March 26, 2014 Calibration

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GlueX Calibration Meeting
Wednesday, March 25, 2014
11:00 am, EDT
JLab: CEBAF Center, F326


Bluejeans Information

The meeting this week will be made using the bluejeans video conferencing solution supported by Jefferson Lab. You can find information from Jefferson Lab on this product as well as some notes that we within GlueX have made GlueX Bluejeans Video Conferencing. You should be able to connect seamlessly with virtually any device. If you have a polycom device, or want to connect through your web browser or tablet, use the Network Connection below. If you want to connect via phone, then use the phone information from below. The main drawback is that you may not be able to connect via a browser using a linux computer.

Bluejeans Applications

The first time that you connect to a bluejeans meeting, you will be prompted to install an application for your web browser. Versions of these for windows and macos have been placed on docDb as document 2435. You can also find apps for iOS and android.

Connect to the Meeting

Join via Polycom room system

    • Network Connection
      • IP Address:
      • URL:
    • Enter Meeting ID: 630804895

Join via a Webbrowser

    • If you have not registered with bluejeans through JLab:
    • If you have registered with bluejeans through JLab:
      • URL: [2]
      • Enter Conference ID: 630804895

Join via Phone

    • Dial-in phone number:
      • US or Canada: +1 408 740 7256 or
      • US or Canada: +1 888 240 2560
      • Dial-in international phone numbers
    • Enter Conference ID: 630804895


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


Attending: Sean, Amiran (NU); Beni, Simon, Mark, Michael S. (JLab); Curtis, Naomi (CMU); Eric (FIU); Justin (MIT)

Note: We used Bluejeans in this meeting for the first time. People were able to connect from a variety of locations, and generally the audio and video quality seemed good, although there was some feedthrough likely from built-in laptop microphones. Desktop sharing worked for the first time for the chair, and he was happy about that.

  1. Status Update
    • Sean asked about how to tag CCDB usage for data production (e.g. data challenges). Mark said that the best way to do this would be specify a certain value of the CCDB_CONNECTION environmental variable which would include a specific data/time (and variation if necessary). There was agreement that we should do this in the future.
  2. Tracking
    • Simon described progress in FDC alignment
      • He added tables to describe the constants needed for the alignment of the wire planes.
      • He is starting to use a cosmic ray event generator, which are giving some promising results and has fixed a bug in his code where one of the wire planes was not being updated. He hopes to have some nice pictures at next meeting.
    • Naomi generated some new time-to-distance tables for the CDC for some different straw sizes and Sean added them to the CCDB under different variations to make it easier to switch between them. The info on the tables will be documented on the wiki and the scripts used put in SVN.
      • Naomi asked what the expected temperature of the gas inside the CDC would be, since that affects the time-distance relation. Beni said that the FDC is 1-2 degrees warmer than inside the hall, and guessed that the CDC would be around 75 degrees F. This is 2 degrees larger than the value Naomi used when calculating her table, which has a negligible affect on the resolution (5 degrees might have some effect).
      • Naomi asked about what magnetic field she should use to generate tables, and there was some discussion on this. Simon sent her some code/ROOT files which she will look at, and mentioned that the largest variations are upstream to downstream. There may be some corrections needed for transverse B field variations, but there will likely be some corrections for longitudinal B field variation needed.
    • Beni said that the CDC is sitting in the hall, and that the survey team is working through some problems with their measurement.
  3. Calorimetry
    • All quiet on the calorimetry front.
  4. Other systems
    • Eric presented a nice update on his work on Start Counter calibrations
      • First he described the geometry of the start counter and showed some simulations of random tracks through the start counter.
      • He then described his analysis of propogation speed and attenuation corrections based on an analysis of test stand data.
      • The propagation speed correction for the TDCs differs in the straight and nose sections, and will be described in both areas by a linear function with two parameters (along with their errors).
      • The attenuation correction for the ADCs has a complicated shape due to geometrical effects. A fifth-order polynomial shape was chosen.
      • He is now moving to work on timewalk corrections. He was referred to several TOF experts and Simon offered to see if he can dig out any information he has on the Hall B start counter.
  5. Simulations and Calibrations
    • Sean and Amiran are looking at a sample of bggen events and promised to show some peaks next meeting.
    • Justin asked if any of the detector groups had expressed interest in any channels beyond what had already been presented, and the consensus was that more studies was needed to move forward with this.