Dec 14, 2017 Calorimeter

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Video Conferencing Information

Meeting Time: 11:00 a.m.

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Participant Direct Lines

  • JLab Phone in CC L207 is 757-269-7084 (usual room)
  • JLab Phone: in CC F326 is 757-269-6460
  • 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. Check in the code, including scripts, that is used for recent calibrations into git (BCAL: Mark)
  2. Add Fcal dead channels into the MC. [Matt and Elton] See links below
  3. Add monitoring plots for charged particle clusterizer [Will to suggest plots and collaborate with Mark]
  4. BCAL matching efficiency: Why the matching efficiency decreased by about 2% when the charged clusterizer was included into the analysis. In progress by Simon

Complete after new launch

  1. Report back on study of eta with in FCAL [Mark]
  2. From Mike's work: -cos(phi) type dependence in the data and a phi dependence at the downstream end of the bcal


  1. FCAL HDFCAL log book
  2. BCAL HDBCAL log book

Tentative Agenda

  1. Announcements
  2. Action Items
  3. FCAL Update
    1. Run preparations
    2. Nonlinear correction in MC
    3. CCDB block efficiency update
    4. Other updates
      • Photon Efficiency Update (Jon)
  4. BCAL update
    1. Run preparations
    2. Other updates
  5. Calibrations
  6. Reconstruction and Simulation
  7. NIM articles
  8. Any other business


Attendees: Elton, Mark, Colin, Simon (JLab); Sean (FSU); Matt, Jon (IU); George (Athens); Zisis (UofR); Will (CMU).

  1. Announcements
  2. Action Items
  3. FCAL Update
    1. Run preparations (Colin)
      • Chris has 14 bases to be replaced tomorrow. 16 additional bases dropping 100 V below set point. Have 10 bases ready for the test bench today. Could be used on Monday.
      • Matt: What is the current failure rate? Colin: too many issues being sorted out to get a good number right now.
      • Elton: What voltages are to be used for the spring 2018? Colin: Would like to take LED data at various voltages to establish gain vs voltage curves. (Mark and Colin will take dat today). Need about 10k events per run.
      • Procedure: Use the measured gains using pi0 peaks and voltages during spring 2017 to predict new voltage to set new gains.
      • Discussion about edge blocks (3 inner layers and 3 outer layers). Gains not determined during calibration. Need to get the best estimate in order to make HV adjustments.
      • Matt: Could also use LED data to adjust relative gains with nearest neighbors, but we expect LED signal input variations due to light collection.
      • Matt: On the longer time scale, would like to use MC to estimate leakage so that pi0 peaks can be adjusted to expected (degraded) position and calibrate accordingly.
    2. LED script (Mark)
      • Modified Fcal LED pulser script to cycle at 10 min intervals at 10 Hz. Blue set to 29V; violet to 11.9 V and green to 9.9 V.
      • Want to run at 2 voltages? Matt: Yes, but careful that outer pmts do not get too much light.
      • Mark: How to choose voltages? -Match dynamic range to limit number of overflows for high light channels, but yet increase distance from pedestals for low light channels.
    3. Nonlinear correction in MC (Matt)
      • Using photon particle gun. Plotted Ereconstructed/Egenerated vs Ereconstructed.
      • Use piece-wise continuous linear+exponential function to fit non-linearity.
      • Sacrificing the lowest point (0.25 GeV), function reproduces data < 0.75 GeV.
      • Mark: The non-linearities should be calibrated in MC in the same was as data (eventually).
      • Elton: Need a better matching at low energies if we are going to reconstruct showers down to 0.25 GeV, where corrected means are off by 6%.
      • Finding the physics channels that require using low-energy photons can be used to drive the reevaluation of this correction.
      • Matt: Could Sean take the constants in the log entry and add them to ccdb? Yes.
    4. CCDB block efficiency update (Elton)
      • Added block efficiencies computed by Matt based on LED data to the ccdb.
      • Peaks in efficiency can be found at zero efficiency (dead channels), and eff~0.6-0.7. This could be due to channels being on 2/3 of the time. Another possibility, mentioned by Matt is that 3 LED colors were used to compute efficiencies and then averaged. If 2 of the 3 LED signals were above threshold that would create the same result.
      • Next step is to generate a large omega MC sample to check calibrations and overall scale in MC.
      • Sean asked if Matt could check linearity to higher energies (e.g. 10 GeV) with adequate input data. Matt: Yes. Sean will ask Thomas to generate more events at higher energies.
    5. Other updates
      • Photon Efficiency Update (Jon)
      • Update on efficiency computations using gp->omega p, omega->pi+pi-pi0, pi0->g(g). Require one reconstructed gamma, E>0.5 GeV. Eliminate events with additional more than 2 clusters.
      • Perform kinematic fit to reaction with one gamma missing. Select on kinematic CL for both samples with two reconstructed photons (numerator) and one or two reconstructed photons (denominator)
      • Estimate efficiency by determining the ratio of events in the omega peak using recoil proton missing mass divided by the number in the omega invariant mass peak.
  4. BCAL update
    1. Run preparations
      • Python libraries became corrupted in June and had to be fixed (David). LED pulser is now running again and Mark left instructions on the BCAL expert page.
    2. Other updates
  5. Calibrations
    • Tegan task is to compare calibrations using exclusive vs inclusive samples (but is in the middle of exams)
  6. Reconstruction and Simulation
    • Zisis: Neutron reconstruction. Andrei continues to study this and will suggest best places to include neutron clusterizer code integrated into the neutral and charged particle clusterizers.
    • Sean: Checking timing resolution for BCAL. Latest updates indicate that situation is ok, though not perfect. He has sent files to Mark for evaluation.
    • BCAL non-linear corrections: Will to evaluate the latest MC updates and check non-linearities in MC using single photon particle gun.
  7. NIM articles
    • Many comments received, which are being included into "final" draft. Elton and Zisis will talk next week to review final changes.
  8. Any other business