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Cryodet - March 2006. The ZEPLIN III Detector Results from surface calibrations (Coimbra, Edinburgh, ICL, ITEP, RAL, Rochester, Texas, UCLA). Cryodet - March 2006. Simultaneous Measurement of Scintillation and Ionisation. Cryodet - March 2006. ZEPLIN III Features. 8kg fiducial mass
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Cryodet - March 2006 The ZEPLIN III Detector Results from surface calibrations(Coimbra, Edinburgh, ICL, ITEP, RAL, Rochester, Texas, UCLA)
Cryodet - March 2006 Simultaneous Measurement of Scintillation and Ionisation
Cryodet - March 2006 ZEPLIN III Features • 8kg fiducial mass • 31 PMTs in liquid • 3.5 cm drift depth • 0.5 cm electroluminescent gap • reverse field region • position sensitivity • open plan – no surfaces - reduced feedback
Cryodet - March 2006 Simulations • Light collection • liquid phase • gas phase • Position sensitivity • gas electroluminescence • Internal gamma/neutron backgrounds • Fully implemented GEANT4 model • Test data set production
year 2 year 3 Araujo et al., 2006
Cryodet – March 2006 ZEPLIN III is built CAPAC - May 2001
Cryodet - March 2006 Three cool-downs so far • Check-out of thermal control system, xenon transfer and PMT response using internal radioactive sources. • Thermal design verified – 1litre/hour LN boil off! • All PMTs operational • Xenon transferred several times during 6 week run • Am241 spectra obtained with up to 17pe/keV! • Dual-range 62 channel DAQ readout • High precision waveforms collected (including neutron source)
Cryodet - March 2006 Three cool-downs so far • First two-phase run (after removal of radioactive sources) • Level setting with capacitive sensors • HV established • Two-phase signal recovery from full depth • HV breakdown seen • Xenon leak into vacuum jacket (☺mass spec.) • Xenon recovery from vacuum jacket – no loss! Open system, located fractured HV feedthrough, replaced, closed up again
Cryodet - March 2006 Three cool-downs so far • Second two-phase run • HV established (~4kV/cm (at the moment) – liquid – sustained for several days without trip) • Two-phase signal recovery • Event classification started • 57Co spectrum from external source – as expected – working on light yield • Purification cycles started – to recover from recent opening of detector
First cool-down 11-14% FWHM • Single phase (no liquid/gas interface) 7-11 pe/keV • Dual phase (with liquid/gas interface) ~17pe/keV • MC simulations imply Xe yield probably > 60photons/keV • Linear to better than 10% - 8 to 60 keV
Third cool-down Primary scintillation
Cryodet - March 2006 Summary • ZEPLIN II is operating in Boulby mine. • Full depth operation • Final in-situ calibrations ongoing • ZEPLIN III is up and running. • Performance so far is as expected. • Some indication of higher photon yield than expected in xenon. • Further surface evaluation and optimisation in progress – another 3 months • FP 7 Design Study proposal for ton scale – ELIXIR – LoI submitted to ILIAS/ApPEC • FP7 Single Project proposal for ZEPLIN III deployment - LoI submitted to ILIAS/ApPEC