Minutes of the forward endcap EMC SeeVogh meeting, 9th of May 2016, 14:00-14:45

Presence:

  • Basel: Werner
  • Bochum: Fritz-Herbert, Malte, Matthias, Tom
  • Bonn: Christoph
  • Groningen: -
  • Stockholm: Karoly, Markus
  • Uppsala: Pawel
  • GSI: -

APD preamp:

  • Recent calculations based on beam time data and comparison with VPTT readout led to the unpleasant result of needing a preamp gain about three times lower than the latest test preamps
  • This intensifies the ringing/oscillation problems with the APD preamps - is it possible to stay with the current preamp design and further reduce gain while getting the amps stable?

Read out electronics:

  • Malte reported about the problem of not having the possibility to pre-trigger in the low gain branch, so one cannot determine a baseline there
  • Double peaks occur in the high gain branch when for example charge injection is used -> biasing even if we record waveforms. The cause is an oscillation ('hum') in the high gain branch modulating the waveform.
  • Pawel: original Uppsala firmware had all those feature necessary to efficiently set thresholds etc.
  • Obviously the KVI firmware/feature extraction does not
  • Markus/Pawel measured linearity of the ADCs: "okay"

HV regulation:

  • Current measurement capability can be realized using four transistors and some resistors which is quite space consuming
  • After some discussion we decided to skip the current measurement capability and only go for an HV regulation (setting and measuring)
  • Christoph will prepare a modified patch panel board with attached piggy-back HV regulation board to test mounting on the backplane in Bochum

-- ThomasHeld - 17 May 2016
Topic revision: r3 - 07 Jun 2016, ThomasHeld
 
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