Jul 11, 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. Send the location of a Wiki page to Matt, with information on the LED colors and voltages (Mark) Matt confirmed that Mark had sent the information.
  2. 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
  1. Run Updates
    1. FCAL
    2. BCAL
  2. Calibrations
    1. GlueX-doc-4118 SiPM saturation using laser knob calibration (Elton)
    2. [2] SIPM Saturation(Dhillon)
  3. Monitoring
  4. Simulations
    1. GlueX-doc-4116 CWP Item #10 Update: Particle Guns dT separation (Tolga)
    2. GlueX-doc-4115 Costhe Efficiencies Update (Elton)
  5. BCAL Deep Learning
    1. First Update on BCAL- Deep Learning.File:BCAL DL update 11 july.pdf
  6. NIM articles
  7. Any other business


Attending: Elton, Mark, Colin (JLab); Will (CMU); George, Christina (Athens); Jon, Matt (IU); Zisis, Ahmed, Karthik, Varun, James, Gabriel Dhillon (Regina): Sean (FSU); Tolga (FIU)

  1. Announcements
    1. Jon has completed his Ph.D. and has taken a post doc position at Regina (stationed at JLab) starting in mid Aug. Congratulations!
  2. Run Updates
    1. FCAL
      • Sasha has taken some FADC data with FCAL LEDs to check new firmware that should solve the 4 ns shifts.
      • The CPP experiment is considering installing the muon detector partially into the dark box. This is make the space inside the darkroom very tight to work (~ 20") but would only be used during the 1-month CPP run. A mockup of cardboard and/or other material will be placed in the dark room to evaluate the practicality of such an option with respect to servicing the FCAL.
    2. BCAL
      • Chillers are being serviced, filters changed, as routine maintenance.
  3. Calibrations
    1. [3] SIPM Saturation(Dhillon)
      • The unexpected small value of SiPM saturation needed for the BCAL calibration is being investigated with direct measurements of the hardware. Dhillon and Breanna were at JLab for 3 weeks and got a test setup working and took considerable data.
      • Setup is in the EEL, using a dark box with a laser in Fernando's lab
      • Laser light was adjusted by inserting filters of known attenuation into the laser beam (followed a by a diffuser)
      • Integral/peak ~ 7, where we find a value of about 12.8 in physics data. The difference is likely due to the increased width of the physics pulses due to reflections in the BCAL.
      • The light intensity scale was scaled to reproduce the measured peak value at low intensity. The saturation is measured relative to this.
      • Preliminary saturation curves were shown. Other data sets will be analyzed and a report completed by the end of the summer.
    2. GlueX-doc-4118 SiPM saturation using laser knob calibration (Elton)
      • After Dhillon and Breanna returned to Regina, we borrowed a calibrated photodiode from Carl Zorn to calibrate the photon flux.
      • We also observed that the intensity of the laser increases as the laser is warming up and opening and closing the dark box to insert filters leads to important systematics.
      • We calibrated the laser intensity knob with the diode and used this to do an intensity scan using the laser knob that did not require opening and closing the box.
      • Preliminary saturation curves were presented.
  4. Monitoring
  5. Simulations
    1. GlueX-doc-4116 CWP Item #10 Update: Particle Guns dT separation (Tolga)
      • Tolga investigated the timing response to photons and neutrons generated with the particle gun.
      • The timing distributions were shown for fixed angle and position but varying momenta.
      • Mark: Suggests that the energy and momenta be thrown over a continuous range. Study the timing as a function of the measured energies.
      • The timing distributions of the neutrons reflect the different path lengths, as expected. There are 2 ns discontinuities in the neutron data. Sean will provide some suggestions on the best variables to study that may avoid RF cuts.
      • Mark encouraged Tolga to call with questions between meetings to avoid misunderstandings in analysis.
    2. GlueX-doc-4115 Costhe Efficiencies Update (Elton)
      • These slides were presented at the Production and Analysis meeting yesterday. In the interest of time, Elton briefly summarized the main conclusions. A student from IHEP will take up the studies, especially on the FCAL.
  6. BCAL Deep Learning
    1. First Update on BCAL- Deep Learning.File:BCAL DL update 11 july.pdf (Karthik)
      • Karthik reviewed goals for machine learning studies: differentiate between charged and neutral showers; between electromagnetic and hadronic showers; options for classifying photon vs neutron showers.
      • Reviewed previous studies by Tegan in 2014.
      • Beginning to extend studies by using point information instead of shower information.
      • Preliminary results are encouraging. Note that training of the data is done with energies in the range of [0.3-3 GeV] and [4-6 GeV]. The Testing is done with energies in the range of [3-4 GeV].
      • Mark: Not sure of the value studying the difference between charged and neutral showers. Zisis: These studies are mainly to investigate the method.
  7. NIM articles
  8. Any other business
    • Matt: Updates to changes in the MC to better match FCAL data to MC especially at low energy (~0.2-0.5 GeV) are entered into a branch in GitHub. Changes need to be coordinated with updated constants in CCDB. Verifying that Sean has these changes on his to-do list
    • Sean: Wants to wait on the commits until 2018 is in process to avoid unintended confusion. Everyone seems to be on the same page.