Revision as of 17:50, 10 July 2014

July 10, 2014 FDC+CDC meeting

Agenda

1. Gas system
2. DAQ (Beni)
3. CDC status [1] (Mike, Beni)
4. FDC status CDC raw data, FDC raw data, [2] (Lubomir)
   • noise studies, [3] (Luke)
5. Electronics (Chris, Nick)
6. Engineering (Bill)
7. Other

Instructions for Bluejeans meeting connection

FDC meeting ID: 290664653

Minutes

Participants: Curtis, Naomi (CMU), Luke, Eugene, Dave, Chris, Nick, Simon, Mike, Beni, Fernando, and Lubomir (JLab).

Gas system

- Last Thursday after the FDC meeting Dave and Lubomir connected the power of the gas controls in the gas room to a UPS. When the power was restored the 4-20mA setting of the two masters were different (40mA as usual), but also the settings of one slave channel did change, that never happened before. Dave will see if he can read the settings and either restore them correctly, or issue an alarm. This has to be discussed also with Hovanes.

- On Saturday the switch on the CO2 bottles didn't work when one set of bottles got empty; it was supposed to switch to the full set of bottles. For one-two hours there was no CO2 flow into the FDC mixing tank, and 0.2l/m (instead of 0.9) was going into the CDC mixing tank. The bottom half of the CDC and 25% of the FDC channels tripped. Dave can implement an alarm, but everybody agrees some kind of a messaging system is needed, as well. Scott contacted the gas company to replace the switch. This switch was working before, and we have the same switch for the Argon bottles.

DAQ

- Beni: The attempt to read synchronously the BCAL and the CDC failed. It's not clear why, the ROCs where receiving the data but then it got lost somewhere. Will try it again tomorrow.

- Beni: there's a problems with the relation between the pedestal positions and the DAC values in the fADC. The relation is different for the CDC and the FDC. For the CDC the pedestals are at ~500 and all the DAC values are set to 0x9000 (hex), and for the FDC the pedestals are at ~1000 but the DAC values are set all at 0x8000 (see plots linked to item 4). Fernando tried to explain this by the difference in the pre-amp gains (factor of 4). Still it's not clear (at least to me) how the fADC knows what pre-amp is connected, is there a difference in the impedances?

CDC noise