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ZEPLIN A Direct Dark Matter Search Programme using Liquid Xenon

ZEPLIN A Direct Dark Matter Search Programme using Liquid Xenon. CCLRC – Rutherford Appleton Laboratory, UK Edinburgh University, UK Imperial College London, UK ITEP – Moscow, Russia LIP – Coimbra, Portugal Rochester University, USA SMU, USA Texas A&M University, USA UCLA, USA.

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ZEPLIN A Direct Dark Matter Search Programme using Liquid Xenon

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  1. ZEPLIN A Direct Dark Matter Search Programme using Liquid Xenon CCLRC – Rutherford Appleton Laboratory, UK Edinburgh University, UK Imperial College London, UK ITEP – Moscow, Russia LIP – Coimbra, Portugal Rochester University, USA SMU, USA Texas A&M University, USA UCLA, USA SNOLAB 21 August 2006

  2. The Programme • ZEPLIN I* – completed/published • ZEPLIN II* – taking quality dark data • ZEPLIN III – ready for immediate deployment • The future – clear route to tonne scale through international collaboration • Technical progress Report – ZEPLIN II/III – Tim Sumner • Technical progress Report – ZEPLIN IVby4 – Hanguo Wang • Infrastructure & Strategy • Schedule SNOLAB 21 August 2006 * Collaboration on these projects includes Sheffield University, UK

  3. World Status SNOLAB 21 August 2006

  4. tonne scale target ZII, ZIII World Status SNOLAB 21 August 2006

  5. Two-Phase Xenon Principles SNOLAB 21 August 2006

  6. ZEPLIN II • Continuous operation for last 100 days with 7day/week support of whole collaboration • It is working well • Its performance is understood • It has collected quality dark matter data …some examples SNOLAB 21 August 2006

  7. ZEPLIN II Purity SNOLAB 21 August 2006

  8. ZEPLIN II Scatter plot SNOLAB 21 August 2006

  9. ZEPLIN II Position recovery (from S2) SNOLAB 21 August 2006

  10. Preliminary Preliminary ZEPLIN II Dark Matter Data • 1.0 tonne.day of quality data collected • 0.1 opened for unblinded analysis • Version 1 data cuts defined • Efficiencies evaluated • zero background in nuclear recoil band (to be confirmed) • 1.35x10-6 pb 1.35x10-7pb* in current data set • Publication intended for IDM2006 • Version 2 cuts + clean  lower energy + larger fiducial volume (lower background/better position recovery) • April 07  3 times current exposure SNOLAB 21 August 2006 * Assumes 0 bg – data not opened yet

  11. ZEPLIN II ZEPLIN III SNOLAB 21 August 2006

  12. ZEPLIN III Features • 8kg fiducial mass • High QE PMTs in liquid for excellent light collection • 3.5 cm drift depth • 0.5 cm electrode-less electroluminescent gap for improved discrimination • reverse field region • 31 small PMTs for fine position sensitivity • open plan – no surfaces - reduced feedback • Copper construction SNOLAB 21 August 2006

  13. DM2006 - February 2006 ZEPLIN III Status • Built and tested • Performs as designed • Journal papers • Simulation – Araujo et al. (2006) Astropart. Phys. In press • Instrument – Akimov et al. (2006) Astropart. Phys. In revision • Vital experience and momentum gained from ZEPLIN II • Ready for immediate deployment SNOLAB 21 August 2006

  14. SNOLAB 21 August 2006

  15. Commissioning Tests • Thermal design verified – 1litre/hour LN boil off! • All PMTs operational – spe established – gains equalised • Xenon transferred several times • Extended runs of up to 8 weeks • Am241 spectra obtained with up to 16pe/keV – a world best! • Dual-range 62 channel DAQ readout • Data processing and analysis system developed • HV established • Full-depth two-phase signal recovery • Bulk light yield established • Neutron calibration done SNOLAB 21 August 2006

  16. Bulk light collection, S1 5 pe/keV - 3.5 x ZII Charge collection, S2 SNOLAB 21 August 2006

  17. Position recovery SNOLAB 21 August 2006

  18. Neutron calibration ZEPLIN III ZEPLIN II SNOLAB 21 August 2006

  19. Sensitivity prediction SNOLAB 21 August 2006 Araujo et al., 2006

  20. ZEPLIN long term strategy I 30kg ZEPLIN II + = ZEPLIN III 8kg 0.250 ton ZEPLIN IV/MAX SNOLAB 21 August 2006

  21. Direct Scale-up Based on the ZEPLIN II/III • 250kg fiducial mass • Two phase xenon • 50 5-inch-PMT • 19(7 eight-in)on bottom • 31 on top • 30-cm total drift length • Light yield ~ 4pe/keV • 45kV @ E=1.5kV/cm • Xenon Purification Forced Circulation in liquid phase (system being studied) • Active liquid recovery • ~R x H = 0.5 (m) x 1.0 (m) No R&D needed for this design! 250kg SNOLAB 21 August 2006

  22. Self Shielding Fiducial Limit µs Spatial separation of double scatter (S2) background events in drift direction SNOLAB 21 August 2006

  23. “Club54” • 500kg fiducial mass • Two phase xenon • 50 5-inch-PMT • 19(7 eight-in)on bottom • 31 on top • 60-cm total drift length • Light yield ~ 4pe/keV • 90kV @ E=1.5kV/cm • Xenon Purification Forced Circulation in liquid phase (system being studied) • Active liquid recovery • ~R x H = 0.5 (m) x 1.3 (m) 250kg SNOLAB 21 August 2006

  24. Neutron sources • Neutron production from • U/Th in detector material • U/Th in shielding material • U/Th in rock • µ spallation in detector material • µ spallation in shielding material • µ spallation in rock SNOLAB 21 August 2006

  25. 250kg detector SNOLAB 21 August 2006

  26. Xenon Purification and Safety System for ZEPLIN IV Manual Valve C.B. Control Box VI, VII, are vacuum pumps Active Xenon collection system will take less space (1.4 x linear size) Xenon purification in liquid phase (less cooling power) Cooling VI Cooling VII . Forced recirculation system Getter Safety Dump Xe Target Pump C.B. SNOLAB 21 August 2006 Vacuum Insulated Line

  27. ZEPLIN IV/MAX layout 1, Target Detector: (250kg  ton scale)8m x 8m x 6m (WxLxH) Central detector, Active neutron and Compton veto Lead shield, Neutron Shield. 2, Electronic & Control:5m x 4m x 3m DAQ system, Slow control, 3, Auxiliary systems:8m x 8m x 4m Active xenon recovery system and related pipe-works and controls 4, Total Peak Power 25kW 5, Office SNOLAB 21 August 2006

  28. tonne scale target ZII, ZIII (ZEPLIN III+IV/4) ZEPLIN IVby4 FY07 Engineering Design (SNOLAB Invitation for Tech. Design) FY08 Start Construction FY09 Underground Installation Total US Construction $3.5M + equivalent European contribution ZEPLIN III FY07 Deployment/Operation Requires shield plus veto and local collaborators FY08 Upgrade/operations (PMT, depth) FY09 Completion Canadian collaborators are very important to both instruments at SNOLAB SNOLAB 21 August 2006

  29. Summary • ZEPLIN II is working with >1000kg-days data on tape. • First limit is encouraging • Routine electron lifetimes > ms • Analysis cuts defined • More data to come with reduced background and improved analysis lower threshold/larger fiducial • ZEPLIN III is ready to go and performs as designed. • Bringing ZEPLIN III to SNOLAB provides an early science result from an existing detector and paves the way for ZEPLIN IVby4 • ZEPLIN team is well versed in ‘mine’ operation/usage • Combining Zeplin II&III and Xenon10, (Club54) we know the next step to 10-10pb (500kg) • – looking for Canadian involvements SNOLAB 21 August 2006

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