Tau(Neutrinos) from

Suppression

By decay

pair contribution

GZK Neutrino ProductionGZK Neutrino Production

2.725 K

411 photons / cm3

Gamma Beam Energy (GeV)

Cro

ss S

ect

ion (mb)

0.1

0.01

γ + p→Δ （1232）→ π o p or π + n

Gamma Beam Energy (GeV)

Cro

ss S

ect

ion (mb)

0.1

0.01

γ + p→Δ （1232）→ π o p or π + n

Gamma Beam Energy (GeV)

Cro

ss S

ect

ion (mb)

0.1

0.01

γ + p→Δ （1232）→ π o p or π + n

0.6 x 10-27 cm2

γp

n p

π＋ μ＋ ν

e＋

νγ

E = 10 20 eV

E 0.8 x 10 20 eV ~

Conventional Mechanism of EHE neutrinos!!Conventional Mechanism of EHE neutrinos!!　　

Chiba/Nagoya 2003

Chiba/Nagoya 2003

１．４ｋｍ

１ｋｍ

Upward

Ice

Rock ν

±πγ

ν

+e －e１ｋｍ lepton

ν

Chiba/Nagoya 2003

A factor of 2 enhancementDue to the heavier lepton production

Chiba/Nagoya 2003

e

e

e/

e/

Weak

Weak

Weak

Inco

min

gProducts

Weak

Weak

Weak

Cascades

Cascades

Decay DecayWeak

Pair/decayBremss Pair Pair PhotoNucl.

PhotoNucl.DecayPair Pair

PairBremssDecay

DecayWeak

Decay

Chiba/Nagoya 2003

Upward-going

Chiba/Nagoya 2003

Downward going!!

１．４ｋｍ

１ｋｍ

Upward

Ice

Rock ν

±πγ

ν

+e －e１ｋｍ

Downward

ν

γ

γ

+e －e

lepton

lepton

Chiba/Nagoya 2003

Chiba/Nagoya 2003

Down-going events dominates…

1400 m

2800 m

11000mUp Down

１．４ｋｍ

１ｋｍ

Downward

Upward

Ice

Rock

ν

ν

±π

γ

γ

γν

+e －e１ｋｍ

+e －e

lepton

lepton

EHE events!

Chiba/Nagoya 2003

Downward going!!

1 km2 year

Energy Spectrum Diffuse SearchEnergy Spectrum Diffuse Search

Blue: after downgoing muon rejectionRed: after cut on Nhit to get ultimate sensitivity

Chiba/Nagoya 2003

Intensity of EHE Intensity of EHE and and

GZK GZK modelmodel II(E>10PeV)(E>10PeV) II(E>10PeV)(E>10PeV) RATE RATE [/yr/[/yr/kmkm22]]

m=4 Zm=4 Zmaxmax=4=4

DownDown 5.90 105.90 10-19-19 5.97 105.97 10-19-19 0.370.37

UpUp 3.91 103.91 10-20-20 6.63 106.63 10-20-20 0.030.03

m=7 Zm=7 Zmaxmax=5=5

DownDown 8.88 108.88 10-17-17 9.10 109.10 10-17-17 53.453.4

UpUp 5.72 105.72 10-19-19 9.73 109.73 10-18-18 4.644.64

[cm-2 sec-1]

Chiba/Nagoya 2003

GZK model dependenceGZK model dependence

Chiba/Nagoya 2003

Findings…

appeared in EeV-10EeV is our prime target on UHE detection.

1/100-1/500 of primary intensity!

Downward and make main contributions in EeV

Energy Estimation would be a key for the bg reduction

GZK is DETECTABLE by IceCube 0.4-50 events/year

Chiba/Nagoya 2003

We still need…

•IceCube Sensitivity on energy-deposit basis-Simulation of the EHE energy deposit profile-Smart Background rejection