Gain of APD preamp: gain depends on 1 pF capacitor. Precision +-0.2 pF. Same charge have very uniform values. However versions from two different producers soldered (white/vilolet) version. Check for gain differences for these preamp versions. Basel will check in preamplifier test database whether different rise times are observed. (Werner)
Ringing of APD preamp in cold (Tom). Basel and Bochum will check different options (capacitors). This will increase rise time. Question: What is allowed from the pileup detection? (Werner, Matthias)
APDs
Measurements at ELSA with Proto192 show variations of calibrated signals of about 20%; in addition a few channels have only 50% of the signal height. Reasons are unknown. What can we expect from APD gain calibration? (Fritz-Herbert)
The dark current measurements for currents below 1nA are problematic. It has to be investigated by ISEG. This gives for some APDs an error on the M=1 normalization. (Andrea). Andrea will check which APD measurements had this problem.
In which range is the parameterization (modified Miller function) used (Malte)? Below M=20 linear function, for about 200-450 V fit by the function.
Action: Andrea will send curves (data points vs. HV) of measurements at -25 and +20 degrees to Bochum.
Action: Bochum will send Andrea measurements of DC vs. pulsed.
Measurements of first 750 APDs ongoing. Measurement results will be made available asap. (Andrea)
Cables
"PatchPanel PCB": new selections of connectors (Christoph)
For tests of cable routing at 1:1 model or real backplate one will need 18 PatchPanelPCBs and Cables (Claudius). Christoph orders signal cables for tests asap and sends them to Bochum.
Bochum will check damping with preamp signals with ~10m cables.
LV cables still to be decided (Mario will check availability of shielded cables). LV distribution scheme to be decided on.
Claudius needs up to date NX CAD files from KVIcart for the cable routing to the ADCs.
Mechanics
Production at Bonn (Christoph):
Interface pcs.: One needs for the finalization a list of angles and drawings for the mounting tool holes from KVIcart.
Alveoli: 50 % ready
Mountingplate: need to check/correct hole for LP.
Inserts: ok.
Production at KVIcart (Added information from Myroslav by phone after meeting)
Henk will arrange the delivery of the backplate and frame to Bochum
A.o.B.
New shaper: Bonn will design a 4 channel shaper module similar to the version on the newest ADC. Input UFL, output Pfostenfeldstecker. Power via VME if possible. (Christoph)
Mailing list had problems. So people did not receive the invitation.