CCAPP DM Miniworkshop 1
IceCube Galactic Halo Analysis
Carsten Rott Jan-Patrick Huelss
CCAPP Mini WorkshopColumbus OH
August 6, 2009
1450 m
2450 m
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CCAPP DM Miniworkshop 2
1450 m
2450 mVeryclearice
Dust concentration
Ereco= 500 TeV
IceCube Detector and DeepCore
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General Detector Capabilities
Muon from IC40 Data
Tracks Cascades
Track-Like IceCube AMANDATime Resolution 2 ns 5-7 ns
Energy Resolution (log10E)
0.3 – 0.4 0.3 – 0.4
Field of View 2π 2π
Noise Rate low
Angular resolution <1o ~1.5-2.5o
Cascade-Like IceCube AMANDATime Resolution 2 ns 5-7 ns
Energy Resolution (log10E)
0.18 0.18
Field of View 4π 4π
Noise Rate low
Angular resolution 30o ~30-40o
IceCube Angular Resolution < 1°
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Dark Matter Searches
Solar Earth HaloNeutrino Flux, Scattering
cross-sectionNeutrino Flux, ? Neutrino Flux, Self-
annihilation cross-section
Muon neutrinos Muon neutrinos Muon neutrinos, Cascades
Background off-source on-source
Background simulations Background off-source on-source
Excess Excess Anisotropy, Spectrum
IceCube ( + Deep Core) IceCube ( + Deep Core) DeepCore ( + IceCube)
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Annihilation rate ∝r 2
Galactic Center on Southern hemisphere -30o
-Requires identification of down-going starting events
Neutrino signal “least detectable”, hence allows to set conservative limit on the total self-annihilation cross-section
[Yuksel, Horiuchi, Beacom, Ando (2007)]
Halo WIMPs
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Galactic center: cos(y)=1 (B=0,L=0)
Example: 10 degree zenith angle band mapped in galactic coordinates
[L=0,B=0]RA(f)
q
DfDf
A neutrino flux from annihilations in the Milky way halo might be observable as neutrino flux anisotropy.Use up-going tracks (from the Northern hemisphere) to have access to TeV range neutrinos.
Preliminary
Halo WIMPs
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Preliminary
What to look for ?
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• Deep Core Strings 6 strings with high quantum
efficiency PMTs, densely spaced 7 “standard” IceCube strings
located in best ice (below 2100 m exceptionally clear)
Interstring spacing 72m Uses high Quantum Efficiency PMTs,
that have about 40% higher efficiency Located in the deep ice Lower atmospheric muon
background Larger scattering length ~40m
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Deep Core Extension
arXiv:0810.3698
99
Fermi
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Effective Area
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ConclusionsIceCube DarkMatter Halo Analysis underway using
Northern Hemisphere with 22 string datasetAccess to Southern Hemisphere with IceCube 40 and
DeepCore will significantly improve sensitivityIceCube Neutrino Effective Area not so different from
Fermi
Conclusions
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Motivation
gap
Spin-dependent WIMP-proton cross-section
Spin-dependent WIMP-nucleon cross-section very difficult to access in direct detection experiments
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Search for an excess neutrino flux from the direction of the sunAnalysis performed with the IceCube 22 string detector and 104 days of livetime (when the sun below the horizon)
Solar WIMPs
Cold Dark Matter candidate particle is assumed to be the LSP (neutralino) in MSSM, R-parity conserving scenarioNeutralino is a Majorana particle and self-annihilatesConsider two annihilation channels:
– Hard: cc → W+ W–→ n n
– Soft: cc→ bb → n nConsider 7 neutralino masses from 50 GeV to 5 TeV
Solar WIMPscc
Preliminary
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(for equilibrium):
July 8, 2009 Carsten Rott - ICRC09 Lodz 13
Solar capture rate:
)07.0()1(~ HeSI
HSI
HSD
locallocalC v
C r
CA C21
Cross-section Limits
WIMP Annihilation Rate:
c
nm
nm
or
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CCAPP DM Miniworkshop
• Look for an excess of (muon) neutrinos in the direction of the sun
• No evidence for a signal observed• Upper limits on muon flux from neutralino
annihilations in the Sun
• Under the assumption of equilibrium condition in the Sun, a limit on the WIMP-Nucleon cross-section can be obtained
• For spin-dependent couplings, IceCube’s sensitivity is about 2-orders of magnitude better than direct searches arXiv: 0902.2460 (PRL 102, 201302)
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Solar WIMPs
Preliminary
Preliminary
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Solar WIMPs (AMANDA Limits and Future Prospects)
Preliminary
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• AMANDA analysis on-going• IceCube analysis on-going
• Understanding of low energy vertical tracks extremely important
CCAPP DM Miniworkshop
Earth WIMPs Dark Matter could be clustered in the
centre of the Earth
Annihilation signal might be
observable in vertically up-going
events
Earth WIMPs
Energy and zenith angle of muon neutrino events in the signal region
(see also “Search for Atmospheric Oscillations with IceCube”)
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nm
String Trigger:5 DOMs hit within a series of 7 DOMs within a time window of 1500ns
Preliminary
Earth WIMPs
Beginning with 40 string data, IceCube lowered the multiplicity 8 trigger threshold to 5 applying a string trigger
Preliminary
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Spin Independent Result
• Under the assumption of equilibrium condition in the Sun (and the assumption that capture is dominated by spin-independent cross-section), a limit on the WIMP-Nucleon cross-section can be obtained
• IceCube limits are competitive with direct detection experiments at WIMP masses, where IceCube is sensitive
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New stringent limit on the WIMP-nucleon scattering cross-section using IceCube 22-string data
DeepCore combined with IceCube will allow to probe a large region of SUSY parameter space that is difficult to access in direct detection experiments
Preliminary
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IceCube Detector StatusSeason Deployed2004-2005 1 string
2005-2006 8 strings
2006-2007 13 strings
2007-2008 18 strings
2008-2009 18+1 strings
04/05
05/06
06/0707/08
08/09
09/10
10/11
IC40
IC22
IC22IC40
DeepCore
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Systematic uncertainties on the effective volume:• Neutrino oscillation: 4%• Neutrino-nucleon cross-section: 3%• Muon propagation in ice: <1%• Proton propagation & absolute OM sensitivity: 17-24%• Spread in OM sensitivity: <5%• Time & position calibration: <5%• Signal MC statistics: 3-5%Total systematic uncertainty: 19-26%
Preliminary
Solar WIMP analysis