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

Presence:

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

APD-Submodules:

• 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

VPTT-Submodules:

• 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    • It is not yet clear whether the CAD model is outdated (maybe does not contain the capsules?)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?