Minutes-7-31-2014

July 31, 2014 FDC+CDC meeting

Agenda

1. DAQ (Beni)
   • Pedestals FDC and CDC pedestals as a function of time
2. CDC status (Mike, Beni)
   • noise studies
   • File:CDCNoise7-31-2014.pdf
3. FDC status [1], [2], [3], [4] (Lubomir)
4. Electronics (Chris, Nick)
5. Cathode scan deviation from nominal polsition1, polsition2(Luke)
6. Other

Instructions for Bluejeans meeting connection

FDC meeting ID: 290664653

Minutes

Participants: Sean (NU), Curtis (CMU), Eugene, Luke, Mike, Sergey, Dave, Chris, Nick, Simon, Beni, and Lubomir (JLab).

DAQ

- Beni showed several results, explained in the logbook linked above. There are some fADC channels that don't report valid data (log entry 3290451). There's one module (ROCFDC3 slot 4) that was OK at the beginning of the run but at some point (after ~1k events) started reporting this problem for all of the channels.

- Typical CDC and FDC signals (from fADC) are shown in entry 3290447. The noise in the CDC is a factor of 2 higher than in the FDC (entries 3290447 and 3290445), also interestingly the frequency of the correlated noise in the CDC is a factor of 2 bigger. Lubomir: the CDC boards have 1/2 divider of the input signal, in contrast to the FDC. Would be interesting to check the noise without these resistors using also an FDC pre-amp.

- Beni found that there's some instability of the pedestals (3290411). For some of the channels there's even oscillation (3290403) with a period of about one hour.

- The plan is to have a synchronized (CDC&FDC + BCAL) run over the weekend.

CDC update

- Mike showed his studies of the noise (linked above). The burst noise (200kHz burst with 25MHz noise) disappears when turning off the HV of all/most of the channels. The other (white) noise doesn't depend on the HV. Mike showed possible sources of noise with a clock closer to 25MHz. For the FDC noise within the bursts is 12.5MHz.

- Noise discussions - Eugene: you should try with the cell repeater turned off. Beni: install some kind of copper mesh to shield the whole front of the CDC; the old FDC cathodes can be used for that? Sergey: try to shield the pre-amps with a box around them; some kind of pre-amp shield was already tried.

FDC update

-