La rivelazione di neutrini astrofisici - INFN Lecce web · La rivelazione . di . neutrini astrofisici. T. Montaruli. Università . di . Bari & INFN • Neutrino Astrophysics Motivations

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La La rivelazione rivelazione di di neutrini astrofisicineutrini astrofisiciT. T. MontaruliMontaruli

Università Università di di Bari Bari & INFN& INFN

• Neutrino Astrophysics Motivations• Physics Issues• Current Neutrino Telescopesand Experimental Results• Future Outlook

XV IFAE, XV IFAE, LecceLecce, 23, 23--26 26 Aprile Aprile 20032003

Teresa Montaruli, IFAE, Lecce, 24 Aprile 2003

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Probes of the UniverseProbesProbes of the of the UniverseUniversePhotons: straight-line propagation but reprocessed in sources and extragalacticbackgrounds absorb Eγ > TeV (pair production on IR, CMBR, radio)Protons: directions scrambled by magnetic fields (deflection<1° E>50 EeV) Neutrons: γcτ ∼10kpc for E ~EeV Absorption length of photons and protons

Mrk 501

Gal Cen

γ+IR

γ+CMWB

γ+Radio

p photopionpγ→e+e-

<100 Mpc E~ 1-1010TeV

UHE particles (γ, p, n, …) have small path-lengths respect to Hubble scale (GZK cut-off)

Survey of remote regions and engines inside sources through neutrinos: small interaction cross section and undeflected [also gravitational waves!] ⇒discovery potential


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Kinetic energy per nucleus (eV)

knee ~3000 TeV

New componentwith hard spectrum?

ankle~10 EeV 1 par km-2 yr-1

~E-3

~E-2.7 10% of SN power is enough to feed CRs: 1051 erg per SN + ~3 SN per century in disk ~ 10-25 erg/cm3s

Power spectrum for diffusive shock acceleration with differential index α ~ -2; but αobserved ~ -2.7 due to propagation effects and escape time from Galaxy

Ankle: extragalactic sources (Galaxy cannot contain EHECR, no such powerful galactic source candidates, no evident anisotropy correlated with galactic plane

The cosmic ray connectionThe The cosmic raycosmic ray connectionconnectionCosmic ν’s can provide an answer to the debated question:Which are the sources of the HE cosmic rays (E> 1014 eV) ?

Cosmic ray spectrum: 106 eV to ~1020 eV


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The ankle and the GZK cut-offThe The ankleankle and the GZK cutand the GZK cut--offoff [Greisen 66; Zatsepin & Kuzmin66]

1 event/km2/century

GZK cut-off due to interactions of CRs (E> 5 1019 eV) on CMBR

EHECR data: light composition favored

Bahcall & Waxman, Phys. Lett B 556 (2003): Fly’s Eye, HiRes, Yakutsk consistent with UHE protons + GZK at 7σ. AGASA (30% of total exposure) favors more exotic models. Change energy scale ⇒No need or exotic models to explain EHECR!


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Top-down: decays of unstable or meta-stable particles produced by radiation, interaction or collapse of topological defects or decay of relic particles Z decays due to UHE ν interaction on relic ν’s (Weiler, 1982)

ν production and sourcesνν production and production and sourcessources

Bottom-up (beam-dump model): cosmic accelerator + interaction on matteror γ’s: π0 → γ-astronomy π± → ν-astronomy

Cosmogenic ν’s: UHE ν interactions on CMB (Engel Seckel, Stanev, 2001)

Proton acceleration: Emax ~ ΓBR and if collapsed objects Emax ~ ΓBM

• Jets of AGN, GRB fireballs• Accretion shocks in galaxy

clusters , Galaxy mergers• Young supernova remnants

(p or heavy ion accelaration)• Pulsars, Magnetars (large

magnetic fields)• Micro-quasars (binaries with

jets seen in radio)


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The link with γ astronomy The The link withlink with γγ astronomy astronomy Neglecting γ absorption (large uncertainty) Φν ∼ Φγ 1st order Fermi acceleration mechanism: harder spectra than atmospheric ν’s

Observations consistent with em mechanisms BUT first evidence in a SNR of hadronic mechanism? RXJ1713-39 CANGAROO, Nature 416 2002

Syncrotron IC

π0

Reimer et al, A&A 390, L43 (2002): any GeV emission should be compatible with EGRET measured flux 3EG J1714-3857 (even if not coincident with CANGAROO source)


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Detected Sources emitting γs with E>TeVDetected Sources emitting Detected Sources emitting γγs withs with E>E>TeVTeV

AMANDA location ANTARES location11 visible 100% of day 3 visible 100% of day8 never visible 8 visible >50% of day

3 visible 20-50% of day8 visible <20% of day

RXJ1713-39 not visible

BL Lacs, Pulsars and SNRs Cygnus OB2: association of stars

Earth shadowing not considered, only visibility

AMANDA location: sources always at same elevation, constant sensitivitywith time possible advantage for transient sources BUT INSENSITIVETO HALF OF THE SKY


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Detection principle Detection Detection principle principle ν interaction cross-section very low ⇒huge detectors (km3) not feasible underground!Markov/ Greisen idea (1960)ν + N → µ + XTarget is surrounding matter M = ρ Rµ S (Eµ = 1 TeV : Rµ = 2.5 km)3d PMT array reconstructs µ tracks andcascades. Also νe and ντ can be detected(better energy resolution but worse angular resolution) ν

νµ


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Cosmic νs Oscillations ν interaction length ~Earth diameter @40 TeVντ undergoes regeneration through CC + τ decay cosmic ν’s at surce: νe:νµ:ντ = 1:2:0 (if µ’s decay) ⇒ oscillations with atm ν’s parameters and L ~ Mpc ⇒ νe:νµ:ντ = 1:1:1

ντ/νµ: 2.85, 1.29 (reduced to 1.11, 1.07 for E-2)

νe/νµ secondaries/ντ: 37%,6% (reduced to2.2%,0.2% for E-2)

E-1 diff. spectrum

Cosmic Cosmic ννs Oscillations s Oscillations


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The backgrounds The The backgrounds backgrounds •Environment (40K, bioluminescence) andelectronics•Atmospheric ν’s•Atmospheric µ’s (sea/iceshielding)

Rejection: direction and energy,time for bursters

Problem: 2 orders of magnitude uncertaintyon current predictions of prompt νs

Prompt ν’s: Costa, Astrop. Phys. 16 (2001)

Ang

leav

erag

edE2

.5dΦ

/dE

(GeV

1.5

cm-2

s-1

sr-1)

log10Eν(GeV)

ANTARES

E-2

Atmospheric νs


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Neutrino telescope parameters Neutrino Neutrino telescope parameters telescope parameters ‘Background free’ region: direction and/or time constraint, energy cut ⇒upper limits scale with 1/exposure

‘Background limited’ region: upper limits scale with 1/sqrt(exposure)

Sensitivity: N are events from ν source and B events from atm ν background number of sigmas=N/sqrt(B) ∝ √(AT) / ∆θ

∆θ = angular resolutionAT = exposure

Discovery potential at 100 TeV: source luminosity to have 10 events/km2/yr with Pν --> µ ~ 10-4 and N = fν/Eν Pν →µ AT

~4πd2 fν ∼ 4πd2 5 ·10-12/[AT (km2 yr)] in erg/s

Pulsars/SNRs/magnetars/µquasars ⇒ 1035 erg/s (5 kpc)

AGN/BL Lacs/GRBs ⇒ > 6 ·1043 erg/s (>100 Mpc)

~200 ev/yr/km2 W&B limit (4.5 10-8 E-2 GeV cm-2 s-1 sr-1)

LLνν


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Effective areasEffective areasEffective areasEvent rates ⇔ Effective area (volume): includes reconstruction efficiencies, affected by absorption length and coincidence requests to suppress backgrounds, strongly dependent on spectrum

ANTARES: for hard spectra bulk of the events at 10-100 TeV

Aeff =Selected event rate

Incident muon flux


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Angular and energy resolutionsAngular Angular and and energy resolutionsenergy resolutions

Resolution dominated byreconstructonLimiting value ~0.15°

ν

µ

Resolution dominated by kinematicangle θνµ

Energy resolutionlog(Erec/EMC)

Factor 3

Factor 2

Reconstruction resolutionlimited by phototube TTSand light diffusion in water


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Expected sensitivity AMANDA 97-02 data

4 years Super-Kamiokande

5.6 years MACRO

170 daysAMANDA-B10

-90 0-45 9045

10-15

10-14

µ⋅c

m-2

s-1

declination (degrees)

southernsky

northern sky

Point-like sourcesPointPoint--like sourceslike sources

ANTARES 1 yr


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AMANDA II (νe)[3](prelim)

[2]

All flavorsDiffuse fluxes Diffuse Diffuse fluxes fluxes νµ limits for E-2

AMANDA Cascades (νe+νµ+ντ) 130 d (PRD67, 2003): 9.8 10-6 GeV cm-2 s-1 sr-1

AMANDAII 197d: 6 10-7 GeV cm-2 s-1 sr-1

AMANDA (νµ) 130 d (astro-ph/030328): 8.4 10-7 GeV cm-2 s-1 sr-1

AMANDA UHE >1016eV: 2 (no sys)/4.8 (sys) 10-6 GeV cm-2 s-1 sr-1

Baikal (νe+2νµ) 234 d NT200+70d NT96 (Neutrino02): 1.3-1.9 10-6 GeVcm-2 s-1 sr-1


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Search for Dark MatterNeutralinos from the Sun Relativistic Monopoles


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AMANDA B-10:302 OM’s/10 stringsResults recently published on atm ν’s (30% sys), diffuse muon fluxes &cascades (6-1000 TeV), UHE ν’s (>10-5000 PeV),WIMPs, SNsAng. resolution 3.9° (EAS check)E resolution ~30-60%Effective area Eµ > 10 TeV > 104 m2

AMANDA II: about factor of 10

120 m

400 m

Absorption length (480 nm): 110 m

Effective scatter length ~ 25 m

Baikal Neutrino Telescope1100 m depth in Siberian Lake 3.6 km off-shore 51°N 104°E deployment+EAS on ice platform Ang. res 4° 192 OMs on 8 strings

Absorption length (480 nm): 28 m Effective scatter length > 200 m

70m

Planned upgrade 2003-4Future 1300 OMs/91 strings

70m37 cm QUASAR PMTs


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2475m2475m

350m350mactiveactive

Electro-opticalsubmarine cable

~40km

Junction boxJunction box

Readout cablesReadout cables

anchoranchor

floatfloat

Electronics containersElectronics containers

~60m~60mCompass,Compass,tilt metertilt meter

Optical moduleOptical module

Acoustic beaconAcoustic beacon

~100m

12 equipped strings90 OMs/line

Shore station

Absorption length (460 nm): 55-65 m Effective scatter length > 100 m

ANTARES http://ANTARES http://antaresantares.in2p3..in2p3.frfr


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Detector Deployment: Detector Deployment: achievemets achievemets and planningand planning

Jun 00: Jun 00: implosion testimplosion test

Collaboration formedCollaboration formed

Technical design report completedTechnical design report completedMar 01: sea bed surveyMar 01: sea bed survey

Oct 01: Electro Optical Cable Oct 01: Electro Optical Cable

Deployment of 12 linesDeployment of 12 lines

RR&&D and Site evaluation D and Site evaluation programme to select a suitable siteprogramme to select a suitable site

Apr 02: 900 OM production at Apr 02: 900 OM production at SaclaySaclay

Nov 99Nov 99-- Jun 00: “demonstrator” line Jun 00: “demonstrator” line deployment + operation deployment + operation ⇒⇒ atmospheric atmospheric µµss

1616--17/03/03 Connections by submarine 17/03/03 Connections by submarine 12/02/03 Instrumentation line deployed12/02/03 Instrumentation line deployed

24/12/02: Prototype line deployed24/12/02: Prototype line deployed77--9/12/02: Junction box deployed9/12/02: Junction box deployed


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•n. 64 towers, 16 storeys/tower, 600 m implemented• 4096 PMTs

main electro optical cable

main JB

200 m

200 m

1400 m

http://nemoweb.lns.infn.it

NEMO.RD Issues:•selection of the optimal site for km3 site in Mediterranean (Capo Passero)•R&D on materials and mechanical structures suited for long-term measurements in sea water and on low power consumption electronics •feasibility study and physics simulations•Test site off-shore Catania: first multi-purpose underwater Lab connected to shore in real time

Shore station 25 km Electro25 km Electro--OpticalOpticalCable Cable (installed Sep01)to JB splits for 2 sites

GEOSTAR (seismologicmonitoring),...

NEMONEMOActual proposal of general layout for KmActual proposal of general layout for Km33 detectordetector


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ConclusionsConclusions

• Cosmic neutrinos are reasonably expected but fluxes are low• AMANDA and Baikal are already producing results at the level of SK and MACRO, AMANDA II 1 order of magnitude better, BUT all flavors•Towards a km3 detector:ICE/sea water have complementary optical properties ICE: larger scattering but longer absorption lengths (better calorimeter butworse angular resolution) deployment from ice platform but no recoveryEAS to check pointing capabilities, no 40K and bioluminescence2 detectors in upper and lower emisphere are needed to ensure full sky coverage

ICECUBE: 4800 OM’s/80 strings construction in austral summer 2004-5Funding request: $295 MANTARES 2 lines taking data at 2500 mANTARES/NEMO joined their efforts to study feasibilty of Med detector

NESTOR: Mar 2003 1 floor with 12 OM’s at 4000 m connected to shore by 28 km EOC taking data

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La rivelazione di neutrini astrofisici - INFN Lecce web · La rivelazione . di . neutrini astrofisici. T. Montaruli. Università . di . Bari & INFN • Neutrino Astrophysics Motivations