Delivery of all VPTT preamp boards (modified to three different gain-versions) by Basel end of May
Transport of components (alveoles, cables, aluminum mechanics) from Bonn to Bochum next week (i.e. this week...)
It is foressen to build the VPTT subunits in the same way as the 'final' VPTT subunit version currently in the test stand in Bonn as the 'reflecting foil problem' hardly affects VPTT crystals
Malte presented a way to introduce blue, DC operated LEDs to the subunits (one per crystal) for radiation damage recovery
Readout/TRBs:
Malte with the help of Peter Schakel (KVI) finally managed to get the Bochum TRB operating
Markus managed to extract data with the Stockholm TRB, remaining problems are on the electonics side (grounding, noise) of the LaBr /VPTT setup
HV regulator board:
Christoph is going to develop a channel-wise HV shunt regulator board in order to fine tune gain settings of APDs on the same HV supply channel
Definition of 'channel': can we regulate every single APD (very much appreciated) or just two paired APDs on one (better: different) crystal(s)?
Development in close contact with Hans-Georg, who develops this kind of circuit for the barrel: selection of parts, tests of radiation hardness of components
What regulation volume is needed? Gain (M) variation about 8%/V at M=200, radiation damage at full Panda dose in the order of a few volts maximum at -25 degrees C
Suggestion by Christoph: 70 mV/step (8 bit chip), resulting in -12.5 V regulation volume
As a consequence of integration of those regulators to the backplate PCBs the hole in the middle of the PCBs for cable feedthrough is shrinking
Communication to HV regulation via I2C: How many physical bus lines needed (number of addresses)? Sub-busses hidable behind addresses?