Large prototype goals Endplate design

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Large prototype goalsEndplate design

• P. Colas

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General ideas

• We have to agree first on the goals to understand
  how to build the endplate
• The design should be as close as possible for GEM
  and Micromegas (requires regular common
  meetings), but no mix possible
• A (small) space should be kept for digital pixel
  readout (EUDET contract)
• The endplate should be a support for several
  pannels or tiles.

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Goals (open for discussion)

• What it is
• Demonstrate feasability and performances of the
  real detector, in particular possibility to cover
  by modules and to obtain the target resolution
  and feedback
• Study various solutions for amplification, pad
  geometry, electronics
• Gain a long-term experience of running in real
  conditions
• Study distortions (their effect and how to
  correct them)
• What it is not

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Goals (open for discussion)

• What it is not
• An apparatus to study in detail gas properties
  (smaller devices do better for this)
• An apparatus for detailed aging studies (special
  devices will allow testing of various materials
  and gases in high radiation, already started at
  Saclay and NIKHEF)

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Ion feedback in the LP

• Possibility to test the effect of the ion sheet
  (at each beam crossing a fraction of the positive
  ions flows back to the cathode
• What is the effect of such an ion sheet on the
  electrons drifting from a track?
• This can be studied using an UV lamp (as NIKHEFs
  Xe lamp) to produce photoelectrons on the foil.
• How to do this in practice? UV window? Lamp in
  the gas volume?

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Optimization of the configuration

• With David Attié, we studied the possible
  configurations to have
• Identical (interchangeable) modules
• Enough boundary configurations
• (some modules can be dummy, just carrying the
  right potential)
• Each tile must have its own seal-ring (see Dan
  Petersons drawing)

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Options for the Micromegas endplates

• Should try the latest kind of bulk available at
  that time
• Most likely resistive foils have to be included