July 2, 2014 Calibration

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GlueX Calibration Meeting
Wednesday, July 2, 2014
11:00 am, EDT
JLab: CEBAF Center, F326

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  1. Announcements
  2. Status Update
  3. Tracking
  4. Calorimetry
  5. Other systems
  6. Simulations and Calibrations


Attending: Sean, Amiran (NU); Curtis, David L., Lubomir, Simon, Beni, Mark I. (JLab); Naomi (CMU)

  1. Announcements
    • Mark I. has tagged CCDB v1.02. This mainly fixes bugs related to when a primary variation for a JANA program is specified on the command line (e.g. JANA_CALIB_CONTEXT="variation=mc").
  2. Tracking
    • Naomi put together this document which describes her investigations on correcting for B-field variations. She also redid her studies of radial B-field variation with finer resolution and found a maximum difference of 3 ns at maximum drift time.
    • The current time-to-distance tables for the CDC are generated assuming a magnetic field. Simon is being provided with tables corresponding to zero magnetic field. It was noted that the gas mixture in the CDC has a temperature around 296K.
    • Beni has been taking cosmics data with both the CDC and FDC, and on his latest overnight run he got 50k events which took up ~900 GB of disk space. The triggers are prescaled, since right now he is reading out the entire CDC and FDC on raw mode for each trigger, so full rate running is going to require sparsification and/or moving to pulse mode, which will require the new FADC125 firmware which is currently in David L.'s hands.
    • Sean asked if there was a plan to keep metadata (e.g. start/end times, number of triggers, etc.) about the upcoming cosmic runs. David L. mentioned that originally this information was going to be stored in one of the database projects Dmitry was working on, but that is not going to be ready this summer. He said that writing a small database application to keep track of this info shouldn't be too difficult, and offered to add this to his task list.
    • There was also a discussion about how to give runs uniquely identifiable numbers before the full DAQ system is comissioned. There were a few possibilities discussed, with no consensus, but Mark I. mentioned that as far as the CCDB is concerned, all the subdetectors could start at the same run number but use different variations for each subdetector.
    • Naomi mentioned that she had looked at some of the EPICS variables (~1 minute's worth) and noticed that there was a 2-3 degree difference between the temperature of the endplates. This is perhaps not surprising, but it's not clear how this will affect the temperature of the gas. At least it's another z-dependent effect to look at.
    • David L. mentioned that it was found that the CDC straw numbering in the translation table didn't match the actual numbering as given on the endplates. This number was fixed, and he showed the results of an analysis of cosmic events that validated the fix.
  3. Calorimetry
    • Zisis (via email) reported on a discussion during the BCAL Commissioning meeting. The current plan to to have the Regina students at JLab begin analyzing the BCAL LED pulser & cosmic data that they are taking, under the supervision of Elton and Mark D. These data will be compared against the standard HDGeant simulations, and a standalone BCAL simulation which contains a more detailed geometry.
  4. Other systems
    • Richard J. (via email) has put constants in the CCDB for the energy ranges that correspond to hits in the tagger microscope & fixed array, based on an analysis by Dan Sober. He is updating the simulation to use these values.
  5. Simulations, etc.
    • Mark I. reminded us that we should be using different variations as we update the values of constants, e.g., if they correspond to calibrations for data or MC.