Searches for Dark Matter and
Neutrino Oscillations with IceCube
Carsten Rott
Pennsylvania State University
CCAPP Ohio State University
Columbus, Ohio
March 25, 2008
March 25, 2008
Carsten Rott - CCAPP Seminar
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Overview
•
•
•
•
•
•
Neutrino Astroparticle Physics
IceCube Neutrino Observatory
Recent Results
Dark Matter
Neutrino Oscillations
Extensions and Outlook
March 25, 2008
Carsten Rott - CCAPP Seminar
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Cosmic Neutrino Sources
p + (p or )  0   
 ±  e  e
(1:2:0)
(1:1:1)
• Protons interact in target
and produce pions
• Neutral pions  photons
• Charged pions  neutrinos
• Oscillations result in 1:1:1
flavor ratio at detector
Sources:
• Active Galactic Nuclei
• Supernova Remnants
• Gamma Ray Bursts
March 25, 2008
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Astronomical Messengers
AMANDA
IceCube
Protons
• bent below 10 EeV
• above 50EeV GZK cut-off
Photons
• scattered/absorbed above 50 TeV
Neutrinos
• Unobscured view
• Point back to their sources
• Cover entire energy spectrum
March 25, 2008
Carsten Rott - CCAPP Seminar
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Active Galactic Nuclei
as cosmic accelerators
Auger Collaboration:
20 of 27 events with E > 57 EeV
are within 3.1 degrees of an AGN
less than 75 Mpc away.
Centaurus-A (4 Mpc, white dot) is
especially prominent.
( 57 EeV = 0.01 Joule )
( 1 Mpc = 3 million light years )
•
•
AGN are cosmic accelerators
Accelerated protons may (or may not)
interact in or near the sources
to produce neutrinos
We want to find out by looking
for neutrinos from AGN
March 25, 2008
Carsten Rott - CCAPP Seminar
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A Generic Optical Neutrino Telescope
• Neutrinos interact in or near
the detector
• O (km) muons from νμ
• O (10m) cascades from νe, ντ, NC
l, νl
νl
W, Z
Cherenkov
radiation
hadronic
shower
• Optical modules record:
• absolute time with high precision
• March
intensity
of light (photon
counting)
25, 2008
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…Dumand
Optical Neutrino Telescopes
Nemo
Lake Baikal
Antares
Nestor
KM3Net
March 25, 2008
AMANDA /
IceCube
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The IceCube Collaboration
University of
Alaska, Anchorage
University of California,
Berkeley
University of California, Irvine
Clark-Atlanta University
University of Delaware / Bartol
Research Institute
University of Kansas
Lawrence Berkeley Natl.
Laboratory
University of Maryland
Pennsylvania State University
Southern University and A&M
College
University of Wisconsin,
Madison
University of Wisconsin, River
Falls
Stockholms Universitet
Uppsala Universitet
Vrije Universiteit Brussel
Université Libre de
Bruxelles
Universiteit Gent
Université de MonsHainaut
Chiba University
University of Canterbury,
Christchurch
Universiteit Utrecht
Universität Dortmund
Oxford University
MPIfK Heidelberg
Humboldt Universität, Berlin
Universität Mainz
Team South Pole
DESY, Zeuten
BUGH Wuppertal
March 25, 2008
Carsten Rott - CCAPP Seminar
RWTH Aachen
8
Amundsen Scott
South Pole Station
South Pole
IceCube
Living
facilities
AMANDA
March 25, 2008
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The IceCube Detector
Instrumenting 1km3 of Antarctic Ice
to detect extraterrestrial neutrinos
Counting House
IceTop
Surface air shower array
InIce
70+ strings, each with 60
digital optical modules
(DOM)
AMANDA
17 m between modules
125 m string separation
IceCube is sensitive to neutrinos of all
flavors at energies from ~1011 eV to 1020
eV
March 25, 2008
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10
Digital
DigitalOptical
OpticalModule
Module (DOM)
(DOM)
10 inch Hamamatsu PMT (R-7081-02)
Ø~32.5 cm
Measure individual photon
arrival time:
• 2 ping-ponged four-channel
Advanced Transient Waveform
Digitizers:
• 128 samples (400 ns
max range)
• ~3.3ns bin
• 400 pe / 15 ns
• Fast Analog-to-Digital
Converter:
• 40 MHz
• 6.4 s range
• Dark Noise rate ~ 700 Hz
• Local Coincidence rate ~ 15 Hz
• Deadtime < 1%
• Signal digitized in the ice
March 25, 2008
Carsten Rott - CCAPP Seminar
Example:
Digitized Waveform
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IceCube Deployments to Date
78
76
75
74
73
72
71
70
69
68
64
63
62
56
55
59
58
57
54
52
67
66
65
61
60
77
AMANDA
53
47
44
45
50
49
48
46
2004-2005
1 string deployed
First data
astroph/0604450
2005-2006
8 string deployed
40
39
38
30
29
21
2006-2007
13 strings
deployed
2007-2008
18 strings
deployed and
commissioned
50 % of full detector installed (40 strings to date)
Completion by 2011!
March 25, 2008
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Muon bundle from interaction of a highenergy cosmic ray in the atmosphere
IceCube real-time event viewer at pole
March 25, 2008
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IceCube Data Quality Assurance
• Example: Use in situ
remotely-controllable
LEDs and downwardgoing muons to check
relative DOM timing
– DOMs have individual
free-running clocks
– clocks must be
calibrated to within
several ns to allow us
to reconstruct events
– figure shows example
of how this works
with LEDs
March 25, 2008
Dt
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18 new strings
As IceCube is a newly constructed detector, we first verify
the detector performance in order to achieve physics goals
 Stability and performance verified
 Very successful deployment season this year
 New strings seem to be working fine
 IceCube 50% complete
 IC-40 physics run will start end of April
Relative sensor efficiency

Time between Events
Nucl.Phys.B, Proc.Suppl.175-176:409-414,2008.
Integrated Exposure
• 1 km3∙yr by early 2009
• Close to 4 km3∙yr after
one year of operations
5
80
km3·yr
Strings
4.5
70
4
with full detector
60
3.5
+IC9
AMANDA
March 25, 2008
KM3NeT
ANTARES
km3·yr
Full IceCube
|
+IC36-40
+IC22
2.5
40
2
30
1.5
20
1
10
0.5
0
2005
Carsten Rott - CCAPP Seminar
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2006
2007
2008
2009
2010
2011
2012
Date
16
# Deployed Strings
50
3
Scientific Scopes
?
Energy
Physics
~MeV
GeV-TeV
TeV-PeV
PeV-EeV
Supernovae
Neutralino
Atmospheric 
Point sources
(AGNs, GRBs,
MQs) and
AGNs, TDs,
GZK neutrinos
?
Almost
horizontal events
Down-going

EeV
Diffuse
Signature
March 25, 2008
Average
increase in the
PMT counting
rate
Up-going muons
Contained
events
Up-going muons
and cascades
Carsten Rott - CCAPP Seminar
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Alien signals ?
March 25, 2008
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IC9 - Diffuse Analysis
Comparison of atm. muon
neutrino predictions to
data
AMANDA-II 2000-2003 data
Lifetime 807days
E-2 < 7.4x10-8GeVcm2s-1sr-1
Phys Rev. D76, 042008 (2006)
March 25, 2008

Atmospheric neutrinos behave like E-3.7

Typical extraterrestrial fluxes behave like E-2
IceCube-9 2006 data
Lifetime 137days
E-2 < 1.3x10-7GeVcm2s-1sr-1
Carsten Rott - CCAPP Seminar
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Limit on diffuse extraterrestrial fluxes
AMANDA HE analysis
Baikal
IceCube 9 – 137days
AMANDA-II 4yr
WB Limit
Icecube,
muons & cascades
4 years
GRB (WB)
March 25, 2008
IceCube muons,
1 year
Carsten Rott - CCAPP Seminar
2003
2006
2009
2013
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Neutrinos from GRBs
 Search time window: from 10 sec before
the burst start to the end of the burst.
 Precursor: from -110 sec to -10 sec.
 Background estimation: from 1 hour
before to 1 hour after (except 10 minutes
around the burst)
10-7
BATSE, IPN, SWIFT


close to WB
within < factor 2
with IceCube:
test WB within
a few months
E2flux (GeVcm-2s-1sr-1)
Check for coincidences with
AMANDA limit from 408 bursts
1997-2003
10-8
Waxman-Bahcall
GRB prediction
10-9
10-10
104
March 25, 2008
105
106
107
neutrino energy E (GeV)
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AMANDA Point Source Analysis
Signal hypothesis  E-2
On-Source
OffSource
= 2.25°-3.75°
Optimal search window
2000-2004:
4282 up-going events
1001 days live-time
March 25, 2008
Search for an excess of events
• from candidate sources
• anywhere on the northern sky
Atm- Background from ‘off-source’ data
Carsten Rott - CCAPP Seminar
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Grid search for neutrino point sources ...
Limit map
90% confidence level flux upper limits for the northern
hemisphere (15% systematic error included)
March 25, 2008
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Search for neutrinos from candidate objects
1ES1959
Cyg-X3
Mk421
Mk501
Cyg-X1
crab
M87
SS433
3C273
event selection optimized for both dN/dE ~E-2 and E-3 spectra
expected
background
(5 years)
(5 years)
E-2 flux upper limit
(90% c.l.)
-11
[10 TeV-1 cm-2 s-1]
Markarian 421
6
7.4
7.4
M87
6
6.1
8.7
1ES 1959+650
5
4.8
13.5
3C 273
8
4.72
18.0
SS433
4
6.1
4.8
Cygnus X-3
7
6.5
11.8
Cygnus X-1
8
7.0
13.2
6.7
17.8
source
•
Systematic error on signal
prediction included in
limits
March 25, 2008
AGN
No significant excess, no
indication for a neutrino
source
Microquasar
•
… out of 32 sources in
candidate list
SNR
•
Crab
Nebula
10
Carsten
Rott - CCAPP Seminar
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No significant excess observed
nr. of 
events
st
1
March 25, 2008
IceCube Sky Map
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Dark Matter
Strong observational evidence for dark matter

Rotational profiles

Gravitational lensing

Large scale structures

WMAP’s measurement anisotropy measurement of the cosmic
microwave background
Characteristics of Dark Matter (DM)




Stable
Non baryonic
Non relativistic
Weakly interacting particle
-> “Weakly Interacting Massive Particles”
In low energy SUSY with R-parity conserved, the Neutralino is an
excellent candidate for dark matter
March 25, 2008
Carsten Rott - CCAPP Seminar
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WIMPs
Massive bodies could gravitationally trap Dark Matter

The Sun could capture WIMPs directly

WIMPs orbiting the sun could be captured by the Earth
Neutralinos could accumulate in the center of these massive bodies and
annihilate to produce neutrinos as part of the annihilation products
Neutrino Telescopes can search indirectly for DM by detecting these neutrinos
Solar capture rate:
Annihilation rate (for equilibrium):
C ~ local (
1
vlocal
) (    0.07 )
March 25, 2008
3
H
SD
H
SI
He
SI
1
  C
2
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WIMPs signal
March 25, 2008
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Earth WIMPs
March 25, 2008
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Earth WIMPs




No statistically significant
excess of neutralino induced
neutrinos from the center of
the Earth
AMANDA limits competitive
with other indirect searches
AMANDA String trigger
essential for low energy
sensitivity
More data being analyzed
now
March 25, 2008
Carsten Rott - CCAPP Seminar
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Solar WIMPs
c
Cosmic Rays:
Earth



Analysis Strategy:
Scramble azimuth and use entire
dataset for cuts optimization
Detector
Off-source data to predict background
March 25, 2008
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Solar WIMPs
March 25, 2008
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Solar WIMPs
•
•
•
•
No statistically
significant excess of
neutralino induced
neutrinos from the
center of the Sun
AMANDA limits
competitive with other
indirect searches
AMANDA String trigger
essential for low energy
sensitivity
More data being
analyzed now
March 25, 2008
Carsten Rott - CCAPP Seminar
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Contained and Partially contained events
•


Inner
Core
AMANDA
– Fully integrated detector
– Combined trigger / event
builder
– New AMANDA DAQ has
lower energy threshold
•
7 IceCube + 18 AMANDA
strings form a densely
instrumented “Inner Core”
– Lower energy threshold
•
Peripheral IceCube strings
form veto volume
– Especially useful for
physics with contained
and partially-contained
events
veto
IceCube 07
March 25, 2008
Carsten Rott - CCAPP Seminar
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Atmospheric Muon Neutrino Sensitivity
Atmos. 
per 200 days
(trigger level,
IC22+AMANDA)
8200
incl.
AMANDA
AMANDA forms more densely
instrumented sub-array inside IceCube
 Lower energy threshold
 Contained events
Increased WIMP sensitivity has been
achieved using this method
30 GeV!
5400
IceCube
only
March 25, 2008
Gross, Tluczykont, Ha, Rott, DeYoung,
Resconi, & Wikström, ICRC 2007
Carsten Rott - CCAPP Seminar
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Solar WIMP Sensitivity
AMANDA
limits:
astro-ph/
0508518
current
AMANDA-II
2001
Expected sensitivity with
IC22 + AMANDA
G. Wikström ICRC 2007
March 25, 2008
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Combined IceCube & AMANDA
Detector
• Improved angular resolution
March 25, 2008
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Atmospheric Neutrinos in IceCube
Final Cuts
Achterberg et al. astro-ph/0705.1781
March 25, 2008
Carsten Rott - CCAPP Seminar
• 9-string data
(2006)
• Cosmic ray
background
seen with
weak cuts
• Atmospheric
neutrinos
seen with
strong cuts
• Agreement in
event rate
over 6
decades
38
IceCube String Trigger Sensitivity
•
Topological trigger allow to lower the energy threshold further
compared to the default multiplicity 8 trigger
– Selects events based on a certain pattern present in the detector
•
IceCube geometry especially sensitive to vertical events
•
String Trigger selects events
consistent with vertically
up/down-going muons
•
String Trigger essential for:
– Dark Matter searches
30GeV
• Earth Wimps
• Halo Wimps
– Neutrino Oscillations
March 25, 2008

Detectable events were defined as events that
have at least one hit in the detector
Carsten Rott - CCAPP Seminar
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 disappearance
•
Lowest energy threshold is realized in vertical events
Reconstruction might be possible for those events due to the IceCube
geometry
E<30 GeV reachable with vertical muons
–
17m spacing in z-dimension
• muon travels ~5 m/GeV
 survival probability
•
•
2
D
m
L
P  = 1  sin 2 2 23cos 413sin 2 31  Pme
4 Eν
Dm2 = 2.4e-3 eV2
vertically upward 
E (GeV)
• need at least 5 DOMs: 68 m
• E,min = 68/5 = 14 GeV (E,min = ~25 GeV)
–
up/down could be used for normalization
• difficult due to background contributions, “directionality”
DOMs (face down)
–
Related idea discussed in Albuquerque and Smoot,
PRD.64.053008
–
issues:

4x17m

• Kinematic - angle
• ~flat inelasticity (y) distribution
• Atmospheric muon background
March 25, 2008
Carsten Rott - CCAPP Seminar
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Kinematic angle smears out
directional information of
low energy neutrinos
Muon neutrino survival probability
Does not really effect study
of first oscillation maximum
E < 100GeV
String triggered
Akhmedov, Maltoni & Smirnov, hep-ph/0612285
March 25, 2008
Carsten Rott - CCAPP Seminar
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Why study neutrino oscillations in
IceCube now ?
• Never been observed (tested) at the energy range
accessible to IceCube (E ~ 20-50 GeV)
• Actual observation of a “signal”
• Energy reconstruction especially challenging, this can also
serve as a cross-calibration measurement
• 40km of strings available now
– Several thousand high quality “low” energy vertical neutrinos
events per year
March 25, 2008
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Low energy extensions of IceCube
0m


Funding for 6strings recently approved.
Shows clear interest in 10-100GeV
Neutrino physics
AMANDA
Favored design

6 strings each with 60 DOMs, spaced by
10 m (final geometry choice end of April)

located in best ice (below 2100 m
exceptionally clear)

Large veto region from top and
surrounding strings against down-going
muons -> 4pi steradians

deep core
1500m
2100m
uses IceCube technology … but HQ PMTs
2500m
March 25, 2008
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Low Energy Extensions
•
•
•
•
Forms dense sub-array
Large veto region can more
effectively remove downgoing muon background
Considerably better
performance at low
energies
Would be deployed in the
deep ice
– Lower atmospheric muon
background
– Clear ice (below 2100m)
– Effective Veto from
surrounding IceCube
strings and DOMs above
First string end of this year !
March 25, 2008
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Physics with Deep Core
•
•
•
•
•
•
•
•
•
•
4 Pi detector and 24 h
Wimp improvements
Galactic Centre - Galactic plane
Low energy atmospheric neutrinos
Oscillations
Neutrino Tomography
Cascade direction and reconstructions
Atmospheric electron neutrino spectrum
Staus
Monopoles
March 25, 2008
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March 25, 2008
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Neutrino Mass Hierarchy
• Matter effects enhance the oscillation probability
for (anti-)neutrinos if the mass hierarchy is normal
(inverted)
• In the relevant energy range the anti-neutrino
cross-section is smaller than that of neutrino by
roughly a factor of 2
hep-ph/08033044
March 25, 2008
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Neutrino Mass Hierarchy
Normal hierarchy
Inverted hierarchy
Vertical tracks
10 years exposure
March 25, 2008
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Conclusions
• IceCube finished phenomenal season 07/08 with 18
new strings deployed
• AMANDA and IceCube are operating jointly and
collecting data
• First physics results of IceCube already competitive
with AMANDA
• Dataset especially interesting towards low energy
analysis
• New searches for WIMPs, Neutrino Oscillations, ...
underway
• Studies towards new deeper low energy core ongoing
– design choices to be made in about a month
• … many more exciting results to come (Neutrino 08)
March 25, 2008
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Backup Slides
March 25, 2008
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IceCube  Flavor Separation
Neutrino flavor

full flavor ID
e
e
(supernovæ)
showers vs. tracks

6
9
12
15
18
21
Log(E/eV)
March 25, 2008
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WIMPs Sensitivity
Earth
Sun
March 25, 2008
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Observations in the direction of
1ES 1959+650
An interesting coincidence with a gamma ray flare:
3.7 atmospheric neutrino events expected between 2000 and 2003.
5 events observed, incl. 3 in 66 days in 2002, during active period of source
“Orphan flare”
(MJD 52429)
AMANDA events within 2.25o of
the direction of 1ES 1959+650
March 25, 2008
Carsten Rott - CCAPP Seminar
Whipple light curve
[Holder et al 2003]
53
Supernova Neutrino Search
Bursts of low-energy (MeV) neutrinos
from core collapse supernovae
e+ p  n + e+
SNEWS (SuperNova Early Warning System)
is a collaborative effort among Super-K, SNO,
LVD, KamLAND, AMANDA, BooNE and
gravitational wave experiments
The produced positron is emitted
almost isotropically
AMANDA
Detection via rate increase of the dark
noise rate
Count rates
Simulation
(IceCube)
IceCube
30 kpc
O(10cm) long tracks
0
March 25, 2008
5
10sec
- AMANDA sees 90% of the galaxy
- IceCube will see out to the LMC
Carsten Rott - CCAPP Seminar
(Large Magellanic Cloud, ~50 kpc)
54