Dec 12, 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. Take a new noise measurements of the BCAL FADC baselines (Mark and Jon) ✔️
  2. Evaluate effect of conversions in FCAL efficiency determination with particle gun and reactions (Richard suggestion -> Jon) ✔️
  3. Proposal for updating BCAL gain constants 2019 / extrapolation to higher energy (Karthik)
  4. Read calorimeter section of NIM paper and provide feedback (Matt)
  5. Complete Calorimeter work packages

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
  5. Monitoring-
    • BCAL-LED update (Varun)[2]
  6. Efficiencies
  7. Simulations
    1. FCAL energy resolution
  8. NIM articles
  9. Any other business


Attending: Elton, Colin, Rupesh, Jon, Mark (JLab); Varun, Karthik, Ahmed, Zisis (UofR); Tolga (FIU); Sean (FSU); Matt (IU)

  1. Announcements
    • One more week of beam; period extended by one day into Friday morning.
  2. Action Items
    • See first two items discussed below
    • Karthik: Bcal gain constants are ready to upload to ccdb. Details in draft report to circulate in the next couple of days. This can be discussed offline. Elton: We should try to get these constants uploaded before the end of the year. Sean: It is a good time to come up with a plan that can be implemented systematically for future runs.
    • NIM paper: Matt will provide a paragraph to Elton for inclusion into the draft. Mark: Has read the section and feels that the performance should give Bcal and Fcal equal time.
  3. Run Updates
    1. FCAL
      • Rocfcal1 is now working. Found many cable swaps after changing crate. These are now fixed.
      • Should find a good time to redo the labels on the Fcal crate, as they are degrading.
      • Need to swap out 10-15 bases. No spares, but 30-40 in the repair stack.
      • FCAL PDU no longer has a network connection. Could use spare BCAL PDU. Elton: need to order another to have a spare
      • Anagate Quattro on detector has required rebooting lately. May need replacing. We should consider purchasing a spare, also the anagate controller.
      • 10-20% of the repaired bases are not delivering the expected voltages. They should be collected and shipped back to IU. Matt: Make sure that detailed diagnostic information be kept with the base.
    2. BCAL
      • Have two dead channels because the FADC DAC cannot be set.
      • Have one hot channel, both in the Flash and the TDC. Likely not a pedestal or threshold if it is hot in both.
    3. BCAL pedestals
      • SiPM damage report (Jon)
      • Data were taken to measure pedestal widths as a function of over-voltage at three temperatures (5, 10 and 18 degC).
      • Compared to data taken in 2015 and 2017
      • Mark: In subtracting the offset, one should do this in quadrature. Also, a more reliable baseline can be obtained by fitting (or averaging) the first few points.
      • The pedestal widths have increased very slightly from previous years. However they do exhibit the expected behavior for radiation damage: downstream is more affected than upstream, and inner layers are more affected than outer layers.
      • Next steps: a) Estimate approximate dose received to compare increased pedestal width with expected radiation damage. b) Continue to monitor, especially as heavier targets are used.
  4. Calibrations
    • FCAL (Colin). Spring 2019 PRIMEX calibration: non-linearity correction "broke everything". This is due to limited range fo data at higher photon energies (symmetric data <~ 3 GeV, instead of 4 GeV for other run periods).
    • Need to evaluate the functional form for the non-linearity correction.
    • Matt: Should also develop a procedure to fix one photon and use the second photon for the non-linearity calibration. Without the symmetric requirement, much higher statistics is available.
    • Mark: Studies using etas, provides access to higher energies also.
  5. Monitoring-
    • BCAL-LED update (Varun)[3]
    • Evaluated runs taken by Jon in raw mode that contain waveforms.
    • Shows that multi-peaked waveforms are consistent with reflections.
    • Mark: This effect has been known for some time. Elton will provide a reference to early toy studies of this effect.
  6. Efficiencies
    • FCAL omega update
    • Follow-up on Richard's suggestion at last collaboration meeting to include multi shower events into the analysis of the photon gun.
    • Removal of 2 shower events from the photon gun evaluation makes it more comparable to the omega analysis and increases the reported efficiency and brings it closer into agreement with the omega results.
    • Mark: There remain discrepancies between the two evaluations at low angles (near the hole) and at large angles (outer edge), but these are likely due to resolution effects.
    • Jon: The DIRC will also likely affect these efficiency evaluations and should be studied.
  7. Simulations
    1. FCAL energy resolution (Mark)
      • New comparison of energy resolution using eta decays for the NIM paper has been produced. Both BCAL and FCAL simulations underestimate the data by a small amount (a "hair"), but are reasonably close. The updated constants are in ccdb and should improve comparisons between MC and data.
  8. NIM articles
    • Matt and Rebecca have a draft of their ML classification of Fcal showers to be submitted to NIM. GlueX-doc-4282. Comments and requests for authorship are welcome by Dec 20.
  9. Any other business
    • Happy Holidays! Our next meeting will be Jan 9, 2020.