Mar 21, 2019 Calorimeter

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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


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

Goals for Calorimetry Group

  1. Determine preliminary photon reconstruction efficiencies as a function of E, phi and theta in data and simulation with a point-to-point precision of at least 5%.
  2. Measure systematics of pi0/eta mass calibration as a function of detector position to a precision of at east 5 MeV.
  3. Demonstrate agreement of photon reconstruction efficiency and resolution between data and simulation as a function of E, phi and theta to within 5%.

Action Items

Short term items:

  1. Complete Calorimeter work packages
  1. BCAL: Check pulsing rate of LED triggers when FP trigger bit is missing (start with early runs in fall 2018). With discerning software, check pulsing rate of later runs where it appeared that the downstream FP LED bit was not firing. (Ahmed)

Long term items:

  1. From Mike's work: -cos(phi) type dependence in the data and a phi dependence at the downstream end of the bcal. See Sep 21, 2017 Calorimeter Meeting.
  2. FCAL: It has been noticed that the pi0 mass shifts when the LED pulser runs at high rate. This is still not understood. See Log Entry 3595928 and references. Several runs have been taken in raw mode. These runs exhibit the shift in pi0 mass with LED running at 1 kHz. There is a need to analyze these to try to determine the cause:
    1. 50634 - FCAL Green LED: 1kHz, 29 V, Livetime is 9%, 1.7 M events
    2. 50635 - FCAL Violet LED: 1kHz, 22 V, Livetime is 9%, 1.4 M events
    3. 50636 - FCAL Blue LED: 1kHz, 15 V, Livetime is 9%, 1.5 M events

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Run Updates
    1. FCAL
    2. BCAL
  4. Calibrations
    1. File:Fall18 gain calib.pdf
    2. Study of Fiducial Cuts for Photons in the BCAL/FCAL Transition Region
  5. Monitoring
  6. NIM articles
  7. Any other business


Attending: Zisis, Elton, Karthik, Mark, Sean, Colin (JLab); Tegan, Ahmed (UofR); Will, Curtis (CMU); Christina, George (Athens); Matt,, Jon (IU); Tolga (FIU).

  1. Announcements
  2. Action Items
  3. Reviewed status of Calorimeter work packages. I have added item numbers for ease of identification. We have been asked to produce a summary document on these questions to be reported at the next collaboration meeting.
    1. See report under calibrations
    2. This is on Karthik's plate as he completes the pi0 calibration
    3. Completed. Sean: Add link in last column to summarize work (Colin)
    4. Jon needs to summarize work to date as well as make programs available for continuity. Matt: Data/MC agree in analysis, but efficiency is higher by about 5% than calculated using photons from particle gun. This needs to be understood.
    5. Need volunteer. Repeat Jon's analysis for BCAL. Use w -> pi+ pi- pi0, pi0->gg.
    6. Need volunteer. Repeat previous efficiency study using w->pi0 g decay. Lower branch, but wider kinematic range.
    7. Added this new item. Study relative efficiencies in FCAL and BCAL using the Costhe Efficiency method.
    8. Need volunteer to study FCAL resolution vs momentum and angle. Compare to MC.
    9. Need volunteer to study FCAL resolution vs momentum and angle. Compare to MC. Initial studies completed for NIM paper, but need to expand systematic studies.
    10. Need volunteer to study neutral/charged BCAL timing resolution differences. Tolga has started thinking about this problem. This item has lower priority than others above.
  4. Run Updates
    1. FCAL
      • Replaced about 30 bases this run. Steady running.
      • We need to broaden the knowledge base on how to reset bases. Elton and Mark should be trained. Colin will meet with them when one fails to show them. There is a description online under 'expert'.
    2. BCAL
      • The monitoring occupancy plots for shift takers need to be modified to eliminate BCAL LED triggers. This will minimize questions during shift taking. Sean agreed to do this.
  5. Calibrations
    1. File:Fall18 gain calib.pdf
      • Colin: fluctuations in pi0 mass determination for Mpi0 > 3 GeV may be due to double G fits, which makes fits converge poorly. Karthik will check this with Zisis.
    2. Study of Fiducial Cuts for Photons in the BCAL/FCAL Transition Region
      1. Mark went over a very complete study of the transition region between FCAL and BCAL
      2. Matt: See systematic shifts in BCAL reconstruction/thrown. This needs to be adjusted away from the transition region after we check that Richard has included adjustments to Geant4 to match Geant3. (Sean will check on this).
      3. Suggested fiducial volume cut: BCAL z > 384 cm and FCAL R > 104 cm. Page 42.
      4. Studies of merging were discussed.
      5. Mark studied the possibility of merging FCAL and BCAL showers in the transition region. Only about 50% of the energy is reconstructed. Out of a million pi0s thrown, 481k reconstructed (current), 505k (merging), 401k (fiducial volume cut). Page 50.
      6. Matt: May wish to reproduce some of the studies that Jon did for the FCAL by comparing various features (e.g. number of hits, etc) between data and MC.
      7. Mark: Merging uses a "tagged" factory, which calls the standard shower factory and makes adjustments. Can easily be called now with a tag.
      8. Christina: Does the FV depend on energy? Mark: Probably, but this has not been studied in detail. Sean: It might be useful to have recommendations for FV cuts for interesting values of purity vs. efficiency.
      9. Mark posed the question regarding what effort should be devoted to merging showers. Matt: Suggests that the FV cuts be made in order to reduce combinatoric backgrounds. But it could be useful to save a few quantities that characterize the missing energy (e.g. number of showers removed, energy removed, etc). Sean: Could provide the measures of unused energy both in the FV and in the transition region.
      10. Elton: Do we make a FV cut in the FCAL around the beam hole? Matt: No, but showers need to satisfy reconstruction criteria. Elton: We should ensure that energy is contained in the FV. Measures of unused energy around the beam hole could also be saved. Sean: We may wish to select on energy outside the first 3 rings of FCAL for the early data.
  6. Monitoring
  7. NIM articles
  8. Any other business