First Science Results from the ZEPLIN-III direct search T.J. Sumner Imperial College London

z Xenon technology z ZEPLIN-III design z First science run results z Future plans

1 JENAM - April 20th 2009 WIMP elastic nuclear ⇒ phonons, photons and DRIFTI, II recoils deposit < 50keV charge whose relative of energy at a rate 10-5 to GENIUS, proportions and /or 1 event/day/kg IGEX, characteristics depend on NEWAGE particle type

ArDM, LUX, SIGN, ionisation CDMS, EDELWEISS, WARP, XENON10, SuperCDMS ZEPLIN II, III Q

s c in L s t H n il o la n t o ANAIS, CLEAN, DAMA, io h n p COUPP, CRESST I, DEAP, KIMS, LIBRA, NAIAD, XMASS, ZEPLIN I PICASSO, SIMPLE CRESST II, High efficiency particle ROSEBUD World competition is identification requires intense and uses a wide compound information range of complementary and/or large self-shielding mass techniques JENAM - April 20th 2009 z ArDM z CLEAN z DEAP z LUX z SIGN z WARP z XENON10, 100 z XMASS z ZEPLIN I, II, III

JENAM - April 20th 2009 Two-Phase Xenon Operation SUM [H00-H30], SUM 10x[L00-L30]

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LSx10 -1.2 0 1000 2000 3000 4000 5000 6000 time, ns ZEPLIN III Features

• 8kg fiducial mass • PMTs in liquid to improve light collection • 3.5 cm drift depth – higher E-field • 0.5 cm electroluminescent gap • 31 small PMTs for fine position sensitivity • open plan – no surfaces - reduced feedback • Lower-background PMTs available • Copper construction • Low-background (from ITEP)

Low temp PMT study – NIMs A 521 (2004) 407–415 Instrument paper – Akimov et al. (2007) Astropart. Phys. 27, 46-60 Simulation – Araujo et al. (2006) Astropart. Phys. 26, 140-153 Position reconstruction – NIMs A 573 (2007) 200–203 Acceleration samples (1min)

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Low temp PMT study – NIMs A 521 (2004) 407–415 Instrument paper – Akimov et al. (2007) Astropart. Phys. 27, 46-60 Simulation – Araujo et al. (2006) Astropart. Phys. 26, 140-153 Position reconstruction – NIMs A 573 (2007) 200–203 ... Partially shielded February 28th ….

Fully Shielded Science Runs… commenced! Main results with spin-independent limits – Lebedenko et al., arXiv:0812.1150 (2008) Spin-dependent limits – Akimov et al., arXiv:0901.4348 (2009) First Science Run Results (Calibration – 57Co) First Science Run Results (Calibration – AmBe (red), 137Cs (blue)) First Science Run Results First Science Run Results (Science data)

83 days continuous run Feb-May 2008 847 kg.days raw 126.7 kg.days in WIMP search box First Science Run Results (Science data) Current Best Results (Spin-Independent)

JENAM - April 20th 2009 Current Best Results (Spin-dependent)

JENAM - April 20th 2009 ZEPLIN-III future plans • Veto installation (option) • PMT upgrade • Calibration • Physics Exploration • Second science run

Beyond ZEPLIN-III • European – ZEPLIN-III led the European LIquid Xenon Identifier of Recoils (ELIXIR) proposal to EU which brought together the European groups of ZEPLIN III and XENON10 on tonne scale target • Highly rated but no funding • ASPERA roadmap includes ELIXIR and EURECA • New ASPERA call provides opportunity for study •Global – ZEPLIN-III has formally joined with LUX to form LUX-ZEPLIN – Use of Homestake to house tonne-scales on up to 40 tonne-scales