July14, 2016 Calorimeter

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Video Conferencing Information

Meeting Time: 11:00 p.m.

  1. To join via a Web Browser, go to the page [1] https://bluejeans.com/907185247.
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Participant Direct Lines

  • JLab Phone: in CC F326 is 757-269-6460 (usual room)
  • JLab Phone in CC L207 is 757-269-7084
  • 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. FCAL HDFCAL log book
  2. BCAL HDBCAL log book
  3. BCAL Action Items and Working Tasks

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Preparation for REST production
    • Analysis Train e-mail from Paul Mattione. Deadline is July 22.
    • Schedule of analysis reports: e-mail from Paul Mattione
  4. FCAL update
  5. BCAL update
  6. Calibrations
  7. Reconstruction and Simulation
  8. Any other business


Attendees: Elton, Mark, Adesh, Jon (JLab); Christina, George (Athens); Sean (NW); Will, Curtis, Mike (CMU); Andrei, Ahmed, Tegan, Colleen (UofR).

  1. Announcements
  2. Action Items
  3. Preparation for REST production
    • Analysis Train e-mail from Paul Mattione. Deadline is July 22.
    • Schedule of analysis reports: e-mail from Paul Mattione
  4. FCAL update
    1. Hardware update
      • Test setup for Fcal bases is operational at JLab. Chris is learning on how to test and fix bases. There is a Linux computer with software to communicate with the bases.
      • Paul has found that there are four resistors on the mult board that seem to be the source of HV problems. Replacing them should fix those problems.
      • Paul is providing documentation on the fixes and is transferring the information to Chris.
      • Start by fixing dividers with problems seen both on the detector and on the test setup.
    2. Efficiency Studies (from July 12 Analysis Meeting)
      • Jon has posted the slides from his presentation to the analysis meeting on Tuesday with a few updates based on feedback. Most of this information was presented at a previous Cal meeting.
      • He notes that the behavior across the Bcal/Fcal interface is surprisingly smooth, even when tighter cuts are applied to energy conservation.
    3. FCAL Gain Calibration Survey Adesh Subedi
      • Used the output of the monitoring plugins from the REST production to investigate systematics of the calibration as a function of run number and energy
      • The production covered three periods of calibration corresponding to three HV settings.
      • The single calibration for the first period is not adequate to cover the entire period. The early runs yield a pi0 peak below the nominal.
      • For Eg > 1 GeV, Mpi ~ 135 +/- 1 MeV, simga_pi ~ 7.1 MeV (sigma/E ~5.3%)
      • Same trends shown for Eg > 0.5 GeV.
      • Investigated empty target runs. Spectrum has additional peaks, speculated to be due to pi0s reconstructed with incorrect vertex. However, this analysis uses the reconstructed vertex determined from charged tracks, so this may not be the explanation.
      • Investigated runs with no beginning of run record (i.e. incorrect number of samples used in sum). Examples of runs 10591, 10563 have very high Mpi. Will likely remove these runs from the "good runs" list
      • Looked briefly at Mpi and Sigma_pi for photons in Bcal. The systematics seem more stable than for the Fcal (mass varies by 0.5 MeV total). Merged monitoring histograms are available if anyone else would like to use them. Contact Adesh.
      • Plotted stability of Mpi and Sigma_pi vs energy bins (requiring both photons to lie in an energy interval).
      • -> Need to update calibration for early runs ~ run 10400
      • Systematics in pi0 mass (changes from 136 down to 134 MeV) over some in the mid period. Sean: Could be due to beam instabilities and radiator changes.
      • Next meeting will report on Fcal timing
      • Curtis: Good to improve early runs, but beam conditions were not optimal.
      • Matt: Sigma_pi is constant as a function of energy, where a downward trend in sigma/E is expected. Elton: Notes that if Sigma_pi is constant, then sigma/E improves faster than expected for higher energies. Mark: The pi0 resolution combines position and energy, so there could be compensating effects.
  5. BCAL update
    • Will: Has requested that Mpi and Sigma_pi for Bcal be added to the time data base. Sean: Will check that it has been incorporated.
    • Elton: Is taking a look at the trees generated by the REST production to investigate Bcal efficiencies to hadrons. Will report at a later analysis meeting.
  6. Calibrations
    • Time Calibration & Resolution (Andrei)
    • Andrei gave an update on the Bcal TDC timing.
    • Check timing response of protons, which result in a high measured mass, but calibration was done with pions and neutrons.
    • Systematics of resolution check vs shower energy. Variation is of the order of +/- 50 ps.
    • Resolution obtained is Sigma ~ 70ps/Sqrt(E) + 260 ps.
    • Ready to upload constants to CCDB
    • Elton: We need a clear description of the new constants description of method. Sean: Example of implementation should also be added.
    • Elton: At a previous meetings it was decided that the z-position corrections would be done in a second stage pass to the shower timing. Integration of this procedure with the existing veff parameters needs to be clarified.
  7. Reconstruction and Simulation
    1. Update on BCAL Energy DATA/MC comparison (WIll M.)
      • First look into mcsmear behavior (by Will)
      • Recall that pi0 widths are about 50% larger in MC than in actual data.
      • Checking energy response by selectively eliminating various contributions to the resolution by using command-line arguments to mcsmerar
      • Finds that the one input that makes a large difference is the time resolution. Other terms seem to have no effect.
      • Curtis: It may be that if the time resolution is eliminated, the other contributions will show up.
      • Continue to investigate why the time resolution is affecting the pi0 mass width. Marc: Note that the pi0 width depends on both position and energy resolutions. The timing could be affecting the mass width through the position terms.
      • Sean: Identify specific plots, e.g. timing of hits vs cluster times, which could be used to diagnose the influence of the timing resolution.
    2. Monitoring (Ahmed)
      • Checking fluctuations of individual channel response within a single run, which are not understood.
      • Looking at mode 8 runs to see if the pulse shapes can give a clue to the fluctuations. No solid results so far.
      • Elton: Suggest that plots with updates be presented at this meeting so that others can give suggestions and input.
    3. Michel Electrons (Tegan and Colleen)
      • Showed plots of the energy distribution of electrons from muon decay for fixed values of the ratio = Emax_cell/Eshower. There is good agreement in some bins, eg. 0.7-1.0, but poor in some other bins e.g. 0.9-1.0.
      • Considering running the more detailed MC to see if one sees better agreement.
      • Marc: Are the plots separately normalized? Tegan: Yes, to the total number of entries. Marc: Do the numbers match? Take a look at the number of events vs. ratio
      • Elton: Check fraction of events vs ratio to investigate the efficiency of electron detection vs the ratio.
      • Will: Why is the 50 < z < 250 cm selection used? Colleen: that corresponds to the range used in the simulation.
  8. Any other business