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The Zeplin II Dark Matter Experiment
Jianting Gao, Gabe Saninas, James T. White
Texas A&M UniversityFor the Zeplin II Collaboration
03/22/2006
Current Zeplin2 Collaboration group• DB Cline, WC Ooi, F Sergiampietri(a), H Wang, P Smith(b), X Yang
Physics and Astronomy, UCLA, (a)Pisa, (b)RAL&UCLA• JT White, J Gao, G Salinas
Department of Physics, Texas A&M University• T Ferbel, U Schroeder(Chemistry), F Wolfs, W Skulski, J Toke
Department of Physics and Astronomy, Rochester University• Y Gao
Southern Methodist University, Texas• MJ Carson, E Daw, J Davis, T Gamble, VA Kudryavtsev, TB Lawson, PK Lightfoot, JE McMillan,
B Morgan, SM Paling, M Robinson, NJC Spooner, DR ToveyDepartment of Physics and Astronomy, University of Sheffield
• H Araujo, A Bewick, D Davidge, JV Dawson, AS Howard, WG Jones, MK Joshi, V Lebedenko, I Liubarsky, TJ Sumner, JJ Quenby, R Walker
Blacett Laboratory, Imperial College of Science, Technology and Medicine, London• GJ Alner, C Bungau, B Camanzi, TJ Durkin, R Luscher, JD Lewin, RM Preece, NJT Smith, PF
SmithParticle Physics Department, Rutherford Appleton Laboratory, Chilton, Oxon
• AS Murphy, C GhagDepartment of Nuclear Physics, University of Edinburgh
• M Danilov, D Akimov, A Kovalenko, V StekhanovITEP, Moscow
• A Policarpo, I Lopes, V ChepelLIP-Coimbra
Evidence for Dark Matter
More evidence for dark matter
Event rate in detector• The direct search of
WIMP is to witness it’s nuclear recoil.
• High atomic number gives a high rate-131Xe
⎥⎥⎦
⎤
⎢⎢⎣
⎡⎟⎟⎠
⎞⎜⎜⎝
⎛ −−⎟⎟⎠
⎞⎜⎜⎝
⎛ +=
0
min
0
min22
00 )(4 v
vverfv
vverfEFmmvdE
dR eeR
rxeR
ρσ
4220 Nrscalar mAm ∝∝σ
Two phase Xe
Processes inside the detector
Ionization vs Scintillation
Electron recoil
Nuclear recoil
Scintillation
Ioni
zatio
n/S
cint
illatio
n
The Zeplin II DetectorKey properties of the
detector• Fiducial volume: 30kg.• Two fine meshed provide both
electron extraction field and electroluminescence field
• Pure copper rings shapes the electron drift-field in liquid
• HV applies to bottom plate to have a high field for ionization electron extraction in liquid
• Extreme-care taken to avoid HV discharge in gas
• Seven 5-in. PMTs for use in liquid xenon temperature
• Dead region < 0.1%
Details of the detector
Details of the detector
Details of the detector
Gamma event
Purity
With and without neutron source
Reach estimation
Summary• Xenon has a number of advantages for direct WIMP
detection• Two phase Xenon detector has powerful background
discrimination ability.• Zeplin II detector has passed surface test and now
operating underground. • First look at neutron gives positive result.
