Difference between revisions of "Minutes-5-5-2016"

From GlueXWiki
Jump to: navigation, search
(fADC125)
 
(5 intermediate revisions by 2 users not shown)
Line 5: Line 5:
 
# [https://halldweb.jlab.org/wiki/index.php/Connect_to_Bluejeans_Meetings Instructions for Bluejeans meeting connection]
 
# [https://halldweb.jlab.org/wiki/index.php/Connect_to_Bluejeans_Meetings Instructions for Bluejeans meeting connection]
 
# Meeting ID: 290664653
 
# Meeting ID: 290664653
 +
== Headline text ==
 +
 
# To join via a Web Browser, go to the page [https://bluejeans.com/290664653] https://bluejeans.com/290664653.
 
# To join via a Web Browser, go to the page [https://bluejeans.com/290664653] https://bluejeans.com/290664653.
  
Line 12: Line 14:
 
#* CDC update (Beni/Mike)
 
#* CDC update (Beni/Mike)
 
#* FDC update (Lubomir, Vlad)
 
#* FDC update (Lubomir, Vlad)
#** Cathode Gain Calibration
+
#** [http://www.jlab.org/Hall-D/detector/fdc/berdnikov/Present.pdf Cathode Gain Calibration]
 
# Electronics (Fernando, Chris, Nick)
 
# Electronics (Fernando, Chris, Nick)
 
# NIM Papers
 
# NIM Papers
Line 19: Line 21:
 
# fADC125 meeting (Naomi, Cody, Beni)
 
# fADC125 meeting (Naomi, Cody, Beni)
 
# Other
 
# Other
 
<!--
 
  
 
= Minutes =
 
= Minutes =
  
Participants: Curtis, Naomi, Mike (CMU) Eugene, Fernando, Beni, Luke, Simon, Nick, Chris, Vlad, Sergey, Amanda (detector group), Tyler (detector group), Pablo (detector group), and Lubomir (JLab).
+
Participants: Curtis, Naomi, Mike (CMU) Eugene, Fernando, Beni, Luke, Simon, Nick, Chris, Vlad, and Lubomir (JLab).
  
== Detector updates ==
+
== fADC125 ==
 +
 +
- Naomi discussed some issues ( a bug fixed in the timing algorithm?) and future firmware developments, like self-triggering.
  
- CDC has been successfully fixed after the "near-miss" [https://logbooks.jlab.org/entry/3397702 event]. The card that Nick suspected for noise was tested with a scope and was OK. Fernando: "the electronics saved the day" (i.e. the detector).  
+
- Lubomir looked at some runs with the special f125 firmware for the TRD studies and found sometimes the event number (within the same data bank) is different for the different modules. Looking at the time stamps (trigger time) indeed they correspond to events from the past or the future. Sometimes (even the event number per buffer is one) there are several consecutive events from one module. Beni: that is possible if the buffer level is set to >1 in mode 8.
  
- Vlad reported on the FDC gain calibration. He did this before, but now the cathode resolution was improved and he uses now higher statistics (~1M hits per chamber). In the attached plots we see the distribution of the gain coefficients is getting narrower with each iteration - 4 in total. Some channels tend not to be calibrated producing tails in the distributions. Vlad will also work on parallelizing the calculations: separate job for each chamber. 
+
== Detector updates ==
 
+
- FDC monitoring: Lubomir proposed monitoring pages with the hit histograms, i.e. position and timing coincidence b/n the two cathode planes and the wire plane (example shown above). One page with 6 histograms per package. Mike: timing is difficult at early reconstruction, but position correlation is easy. Later Mike implemented such histograms. The complain was that this is next level of reconstruction and for the monitoring it is better to use just the occupancies. 
+
 
+
- We discussed a possible photon background in that Hall based on measurements (logentry linked) with Xe, for which the x-section is 10-100 times higher than for Ar for photon energies in 10-100kev range (picture attached). The observed background difference with Ar/Xe may indicate presence of such photon background. More results and discussions will follow.
+
 
+
== fADC125 (submitted by Naomi) ==
+
 
+
- Naomi is still looking at the differences between firmware and emulated output using the long mode (8) cosmic runs.
+
 
+
* Run 11016  2 CDC fadcs were playing up: roc25 slot 9, even ch 36-40 and roc28 slot 16, even ch 36-40 - there were small errors in 4/5 of hits (firmware time too large by 1 or 2 units (0.8ns), and integral too small by 5 to 8).  There were a small number of problems with the FDC fadcs (differences in time and pedestal) but nothing significant.
+
 
+
* Run 11017  All CDC & FDC fadcs were ok.  For this run the trigger holdoff had been increased to 30us.
+
  
* Run 11075  There were many errors in the same two CDC fadc as in Run 11016, and also in one FDC fadc: roc62 slot 17 even ch 36-42 show same behaviour. For this run the bufferlevel had been set to 1.
+
- Beni: the HV and LV of FDC and CDC were turned off for the summer. As discussed later with Fernando we plan at some point to turn the HV on to look at the CDC card that had issues over the last run and also to test the stability of the FDC HV.
 +
Beni also lowered the gas flow and bypassed the alcohol bubblers. The latter is needed to reduce the effect of the alcohol on some type of glue used in the CDC, which however is not critical.
  
 +
- Most of the remaining time we discussed Vlad's results on the cathode calibration, see attached presentation. The expression to be minimized consists of two terms: (1) the total charge on the top minus the bottom charge and (2) the residuals of the fit (with Matheson function) of the amplitudes for each hit. Vlad demonstrated the convergency of the procedure - after each iteration the distribution of the gain coefficients is getting narrower. However, once the amplitudes are corrected by the gain coefficients, the strip resolution deteriorates. Vlad: it might be a result of the strongly non-uniform hit distribution over the chambers. Eugene proposed to start with a simpler minimization using only the second term, to apply it for one cathode only on a small area and also to add a normalization term. Discussions continued after the meeting.     
  
- Naomi noticed that the fadc configuration parameters in the BOR data read back from the fadcs in run 11075 is corrupt for these 3 boards, ch 36-41 (all) in the CDC boards, and channels 36-47 in FDC roc 62.  These include more than the dodgy channels mentioned above.
+
== NIM papers ==
This indicates a problem reading from the chip.  If it were a write problem, the discrepancies between firmware/emulator would be much larger than observed.  In run 11016 only the CDC boards had BORconfig errors, and run 11017's BOR decoding crashed.
+
  
-->
+
- Beni started working on the CDC paper from the svn directory. He wants to have the first version ready before the summer so that people have what to work on during the break.

Latest revision as of 14:20, 6 May 2016

May 5, 2016 Drift Chamber meeting

Connection

  1. Instructions for Bluejeans meeting connection
  2. Meeting ID: 290664653

Headline text

  1. To join via a Web Browser, go to the page [1] https://bluejeans.com/290664653.

Agenda

  1. Detector updates
  2. Electronics (Fernando, Chris, Nick)
  3. NIM Papers
  4. fADC125 meeting (Naomi, Cody, Beni)
  5. Other

Minutes

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

fADC125

- Naomi discussed some issues ( a bug fixed in the timing algorithm?) and future firmware developments, like self-triggering.

- Lubomir looked at some runs with the special f125 firmware for the TRD studies and found sometimes the event number (within the same data bank) is different for the different modules. Looking at the time stamps (trigger time) indeed they correspond to events from the past or the future. Sometimes (even the event number per buffer is one) there are several consecutive events from one module. Beni: that is possible if the buffer level is set to >1 in mode 8.

Detector updates

- Beni: the HV and LV of FDC and CDC were turned off for the summer. As discussed later with Fernando we plan at some point to turn the HV on to look at the CDC card that had issues over the last run and also to test the stability of the FDC HV. Beni also lowered the gas flow and bypassed the alcohol bubblers. The latter is needed to reduce the effect of the alcohol on some type of glue used in the CDC, which however is not critical.

- Most of the remaining time we discussed Vlad's results on the cathode calibration, see attached presentation. The expression to be minimized consists of two terms: (1) the total charge on the top minus the bottom charge and (2) the residuals of the fit (with Matheson function) of the amplitudes for each hit. Vlad demonstrated the convergency of the procedure - after each iteration the distribution of the gain coefficients is getting narrower. However, once the amplitudes are corrected by the gain coefficients, the strip resolution deteriorates. Vlad: it might be a result of the strongly non-uniform hit distribution over the chambers. Eugene proposed to start with a simpler minimization using only the second term, to apply it for one cathode only on a small area and also to add a normalization term. Discussions continued after the meeting.

NIM papers

- Beni started working on the CDC paper from the svn directory. He wants to have the first version ready before the summer so that people have what to work on during the break.