Imaging the High-Energy Neutrino Universe from the South Pole
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Imaging the High-Energy Neutrino Universe from the South Pole
Results from AMANDAand Status of IceCube
Kurt WoschnaggUniversity of California - Berkeley
Les Rencontres de Physique de la Vallée d’AosteLa Thuile, Feb 27 – Mar 5, 2005
Results and Perspectives in Particle Physics
http://amanda.uci.edu http://icecube.wisc.edu
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Neutrino Astronomy
Protons: directions scrambled by extragalactic magnetic fields
γ-rays: straight-line propagation but reprocessed in sources; extragalactic backgrounds absorb Eγ > TeV
Neutrinos: straight-line propagation; not absorbed, but difficult to detect
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High-Energy Neutrino Production and Detection
Candidate astrophysical
accelerators for high energy
cosmic rays:– Active Galactic Nuclei
– Gamma-Ray Bursts
– Supernova Remnants
– …
Neutrino production at source: p+ or p+p collisions
→ pion decay → neutrinos
Neutrino flavors:
e : : 1:2:~0 at source
1:1:1 at detector
Neutrino astronomy requires
large detectors– Low extra-terrestrial neutrino fluxes
– Small cross-sections
dN/dEE-2
dN/dEE-3.7
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Amundsen-Scott South Pole station
South PoleDome
Summer camp
AMANDA
road to work
1500 m
2000 m
[not to scale]
IceCube
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The Antarctic Muon and Neutrino Detector Array
PMT noise: ~1 kHz
AMANDA-B10(inner core of AMANDA-II)
10 strings302 OMs
Data years: 1997-99
Optical Module
“Up-going”(from Northern sky)
“Down-going”(from Southern sky)
AMANDA-II19 strings677 OMs
Trigger rate: 80 HzData years: 2000-
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Neutrino Detection in Polar Ice
O(km) long muon tracks
~15 m
7.0)TeV/(7.0 E
South Pole ice: (most?) transparent
natural condensed material
Longer absorption length → larger effective volume
cascades
event reconstruction byCherenkov light timing
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Detector medium: ice to meet you
Average optical ice parameters:
abs ~ 110 m @ 400 nmsca ~ 20 m @ 400 nm
Scattering Absorption
bubbles
dust
dust
ice
Ice properties not uniform:vertical structure due to dust
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An up-going neutrino event in AMANDA
color = timesize = amplitude
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Atmospheric Neutrinos
►Neural Network energy
reconstruction (up-going μ)
►Regularized unfolding → energy spectrum
PRELIMINARY
First spectrum > 1 TeV (up to 300 TeV)- matches lower-energy Frejus dataAMANDA test beam(s):
atmospheric ν (and μ)
Neutrino energy [GeV]
100 TeV
1 TeV
Set limit on cosmic neutrino flux:
How much E-2 cosmic ν signalallowed within uncertainty of
highest energy bin?
E2μ(E) < 2.6·10–7 GeV cm-2 s-1 sr-1 Limit on diffuse E-2 νμ flux (100-300 TeV):
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Diffuse ExtraTerrestrial Neutrino Search
Nobs = 1 event
Natm μ = 0.90
Natm ν = 0.06 ± 25%norm
Cascades: 4π coverage
+0.69-0.43+0.09 0.04
After optimized cuts:
Ast
ropa
rtic
le P
hysi
cs 2
2 (2
004)
127
background
signal
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Diffuse PeV-EeV Neutrino Search
Earth opaque to PeV neutrinos
→ look up and close to horizon
Look for very bright events
(large number of Optical Modules with hits)
Train neural network to distinguish
E-2 signal from background
Astroparticle Physics 22 (2005) 339
Nobs = 5 events
Nbgr = 4.6 ± 36% events
Simulated UHE event
angular range for νμ detection
E2all (E) < 0.99·10–6 GeV cm-2 s-1 sr-1 Limit on diffuse E-2 ν flux (1 PeV-3 EeV):
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Diffuse All-Flavor Neutrino Flux Limits
1:1:1 flavor flux ratio AMANDA
1: B10, 97, ↑μ2: A-II, 2000, unfold.3: A-II, 2000, casc.4: B10, 97, UHE
Baikal
5: 98-03, casc.
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Neutrino Point Source Search
No evidence for point sources with an E-2 energy spectrum
2000-2003 sky mapLivetime: 807 days
3329 events (up-going)<5% fake events
Consistent with atmospheric ν
Cuts optimized in each declinationband assuming E-2 spectrum
No clustering observed
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“Hot Spot” Search
Significance Map: Largest excess is 3.35
Assess statistical significance using random sky maps
No statistically significant hot spots !
significance mapequatorial coordinates
AMANDA 2000-2003Highest significance:
3.4σ
σ
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Crab
Mk421
SS433
Mk501
M87
Cyg
Cas A
Significance Map for 2000-2003
Preliminary
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Round Up the Usual Suspects
Search for high energy neutrino excess from known gamma emitting sources
Usual suspect
z Luminosity distance
Nobserved Nback
1ES 1959+650
0.047 219 Mpc 5 3.71
Markarian 421
0.03 140 Mpc 6 5.58
QSO 1633+382
1.8 14000 Mpc 4 5.58
QSO 0219+428
0.44 2600 Mpc 4 4.31
CRAB 1.9 kpc 10 5.36
TeV Blazars
GeV Blazars
Supernova Remnant
No Statistically Significant Excess from 33 Targeted Objects
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Sensitivity to muon flux from neutralino annihilations in the Sun or the center of the Earth
Indirect Dark Matter Search
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Indirect Dark Matter Search
Disfavored by direct search(CDMS II)
Limits on muon flux from Earth center Limits on muon flux from Sun
PRELIMINARY
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The Next Generation: IceCube
• 80 strings with 60 optical modules (OMs) on each
• Effective Volume ≈ 1 km3
– Size required to see “guaranteed” neutrino sources
• Geometry optimized for TeV-PeV (EeV) neutrinos– 17 m OM spacing– 125 between strings
• Surface Array (IceTop)• PMT signal digitization in ice
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IceCube Sensitivity1:1:1 flavor flux ratio
IceCube (3yr)
AMANDA (4yr)
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IceCube All-Flavor Neutrino Detection
Eµ = 10 TeV e e E = 375 TeV
~300m for 10 PeV
μ μ
τ τ + “cascade”
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Simulated 2×1019 eV neutrino event
in AMANDA in IceCube
Size matters for high energies!
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How large is IceCube?
50 m
1450 m
2450 m
300
m
AMANDA-II
Super K
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January 2005:First string deployed!
60 optical modulesDeepest module at 2450 m
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Conclusions
No extraterrestrial ν signal observed…yet
• Limits (TeV-EeV) on diffuse ET neutrino flux• Point source searches:
- No statistically significant hot spots
- No evidence for high-energy neutrino
emission from gamma emitting objects
IceCube is under construction– 2-3 orders of magnitude increase in sensitivity– Higher energies– All flavors
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Bartol Research InstituteUC Berkeley
UC IrvinePennsylvania State
UW MadisonUW River FallsLBNL Berkeley
VUB-IIHE, BrusselULB-IIHE, Bruxelles
Université de Mons-HainautImperial College, London
DESY, Zeuthen
Mainz UniversitätWuppertal UniversitätUniversität Dortmund
Stockholms UniversitetUppsala UniversitetKalmar Universitet
~150 membersSouth Pole Station
United States Europe
Antarctica
The AMANDA Collaboration