13/12/15

Current jumper setup:

     - detector 2977-15 connected to nnaida1,3,5,8 with GND kapton to nnaida1

     - bias of +75V to nnaida3 and nnaida5

     - Jumpers:

           - nnaida1 > Lk1. If Lk3 3 connected unable to bias detector

           - nnaida3 > Lk3. if Lk1 connected unable to bias detector as the HV ground reference is connected at both p- and n-sides of detector.

           - nnaida5 > Lk1 + Lk3

           - nnaida8 > Lk3

Powered system up as it was last night -> 2977-15 connected to nnaida1,3,5,8 with only 4 FEE modules powered.

     - n-side widths ~190-200 ch

     - p-side widths ~100ch

     - jumpers as above, ASIC setting as 2015Dec12_smallSetup, wav thresholds all at 500 apart from nnaida5 @ 250.

Spend remainder of day trying to fit mezzanine cables.

14/12/15

Completed installation of mezzanine cables.

Resistance between all mezzanines and cooling crates still ~200 kOhms (up from ~2-5 Ohms on our arrival), apart from nnaida7+8, which is now at ~5 Ohms

However, all see resistance to main vertical copper pipe of ~3 Ohms.

As best as I can see, isolating tape in still in place for all FEEs     =>     unknown point of contact.

       > LEMO cables to test inputs carry ground connection from NIM bin -> NIM bin in electrical contact with support frame -> coolant loop in electrical contact with support frame  => electrical connection still present between FEEs and coolant loop, even in insulating guide pins are introduced

       > this problem is not observed at DL because the NIM bin in on the wooden table top and isolated from the coolant loop and any support structure

       > is it possible to isolate the NIM bins from the support structure?

       > need to come up with some more systematic and fixed way/positions for measuring these resistances, i.e. always measure mezzanine to X.

Resistance between all mezzanines now ~ 0.5 Ohms.

n-side widths ~ 120ch and p-side widths ~ 120ch    =>    peak widths almost halved in n-side, but increased by ~20% in p-side.

Attempted to bias previously tripped detector.

      - same jumper combination as other detector caused failure to bias > leakage current jumps to 50uA at ~2V and trips shortly after, ramping back down from there.

      - removed all jumpers and see same thing.

Will try again in the morning by attaching 3131-11 to cables currently on 2977-15, but it looks like 3131-11 really is defective somehow.