Minutes-7-10-2014

July 10, 2014 FDC+CDC meeting

Agenda

1. Gas system
2. DAQ (Beni)
3. CDC status (Mike, Beni)
4. FDC status [1] (Lubomir)
   • noise studies, [2] (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 happen before. Dave will see if her can read this setting 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. For one-two hours there was no CO2 flow into the FDC mixing tank, and 0.2l/m (instead of 0.9) 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.

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.

CDC noise

- Fernando suspects the noise may come from the CDC itself, since it depends on the HV, and suggested increasing the CO2 content while keeping the same HV; the idea is to exclude the HV modules as a source of the noise. Eugene/Naomi: same effect will be if decrease/increase the HV by few hundred volts. Also it's difficult to explain with gas discharges the correlation we see in the noise (see plots from the last meeting). In any case, first Mike will study systematically where on the CDC we see the noise.

- Lubomir looked with a scope on the FDC and found noise with very similar pattern on several special channels. That was on the most upstream cathodes in the first and second package, but not in the other two, and always in cards that have both long and short strips (more susceptible to noise). It may indicate that the noise comes from the CDC or the mesh but one has to study this more systematically.

FDC update

- Lubomir started analyzing the fADC data from the last DAQ runs. The pedestal widths for the CDC are about a factor of 2 bigger than for the FDC: 20, 10 fADC units respectively. The widths in the FDC depend on the size of the strips.

- Important is that FDC sees many events with the CDC trigger; the explanation: most of the cosmic events are part of showers. The timing of the first maximum resembles the standard FDC drift time spectrum (histogram linked above). Beni will use this histogram to adjust the FDC pulse window from 20th to 100th sample, thus cutting the size of the files by 2. Before it was 0 to 160, as in the CDC.

Electronics

- Fernando: two CAEN modules back from repair. Chris/Nick will test them before using in the Hall.

Engineering

- Eugene: on the readiness review there was a remark that people stopped using plastic tubes for Fluorinert, only metal. Tim answered that the tube material was chosen to work for Fluorinert.

- Dave: put new mark on the Fluorunert level. Moved all the hardware needed for the cathode scan, the motor, controller and computer, in the ESB.

Other

- Luke Robison, a graduate student from Northwestern University will work on FDC projects for ~2 months: noise studies, cathode scan.

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