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DRIFT I experiment for Dark Matter Search

DRIFT I experiment for Dark Matter Search. Rachid Ayad , Temple University, for: R. Ayad, C. J. Martoff, M. Schachter Temple University, PA, USA J. Kikpatrick, D. P. Snowden Occidental College, CA, USA T. B. Lawson, P. K. Lightfoot, B. Morgon, M. Robinson, N. J. C. Spooner .

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DRIFT I experiment for Dark Matter Search

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  1. DRIFT I experiment forDark Matter Search • Rachid Ayad , Temple University, for: • R. Ayad, C. J. Martoff, M. Schachter Temple University, PA, USA • J. Kikpatrick, D. P. Snowden Occidental College, CA, USA • T. B. Lawson, P. K. Lightfoot, B. Morgon, M. Robinson, N. J. C. Spooner . • University Of Sheffield, UK • Dark Matter Review • Setupand Installation • Results. • R&D for DRIFT II . • Conclusion.

  2. Evidence Of Dark Matter • Zwicky (1930): From speed and mass of galaxies, galaxies cannot hold together • Later on, same problem with galaxies: stars orbit too fast to be bound by visible light.

  3. WMAP(Wilkinson Microwave Anisotropy Probe) A. Kosowsky et al Phys. Rev. D, 66, 63007, 2002. astro-ph/0302218, and astro-ph/0302207 • CMB photons (Cosmic Microwave Background) decoupled during the Big Bang at a temperature of ~ 3K: For a flat universe the size of cluster is ~ 1 Deg., so ~1 • With the help of other peaks, WMAP was able to give: • tot = 1.02 +/- 0.02 • dark-energy = 0.73 +/- 0.04 • CDM = 0.27 +/- 0.04 • baryonic = 0.044 +/- 0.004

  4. DAQ RACK Slow Control RACK AnodeWires Top MWPC (512 Chans) Bottom MWPC (512 Chans) Anode Wires

  5. VME ADC BAORD Gain: -Full range: 2.4 pC -1pC/V,~4000 e-/adc count Shaper: -24 Sec FWHM Digitizer: -Resolution: 12bits -Sampling Rate: 1MS/sec -Buffer Memory Depth: 16K Samples/Channel -Relative Accuarcy: +/- 1 LSB Ribbon Connector 32 wires TPC Input

  6. Electronic Calibration

  7. Trigger System

  8. (modified comedi driver)

  9. Gas Gain Calibration Using Fe55 Source Gain= (2998*158)/300 ~ 1579 Escape Peak

  10. Neutron Calibration • Send Neutrons from 252Cf source: dN/dE = sqrt(E)exp(-E/T) T = 1.3 MeV • Use Geant3 to generate nuclear recoil and dE/dX • Garfield drifts Primary Negative Ions to the anode wires . Simulated Neutron Event

  11. Erecoil = W*NIPS W = 45 eV +/- 5 eV

  12. ...we need neutron shielding to achieve proposal goals. Unshielded vessel With .5m (8 tons) CH2 shielding (installed March 23, 2004)

  13. Daya Analysis • Analysis based on 400 GB recorded data . • ~ 70,000 triggers • trigger rate (veto rejection) below .05 Hz

  14. More Events Range-Energy from 252-Cf source Clean neutron recoil (shielded, no software veto) green; unshielded n 90% limit red: shielded n 90% limit

  15. Analysis Procedures DST produced; then 14 simple, fully automated cuts applied

  16. Bottom Line Rates: Unshielded: 2.4 +/- 0.52 events per day Shielded: 1.1 +/- 0.33 events per day Shielding Effect: 1.3 +/- 0.62 Two independent analyses (Temple, Oxy-Sheffield) consistent on this effect.

  17. Accepted Background: still zero

  18. Focus on WIMP region • Events below the 90% neutron line are WIMP candidates or background neutrons. • One event in 9 days unshielded data looks like a room neutron • 5 more below 1000 NIPS are probably neutrons . Nuclear Recoil Zone

  19. R&D for DRIFT II and Helium Mixtures • NI drift and gain works fine with GEMs (physics-0310124 Miyamoto et al [experiments run at Temple Univ.] • allow pixelization to few 100 um with row-and-column readout • Helium mixtures with CS2 also studied in TPC prototype at Temple Univ., physics-0406114. • Helium buffer gas allows NI drift and gain at total pressure 1 bar • NO vacuum vessel- great cost and BG savings

  20. Conclusion • DRIFT I showed that negative ion gases can be used in TPCs for Dark Matter Search: No need to magnetic field. • Promising low background capability. • Upgrade to DRIFT II is at the development phase: - - Use GEM or TPCs at 1 bar, with light buffer gas, which will reduce the cost of a vacuum vessel and its maintenance. - Use large mass of ionizing medium for WIMP limit study and directionality study/rejection.

  21. WIMP Direct Experiments • DAMA (Dark Matter Search): In Gran Sasso, with 100 kg target NaI scintillator crystal,, where nuclear recoil/ electron-gamma Ionization rejection is achieved by Pulse Shape discrimination. 1400 m deeper • CDMS “Cryogenic Dark Matter Search”: 0.52 Kg of Ge/Si, where Nuclear recoil/electron-gamma Ionization rejection by comparing phonon surface heat to Ge/Si ionization. 10 m deeper (Now In Soudan) • EDELWEISS “Experience pour DEtecter Les Wimps En Site Souterrain” In Modane Site”: 0.32 Kg of Ge/Si, where Nuclear recoil/electron-gamma Ionization rejection by comparing phonon surface heat to Ge/Si ionization. 1700 m deeper • ZEPLIN “Zoned Proportional scintillation in Liquid Noble gases” In Boulby Mine: 3kg of Pure Xenon, where Excited Xenon* gives two Gamma Rays that can be discriminated for Nuclear recoil/electron-gamma ionization by pulse height. 1100 m deeper.

  22. Nuclear-Electron Recoil Rejection in Ge/Si detector

  23. DM experiments Upper limits

  24. CS2-He(Ar) GEM test at Temple Univ.

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