Minutes of the Forward Endcap EMC SADC Crate Design Vibe/eZuce meeting, 9th of March 2020, 14:00-15:15

Presence:

• Bochum: Tom, Matthias, Claudius, Fritz-Herbert, Malte, Marc, Jan, Tobias H., Sebastian
• Basel: -
• Bonn: -
• Groningen: -
• Uppsala: Pawel
• Giessen: Markus, Hans-Georg

Space occupancy of VPTT submodules in FWEC:

• VPTT Submodule dimension measurerments result in 2 mm longer modules compared to sclaes in CAD drawings
• VPTT capsules are included in the CAD model and are therefore not the origin of the extra size
• Interface pieces in the CAD drawings correspond to the real existing ones (that have been changed once the VPTT submodule capsules were introduced)
• We need to measure the free space between front lid and backplate on the detector in Bochum in order to see whether there is a problem with submodule front cooling overlap

Recovery LED:

• Concerning the latest measurements on LED introduced noise in the APD submodules Johannes showed single APD module channels where a 52.9 MHz oscillation is observed
• Oscillation in APD readout channels is a clear sign of open preamp input, that is APD coupling loss. Malte looked up the oscillation frequency of open preamps measured years ago in Bochum lab: 44 MHz, which is quite close
• After the meeting Tobias measured the oscillation frequency of an open input preamp of the latest version and could confirm the 53 MHz for the current version!
• So we need the corresponding APD submodule back in Bochum in order to fix the broken APD - preamp coupling of that channel! (Once the module is brought to Bochum we will give in the order of 10 new modules to Bonn).

SADC crate power supplies:

• The redesigned (still temporary) power supplies arrived
• Efficiency is almost 90%
• Input consumption of supplies is +/- 12 V, > 10 A - considerably more during power up
• Pawel will send them to Bochum along with the SADC backplane PCB and some more SADCs