====== Requirements for GEM Setup of the Prototype (Mittig) ======

{{:prototype_design.jpg|:prototype_design.jpg}}
  * The maximum size foils we want to test are 114.7 mm*114.7mm, be mounted on 200mm*200mm printed circuit boards
  * There will be a UV-photodiode above the Kathode to produce electrons in a semitransparent foil, isolated from the cathhode (Vmax=5kV) (2 connections)
  * For calibration, an alpha particle source will be fixed face down over a hole in the cathode
  * Next to the Kathode there will be 1 or 2 gems, mounted on a printed circuit board, at a variable distance, needing 4 HV connections
  * The voltage division will be done externally, this means 5 HV feed-throughs are needed (+1 spare)
  * The signals will be collected on a segmented anode, with maximum 5 signals to be transmitted to external preamplifiers
  * The most simple seems to be a drawer like device, that allows easily to change configuration, distance of drawers 2 printed board, thicknesses, width 1+ε
  * The final device should be clean and dust-free; all manipulations should be done in a clean environment

====== Updated Design July 29,2008 ======
{{:prototype_design_7_29_08.jpg|:prototype_design_7_29_08.jpg}}


  * Designed to be used with either a laser as the ionization source or an alpha source.  
  * Can be rotated as needed to access particular window.
  * Mounting of GEMs is flexible in order to study gain dependence on the GEM spacings.  
  * Outer box is vacuum tight, enabling various gas mixtures to be introduced into the chamber.  Also has the ability to be run at reduced pressures (as low as 0.2 atmospheres).






====== Updated Design August 8,2008 ======
{{:GEMs_Test_Chamber_080808.jpg|:GEMs_Test_Chamber_080808.jpg}}

__**Modifications from previous design include:**__
  * The addition of handles to facilitate opening the device.
  * Pressure relief valve has been modified to utilize a more reliable manufactured design; valve releases at 15psi.
  * End plate has been extended past the windows so that the chamber can rest on any face (with the exception of the end with the connectors).
  * Feet have been added underneath the internal drawer to provide the proper offset when opening and closing the chamber.
  * Stops are included on both sides of the internal tray structure to secure all trays in place.
  * Document describing modes of operation and orientation of test stand {{:teststandorientation_080808.pdf|:teststandorientation_080808.pdf}}  

__**Minutes from the Design Review (updated: August 11, 2008.)**__

__Action Items:__
  * Craig will remove the tapped holes from the corners of the box.
  * Craig will provide a list of parts to be machined with 2D drawings on Wednesday; the materials required for each part will be identified.
  * Abby will review and approve the materials via email Thursday.
  * Jay will provide an estimate of the shop time required for the job on Friday.


__Notes:__
  * The large components of the assembly will be sent out to be cut via water jet.
  * The stainless pieces that form the external walls of the box will be welded from the inside and tacked on the outside to minimize bowing of the end plate.
  * Once the external structure is assembled the box (minus the Al door) will be set put for electropolishing.
  * The window flanges will be mounted after the electropolishing is completed.
  * The job is likely to be in the 40-80+ hour category, but Jay will provide a more realistic estimate. 
  * Once the time required has been established Thomas G. will be contacted to schedule the work in the shop.