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Direct Search for Dark Matter with XENON100

Direct Search for Dark Matter with XENON100. Oral Examination Ethan Brown June 16, 2009. Overview. Evidence for the existence of Dark Matter Galactic Rotation Curves Gravitational Lensing Matter Distribution Dark Matter Candidates Properties of Dark Matter The Neutralino

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Direct Search for Dark Matter with XENON100

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  1. Direct Search for Dark Matter withXENON100 Oral Examination Ethan Brown June 16, 2009

  2. Overview • Evidence for the existence of Dark Matter • Galactic Rotation Curves • Gravitational Lensing • Matter Distribution • Dark Matter Candidates • Properties of Dark Matter • The Neutralino • Detection Methods • Liquid Xenon Detectors • XENON Experiment • My PhD Project PUT A PICTURE HERE

  3. Far from galactic center Newton says: Galactic Rotation Curves • Vera Rubin et al (1970) measured • Implies existence of Dark Halo

  4. Gravitational Lensing

  5. More Gravitational than Luminous Mass • Gravitational Lensing used to measure cluster mass • Compared to mass measured by X-ray observations • Implies Dark Gravitational Mass

  6. Chandra image of the Bullet Cluster shows baryonic matter displaced from gravitational matter

  7. WMAP measurement of CMB • Best Fit from WMAP : ΩBh2= 0.024 ± 0.001 ΩMh2= 0.14 ± 0.02 Remaining matter must be non baryonic Precision measurement of CMB anisotropy Measure both baryonic and non-baryonic matter densities

  8. What is the Universe made of? 70% Dark Energy 25% Dark Matter 5% Ordinary Matter

  9. What is Dark Matter? • A good candidate: • Has the correct abundance • Does not interact strongly with normal matter Charge and Color Neutral • Falls naturally out of larger theory • Is detectable by experiment Many proposed solutions: • WIMPS • MACHOS, Sterile Neutrinos, Mirror Matter, Extra Dimensions, Daemons... Heavy Particle m~100GeV Weak scale interactions with ordinary matter Thermal equilibrium at beginning of Universe Gives correct relic abundance

  10. Physics We Already Know • Standard Model of Particle Physics Standard Model of Cosmology

  11. SuperSymmetry (SUSY) • Extend Standard Model by imposing new symmetry between bosons and fermions • Doubles # of particles in SM

  12. SUSY Dark Matter Particles and sparticles masses differ Breaks electroweak symmetry • Broken symmetry • Hierarchy Problem • Unification of forces • R-Parity • Neutral SUSY particles Difference between Higgs mass and Planck scale Modified couplings DO meet in 1 point Needs to be conserved LSP is stable 4 neutralinos mass eigenstates The lightest neutralino is stable and is an excellent dark matter candidate

  13. Relic Density • Neutralino is Majorana Thermal Equilibrium Relic Abundance Remains

  14. Indirect Detection Experiments • Search for signatures of WIMP annihilation • Ground based telescopes • VERITAS, ANTARES, IceCube • Space telescopes • Fermi Telescope, PAMELA

  15. Direct Detection Experiments • Cryogenic Crystals • CDMS, CRESST, EDELWEISS • Measure Heat and Light • Liquid Noble Detectors (xenon, argon) • XENON, ZEPLIN, WARP, DEEP/CLEAN • Measure Charge and Light

  16. Status of Direct Detection Search • XENON10 • σ < 8.8 x 10- 44 cm2 at 100GeV • CDMS • σ < 6.6 x 10- 44 cm2 at 60GeV

  17. XENON Program • Liquid Xenon Detector • Direct Search for WIMP Nucleon Interactions • Located in Gran Sasso Underground Laboratory • Phased program • 10kg → 100kg → 1T...

  18. Evolution of XENON • XENON10 • Published Results 2008 • XENON100 • Take Data This Fall • XENON100 Upgrade • Approved for Construction • XENON 1Ton • Proposal submitted • XAX / MAX 10Ton • Published concept 2008

  19. Liquid Xenon Detectors

  20. Electron Recoil Discrimination • S2/S1 Cut • Separates nuclear from electron recoils • Cut at nuclear recoil mean • 99.9% Rejection Xenon 10 Calibration

  21. Self Shielding • Very short interaction length • Fiducial volume cut • Accept events from quiet center

  22. WIMP Signal in Liquid Xenon

  23. XENON100 Experiment • 170kg (50kg Fiducial) • Sensitivity σ ~ 2x10 - 45 cm2 at 100GeV

  24. XENON100 Detector • Low Background Materials • Purified Xenon by removing Kr85 • 242 PMTs in TPC and Active Veto • mm Position Resolution

  25. QUPID Photo Detector • Increased Detector Size requires Lower Background • Low Activity Photo Sensor being developed • 3” Photo Tube • Quartz Structure • Small APD at Center • Necessary for Large Scale Detectors QUartz Photon Intensifying Device (QUPID)

  26. XENON100 Upgrade • Next Phase of XENON Program • Already Approved and Funded • QUPIDs on bottom • R8520s on top • Run in Existing Shield in Gran Sasso

  27. Ton Scale and Beyond • 1 Ton → 10 Ton Target • 4pi QUPID Coverage • XAX 10Ton Detector • Xenon and Argon Targets • Dark Matter, Neutrinoless DBD, pp Solar Neutrinos

  28. My PhD Project • Final Assembly of XENON100 Detector • Software Development • PMT Calibrations • Complete Software Package • Monte Carlo Simulations • Signal Generation / Digitization • Reconstruction / Analysis • Analysis of XENON100 Data • R&D / Simulations for Large Scale Detectors

  29. Final Detector Assembly

  30. PMT Calibration • Illuminate PMTs in-situ with external LED • Measure Gain by single photo electron response

  31. Complete Software Package • Simulate every physical process • Particle Interactions • Gamma, Neutron, WIMP • Photon Propagation (Light Collection) • Electron Drift including Diffusion • Proportional Scintillation (S2) • PMT Response • FADC Digitization • Run Analysis Software on MC and Data

  32. Proportional Scintillation • Simulate Electron Trajectories near Anode • Generate S2 Photons by: N = 70(E/P – 1.3)P x • Use Light Simulations to Generate S2 Signal

  33. QUPID Screening • Screened 4 Mechanical Samples in Gran Sasso Gator Gamma Detector < 0.91 mBq/QUPID 238U < 2.1 mBq/QUPID 232Th

  34. QUPID Field Simulations • First Working • QUPID • Non-uniform electron collection

  35. Electron Trajectory Simulations • 1T Detector with Conventional Wires 10T Detector with Acrylic Vessel

  36. Light Collection Simulations

  37. Summary • Strong Observational Evidence for Dark Matter • Rotation Curves • Gravitational Lensing • Matter Distribution • SUSY and WIMPs as Dark Matter • SUSY as Extension of Particle Physics • Neutralino a Natural Dark Matter Candidate • Detecting Dark Matter • XENON100 Dark Matter Search • Future Large Scale Dark Matter Detectors

  38. BACK UP SLIDES

  39. Precision measurements of 21cm Hydrogen line • 21cm Hyperfine Transition • Precisely measure redshift → velocity • Follows Dark Matter Halo Model

  40. SUSY is Broken Symmetry • Broken SUSY implies particle and sparticle masses different • Automatically breaks Electroweak symmetry V = (|μ|2 + mH2)|H0|2 V = (|μ|2 + mHu2)|Hu0|2 + (|μ|2 + mHd2)|Hd0|2 – (BHu0Hd0 + c.c.) + 1/8 (g2 +g'2)(|Hu0|2 - |Hd0|2) Higgs Potential : Replaced by :

  41. Gauge Hierarchy Problem • In SM, mh ~ Λ naturally • But mh ~ 100 GeV and Λ ~ 1019 GeV Cancellation of 1 part in 1034

  42. SUSY Solves This • Extra term with opposite sign • Since SUSY is broken, cancellation not perfect

  43. Unification of Forces • Couplings do not meet at high energy • In SUSY, Couplings are modified • SUSY also explains αEM < αweak < αS

  44. Proton Decay and R Parity • SUSY allows Proton Decay • Forbid this with R Parity Conservation: • RP = (-1)2(B-L)+2S • Requires 2 super-particles in each interaction • Lightest SUSY Particle (LSP) is stable • Good Dark Matter Candidate

  45. Neutral SUSY Particles

  46. Power Spectrum Sensitive to Baryon Density • Ratio of 1st to 2nd peak gives baryon density. • Best fit from WMAP gives : • Remaining matter must be non-baryonic .

  47. Particle Simulations • Gammas and Neutrons • From Radioactive Decays in Materials • From Sources for Calibration

  48. Photon Propagation • Simulate UV Photons • Absorption in Xenon • Reflection off of Teflon and Liquid Surface • Estimate Collection Efficiency

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