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Imaging the Neutrino Universe with AMANDA and IceCube. Motivations for neutrino astronomy Selected AMANDA results IceCube: Status and Plans. David Hardtke University of California, Berkeley. Lake Louise Winter Institute February 2005. Neutrino Astronomy. Neutrino Production and Detection. - PowerPoint PPT Presentation
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Imaging the Neutrino Universe with AMANDA and IceCube
David Hardtke
University of California, Berkeley
1. Motivations for neutrino astronomy
2. Selected AMANDA results
3. IceCube: Status and Plans
Lake Louise Winter Institute February 2005
Neutrino Astronomy
Neutrino Production and Detection• Candidate astrophysical
accelerators for high energy cosmic rays:– Active Galactic Nuclei– Gamma-Ray Bursts
• Neutrino production at source: p+ or p+p collisions
• Neutrino astronomy requires large detectors– Low extra-terrestrial
neutrino fluxes– Small cross-sections
dN/dEE-2
dN/dEE-3.7
Amundsen-Scott South Pole station
South PoleDome
Summer camp
AMANDA
road to work
1500 m
2000 m
[not to scale]
O(km) long muon tracks
~15 m
7.0)TeV/(7.0 E
South Pole ice:
Longer absorption length larger effective volume
cascades
event reconstruction byCherenkov light timing
Neutrino Detection in Polar Ice
AMANDA test beam(s):
atmospheric (and ): •Neural Net Energy Reconstruction
(upgoing )
•“Unfold” to get neutrino Energy Spectrum
E2 (E) < 2.6·10–7 GeV cm-2 s-1 sr-1 Limit on diffuse E-2 flux (100-300 TeV):
Atmospheric Neutrinos
PRELIMINARY
Muon Neutrino Flux
Maximum E-2
contribution
Nobs = 1 event
Natm = 0.90
Natm = 0.06 ± 25%norm
+0.69-0.43+0.09-0.04
After optimized cuts:
Diffuse Extra-terrestrial Neutrino Search“Cascade” search: 4 coverage
Signal
Background
Astroparticle Physics 22, 127 (2004)
Diffuse PeV-EeV neutrino search• Earth opaque to PeV
neutrinos look horizontally
• Look for superbright events (large number of Optical Modules with hits)
• Train neural network on dN/dE E-2 signal
tracks
Simulated UHE event
Nobserved = 5
Nbackground = 4.6 1.2
Astroparticle Physics 22, 339 (2005)
Summary of Diffuse Flux Limits
CascadesUnfolded Atmospheric (x3)Horizontal UHE
All-flavor Flux Limits vs. Model Predictions
Models Excluded:
S91 (Stecker et al) AGN Core
S96 (Stecker et al) AGN Core (updated)
P97 (Protheroe) AGN Jet
Barely Alive:
M 95 (Mannheim) AGN Jet
Neutrino Point Source Search• Four Year (2000-2003) analysis
– Optimize cuts in each declination band assuming E-2 spectrum– 3369 upgoing events
• < 5% fake events
“Hot spot” searchSignificance Map: Largest excess is 3.35
Assess statistical significance using random skymaps.
No statistically significant hot spots !
Round Up the Usual Suspects• Search for high energy neutrino excess from
known gamma emitting sources:Usual
suspectz Luminosity
distanceNobserved 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
IceCube• 80 strings with 60 optical
modules (OMs) on each• Effective Volume ≈ 1 km3
– Size required to see “guaranteed” neutrino sources
• Surface Array (IceTop)• PMT signal digitization in
ice.
IceCube Sensitivity
IceCube StatusJanuary 2005: First String Deployed!
Conclusions• No Extra-terrestrial neutrino signal observed
– Diffuse flux searches (TeV - EeV)– Point source searches
• No statistically significant hotspots
• No evidence for high-energy neutrino emission from gamma emitting objects
• IceCube under construction– 2-3 order of magnitude improvement in sensitivity
IceCube Simulated EventsEµ=10 TeV
e e E = 375 TeV
~300m for PeV
"cascade"
How large is IceCube?
50 m
1500 m
2500 m
300
m
AMANDAII
Super K