IceCube
High-energy Neutrino Astrophysics
Where we are and where we go

Shigeru Yoshida
Department of Physics
Chiba University2007-2008:
18 Strings

2006-2007:
13 Strings

2008・2009 Data
40 strings
80 IceTop tank

IceCube2009-2010
59 strings
2010-2011
79 strings

2005-2006: 8 Strings

1450m

2004-2005 : 1 String
80+6 Strings
60 Optical Modules
17 m between Modules
125 m between Strings
2450m

The IceCube Collaboration
Germany:

Sweden:USA:
Bartol Research Institute, Delaware
University of California, Berkeley
University of California, Irvine
Pennsylvania State University
Clark‐Atlanta University
Ohio State University
Georgia Tech
University of MarylandUniversity of Alabama, Tuscaloosa
University of Wisconsin‐Madison
University of Wisconsin‐River Falls
Lawrence Berkeley National Lab.
University of Kansas
Southern University and A&M
College, Baton Rouge
University of Alaska, Anchorage

Uppsala Universitet
Stockholm Universitet

UK:
Oxford University

Switzerland:
EPFL

DESY‐Zeuthen
Universität Mainz
Universität Dortmund
Universität Wuppertal
Humboldt Universität
MPI Heidelberg
RWTH Aachen

Belgium:
Université Libre de Bruxelles
Vrije Universiteit Brussel
Universiteit Gent
Université de Mons‐HainautJapan:
Chiba University

New Zealand:
University of Canterbury

33 institutions, ~250 members
http://icecube.wisc.edu

Gigantic operations

DOM
Digital Optical Module
HV Base“Flasher Board”
Main Board(DOM-MB)
10” PMT13” Glass(hemi)sphereData Filtering at South PolePY 2008 season
40 strings ~ a half of the completed IceCube

Simple Majority Trigger
8 folds with 5 μ sec

Muon Filter

EHE Filter

selects“up-going” tracks

selects“bright” events~20 Hz~1.3 Hz~ 950 Hz

Cascade Filter

Many others“cascade”-like events Min Bias
Moon
IceTop~17 Hzetc

NPE > 630 p.e.

To Northern Hemisphereselects

Point Source SearchMaterials to cookνμ Æ μ baseμ filtered, EHE filtered and min-bias events

Require Quality cuts in multiple stages

Common aspects
In many other analysis

Point source specificto filter out vastly dominateddown-going muons
to realize reasonable agreement
between MC and data
to create a sample of eventswith good angular resolution

ν skymap
up-going μ’s w/ atmospheric ν BG

down-going PeV μ’s w/ cosmic-rays BG

All sky search: post-trial p-value 18%
Hottest spot: RA 113.75 Dec 15.15 -log(p)=5.28
Jon Dumm (UW-Madison)

Source List Resultsp-value

Crab--BL Lac0.226
Mrk 501
0.421
Mrk 4210.142
M87--CygA
0.439
PKS 1622-297 0.048

IceCube Preliminary

The highest significancefrom list of the 39 IceCube sources

Pretrial 4.8 % Æpost-trial 62 % for the source list

* Shown here is only a part of the IceCube pre-determined source list

Jon Dumm (UW-Madison)

Point Source Sensitivity
IceCube Preliminary

Jon Dumm (UW-Madison)

Stacking Searches
p-value

Milagro Sources (17 sources)
9 TeV SNRs + 8 new associated with Fermi(6 SNRs with Fermi association)

32 %
1% (a posteriori)

Nearby starburst galaxies (127 sources)

33 %Clusters of glaxies (5 sources)

78 %Followed Murase, Inoue, Nagataki (2008)
Virgo, Perseus, Centaurus, Coma, Ophiuchus

Jon Dumm (UW-Madison)DiffuseνSearchO(100 TeV) ~ 10 PeV
Materials to cook
μ filtered, EHE filtered eventsνμ Æ μ baseRequire Quality cuts in multiple stages

Common aspects
In many other analysis

to filter out vastly dominateddown-going muons
to realize reasonable agreement
between MC and data

Diffuse analysis specificStronger cuts (than PS search) required forenhancing purity of ν sample

Now look at “energy” distribution
Calculates μ’s energy loss (dE/dX) from the Cherenkov γ profile

Sean Grullon (UW-Madison)

Final “Energy” distribution

O(100GeV~TeV)

Sean Grullon (UW-Madison)O(10TeV~100TeV)

Diffuse ν limit
Now below the Waxman-Bahcall limit
IceCube Preliminary

νμ only

This work

Sean Grullon (UW-Madison)

Atmospheric ν spectrum
The quality cuts by the similar philosophy
but with the BDT training method
An independent analysis with slightly different event selections

IceCube PreliminarydE/dX Æ EνSpectrum Unfolding
by SVD method
NIM A 372 (1996) 469

Warren Whuelsnitz (UMD)

No indication of prompt ν and new physics (e.g. quantum gravity)

GZKν
SearchO(PeV) ~ 10 EeV
Materials to cook
EHE filtered events

All ν flavor baseNo strong quality cuts necessary because..

Unique featuresin this particular analysis

these ν’s are more energetic thanatmospheric μ BG
Just increase energy thresholdin analysis leads to better S/NGZK analysis specific issues• Earth filters out signal ν as well

GZK ν search
Energy Dist. @ IceCube Depth

Detection Principle

Zenith Dist. @ IceCube Depth

Yoshida et al PRD 2004

through-going track

Secondary μ and τ from νÆ Sensitive tostarting track/ cascadeνμ ντ

Directly induced events from νÆ Sensitive toνe νμ ντAnd tracks arrive horizontally

The detailed description available in PRD (2010)

GZK ν search
Detection Principle
EnergyÆ NPE (total # of photoelectrons)

Look for luminous (high NPE)
horizontal events

Experimental verification
MC overestimates
NPE by ~18%

Sys. error~ 7% in SIG rate~ 50% in BG rate

DataMCGZK ν search

Aya Ishihara (Chiba)

Signal Selection Criteria for 2008 data (0.5xIceCube)
Level 1
• Pulse Cleaning – using only detectors with pulses
within [-4.4us 6.4us] from timing of the largest NPE• Nch > 200 and NPE > 103.5

Level 2
Shallow events removal of wrongly reconstructed eventsby looking at pulse hit profile on time - z-depth plane
Deep events

NPE>104

A typical deep event

shallow
deepgrazing at the bottom ofthe detector volumeIndex to estimate
track inclination for deep eventseventLength ≡ tLND − t 1stDHorizon

t1st

HorizontalÆ short length
Vertical Æ long length
Exhibited good agreement
between MC and data

DLongThe Largest NPE DOM

tLND

Aya Ishihara (Chiba)

GZK ν searchDistributions at level 2

Shallowhigher energy Æ

up-goinghorizontal

Deephigher energy Æ Aya Ishihara (Chiba)

Å more inclined

down-going

GZK ν search
Final level 3 cut
Selects bright(=high NPE) events penetrating long path from the earth surface
GZK MC (νe + νμ + ντ)Atmospheric μ MC

Obs. data

Shallow
Keep

KeepCutCut

higher energy ÆKeep
Cuthigher energy Æhigher energy ÆDeepCut

Cut Keep

Final BG 0.107 +/- 0.015 (stat.)
GZK
0.573 +/- 0.005 (stat.)+0.065- 0.103 (sys)+0.080 (sys)- 0.066

Keep

Aya Ishihara (Chiba)

GZK ν search
All flavor (νe + νμ + ντ) limits
Systematic errors included

Aya Ishihara (Chiba)

IceCube Preliminary

EHE ν Model Constraint
The 2008 half-IceCube observation
335.5 days sample

IceCube Preliminary

Expected # of events

GZK m=4 Zmax=4 (Yoshida et al ApJ 1997)

0.570

GZK m=5 Zmax=2 (Kalahsev et al PRD 2002)

0.910

GZK Λ = 0.7

0.470(Engel et al PRD 2001)

GZK Fermi constrained m=4.45 (Ahlers et al AstroP 2010)

0.885

GZK Fermi constrained γ=2.5 (Ahlers et al AstroP 2010)

0.431

Z-burst1.027

Top-down SUSY

(Yoshida et al PRL 1998)(Sigl et al PRD 1998)

5.677

excludedby 99.6 % C.L.

Constraints on Ultra-high energy
cosmic ray emission
Fermi limits UHECR luminosity at cosmological distances
Fermi-LAT collaboration PRL 2010Transparent

URB
IR/O
Energy Conservation
CMBE2dN
2 dN
EHE a EGeVdEdE

Constraints on Ultra-high energy
cosmic ray emission
Now IceCube : constrained UHECR cosmological luminosity
at the comparable level with Fermi, but more direct way

A major fraction of the Fermi
diffuse γ is NOT responsiblefor UHECR emissions

IceCuberejected

0.4 events expectedby I3 2008 runslerAhet

1020sy.phartpostral A

The Highest NPE event

KeepCutThis event
p-value for the background hypothesis ~0.2%(posteriori)Aya Ishihara (Chiba)• Detected in 2008 December 10th
• NPE 2.55x105 photo-electrons• Zenith 64.7 deg

The Highest NPE event

p-value for the background hypothesis ~0.2%(posteriori)

Aya Ishihara (Chiba)~ 10 PeV if background~ 100 PeV if (GZK) νNew dimensions in the near futureNew dimensions in the near future
hybrid analysis with IceTop

More multi-messenger analysis coming
Gamma-ray follow-up
Optical follow-up

On-going

Correlations with UHECRs
Extremely-high energy event alert

Patrick Berghaus (MPI-Heidelberg)We will reach this level

Conclusion• A half of full IceCube with 1 year operation
has already led to the world-best flux limit.
The 2008-9 run has marked….

9 the limit below the theoretical bound @ O(100 TeV)
9 GZK rate O(0.5 events) Æ started to constrain UHECR sources
9 rejection of the top-down scenarios
Obviously, more expected in the full operation starting soon

• Some interesting stuff observed; stay tuned.
9 correlations with Milagro/Fermi SNRs
9 The very high energy μ events

And we are getting even more bigger

The main contributors• (Time-independent) Pont Source
Jon Dumm, Chad Finley, Teresa Montarulli• Diffuse νμ search
Sean Grullon, Dima Chirkin, Gary Hill

• Atmospheric νWarren Whuelsnitz• Extremely-high energy (GZK) ν search
Aya Ishihara, Keiich Mase

BackupFlux SummaryDiffuse ν searchμ track likelihood distribution after the final cut

Systematic errors
in the diffuse ν searchLevel 2 cut for shallow events

Neutrino Effective Area
EHE (GZK) regime
IceCube Preliminary
IceCube 2008 Extremely-high energy

Relative Systematic Errors
in GZK (EHE) ν search
Signal rate

BG rateCosmic-ray
composition-83.9 %

Hadronic
Interaction model
Coincidence μ rate

+36.1%NPE yield+37.1%- 46.7%+29.4%+10.5%+3.9%- 7.2%

Neutrino-nucleon
cross section+/- 9.0%

Photo-nuclear
interaction+10.0%+/- 1.00%

LPM

TOTAL

+60.4% -96.0%+14.0% -11.6%