Minutes of the forward endcap EMC eZuce SRN meeting, 20th of November 2017, 14:00-15:15

Presence:

• Basel: Werner
• Bochum: Cathrina, Claudius, Fritz-Herbert, Matthias, Miriam, Tobias H., Tobias T., Tom
• Bonn: Merlin
• Groningen: -
• Stockholm: -
• Uppsala: Pawel
• Giessen: Markus
• GSI: -

VPTT/preamp to crystal assignment:

• The distributions of directly measured preamp gains and preamp/VPTT gain products still do not match the indirectly measured ones (from the units already glues) - mean and width are different
• Is there a problem with the light pulser reference? Tobias was asked to remeasure some of the oldest glued units again to see if the same normalised response results
• Is the statistics of only two units the calculation of the gain of the already glued units is based on too weak?
• Is the light pulser measurement suitable at all? We inject form the read out side of the crystal; the light has to pass the crystal 'back and forth' and the influence of the reflective foil alignment is still questionable
• We currently estimate the effect by measuring the distribution of light entering the two sensors of an APD read out crystal (earlier estimations of that kind were dominated by the "1:2 intensity effect" of failed APD couplings)
• Comment form Pawel: Is it insured that the preamps do not change gain during measurement because of heating up components? Werner in the meantime measured the gain of the preamps as a function of ambient temperature: 1% change between -25 and 70 degrees C