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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