Apr 19, 2018 Calorimeter

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Video Conferencing Information

Meeting Time: 11:00 a.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 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

Action Items

Homework from NIM paper

  1. Non-linearity correction of SiPMs (Elton)

Complete after new launch

  1. Report back on study of eta with in FCAL [Mark]
  2. From Mike's work: -cos(phi) type dependence in the data and a phi dependence at the downstream end of the bcal


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

Tentative Agenda

  1. Announcements
  2. Action Items
  3. FCAL Update
    1. Run related
    2. Other updates
  4. BCAL update
    1. Run related
    2. Other updates
  5. Calibrations
  6. Monitoring
  7. Reconstruction and Simulation
  8. NIM articles
    • Proofs have been returned. Some paperwork remaining for publication
  9. Any other business


Attending: Elton, Mark (JLab); Sean (FSU); Will (CMU); Jon, Matt (IU); Tegan, Ahmed (UofR)

  1. Announcements
    • There is a visit by Ardavan Ghassemi of Hamamatsu scheduled for, APRIL 25, 2018 - 1:00 pm. ARC 225 - the conference room inside the Detector Group Habitat.
  2. Action Items
    • No updates
  3. BCAL update
    1. Run related
      • Smooth sailing. No issues during the run.
    2. Other updates
  4. Calibrations
    1. Log Entry 3562429 BCAL z-position calibration (Mark)
      • The position z = c0 + c1*Deltat + c2*Deltat**2. Constants c0, c1 and c2 are determined for each channel.
      • The values of the c1 constants (veff/2) are systematically higher than pervious years; the c2 quadratic term is lower.
      • The quadratic c2 also seems to have a phi dependence.
      • Systematics may be due to correlation between parameters in the fit. Or possibly the phi dependence is related to some asymmetries in tracking.
      • Sean: Suggest to share result with DC group and see if they have comments. He is not aware of calibrations of the CDCs or FDCs that would affect these parameters. Elton: Could be alignment, which has eliminated some earlier phi dependencies.
      • Mark: Could study this with higher statistics
      • Constants have been loaded into CCDB and as calibrations are completed, we can evaluate their effect on global quantities.
    2. BCAL pi0 calibration plots (Tegan)
      • 14 iterations have been completed to obtain new gain constants from pi0 calibrations
      • Good convergence is seen. Elton: How do these compare to previous years?
      • Will: What cuts are imposed? Tegan: only primary cut from skim (0.4 GeV?) With these cuts, resolutions seem comparable.
      • Elton: Suggest to generate plots with energy cuts, as Will has done for previous periods to be able to compare directly.
      • Will: From iteration 14, which shows a very uniform distribution of 2g mass vs channel number, it is converging nicely.
      • Sean: There are hidden exponents for the axes labels on the last slide, which need to be fixed.
      • Mark: Suggest new constants get uploaded. These are from the first run period 2018. Sean: There are no expected differences in BCAL for the other three run periods (split up for ease of management). Upload constants for entire run and check values don't change for other periods.
      • Mark: New z-position constants are now uploaded. One should check that the gains do not change with new z-calibrations.
      • Sean: Notes that calibration needed 14 iterations, which are very computer intensive. Could it be due to layer 3 dominating the time?
      • Will: Indeed, layers 1 and 2 require less time due to the relatively high S/N. Layer 3 takes more time to converge.
      • Mark: Suggests that a second skim be made to enrich layer 3 events, which could reduce iteration time. Tegan could start with Sean's pi0 skim code and add a requirement that enriches the events with high energy depositions in layer 3.
  5. Monitoring
    • No update
  6. Reconstruction and Simulation
    • No update
  7. NIM articles
    • Proofs have been returned. Some paperwork remaining for publication
  8. FCAL Update (Matt - was not present at the beginning of the meeting)
    1. Timing Calibrations
      • 4 ns offsets are quite problematic because they change so frequently from some channels. See Log Entry 3558996 from Mark.
      • Initial strategy was to fix changes at the channel level that would fix all timing issues. This has been problematic because there are no good references.
      • Second option is to use a hierarchy: first determine crate level shifts, then module shifts, and finally channel shifts. This is being actively pursued.
      • FCAL is now using an energy-weighted average for the time, which minimizes the influence of single channels on the shower time.
      • Elton: Are the present loose cuts in the analysis causing any inefficiencies? Matt: Should not be affecting the clusterizer. However, crate-level shifts may affect shower timing and therefore some event-level Chi2 cuts.
    2. Neural net
      • EM/hadronic shower neural net algorithm is being packaged so that it can be merged into the master. Some of the code needed to be rewritten by Jon to enable the merge and some discrepancies have arisen that are being sorted out. The merge will be made when these differences are understood.
  9. Any other business