Auger as a Neutrino DetectorAuger as a Neutrino Detector

François Montanet

ISN/IN2P3-CNRS/U.Joseph Fourier Grenoble

Chicago , October 2002

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Cosmic Neutrinos Spectrum Cosmic Neutrinos Spectrum

• 2K (2 10-4 eV) CNB: Possible hint with Z-burst ?

• MeV: Solar and SN Neutrinos, SK, SNO,…

• GeV-TeV:Atmospheric and possibly astrophysical sourcesWater and Ice cherenkov detectors, AMANDA, BAIKAL, ANTARES.

• TeV-PeV: the same, but extended to 1 km3. IceCube will come first.

• EeV: EAS detectors tailored to study CR at the GZK cutoff Observe Horizontal or Emerging Air Showers. AUGER, HiRes, EUSO, OWL.

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UHE Neutrinos origin UHE Neutrinos origin • Direct test of astrophysical hot spots

– Galactic: • SNR, pulsars, micro-quasars, interactions of CR with ISM.

– Extragalactic:• AGN, Gamma Ray Bursts, …

“Bottom-Up” Acceleration

• Direct test of Primordial Universe relics – LSP type Relics (Neutralinos),– Topological defects– Super Heavy Relics– “Z-burst” UHECR regenerated locally by νUHE νCNB resonant interactions

“Top-Down” Decay Product

• Assuming maximal mixing: at the earth ννννe:ννννµµµµ:ννννττττ ≈≈≈≈ 1:1:1

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Why are neutrinos so interesting ?Why are neutrinos so interesting ?Three reasons among others:

• No absorption during transport – no magnetic deflection –constant delay:– Point back to the source– Get rid of transport effects and direct access to source characteristics.

• Hints of physics at the GUT scale, if TOP-DOWN mechanisms – photons and leptons should dominate protons and nuclei. – Measure the relative flux of γ and ν w.r.t nucleons at UHE ⇒ discriminate

between TOP-DOWN et BOTTOM-UP.

• High energy gamma rays sources (SNR, AGN, etc…) = electron or hadron accelerators (or both).– Observing VHE Neutrinos from pion decay would raise the ambiguity.

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Flux: base lineFlux: base line

ATM

CMB

Neutrino Energy [eV]

E2J(

E) e

Vcm

-2s-1

sr-1

Yoshida & Teshima,Prog. of Theo. Phys. 89 (1993)

Stecker, Done, Salamon, Sommers, PRL. 66 (1991)

νµ + νµ only

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Flux: Flux: AGNsAGNs and and GRBsGRBs

ATM

AGN coreAGN jets

GRB

Neutrino Energy [eV]

E2J(

E) e

Vcm

-2s-1

sr-1

Stecker SolomonSpace Sci. Rev. 75 (1996)

ProtheroeIAU coll. 163 (1997)

Mannheim Astropart. Phys 3 (1995)

Waxman Bahcall, PRL 78 (1997)

νµ + νµ only

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ATM

Neutrino Energy [eV]

E2J(

E) e

Vcm

-2s-1

sr-1

Protheroe & StanevPhys Rev Lett 77 3708 ('96)

Gelmini & KusenkoPhys Rev Lett 84 1378 (2000)

SHR

TD

Berezinsky, Kachelreib, VilenkiPhys Rev Lett 79 4302 ('97)

Topological defects Topological defects –– SuperSuper--heavy relics and Zheavy relics and Z--burstburstνµ + νµ only

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Present limits on diffuse fluxesPresent limits on diffuse fluxes

Neutrino Energy [eV]

E2J(

E) e

Vcm

-2s-1

sr-1

Experimental limits

AMANDA-B10

Frejus

EAStop

EAStop res

γ=1AGASA γ=2

FlysEye

GOLDSTONE30hr

BAIKAL

FlysEye PR D 31 2192 (1985)

Zas et al PRL 78 3614 (1997)

Baikal Astropart. phys 14 61(2000)

Amanda ICRC2001

Agasa ICRC2001

Goldstone astro-ph/0102435

Theoreticalbounds

Mannheim Protheroe RachenPRD accepted

Waxman Bahcall, PRD 59 (1999)

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SHR

TD

Present limits on diffuse fluxesPresent limits on diffuse fluxes

Neutrino Energy [eV]

E2J(

E) e

Vcm

-2s-1

sr-1

Experimental limits

AMANDA-B10

Frejus

EAStop

EAStop res

γ=1AGASA γ=2

FlysEye

GOLDSTONE30hr

BAIKAL

Theoreticalbounds

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Neutrino cross sectionsNeutrino cross sections

• ν-matter cross sections:

HERA

Extrapolation uncertainty at UHE× 2.4

Glashow resonance× 1000 enhancement

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Particle RangesParticle RangesR

ange

(m

of w

ater

)

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ντνe+µ

secondaryν

Earth opacity and Earth opacity and νννννννν--ττττττττ regenerationregeneration

Zenith angle (o)

Transmissionprobabilityin Earth

Earth is opaque to ν with energy > few TeV

X+τνXN

CC+→ τντ

0νν FF

°= 0zθ

°= 60zθ

10 −∝ EFν20 −∝ EFν

1PeV 1PeV

But ντ regenerate themselves:

Iyer Dutta et alPRD 63 (2001) 094020Bottai Giurgolaastro-ph/0205325

D. Fargionastro-ph/9704205

F. Halzen D. SaltzbergPRL 81 (1998) 4308

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UHE Neutrinos: Horizontal ShowersUHE Neutrinos: Horizontal ShowersAtmosphere: 1000g/cm2 thick vertically

36000g/cm2 thick horizontally

⇒⇒⇒⇒ Look for interactions at deep column densitiesi.e. large zenith angles: 75°< θθθθ < 90°

horizontalfor 10~alfor vertic 10~

:yprobabilitn interactio 1EeVAt 10~

4-

5-

4.018

232 Ecm ×σ

Berezinsky, Zatsepin Phys.Lett.B 28 (1969)Berezinsky, Smirnov Astrophys. Space Sci 32 (1975)Halzen Zas Phys Lett B 289 (1992)Halzen Zas Vàzquez Astroparticle Phys 1 (1993)

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UHE Neutrinos: Horizontal ShowersUHE Neutrinos: Horizontal Showers

Background is: Thousands events per yearEM poor, muon rich, flat and thin frontPrompt signal

Shower front Shower corehard muonsEM shower

1000 g/cm2 3000 g/cm2Shower front

EM shower

3000 g/cm2

ν : “new” showers hadrons: “old” showers

Signal is: Few events per yearEM rich, curved and thick frontBroad signals

P. Billoir, 8th International Workshop on Neutrino Telescopes, (1999) 111.

X.Bertou, P.Billoir, O.Deligny, A.Letessier-Selvonastro-ph/0104452 accepted in Astroparticle Phys.

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Horizontal ShowersHorizontal Showers

• Signal Time Analysis

Distance to shower axis (m)

Tim

e of

arr

ival

(ns)Simulated 1019eV

p-induced showersat different elevation

Requires good sensitivity to muons and good efficiency for grazing incidences

⇒AUGERWater Cherenkov tanks

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The Surface Detector ConceptThe Surface Detector Concept

Water Cherenkov Tanks:- good lateral cross-section

- good efficiency to muons

- homogenous response vs zenith angle

Three 8” PM Tubes

Polyethylene tank

White light diffusing liner

12 m3 of de-ionized water

Solar panel and electronic box

Commantenna

GPSantenna

Batterybox

Nota Bene: Lower energy threshold for low elevation, horizontal showers: 0.1EeV (1017eV) → 300m × 10km ground spot

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Detection prob. Detection prob. vsvs Depth and Zenith angleDepth and Zenith angle

ννννe c.c. (mixed showers) 1 EeV

ννννe n.c. or ννννµµµµ (pure hadronic showers) 1 EeV

Black: 4 stationsabove trigger level

Shaded: 3 stations

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A Very Large Real Horizontal event (may 23A Very Large Real Horizontal event (may 23rdrd))

most probably old hadronic shower

Near vertical (young) shower

82° For comparison:

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Auger sensitivity to atmospheric DASAuger sensitivity to atmospheric DAS

AUGER sensitivity (1 site)

1event / year /decade

P. Billoir, 8th International Workshop on Neutrino Telescopes, (1999) 111.

X.Bertou, P.Billoir, O.Deligny, A.Letessier-Selvonastro-ph/0104452 accepted in Astroparticle Phys.

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TauTau neutrino detectionneutrino detectionντ propagates, through regeneration process or not and interact inthe earth crust, producing a τ that escape to and decays within the atmosphere.

Low zenith angle: many regeneration steps energy saturates 1016 – 1017eV

Quasi horizontal: no or few regeneration steps

⇒ Eτ ≈ EνLloss << Ldecay at E > 1017eV

S. Bottai, S. Giurgolaastro-ph/0205325

X+τνXN

CC+→ τντ

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TauTau neutrino detection by Auger SDneutrino detection by Auger SD• Principle:

– Interaction length in the earth ~ 300 km at 1018 eV– Tau time of flight ~ 50 km at 1018 eV– Tau range in standard rock ~ 10 km at 1018 eV– 1° below horizon ⇒⇒⇒⇒ 200 km of rock– Shower maximum ~10 km after decayIn practice 85°°°° < θθθθz < 95°°°°AUGER window: 1017 to 1020 eV

X.Bertou, P.Billoir, O.Deligny, A.Letessier-Selvonastro-ph/0104452Nucl.Phys.B. 110 (2002) 525

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MultiMulti--bang regenerationbang regeneration

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Detection prob. Detection prob. vsvs depth and Zenith angledepth and Zenith angle

ν→τ ±± e νπ→τ ±±

Ground spots of 1 EeV ττττLevels of averaged signal in tanks :

solid : local trigger ; dashed : 1/3 ; dotted : 1/10

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TauTau decay showersdecay showers

• Space/time alignment: compatible with c within 100ns

• Rectilinear shapes: ±1km from trace

• Large rise times: (hadron background)T10-50 > 50ns and T10-90 > 150ns

• Accumulation around sinθθθθ =1

(shower center : 10 km after the decay)triangles: 3 ; squares: 4 stations ;black circles: 4 + compact topology.

⇓⇓⇓⇓

Get rid of mini-shower and

random coincidences BG < 1evt/year

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AUGER Exposure to AUGER Exposure to TauTau NeutrinosNeutrinos

Analytic calculation

2 Deep Inelastic Scattering cross sections hypothesis

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TauTau event ratesevent rates

J(E) = 3.1 E-1 EeV-1 km-2 y-1 sr-1

3.1 EeV km-2 y-1

= 10 eV cm-2 s-1 sr-1

J(E) = 3.1 E-2 EeV-1 km-2 y-1 sr-1

no DIS

Events per year

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BackgroundBackground

Atmosphere contribution

ντ contribution

RMS on reconstructed sinθ ~ 0.005

Main background:

Atmospheric deep showers from neutrinos

ννννττττ contribution peaked at sinθθθθ ~ 1

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Expected sensitivity from AUGERExpected sensitivity from AUGERX.Bertou, P.Billoir, O.Deligny, A.Letessier-Selvon

astro-ph/0104452v4 Accepted in Astropart. Phys.

Models from Protheroe(astro-ph/9809144)

lower edge : B + PP ; upper edge : B + PP + ph-nucl(high)dash-dotted : upper limit (90% C.L.) after 5 years, with a flux in E2 (low edge option)

3.1

EeV

km-2

y-1

= 10

eVcm

-2 s-1

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Futures sensitivitiesFutures sensitivities

Neutrino Energy [eV]

E2J(

E) e

Vcm

-2s-1

sr-1

IceCube 1 ev/yr sensitivity νµ

AUGER 1 ev/yr sensitivity

Atmosphere νe and νµ

AUGER 1 ev/yr sensitivity ντ

EUSO sensitivity Quasi horizontal showers

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Futures sensitivitiesFutures sensitivities

ATM

CMB

Neutrino Energy [eV]

E2J(

E) e

Vcm

-2s-1

sr-1 AMANDA-B10

Frejus

EAStop

EAStop res

γ=1AGASA γ=2

FlysEye

AMANDA-II

GOLDSTONE30hr

BAIKAL

IceCube 1 ev/yr sensitivity νµ

AUGER 1 ev/yr sensitivity

Atmosphere νe and νµ

AUGER 1 ev/yr sensitivity ντ

EUSO sensitivity Quasi horizontal showers

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ConclusionsConclusions• UHE neutrino astronomy aims:

– Find the sources of cosmic – Test TOP-DOWN models (GUT scale physics, Relic neutrinos)

• Kilometer scale muon tracking detectors (ICECUBE) have competitive sensitivity to UHE neutrino, don’t underestimate their capability.

• Even with huge acceptance, observing HAS will depends on upon Nature’s good will… AUGER can only test the most optimistic models that predict high fluxes above 1017ev. Space based FDs (EUSO) may have a better chance.

• Nu-Tau interact in the earth crust producing an atmospheric Tau shower. This would enhances the sensitivity of SD array by a factor ××××30 making AUGER very efficient in finding cosmic neutrinos in an energy window 1017 à 1020 eV, if they exist.