Minutes of the forward endcap EMC SeeVogh meeting, 23rd of May 2016, 14:00-15:00


  • Basel: Werner
  • Bochum: Claudius, Fritz-Herbert, Malte, Matthias, Miriam, Tobias, Tom,
  • Bonn: Christoph, Matthias, Merlin
  • Giessen: Hans-Georg
  • Groningen: Myroslav
  • Stockholm: -
  • Uppsala: -
  • GSI: -

APD preamps:

  • The test setup with a free running cosmics measurement on a vertically suspeded crystals with APD readout gives hard to interprete results due to the absence of a clear visible peak in the resultung cosmics spectrum
  • We agreed to bring the crystal - mounted to a subunit - to Bonn as there is the setup specifically designed for these measurements with the ability of triggering cosmics fully passing the crystal length, resulting in a more prominent peak
  • We will try to prepare the subunit and bring it on Friday or Monday to Bonn
  • For the time being we expect the necessary preamp gain for APD readout to be about three times lower than tested so far (~0.1 V/pC), estimated from beam data and comparison to VPTT readout
  • Werner will prepare four preamps with this extremely low gain and send it to Bochum for testing - he already tested this version in Basel and achieved stable performance
  • We try to test this preamps before the June-Meeting at GSI
  • Malte suspects the general ringing/oscillation problem of the APD preamps being influenced by the grounding scheme
  • In this context there was some confusion about the grounding layout of the different ISEG HV power suppliy versions: the 16 channel units are not channel wise floating as the 8 channel and VPTT units but have a floating ground common to all 16 channels!
  • Delivery of the VPTT preamps is delayed by about four weeks. They are expected to arrive end of June.

Read out electronics:

  • There was some discussion about the definition of thresholds:
    • Malte and Matthias remarked that the effective threshold is not the stated threshold as there are additional requirements to be fulfilled, i.e. a time over threshold constraint, before accepting a signal, effectively increasing threshold
    • Myroslav explained that the difference in thresholds is not that dramatic
    • He will report on the triggering mechanism in the KVI-firmware in detail on the upcoming GSI-Meeting in June
  • The four shaper versions have been tested:
    • There is a ringing in the high gain branches causing double peaking spectra
    • The factor between high and low gain branch is clearly lower than 16
    • The absolute gains of the branches are not properly adopted to our needs (2 V preamp output to 1 V (?) ADC input)
    • Linearity test with six different amplitudes done (okay)
  • Malte will prepare a brief report on this measurements and send it around

HV regulation:

  • Christoph presented some slides showing the integration of the HV regulation board to the patch panel board (sitting on top as piggy back board)
  • The HV regulation boards also acts as security lock for the signal U.FL connectors
  • A mock-up for installation feasibility test may be available the week after next week
  • A real version of the fully equipped HV regulation board will arrive at Bonn soon, tested there and then go to irradiation tests to Giessen

-- ThomasHeld - 24 May 2016
Topic revision: r2 - 24 May 2016, ThomasHeld
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding PANDA Wiki? Send feedback
Imprint (in German)
Privacy Policy (in German)