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Neutralino searches with AMANDA/IceCube –– past, present and future ––

Daan Hubert for the IceCube Collaboration dhubert@vub.ac.be Vrije Universiteit Brussel, Belgium. Neutralino searches with AMANDA/IceCube –– past, present and future ––. Outline. indirect neutralino detection with neutrinos published AMANDA-B10/AMANDA-II analysis methods, results

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Neutralino searches with AMANDA/IceCube –– past, present and future ––

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  1. Daan Hubert for the IceCube Collaboration dhubert@vub.ac.be Vrije Universiteit Brussel, Belgium Neutralino searches with AMANDA/IceCube–– past, present and future ––

  2. Outline • indirect neutralino detection with neutrinos • publishedAMANDA-B10/AMANDA-II analysis methods, results ongoing AMANDA-II analysis/detector improvements future IceCube expected sensitivities • conclusion

  3. Neutralinos as dark matter candidate neutralinos • main matter component of our Universe/Galaxy? • LSP = weakly interacting massive particle • mass/composition depend on SUSY model

  4. Neutralino detection indirect – annihilation in Standard Model particles in high regions

  5. ...with neutrino's neutralino signal • 30 GeV < Mc < 5000 GeV • rate depends on SUSY parameters • vertically upward (Earth)horizontal (Sun) atmospheric background • muons ~O(109) events/year downward going • neutrinos ~O(103) events/year all directions up down

  6. Amundsen-Scott South Pole station SouthPole IceCube AMANDA-II(not to scale)

  7. The IceCube neutrino detector AMANDA-B10(B13): 1997-1999 • 302-428 OMs on 10-13 strings • diameter ~120m, height ~500m AMANDA-II: 2000-... • 677 OMs on 19 strings • diameter ~200m, height ~500m IceCube: 2005-... • feb 2006: 9 strings deployed • diameter ~1000m, height ~1000m (more details in D. Hardtke’s talk) AMANDA-II IceCube  

  8. Experimental and simulated data experiment • 1997-1999: 5.0x109 events 536.6 days eff. livetime • 2001: 8.7x108 events 143.7 days eff. livetime simulation • neutralino: 50 GeV < M < 5000 GeV [DARKSUSY] hard (W+W-) and soft (bb/t+t-) ann. channel 90° <  < 113° (Sun)  ~ 180° (Earth) • atm. :[CORSIKA] 600 GeV < Ep < 1011 GeV 0° < p < 90° • atm. :[NUSIM/ANIS] 10 GeV < E < 108 GeV 80° <  < 180°

  9. Neutralino analysis strategy general analysis • optimize each neutralino model separately better sensitivity, especially for low energy models • blind analysis randomize azimuth/subsample data milestones • remove atmospheric muons ~O(109)direction, reconstruction quality, … • reduce atmospheric neutrinos ~O(103)final search bin • claim discovery or calculate limits estimate background from MC or off-source data

  10. Selection efficiencies Earth 1997-1999 Sun 2001 Astropart. Phys. (2006) 459-466 Astropart. Phys. (2006), in Press

  11. Data consistent with background Sun 2001 (Astropart. Phys. (2006) 459-466) Earth 1997-1999(Astropart. Phys. (2006), in Press) final search bin final search bin

  12. Muon flux limits – Earth ’97-’99 improvement (wrt. ’97) separate filter for each neutralino model better reconstructions more statistics ASTROPART. PHYS. (2006), in Press

  13. Muon flux limits - Sun 2001 1st AMANDA solar neutralino result 200m diameter enables robust reconstruction of horizontal tracks competitive with only 144 days lifetime 2001 ASTROPART. PHYS. (2006) 459-466

  14. Present efforts improvement on published analyses • more statistics multi-year data sets 2001-2003, 2000-2005 • better reconstructions more efficient background rejection • additional trigger more efficient for low energy (<250GeV) events • more refined systematics better ice model simulation

  15. Additional trigger: results sun neutralinos • Veff = (Nsel/Ngen)x Vgen • additional trigger improves signal selection efficiency for low energy models(at low levels in the analysis)

  16. AMANDA-II 2001-2003 preliminary 2001-2003 earth neutralinos • expected sensitivity, before unblinding • ~540 days lifetime • no systematic uncertainties included • better sensitivity for low energy models EARTH 01-03 preliminary

  17. Detection efficiency systematics detection systematics = OM sensitivity + muon propagation + ice model with systematicswithout systematics

  18. IceCube prospects Earth Sun

  19. Conclusion & outlook No statistically significant excess of neutralino-induced neutrinos from the center of the Earth or the Sun observed AMANDA upper limits on the muon flux competitive with other indirect searches Improvement of AMANDA data analysis is under way IceCube analysis will start soon!

  20. backup slides

  21. Rejection of atmospheric muons 1-dim – sequential cuts multi-dim – neural network esig(1-ebg) esig/sqrt(ebg) WIMP MC ATM. MU MC DATA NN output

  22. additional trigger multiplicity trigger 24 OMs within 2.5µs string trigger 6/9 (7/11) OMs within 2.5µs

  23. AMANDA-II 2001-2003 preliminary EARTH – preliminary 2001-2003(hard, soft)

  24. AMANDA-II 2001-2003 preliminary EARTH – preliminary

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