The GEM Readout Alternative for XENON

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Multi-GEM Structures and CsI Coating
The charge gain can be increased by employing
several GEMs in a sequence. This is particularly
important for pure noble gases, where the gain of
a single GEM is limited to 100. Recent tests
with a triple-GEM structure, operated with pure
xenon gas at room temperature, demonstrated
achievable gains of several 1000 at pressures of
1-2 atm. (A. Bondar et al., prepr.
physics/0103082)
For the conversion of upwards orientated primary
scintillation photons that escape through the
liquid/gas surface, the lowest GEM can be coated
with CsI. Recent results on CsI-coated multi-GEM
structures showed excellent performance as gas
avalanche photomultipliers. (D. Mörmann et al.,
NIMA 471, 333 2001 and prepr. WIS/12/01-jun-DPP
Weizmann Inst., Israel)
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GEM Implementation in the XENON Detector

• Triple-GEM structure with CsI coating.
• Mesh stearing electrode to tune field for
  optimum charge transmission and
  photoelectron extraction from the CsI.

Replace

• Double-sided PC board with X/Y strips for fine
  spatial resolution.
• Low-noise electronics for optimum thresholds.

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Studies of a GEM Readout for XENON at

• Goals
• 1. Explore the feasibility of a combined charge
  and photon readout with a CsI coated multi-GEM
  structure for XENON.
• 2. Develop a design for integration in the 10 kg
  module.
• Ways
• Set up a small test chamber and gas purification
  system.
• Assemble a Triple-GEM structure with a simple
  readout, procuring the GEMs from CERN.
• Evaluate the performance of a 3-GEM structure at
  the operating conditions of a 2-phase xenon
  detector, wrt. maximum gain, impact on Xe purity,
  stability with time, ...
• Evaluate the detection of primary scintillation
  light with a CsI coated GEM structure and
  stearing electrode.
• Convert the experience into a design for the 10
  kg module.