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The Status of DAMA and Direct Detection of WIMPs Limits from DAMA and Other Experiments

The Status of DAMA and Direct Detection of WIMPs Limits from DAMA and Other Experiments. Christopher M. Savage Fine Theoretical Physics Institute University of Minnesota. Katie Freese (University of Michigan) Graciela Gelmini (UCLA) Paolo Gondolo (University of Utah) arXiv:0808.3607.

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The Status of DAMA and Direct Detection of WIMPs Limits from DAMA and Other Experiments

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  1. The Status of DAMA and Direct Detection of WIMPsLimits from DAMA and Other Experiments Christopher M. Savage Fine Theoretical Physics Institute University of Minnesota Katie Freese (University of Michigan) Graciela Gelmini (UCLA) Paolo Gondolo (University of Utah) arXiv:0808.3607 Cosmo 08 - DAMA and Direct Detection

  2. Overview • DAMA/NaI (1996-2002) • Observes annual modulation (6.3)  first claimed signal for direct detection of WIMPs • Apparent incompatibilities with other experiments in standard frameworks • Many proposed explanations, including spin-dependent couplings • DAMA/LIBRA (2003+) • Confirms annual modulation (8.2) • Can WIMP scattering still explain both DAMA signal and null results of other experiments? Cosmo 08 - DAMA and Direct Detection

  3. Outline • WIMP direct detection & modulation • DAMA modulation signal • Explanations and detector effects • Compatibility with other experiments (effective WIMP-nucleon couplings) Cosmo 08 - DAMA and Direct Detection

  4. Elastic Scattering and WIMP Detection • Direct detection • Annual modulation • Indirect detection (Sun/Earth) Cosmo 08 - DAMA and Direct Detection

  5. Detector WIMP Scatter WIMP Direct Detection Talk by Uwe Oberlack Goodman & Witten (1985) • Elastic scattering of WIMPoff detector nuclei • Rate: X = Ge, Xe, … • Recoils: • Efficiencies, quenching, multiple elements • CDMS, XENON, CRESST, TEXONO,CoGeNT, COUPP, etc. Cosmo 08 - DAMA and Direct Detection

  6. Direct Detection • Recoil spectrum Cosmo 08 - DAMA and Direct Detection

  7. 30 km/s WIMP Halo Wind ~300 km/s Annual Modulation Drukier, Freese & Spergel (1986) • Earth’s motion • With disk (June)Against disk (December) Cosmo 08 - DAMA and Direct Detection

  8. Annual Modulation Cosmo 08 - DAMA and Direct Detection

  9. Annual Modulation • DAMA/NaI & DAMA/LIBRA (R. Bernabei et al., 2008) Modulation amplitude: Sm = 0.0131 ± 0.0016 /kg/day/keVee (2-6 keVee) Cosmo 08 - DAMA and Direct Detection

  10. n WIMP Indirect Detection Silk, Olive & Srednicki (1985), Freese (1986) • Elastic scattering of WIMP off Sun/Earth nuclei gravitational capture annihilation (neutrinos) • Flux  XX = H, He, … • SuperK, AMANDA/IceCube, etc. Cosmo 08 - DAMA and Direct Detection

  11. Indirect Detection • Cross-sections • Gravitational capture  scattering • Annihilation  ann • Assumptions • No large WIMP/anti-WIMP asymmetry • Annihilation cross-section large “enough” • Annihilation not to light quarks Majorana () Relic abundance <annv> ~ 10-26 cm3/s Majorana () Cosmo 08 - DAMA and Direct Detection

  12. Axial vector(spin-dependent) Scalar(spin-independent) Effective Coupling • Effective Lagrangian (-quark): • SUSY 2q, 3q Cosmo 08 - DAMA and Direct Detection

  13. Scattering Cross-Section • Spin-independent (SI) • Couples to scalar density of quarks and gluons • Scales as A2 • MSSM: fp fn  only one parameter: SI,p • Spin-dependent (SD) • Couples to spin • Multiple form factors due to spins of proton and neutron groups • Does not scale with A Cosmo 08 - DAMA and Direct Detection

  14. Scattering Cross-Section • Total • Couplings • fp , fn , ap , an SI,p , SI,n , SD,p , SD,n (+ 2 signs) • SD scattering cross-section for a nucleon typically much larger (102 - 104+) than SI cross-section in CMSSM • Indirect detection: Sun is primarily hydrogen • Direct detection: SI A2 boost Cosmo 08 - DAMA and Direct Detection

  15. DAMA Modulation • DAMA/NaI (1996-2002)R. Bernabei et al., Riv. Nuovo Cim. 26N1, 1 (2003) • Observes annual modulation (6.3)  first claimed signal for direct detection of WIMPs • DAMA/LIBRA (2003+)R. Bernabei et al., arXiv:0804.2741 [astro-ph] • Confirms annual modulation (8.2) Cosmo 08 - DAMA and Direct Detection

  16. DAMA Modulation • DAMA/NaI (6.3) Bernabei et al. (2003) Cosmo 08 - DAMA and Direct Detection

  17. DAMA Modulation • DAMA/NaI + DAMA/LIBRA (8.2) Bernabei et al. (2008) Cosmo 08 - DAMA and Direct Detection

  18. DAMA Modulation Cosmo 08 - DAMA and Direct Detection

  19. DAMA Modulation • Requirements for DM signal • Cosine modulation • 1 year period • Phase ~ June 2nd (standard halo) • Modulation at low energies only • Modulation in single scatter events only (not in multiples) • Modulation amplitude  ~7% • Multiple hits 2-6 keVee -0.0004 ± 0.0006 cpd/kg/keVee • High energies • 90+ keV -0.05 ± 0.19 cpd/kg (one cycle) Cosmo 08 - DAMA and Direct Detection

  20. DAMA Modulation • Backgrounds/systematics • Temperature • Neutrons + other backgrounds • Radon • Muon flux modulation • Detector noise • None reproduce all signal characteristicsor capable of producing level of signal Cosmo 08 - DAMA and Direct Detection

  21. DAMA/NaI • Incompatible? • Standard framework • Spin-independent • Isothermal halo • Cutoff: mass > 30 GeV Cosmo 08 - DAMA and Direct Detection

  22. DAMA/NaI • Explanations/effects • Low mass WIMPs • P. Gondolo & G. Gelmini, PRD 71, 123520 (2005) • Streams/caustics • Gondolo & Gelmini (Ibid) • Spin-dependent couplings • CS, P. Gondolo & K. Freese, PRD 70, 123513 (2004) • F. Giuliani & T.A. Girard, PRD 71, 123503 (2005) • P. Ullio, M. Kamionkowski & P. Vogel, JHEP 0107, 044 (2001) • Inelastic scattering • D. Tucker-Smith & N. Weiner, PRD 72, 063509 (2005) • Mirror matter • R. Foot, PRD 74, 023514 (2006) • Etc. • Channeling effect • Migdal effect Cosmo 08 - DAMA and Direct Detection

  23. Low mass WIMPs • Relax 30 GeV mass cut – scattering off Na P. Gondolo & G. Gelmini, PRD 71, 123520 (2005) Cosmo 08 - DAMA and Direct Detection

  24. Spin-dependent • Spin-dependent couplings CS, P. Gondolo & K. Freese, PRD 70, 123513 (2004) F. Giuliani & T.A. Girard, PRD 71, 123503 (2005) P. Ullio, M. Kamionkowski & P. Vogel, JHEP 0107, 044 (2001) Cosmo 08 - DAMA and Direct Detection

  25. Channeling • Nuclear recoil energy (keV) • Electrons – ionization/scintillation • electron equivalent (keVee) • Other nuclei – phonons/heat • Quenching factor Q: • fraction of recoil energy into measured channel • QNa 0.3, QI 0.09  2 keVee DAMA event from: • 6.7 keV Na recoil • 22 keV I recoil Cosmo 08 - DAMA and Direct Detection

  26. Channeling • Ion channeling (R. Bernabei et al., 2008) • Recoils along channels in crystal • Energy dependent fraction of recoils have Q 1 Cosmo 08 - DAMA and Direct Detection

  27. DAMA Channeling Bernabei et al. (2008) Cosmo 08 - DAMA and Direct Detection

  28. Migdal Effect Migdal (1941) • Velocity change of recoiling nucleus excited/ionized electrons • Extra EM energy (ionization/scintillation) Bernabei et al. (2007) Cosmo 08 - DAMA and Direct Detection

  29. DAMA Migdal Effect Bernabei et al. (2008) Cosmo 08 - DAMA and Direct Detection

  30. DAMA/LIBRA • DAMA/LIBRA analyses (selected) • CS, G. Gelmini, P. Gondolo & K. Freese, arXiv:0808.3607 [astro-ph] • F. Petriello & K.M. Zurek, arXiv:0806.3989 [hep-ph] • S. Chang, A. Pierce & N. Weiner, arXiv:0808.0196 [hep-ph] • D. Hooper, F. Petriello, K.M. Zurek & M. Kamionkowski, arXiv:0808.2464 [hep-ph] • Assumptions • Isothermal spherical halo model • Elastic scattering Cosmo 08 - DAMA and Direct Detection

  31. DAMA/LIBRA • Binning • Channeling • Statistical methods • Spin-independent (SI) • Spin-dependent (SD) • Proton-only coupling (an = 0) • Neutron-only coupling (ap = 0) • Equal magnitude (an = ±ap) • General couplings Cosmo 08 - DAMA and Direct Detection

  32. DAMA Binning • DAMA/NaI: 2 bins • Low energy • 2-4 keVee 0.0252 ± 0.0050 cpd/kg/keVee • 2-5 keVee 0.0215 ± 0.0039 cpd/kg/keVee • 2-6 keVee 0.0200 ± 0.0032 cpd/kg/keVee • High energy • 6-14 keVee -0.0009 ± 0.0019 cpd/kg/keVee • DAMA/NaI + DAMA/LIBRA: 36 bins • Low energy (2-5 keVee): positive modulation signal • High energy (~6-20 keVee): consistent with zero modulation Cosmo 08 - DAMA and Direct Detection

  33. DAMA Binning Cosmo 08 - DAMA and Direct Detection

  34. DAMA Binning Cosmo 08 - DAMA and Direct Detection

  35. DAMA Binning Cosmo 08 - DAMA and Direct Detection

  36. DAMA Channeling Cosmo 08 - DAMA and Direct Detection

  37. DAMA Channeling Cosmo 08 - DAMA and Direct Detection

  38. DAMA Statistical Tests • Likelihood ratio confidence region • Parameter estimation – preferred region • 2 goodness of fit (g.o.f.) • Excluded region Cosmo 08 - DAMA and Direct Detection

  39. DAMA Statistical Tests Cosmo 08 - DAMA and Direct Detection

  40. DAMA Statistical Tests Cosmo 08 - DAMA and Direct Detection

  41. Null Experiments Cosmo 08 - DAMA and Direct Detection

  42. Spin-independent Cosmo 08 - DAMA and Direct Detection

  43. Spin-independent Cosmo 08 - DAMA and Direct Detection

  44. Spin-independent Cosmo 08 - DAMA and Direct Detection

  45. Spin-dependent: proton-only (an = 0) Cosmo 08 - DAMA and Direct Detection

  46. Spin-dependent: proton-only (an = 0) Cosmo 08 - DAMA and Direct Detection

  47. Spin-dependent: proton-only (an = 0) Cosmo 08 - DAMA and Direct Detection

  48. Spin-dependent: neutron-only (ap = 0) Cosmo 08 - DAMA and Direct Detection

  49. Spin-dependent: neutron-only (ap = 0) Cosmo 08 - DAMA and Direct Detection

  50. Spin-dependent: neutron-only (ap = 0) Cosmo 08 - DAMA and Direct Detection

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