July 9, 2020 Calorimeter

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Meeting Time: 11:00 a.m. JLab time

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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
  3. Calibrations: 2020 Data Production; RunPeriod-2019-11 Validation; Offline Monitoring Data Validation

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 least 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

  1. Checks of monitoring comments of Batch 5-8
    1. Timing anomalies: 72123-72416 (2ns peaks), 72417-72435 (time offset) -> Mark
    2. Hit efficiencies: 72316-72435 (especially visible in "enhanced" efficiencies) -> related to next item?
    3. Recon Matching: 72271 (inefficiency at module~12, and 90deg), 72385 (degraded efficiency at module~47) -> Elton
  2. Long term items

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Run Update
    1. FCAL
    2. BCAL
  4. Calibrations
    1. Spring 2020 gain calibrations (entire run period) Update
    2. FCAL PRIMEX [2][3][4]
  5. Monitoring
    1. BCAL LED
    2. BCAL (offline)
    3. FCAL (offline) status statusII
  6. Reconstruction
    1. Reconstruction Systematics Task Force
    2. Efficiencies
  7. Simulations
  8. Any other business


Attending: Elton, Jon, Zisis, Varun, Foda, Igal, Rebecca, Sean, Tolgae, Curtis, Beni, Churamani, Karthik, Mark, Christina, Matt, Susan, Sasha

  1. Announcements: none
  2. Action Items:
    1. Reviewed Item #3 above. Elton showed slides at the Reconstruction meeting. Runs 72316-72369 show a hot channel. Run 72271 was found by Naomi to be related to a CDC crate crash. Slide 4 shows cell inefficiencies and timing issues (Mark is looking into the timing); Mod 37 is affected.
  3. Run Update
    1. FCAL: Mark reported that FCAL has been running for 3 weeks and shows suprisingly few issues (touch wood). Matt's explanation is 'herd immunity'.
    2. BCAL: Jon and Varun have been working with the DAQ in collecting LED events before the run. They communicate with Sergey and Sasha. Mark reminded us that the temps to check are 18, 10, 5 deg. A regular (morning?) schedule should be devised and communication with DAQ and DIRC people for DAQ use, and with technical staff to change the chiller temps.
  4. Calibrations
    1. Spring 2020 gain calibrations: Karthik has regrouped batches 1-8 into 4 batches, that showed similar gains behaviour. He is currently calibrating to extract 4 sets of constants for these.
    2. FCAL PRIMEX: Igal showed pedestal behaviour (it was not calibrated since 2018). There is a pedestal variation over the run periods. He is running iterations and it seems that the width will come down slightly, but not significantly. Sasha asked that the pedestal time evolution be looked at for the inner rings. Matt added that noise sometimes tiggers the Flash and can contaminate the pedestal.
  5. Monitoring
    1. BCAL LED: nothing to report.
    2. BCAL (offline)
      • See Action item above.
    3. FCAL (offline) : Susan went over monitoring plots in pursuing interesting problems. Now dividing by the correct occupancy plot. Effects seen can be related to crate position and possibly to temperature, in terms of crate fan failure. Mark commented that crate position matters for the BCAL and that the BCAL baseline can be recalibrated which should improve things by 1-1.5 channels. Matt mentioned that LED intensity affects zero suppresion at the tune of +/-5 counts. The discussion over the FCAL plots will be continued on Slack.
  6. Reconstruction
    1. Reconstruction Systematics Task Force
    2. Efficiencies: Elton discussed his efficiency studies, showing only data today (MC will follow in the future). He compared the 2018 run periods to 2017 for gg in BCAL, gg in FCAL and one g in each calorimeter. Things look reasonably in the comparison to 2017, with the FCAL having a few minor excursions from a ratio of 1 at low energies. Elton's curves are relative efficiencies (he effectively shows the product of two efficiencies) so they can be moved up or down, particularly in wanting to compare to Jon's (IU points) direct measurements using the omega. Elton uses gp->pi+pi-pi0 with pi0->gg and extends to much higher invariant mass that the omega. He has cuts to reduce the rho and Delta; uses the nominal FCAL QF=0.5 and a chi^2 cut that is aggressive at <2.5.
  7. Simulations
    1. Mark talked about the G4 bug and divided geometries which are summed up in BCAL. It was agreed that the G3-G4 fudge factor should be set to 0.7%. After the meeting, Richard was contacted to make the change.
    2. Zisis brought up Richard's email on propagating the magnetic field in the BCAL. Mark will recheck the energy calibration. Sean mentioned that this might affect the timing of charged particles inthe BCAL but should not affect the calibration.
    3. Neutral particle reconstruction. Beni showed simulations using an eta particle gun and p+b1 final state. He showed the number of neutral showers with QF and fiducial cuts. The fiducial cut hardly affects the distributions or their statistics. The QF cut has a consireable effect which gets larger as the eta angle increases; it cuts signal (events with exactly 6 gamma, and shifts 6g to 5g events in the multiplicity plot). The effect on the invariant mass plots was also shown. Multiplicity plots for BCAL and FCAL were shown, illustrating how multiplicity changes for larger eta angles as showers cross from FCAL to BCAL. Matt explained that the gaps at low and high QF values on slide 5 come from how the ML algorithm works, which needs tracks otherwise feature importance is lessened for some observables. The bottom line is that care must be exercised in using QF as a cut; it's indended use is to address hadronic splitoffs, so it make cause strange effects on channels with many neutrals. Sean suggested that it is easy to run two launches with different criteria sets (rather than customizing these sets per channel which is cumbersome). It was also noted that for Primakoff, the target recoild is too low to be detected, although some of those spiral and hit the FCAL.
  8. Any other business:
    1. BCAL Wiki (Elton): Elton is reorganizing this page, moving the old content under 'BCAL Construction'. Feedback is sought.