Difference between revisions of "Minutes-7-17-2014"

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FDC meeting ID: 290664653
 
FDC meeting ID: 290664653
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= Minutes =
 
= Minutes =
  
 
Participants: Curtis, Naomi (CMU), Sean (NU), Luke, Dave, Chris, Mike, Simon, Beni, Fernando, and Lubomir (JLab).
 
Participants: Curtis, Naomi (CMU), Sean (NU), Luke, Dave, Chris, Mike, Simon, Beni, Fernando, and Lubomir (JLab).
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e difference in the pre-amp gains (factor of 4).
 
  
 
== CDC update ==
 
== CDC update ==
  
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- Mike made a report, linked above: the
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Mike made a report, linked above:
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== FDC update ==
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- Lubomir looked at the raw fADC data: plots linked above represent the distributions of the ADC values (from all the samples) as function of the channel. The plots are very useful since one can identify different kinds of problems: noisy channels when the area below the pedestal is populated, missing bit (like in the CDC plot ch.63), detector problem when the signals are small (like chan.71 in the FDC plot), connection issue when there's only a thin pedestal. Another problem is like ch.69 FDC plot: there's no pedestal visible, all values are overflown, however, if you look with a scope with differential probe we do see normal signals. If you connect another "good" cable to the same fADC connector everything is OK. What is then the difference between the fADC and the differential probe? Is this problem related to the pedestal problem Beni discussed above?
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- first slide shows the positions of the channels with noise as analyzed from the fADC data.
  
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- Summary of these observation are shown in a spreadsheet linked above (only half of the crates are included so far). The number of bad detector channels is about the same as we had right after the installation as studied with a scope.
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- next several slides demonstrate the "missing bit" problem. In one case all the channels in one module have that. Naomi: such problem was fixed be re-floating the circuit board. 
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- last slide shows the mean and the RMS of the pedestals. Questions about the meaning of the overflow/underflow in these histograms: Mike will work on that.
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- Mike: the strain relief of the signal cables is not good enough: sometimes may lose contact. Fernando will find a way to improve it.
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- According to Mike the pedestal subtraction in the Dave's code is done correctly, so this is not an explanation for the low CDC efficiency as discussed yesterday in the calibration meeting.
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== FDC update ==
  
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- Luke showed his studies (linked) of the noise in the FDC using a scope. He was looking for similar correlated noise that is seen in the CDC. This kind of noise is well visible only on these long strip that have short strips next to them (due to having ground from both sides of the frame). Luke's summary: most of the noise in the first and second package and mostly in the outer cells (one and six), frequencies 200kHz, 80kHz and 40kHz, amplitudes 10-15mV. Interestingly, if the cable is not well plugged into the adapter card, one can see the same noise on all the channels and the noise increases when the card is close to the VME crates (see picture).
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- Lubomir presented a table (xls file linked) with the all the problematic cathode channels as identified from the latest DAQ runs. Luke checked this channels with a scope which information is included in the
  
 
== Engineering ==
 
== Engineering ==

Revision as of 17:03, 17 July 2014

July 17, 2014 FDC+CDC meeting

Agenda

  1. DAQ (Beni)
  2. CDC status File:MStaibCDCUpdate17July2014.pdf (Mike, Beni)
  3. FDC status (Lubomir, Luke)
  4. Electronics (Chris, Nick)
  5. Engineering Cathode Scan system (Bill)
  6. Other

Instructions for Bluejeans meeting connection

FDC meeting ID: 290664653

Minutes

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

CDC update

Mike made a report, linked above:

- first slide shows the positions of the channels with noise as analyzed from the fADC data.

- next several slides demonstrate the "missing bit" problem. In one case all the channels in one module have that. Naomi: such problem was fixed be re-floating the circuit board.

- last slide shows the mean and the RMS of the pedestals. Questions about the meaning of the overflow/underflow in these histograms: Mike will work on that.

- Mike: the strain relief of the signal cables is not good enough: sometimes may lose contact. Fernando will find a way to improve it.

- According to Mike the pedestal subtraction in the Dave's code is done correctly, so this is not an explanation for the low CDC efficiency as discussed yesterday in the calibration meeting.


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