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IceCube Galactic Halo Analysis . Carsten Rott Jan-Patrick Huelss CCAPP Mini Workshop Columbus OH August 6, 2009. 1450 m. 2450 m. IceCube Detector and DeepCore. E reco = 500 TeV. 1450 m. Dust concentration. 2450 m. Very clear ice. General Detector Capabilities.

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slide1

IceCube Galactic Halo Analysis

Carsten Rott

Jan-Patrick Huelss

CCAPP Mini Workshop

Columbus OH

August 6, 2009

1450 m

2450 m

CCAPP DM Miniworkshop

slide2

IceCube Detector and DeepCore

Ereco= 500 TeV

1450 m

Dust concentration

2450 m

Very

clear

ice

CCAPP DM Miniworkshop

general detector capabilities
General Detector Capabilities

Muon from IC40 Data

Cascades

Tracks

IceCube Angular Resolution < 1°

3

CCAPP DM Miniworkshop

slide4

Dark Matter Searches

CCAPP DM Miniworkshop

slide5

Annihilation rate ∝r 2

Halo WIMPs

  • 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)]‏

CCAPP DM Miniworkshop

slide6

Halo WIMPs

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.

Galactic center: cos(y)=1 (B=0,L=0)‏

q

Example: 10 degree zenith angle band mapped in galactic coordinates

Preliminary

Df

Df

CCAPP DM Miniworkshop

RA(f)‏

[L=0,B=0]

slide7

What to look for ?

Preliminary

CCAPP DM Miniworkshop

slide8

Deep Core Extension

  • 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

CCAPP DM Miniworkshop

8

8

slide9

Effective Area

Fermi

CCAPP DM Miniworkshop

arXiv:0810.3698

9

9

conclusions
Conclusions

IceCube DarkMatterHalo Analysis underway using Northern Hemisphere with 22 string dataset

Access to Southern Hemisphere with IceCube 40 and DeepCore will significantly improve sensitivity

IceCube Neutrino Effective Area not so different from Fermi

Conclusions

CCAPP DM Miniworkshop

slide11

Motivation

Spin-dependent WIMP-proton cross-section

gap

Spin-dependent WIMP-nucleon cross-section very difficult to access in direct detection experiments

CCAPP DM Miniworkshop

slide12

Solar WIMPs

Solar

WIMPs



Search for an excess neutrino flux from the direction of the sun

Analysis performed with the IceCube 22 string detector and 104 days of livetime(when the sun below the horizon)

  • Cold Dark Matter candidate particle is assumed to be the LSP (neutralino) in MSSM, R-parity conserving scenario
  • Neutralino is a Majorana particle and self-annihilates
  • Consider two annihilation channels:
    • Hard: cc → W+ W–→ n n
    • Soft: cc→ bb → n n
  • Consider 7 neutralino masses from 50 GeV to 5 TeV

Preliminary

CCAPP DM Miniworkshop

slide13

c

nm

Cross-section Limits

nm

Solar capture rate:

WIMP Annihilation Rate:

(for equilibrium):

or

CCAPP DM Miniworkshop

July 8, 2009

Carsten Rott - ICRC09 Lodz

13

slide14

Solar WIMPs

  • 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

Preliminary

Preliminary

  • 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)

CCAPP DM Miniworkshop

slide15

Solar WIMPs (AMANDA Limits and Future Prospects)

Preliminary

CCAPP DM Miniworkshop

slide16

Earth WIMPs

Earth WIMPs

  • Dark Matter could be clustered in the centre of the Earth
    • Annihilation signal might be observable in vertically up-going events
  • AMANDA analysis on-going
  • IceCube analysis on-going
    • Understanding of low energy vertical tracks extremely important

Energy and zenith angle of muon neutrino events in the signal region

(see also “Search for Atmospheric Oscillations with IceCube”)

CCAPP DM Miniworkshop

slide17

Earth WIMPs

Beginning with 40 string data, IceCube lowered the multiplicity 8 trigger threshold to 5 applying a string trigger

Preliminary

Preliminary

String Trigger:

5 DOMs hit within a series of 7 DOMs

within a time window of 1500ns



CCAPP DM Miniworkshop

slide18

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

CCAPP DM Miniworkshop

slide19

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

CCAPP DM Miniworkshop

slide20

IceCube Detector Status

07/08

IC22

06/07

IC40

IC40

IC22

DeepCore

09/10

05/06

08/09

10/11

04/05

CCAPP DM Miniworkshop

slide21

Solar WIMP analysis

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

CCAPP DM Miniworkshop