May 7, 2014 Calibration

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GlueX Calibration Meeting
Wednesday, May 7, 2014
10:45 am, EDT
JLab: CEBAF Center, F326

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  1. Announcements
  2. Collaboration Meeting May 12-14
  3. Status Update
  4. Tracking CDC_B_field
  5. Calorimetry
  6. Other systems
  7. Simulations and Calibrations


Attending: Sean, Amiran (NU); Curtis, Naomi (CMU); Simon, Lubomir, Mark (JLab); Justin (MIT)

  1. Collaboration Meeting May 12-14
    • Sean will collect information about the measurements that each subdetector group is planning to make this year for the calibration discussion next Tuesday,
  2. Status Update
    • Sean has been working on applying constants to the digitized values. This has involved reviewing the constants needed and working through some lingering bugs with EVIO file reading/writing with David L.
  3. Tracking
    • Naomi reported on plans to correct the drift distance calculations for the variation of the magnetic field in the CDC.
      • In the CDC volume, the magnetic field varies from 1.3T to 1.9T at nominal current, primarily in z.
      • At large drift radius, she finds that the drift radius changes by a maximum ~30um per 0.1T, compared to a resolution of 80-100um.
      • To correct for this effect, the plan is to get a best guess for the r,z of the hit, guess the B field at that point, correct the drift time to what it would be in a 1.3T B field, then convert the time to distance using lookup tables. These corrections would be applied at the point of converting the digitized hit into a normal CDC hit.
      • With a "simple" parameterization of these effects, Naomi gets to within 2.5ns -> ~15um of the actual drift distance.
      • Sean suggested that we should have a discussion during one of the breaks in the Collaboration Meeting about how to integrate these (and other) effects into mcsmear.
    • Simon has added in some constants to be used for dE/dx determination.