June 30, 2016 Calorimeter

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Video Conferencing Information

Meeting Time: 12:00 p.m.

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Participant Direct Lines

  • JLab Phone: in CC F326 is 757-269-6460 (usual room)
  • JLab Phone in CC L207 is 757-269-7084
  • Phone in the Regina Video-conference Suite is 306-585-4204
  • Athens Phone: in Christina's office is 011-30-210-727-6947

Action Items


  1. FCAL HDFCAL log book
  2. BCAL HDBCAL log book
  3. BCAL Action Items and Working Tasks

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Preparation for REST production
  4. FCAL non-linear shower corrections update
  5. BCAL update
  6. Calibrations
    1. Z-Dependance in the Time Calibration of BCAL (Andrei)
    2. Michel electron update
  7. Reconstruction and Simulation
    1. Neutron efficiency
  8. Any other business


Attendees: Elton, Jon, Adesh, Mark (JLab); Zisis, Ahmed, Andrei, Tegan, Colleen (UofR); Curtis (CMU); Sean (NW); George (Athens); Maria (MIT);

  1. Announcements
    • Manuel Lara is defending his thesis today.
  2. Action Items
  3. Preparation for REST production
    • Adesh: Preparing non-linear constants for FCAL for upcoming launches. Need one set for each of the two sets of HV settings.
  4. FCAL non-linear shower corrections update
    • Use symmetric showers (shower energies close to each other) from pi0 decays
    • Non-linear corrections set to 1 up to now
    • Parameterization is a piece-wise correction with linear fit (<1.5 GeV) and exponential (>1.5 GeV)
    • After correction a scale factor of about 1.005 needs to be applied to the data.
    • MC resulted in pi0 peak at about 90 MeV when new non-linear corrections were applied. This was due to the fat that the original non-linear correction included a scale factor in addition to an energy dependent correction.
    • Fix to MC includes introduction of a scale factor (~1.3) and new parameterization.
    • Non-linear parameterization for MC uses only an exponential. This is included in the program by adding a parameter for the transition between linear and exponential functions (set to 0 for MC, set to 1.5 GeV for data)
    • Adjusted per block energy threshold (reduced by about 20 down to 13 MeV).
    • Code changes needed to be made to match the parameter additions to CCDB. These have been completed and ready for next launch.
    • Long-term plan for matching MC and data non-linear behavior is to have the MC output digi-hits. This will allow using gain calibrations in MC, similar to the way it is done for data (using pi0 calibration). Matt will work on this.
    • Next effort will be to determine timing offsets.
    • Mark: How is this done? Answer: Use global fit to match timing of adjacent hits in a single shower. Mark: Check that low-energy hits are excluded from calibration sample.
  5. BCAL update
  6. Calibrations
    1. Z-Dependance in the Time Calibration of BCAL (Andrei)
      • Use charged and neutral hits to develop time-walk corrections
      • Finds consistent parameters for both charged (pions) and neutral hits.
      • To find optimal timing, need also to make position dependent corrections
      • Checked hypotheses for non-constant veff data. Found consistency with explanation of shower size influence on timing
      • Using quadratic for for veff finds good resolution and correct systematic effects seen in pi+ timing. There remain systematic issues in the proton timing.
      • Conclude that for optimal timing, corrections will be needed which depend on particle type and position of energy deposition
      • Mark: Need to clarify nomenclature: time-walk should be a function of pulse height only. Andrei: Notes that shower (and energy deposition) does depend on particle type and therefore could depend on pid and possibly position.
      • Elton: From a practical view of calibrations, we should have a time-walk correction that only depends on pulse height at the level of hits. Corrections to the timing (at the shower level) could be done at a higher level using all hits in a shower.
      • Zisis: Andrei and Tegan will be checking consistency of MC with data over the next month. Will take this discussion offline. For example, Jane's analysis shows that the pi0 width in MC is about 50% larger than in real data and this needs to be understood and fixed.
    2. Michel electron update
      • Zisis summarized the work on Michel electrons by Colleen and Tegan
      • Comparison of muon distributions in MC and data show fairly good agreement between 10 and 60 MeV of energy deposition.
      • Distributions of shower energies of Michel decays for three different selections on the fraction of energy deposited in the cell with maximum energy relative to the total. The comparison with MC is quite reasonable.
      • Data shown are for mode 7. (Mode 8 show larger discrepancies)
  7. Reconstruction and Simulation
    1. Neutron efficiency (Maria)
      • Update MC simulations of neutron detection efficiencies in the Bcal were shown. Efficiencies coming out of the matching factory show efficiencies of between 20-40% over the neutron momentum range of 0.5-0.9 GeV.
      • The MC input were neutrons from the particle gun with momentum between 0.2 - 0.9 GeV.
      • Next will move to look at real data. Will try to select exclusive reaction g p -> n pi+. Sean: Might want to consider the reaction g p -> n pi+ pi0, which will have more constraints.
      • It was not clear at the meeting what is in the matching factory, so that should be tracked down.
      • Zisis: Andrei had completed a study of neutrons previously, which is documented in GlueX-doc-1865.
  8. Any other business
    • Note the schedule for update talks in the e-mail from Paul Mattione
    • Check to see if you are on the list and that the schedule is reasonable.