Minutes of the forward endcap EMC Vibe/eZuce meeting, 26th of August 2019, 14:00-14:50


  • Basel: -
  • Bochum: Matthias, Thorsten, Tom
  • Bonn: Christoph, Christian
  • Groningen: -
  • Stockholm: -
  • Uppsala: Pawel
  • Giessen: -
  • GSI: -


  • Cosmics measurment results of the first 16-crystal APD submodule:
    • The 12 GeV Panda FWEC EMC single crystal energy maximum is probably detetcable with all channels (detailed analysis follows)
    • The spread of channel responses (inter crystal and between APDs on one crystal) is as expected and acceptable
    • Second APD submodule is going to cosmics test stand soon
    • Noise figures of both submodules comparable in terms of sigma, but a closer look to the shape (non gaussian contribution) is needed as this indicates the occurance of pickup noise
  • Annealing LED cabling appears to be short (probably not too short but close to limit) - does this come from cable routing through the aluminum tube (as tested for one of the two submodules built)? Checked: no!
  • The signal labeling/color coding should be improved: ideal would be an omission of the shrinking tube as it hinders cabling to the PCB and preferred is a labeling that does not move along the signal cable
  • We therefore will change to the newly tested paper cable labels that we print on our own and that include the color coding by colored prints


  • Christian presented measurements of the outer dimensions made on 13 VPTT submodules
    • He presented results of scans of the alveole surface
    • All submodules turn out to be between 1.6 and 2.2 mm longer than expected from an existing CAD model
      • These numbers agree with the caliper measurements made on the submodules after finishing in Bochum
      • It is not yet clear whether the CAD model is outdated (maybe does not contain the capsules?)
      • Is the spread of elongation (1.6 - 2.2 mm) compatible with the thickness variation of the VPTT capsules?
      • Christian also presented x-ray images of a submodule showing about 0.4 (0.6) mm free space between crystal front faces and carbon inner (outer) fibre front
      • Does the difference of (1.6/2.2 - 0.6) mm = (1 - 1.6) mm correspond to the VPTT capsule thicknesses?
    • We therefore need to measure the resulting maximum distances of submodules (corners) to the backplate (minimum free space to the front lid)
    • Has there been a redesign (decrease of height) in the interface pieces in order to account for the elongation of the submodules by the introduction of the capsules?

-- ThomasHeld - 27 Aug 2019
Topic revision: r3 - 2019-08-27, ThomasHeld
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