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The DRIFT Dark Matter Experiment. Jennie Davies University of Sheffield (UK) IoP HEPP Conference - Dublin 21st - 23rd March 2005. Outline. Why? Dark matter Who? What? Where? When? How? The detector Recent developments. DRIFT... Why?.
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The DRIFTDark Matter Experiment • Jennie Davies • University of Sheffield (UK) • IoP HEPP Conference - Dublin • 21st - 23rd March 2005
Outline • Why? • Dark matter • Who? What? • Where? When? • How? • The detector • Recent developments
DRIFT... Why? • To search for dark matter and identify a signal of galactic origin using directional information from nuclear recoil tracks.
DRIFT... Why?Dark Matter: The Evidence • Observational evidence • Rotational curves of galaxies • Gravitational lensing • Theoretical support • Supersymmetry
DRIFT... Why?Dark Matter: The Candidates • Baryonic particle candidates • Non-baryonic particle candidates • Neutrinos • Weakly Interacting Massive Particles (WIMPs) - The stable LSP (neutralino) • Axions • Dark Energy
DRIFT... Why?Dark Matter: WIMPs • Cold Dark Matter • Neutral • High mass (10 -1000 GeV) • Interact only very weakly • Postulated ‘WIMP Wind’ • Daily fluctuations due to the Earth’s rotation
DRIFT... Who?The DRIFT Collaboration • UK Dark Matter Collaboration • University of Sheffield • University of Edinburgh • Imperial College, London • Rutherford Appleton Laboratory • Occidental College, Los Angeles, USA • Temple University, Philadelphia, USA • University of New Mexico, USA • University of Boston, USA • University of Thessaloniki, Greece • University of Darmstadt, Germany
DRIFT... What? • Directional • Recoil • Identification • From • Tracks
DRIFT... What? • Negative Ion Time • Projection Chamber (NITPC) • Two back-to-back field cages • with a shared central cathode • Two readout planes - Multi-Wire Proportional Chambers (MWPCs) • Filled with CS2 gas at low pressure Martoff et al. NIM-A 440 (2000) 355
DRIFT... Where? Boulby mine Cleveland Potash Ltd.
DRIFT... When? • DRIFT-I • Underground in 2001 • Data taking 2001-2004 • Shielding installed 2004 • Decommissioned 2004
DRIFT... When? • DRIFT-II • Underfloor shielding Autumn 2004 • 1st vessel u/g December 2004 • 1st detector u/g February 2005 • Further modules to go u/g throughout 2005 and on
DRIFT... How? • Nuclear recoils (elastic scattering) • Low energy ionisation • 0.01 - 1 kg-1 day-1 • Directionally sensitive • IMPORTANT: • Background reduction • gammas, alphas, neutrons etc. • require << 1 recoil per year
Simulations • Using SOURCES, GEANT4 and FLUKA • Neutron energy spectra (U & Th contamination) • Muon-induced neutrons • Geometry and particle tracking Carson et al. Astrop. Phys. 21 (2004) 667 Carson et al. hep-ex/0503017 (accepted to NIM-A)
Simulations • Single and grouped DRIFT modules • Hydrocarbon neutron shielding • Reduce recoils due to neutron background to < 1 per year per module
Alner et al. NIM-A 535 (2004) 644 Data Analysis • DRIFT-I Snowden-Ifft et al. NIM-A 498 (2003) 155
55Fe gamma Cosmic neutron Alpha Data Analysis • Commissioning of the first DRIFT-II detector has been performed at Occidental College, L.A. • Initial calibration and background runs successful • Data analysis software is progressing as early data is being taken • Waveform plotting and data reduction • Parameter calculation and plotting • Software cuts in progress
Looking ahead ... • DRIFT-II • In progress • DRIFT-III • towards 1000 kg • target mass • Plus • Further improved simulations • Charge readout R & D • Much data taking and analysis