1. High-energy Neutrino Astrophysics with IceCube Neutrino Observatory
Shigeru Yoshida
Department of Physics
Chiba University

2. The IceCube Neutrino Observatory
Completed: Dec 2010
Configuration
chronology
2006: IC9
2007: IC22
2008: IC40
2009: IC59
2010: IC79
2011: IC86
2004: Project Start string
2011: Project completion 86 strings 8
DeepCore
8 strings – spacing optimized for lower energies
480 optical sensors
PMT
Digital Optical Module (DOM)

3. The IceCube Collaboration
36 institutions, ~250 members
Canada
University of Alberta US
Bartol Research Institute, Delaware
Pennsylvania State University
University of California - Berkeley
University of California - Irvine
Clark-Atlanta University
University of Maryland
University of Wisconsin - Madison
University of Wisconsin - River Falls
Lawrence Berkeley National Lab.
University of Kansas
Southern University, Baton Rouge
University of Alaska, Anchorage
University of Alabama, Tuscaloosa
Georgia Tech
Ohio State University
Barbados
University of West Indies
Sweden
Uppsala Universitet
Stockholms Universitet
Germany
Universität Mainz
DESY-Zeuthen
Universität Dortmund
Universität Wuppertal
Humboldt-Universität zu Berlin
MPI Heidelberg
RWTH Aachen
Universität Bonn
Ruhr-Universität Bochum UK
Oxford University
Japan
Chiba University
Belgium
Université Libre de Bruxelles
Vrije Universiteit Brussel
Universiteit Gent
Université de Mons-Hainaut
Switzerland
EPFL, Lausanne
New Zealand
University of Canterbury
ANTARCTICA
Amundsen-Scott Station 3

4. DOM Digital Optical Module
HV Base
“Flasher Board”
Main Board
(DOM-MB)
10” PMT
13” Glass (hemi)sphere

5. Neutrino Detection Principle
Observe the charged secondaries
via Cherenkov radiation detected
by a 3D array of optical sensors νl
l, νl
hadronic
shower
W, Z
Need a huge volume (km3)
of an optically transparent
detector material g m
Antarctic ice is the
most transparent
natural solid known
(absorption lengths up 200 m) n

6. Note: Different dataset
IC86 = full IceCube (2011~)
IceCube
IC79 ( )
IC59 ( )
IC40 ( )
IC22 ( )
IceCube
IceCube
IceCube
IceCube

7. Point Source Search nm  m base m m m North CR signal + background
hypothesis vs
background only
null hypothesis
North CR m
North
South m
Note:
It’s ALL SKY survey m

8. n skymap IceCube + IceCube IceCube Preliminary
Hottest spot: RA Dec log(p)=4.65
~36 % probability with trial factors
up-going m’s w/ atmospheric n BG
down-going PeV m’s w/ cosmic-rays BG

9. GRB Search nm  m base T0: From a satellite GCN Zenith > 85 deg.
Off-time
On-time
Off-time
Precursor (~100 s)
GRB n modeling – individual GRB bases
Prompt
Guetta et al Astropart.Phys. 20 (2004) 429
Model Independent (24 h)
Background (full year)

10. No association of n’s with GRB..
Model-dependent limits
IceCube
IceCube +
IceCube
We are on the way to indicate GRBs are
unlikely to be a major UHECR origin.

11. Searches for a Diffuse Neutrino Flux
Diffuse Flux = effective sum from all (unresolved) extraterrestrial sources (e.g., AGNs)
Possibility to observe diffuse signal even if flux from any individual source is too weak for
detection as a point source
Search for excess of astrophysical neutrinos with a harder spectrum than background atmospheric neutrinos
Atmospheric , 
Harder Spectrum  (E-2)
Astro. 
Energy
Advantage over point source search:
can detect weaker fluxes
Disadvantages:
high background
must simulate background precisely
Sensitive to all three neutrino flavors in principle
Atm. 
Atm.  11

12. Diffuse n limit nm  m base Now below the Waxman-Bahcall limit
30 TeV ~ 10 PeV
Now below the Waxman-Bahcall limit
nm only
Waxman-Bahcall bound
(theoretical reference
estimated from cosmic rays flux
assuming optically thin sources)
IceCube
IC40
PRD (2011)

13. Diffuse n limit All flavor base By looking for cascade events
30 TeV ~ 10 PeV
By looking for cascade events
IceCube
IceCube
(expected)
PRD (2011)

14. GZK n search Detection Principle nm nt ne nm nt
Energy IceCube Depth
Zenith IceCube Depth
through-going track
And tracks arrive horizontally
Secondary m and t from n
nm nt
 Sensitive to
starting track/ cascade
Yoshida et al PRD (2004)
Directly induced events from n
ne nm nt
 Sensitive to

15. GZK n search Detection Principle Experimental verification
The detailed description available in
PRD (2010)
GZK n search
Detection Principle
Energy
 NPE (total # of photoelectrons)
Look for luminous (high NPE)
horizontal events
Experimental verification
Data
MC overestimates
NPE by ~18% MC
Sys. error
~ 7% in SIG rate
~ 50% in BG rate

16. GZK n search All flavor limits IceCube IceCube IceCube
PRD (2011)
All flavor
(ne + nm + nt)
limits
Systematic errors included
IceCube
IceCube
IceCube
(expected)
The world’s best all-flavor  upper limits to date from 106 to 1010 GeV

17. Expected EHE signal events
PRD (2011)
Models
The half IceCube
# of events
The full IceCube
(3 years)
　GZK1 (Yoshida et al) *
0.57
3.1
　GZK2 Strong Evol. (Sigl) **
0.91 (C.L 53.4%)
4.9
　GZK3 (ESS with WL=0.0) ***
0.29
1.5
　GZK4 (ESS with WL=0.7) ***
0.47
2.5
　GZK5 (Ahlers max) ****
0.89 (C.L 52.8%)
4.8
　GZK6 (Ahlers best fit) ****
0.43
2.3
　Z-Burst #
1.03 (C.L 55.7%)
5.1
　Top Down(SUSY) ##
5.68 (C.L 99.6%)
31.6
　Top Down(QCD) ###
1.19 (C.L 66.4%)
6.3
　W&B(evol) ^
3.7
24.5
　W&B(no evol) ^
1.1
5.5
IceCube
Here is the expected event rate for various models, with the half IceCube configuration and the full IceCube configuration.
It can be seen that by the 2012/5 we can expect a few GZK neutrinos.
*Yoshida et al The ApJ (1997), **Kalahsev et al , Phys.Rev.Rev. D (2002), ***Engel et al, Phys. Rev. D, 64(9):093010, 2001, ****Ahlers et al, Astropart. Phys (2010) #Yoshida et al, Phys.Rev.Lett (1998),##Sigl et al , Phys.Rev.Rev. D (1998), ^Razzaque et al(2003)

18. p-value for the background hypothesis ~0.2%
The Highest NPE event
IceCube
Keep
Cut
This event
p-value for the background hypothesis ~0.2%
(posteriori)
Detected in 2008 December 8th
NPE 2.55x105 photo-electrons
Zenith 64.7 deg
Aya Ishihara (Chiba)

19. Diffuse n limits – global picture
As of 2011 reported
All “IceCube” is “a half IceCube”
with configuration
RICE
ANITA
Auger
IceCube
HiRes
ANTARES 2010
IceCube EHE
PRD (2011)
IceCube UHE
PRD (2011)
IceCube VHE
1TeV
1PeV
1EeV
1ZeV

20. nN CC cross section bound with the IceCube 2008 observation
Flux of cosmic n
(“Beam Intensity”)
Cooper-Sarkar & Sarkar
JHEP01:075 (2010)
snNSM calculated by
Standard Model
predictions
S.Yoshida PRD (2010)

21. Fluxes at the IceCube depth Black Hole evaporation scenario
J.Alvarez-Muniz et al PRD 65, (2002)
x=1 SM
S.Yoshida PRD (2010)

22. Number of events in the IceCube 2008 run Black Hole evaporation scenario
Excluded
90 % C.L. (2.44 events)
Cosmic n intensity
@ 1 EeV
Expected
S.Yoshida PRD (2010)

23. MSSM Neutralino Dark Matterc
North CR m n m
Spin Dependent cross-section: Abundant hydrogen in Sun suitable
for spin dependent cross-section measures
Spin Independent cross-section: Many direct dark matter searches sensitive

24. Dark matter searches: Solar WIMPs
Determine the muon flux from the direction of the Sun
A few to 103 events per year
GeV to TeV energies
Limit the neutrino-induced muons from WIMP annihilation
A strong limit on SD cross-section and good potential
IceCube
IceCube
Phys. Rev. Lett arXiv:
IceCube Preliminary

25. Dark Matter from the Galactic Halo
Dark matter density profile
Dark matter model
IceCube
IC22 (275 days)
found no excess
PRD (2011)
Measure or limit