1. Imaging the Neutrino Universe with AMANDA and IceCube
David Hardtke
University of California, Berkeley
Motivations for neutrino astronomy
Selected AMANDA results
IceCube: Status and Plans
Lake Louise Winter Institute February 2005

2. Neutrino Astronomy

3. 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/dEE-2
dN/dEE-3.7

4. Amundsen-Scott South Pole station
Dome
road to work
AMANDA
Summer camp
1500 m
Amundsen-Scott South Pole station
2000 m
[not to scale]

5. Neutrino Detection in Polar Ice
event reconstruction by
Cherenkov light timing
South Pole ice:
O(km) long muon tracks
~15 m
cascades
Km tracks at TeV, cm at MeV
Longer absorption length  larger effective volume

6. Atmospheric Neutrinos
PRELIMINARY
Muon Neutrino Flux
Maximum E-2
contribution
AMANDA test beam(s): atmospheric  (and ):
Neural Net Energy Reconstruction (upgoing )
“Unfold” to get neutrino Energy Spectrum
Limit on diffuse E-2 flux ( TeV):
E2 (E) < 2.6·10–7 GeV cm-2 s-1 sr-1

7. Diffuse Extra-terrestrial Neutrino Search
Astroparticle Physics 22, 127 (2004)
“Cascade” search: 4  coverage
Signal
Background
After optimized cuts:
Nobs = 1 event
Natm  = 0.90
Natm  = ± 25%norm
+0.69
-0.43
+0.09
-0.04

8. Diffuse PeV-EeV neutrino search
m tracks
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
Simulated UHE event
Nobserved = 5
Nbackground = 4.6  1.2
Astroparticle Physics 22, 339 (2005)

9. Summary of Diffuse Flux Limits
All-flavor Flux Limits vs. Model Predictions
Cascades
Unfolded Atmospheric (x3)
Horizontal UHE
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

10. Neutrino Point Source Search
Four Year ( ) analysis
Optimize cuts in each declination band assuming E-2 spectrum
3369 upgoing  events
< 5% fake events

11. “Hot spot” search Significance Map: Largest excess is 3.35 
Assess statistical significance using random skymaps.
No statistically significant hot spots !

12. Round Up the Usual Suspects
Search for high energy neutrino excess from known gamma emitting sources:
Usual suspect z
Luminosity distance
Nobserved
Nback
1ES
0.047
219 Mpc 5
3.71
Markarian 421
0.03
140 Mpc 6
5.58
QSO
1.8
14000 Mpc 4
QSO
0.44
2600 Mpc
4.31
CRAB
1.9 kpc 10
5.36
TeV Blazars
GeV Blazars
Supernova Remnant
No Statistically Significant Excess from 33 Targeted Objects

13. 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.

14. IceCube Sensitivity

15. January 2005: First String Deployed!
IceCube Status
January 2005: First String Deployed!

16. 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

17. IceCube Simulated Events
Eµ=10 TeV
e  e
E = 375 TeV
~300m for
PeV t

18. How large is IceCube?
AMANDAII
300 m
Super K
1500 m
50 m
2500 m