GlueX Start Counter Meeting, December 12, 2014

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GlueX Start Counter Meeting
Friday, December 12, 2014
2:00 pm EST
CEBAF Center F326/327


  1. Announcements
  2. Review minutes from the November 13 meeting
  3. TDC Timing Update (all)
  4. Calibration (Eric)
  5. Action Item Review




Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2014-4Q on the JLab CUE. This directory is accessible from the web at .



  • FIU: Werner Boeglin, Mahmoud Kamel, Eric Pooser
  • JLab: Mark Ito, Beni Zihlmann

Online Monitoring Histograms

Eric has been looking at the histograms to check status of the start counter. He has some suggestions for histograms that should be pulled out and put into the "highlights" list for the online monitoring browser. He will send Justin an email with the list.

Start Counter Studies

Eric presented some slides on recent work to understand the data we are getting from the start counter. We had extensive discussion on each slide. The main themes were:

  • Timing. Now that he is using the reference signal to the F1-TDCs, reasonable timing results were shown.
  • Tracking Projections. The intersection points of charged tracks and the start counter are generally sensible, but in detail present many anomalies.


We identified the front-burner issues:

  • better understanding of charged track projections
  • counter-by-counter time offsets

Precision on the latter will depend on the former.

The Sector 2 Blues

Eric has noted consistently lower rates in sector 2 compared to the others going back to the early days of the run. The raw ADC and TDC spectra and occupancy do not explain it. More investigation is needed.