GlueX TOF Meeting, October 21, 2014

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GlueX Time-of-Flight Meeting
Tuesday, October 21, 2014
11:00 am EDT
JLab: CEBAF Center F326/7


  1. Announcements
  2. Work in the Hall (Aristeidis)



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 .



  • FSU: Hussein Al Ghoul, Sasha Ostrovidov
  • JLab: Mark Ito, Aristeidis Tsaris, Beni Zihlmann

Work in the Hall

Aristeidis brought us up-to-date with recent TOF work.

  • He conducted a cross-training session on October 13 for would-be TOF experts along with the start counter training conducted by Eric Pooser.
  • There were two inefficient modules in the monitoring histograms last week. See the vertical band on page one of his plots. He traced this to a double swap, both the high voltage and the signal cables from neighboring PMTs had been exchanged.
  • Two channels showed a negative overshoot in the ADCs. See page two for the waveform. This was fixed by swapping out the cables from the splitter to the ADCs for new ones for both channels.
  • He has checked in the initial set of online monitoring histograms for the TOF.
  • He is working with Simon Taylor to incorporate a TOF display into hdview2. This version is like the "simple viewer" developed at FSU.

The Mode 7 Blues

  • Data taken over the weekend (24 million events) in mode 7 has problems with the ADCs
    • Mode 7 does not have waveform data, instead it reports pedestal, pulse integral, and leading-edge time.
  • The read-out threshold was set at 10 counts, when the pedestal value was 200. Only pulse integral data was non-zero as expected for this (mis-)configuration.
  • Aristeidis tried a value of 200 counts for the threshold and some of the channels were fixed.
  • He will try 210 and see if they all come around.
  • Beni suggests a 5 sigma threshold. Sasha reports that the pedestal width is about 1 to 2 counts.
  • We discussed an appropriate value of the number of samples before threshold crossing (NSB) and the number after threshold crossing (NSA) that are kept in the pulse integral. We decided that NSB = 10 and NSA = 45 were good values. There is another pair of NSB/NSA parameters for the trigger. We were not sure how they are used.
  • Aristeidis noted that the stand-alone TOF trigger could not be run from Sergey Furletov's general DAQ GUI, only by using the system that Sascha Somov set-up for us. We thought it would be nice if we could run both ways.
  • The standalone trigger was broken recently. Sascha S. fixed it; we don't know how.