Mar 22, 2018 Calorimeter

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Video Conferencing Information

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

Action Items

  1. Decide on approach to FCAL timing calibration and proceed with it (Matt, Mark, Colin) High level timing cut on Fcal of < 2.5 ns was eliminating matches in the Fcal due to some 4 ns crate offsets. Relaxing the cut to < 6.5 ns prevents this problem and is used as a temporary fix.
  2. Checks of MC calibrations for BCAL. Timing (Sean and Mark) See reports below.
  3. Determine what fraction of pi0's skims from 2018 data are needed for calibration work. See notes below.

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

References

  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. Reconstruction and Simulation
  7. NIM articles
    • BCAL paper has been resubmitted to NIM
  8. Any other business

Minutes

Attending: Elton, Mark, Colin (JLab); Will, Curtis (CMU); Zisis, Ahmed (UofR); Matt (IU); George (Athens); Tolga, Rupesh (FIU); Sean (FSU)

  1. Announcements
  2. Action Items
    • All immediate action items addressed.
  3. FCAL Update
    1. Run related
      • Ready to go for the weekend. Past two weeks only 2 bases have lost voltage. Could the low fatality rate be due to no beam in the hall?
      • Replaced about 10-20 bases per week during the run, but criteria for replacement was very aggressive compared to previous periods (require a single drop of HV, not complete failure).
      • Elton:
    2. Other updates
  4. BCAL update
      • Cosmic runs have been taken 41759 (16 hours, 38 M events), 41730 (49 hours, 115 M events), 41675 (67 hours, 180 M events) with the production cosmic-ray trigger. Zisis will check the files with Tegan and prepare for Colleen to work with them during the summer.
      • Sean inquired about analysis of the BCAL LED runs. Ahmed (after fixing mic at the end of the meeting): He is currently running the plugging on runs 41143-41590. Previous runs have already been processed. He will used these to determine a reference file.
    1. Run related
    2. Other updates
  5. Calibrations
    1. Statistics needed for pi0 calibrations
      • Will: Collected information based on calibration experience in 2017. Approximately 70M pi0s needed to complete calibration up to layer 3 with an energy cut of 0.5 GeV. For the non-linear correction one requires symmetric decays and therefore requires about x5 more statistics to determine the correction up to about 2.5 GeV. Will used about 10-20 runs in 2017 for the calibrations and about >50 runs for the non-linear corrections.
      • Sean: To date we have taken about 300 runs and skimmed about half. So this should be plenty of data for this part of the run. Proposal: skim about 10-25% of the upcoming data and see how the calibration works on this sample. Mark: Eventually all files should be skimmed for full reconstruction.
    2. Sean's Calibration list
      • Mark has kept up with BCAL low level calibrations for 2018.
      • Attenuation length, Gain ratio and z position calibration constants are taken from 2017. They will be updated with the upcoming launch data.
      • Fcal: Colin has completed pedestal, gains and non-linear corrections using the skimmed data (about 2/3 of the data is processed). He will update Sean's table with the range of run numbers.
  6. Reconstruction and Simulation
    1. BCAL timing resolution (Mark)
      • Analyzed 2017 data and compared to recent bggen MC data produced by Thomas
      • Current MC simulation uses a constant smearing of sigma=220 ps.
      • Summary: neutrals match fairly well assuming an energy dependent sigma = 0.16ps /sqrt(E) + 0.1 ns
      • Measured charged track resolutions are similar in structure to neutrals. However, the MC generates resolutions of about 400 ps independent of energy with no additional smearing.
      • Mark showed examples of fits at 1 GeV
      • Proposal: change MC to use the sigma = 0.16ps /sqrt(E) + 0.1 ns in mcsmear. This will match the neutrals and the charged are roughly unaffected because the base level is so high to start.
      • Sean: Look at particular reactions to understand resolution. Elton: Perhaps investigating timing of neutron showers could shed some light on the timing distribution of hits in MC.
    2. Track matched hit timing in MC: Proton in SC proton in BCAL (Sean)
      • Sean: We are finding losses in the tracking system and he was investigating how the timing could be affecting the efficiency.
      • Simulated single proton tracks and plots the true - matched time propagated back to the vertex.
      • Finds resolution constant vs transverse momentum (pT) for the start counter. For the BCAL, there seems to be a systematic dependence.
      • Elton: Interesting that the resolution (by eye) is about 200 ps, although Mark was finding about 400 ps for pions. It does not seem like the systematics should affect the track matching very much
  7. NIM articles
    • BCAL paper has been resubmitted to NIM
  8. Any other business