July 28, 2016 Calorimeter

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Meeting Time: 11:30 a.m.

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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

References

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
4. FCAL update
5. BCAL update
6. Calibrations
7. Reconstruction and Simulation
   1. BCAL MC/DATA comparisons (Will M.)
   2. Michel Electrons
8. Any other business

Minutes

Attendees: Elton, Mark, Adesh, Jon (Jlab); Matt (IU); Will, Curtis, Mike (CMU); George (Athens); Andrei, Colleen, Tegan (UofR)

1. Announcements
   • JLab Physics Division conducted an all-hands safety meeting this morning. Three events were recorded in the last couple of weeks (2 FEL, 1 in Hall C Beam Dump Cooling building). Everyone was reminded to pay attention to work and associated hazards and follow safe operating procedures.
2. Action Items
3. Preparation for REST production
4. FCAL update
   1. Calibration (Adesh)
      • Updated gains and pedestals were entered into CCDB for a few runs with pi0 peaks at 131 MeV.
      • Machinery to determine the timing offsets of all channels is mostly in place. The algorithm uses showers and compares timing information for cells that contribute to the shower. One overall constant will be determined and then relative offsets from channel to channel.
   2. Hardware and Efficiency studies (Jon)
      • Chris has checked that the procedure is in place to fix bases and that he understands it. However, not much rework has started.
      • Method for determining shower efficiencies is being refined to avoid false acceptance and rejection.
5. BCAL update
6. Calibrations
7. Reconstruction and Simulation
   1. BCAL MC/DATA comparisons (Will M.)
      • Comparing MC to data. Updating on previous work that showed that MC gives larger pi0 widths than data.
      • First look at single shower with MC particle gun. DeltaE/E is consistent with expected resolution.
      • Deltat in beta vs p plots visually give much broader distributions than data, This seems to confirm that the problem in MC comes from large timing resolutions (nominal sigma~ 300 ps). Plots seem to match data better if sigma_t ~ 50 ps is used.
      • Comparison of pi0 widths show that resolution is dominated by energy with at low energies and dominated by position widths at high energy.
      • Using sigma_t ~ 50 ps in the mcsmear time width parameter, MC matches data fairly well down to about 150 MeV.
      • Mark: Why are the lowest energy points not plotted for the lowest energy points? Will: Mostly due to bad fits, but need to investigate this further. Mark: Interesting to see the fitted distributions
      • Elton: Next step would be to refine timing width parameter in mcsmear using the pid plots? Will: yes
      • Mark: Note that it is possible that the time resolution in the sum (flight time ~ up an down) and the resolution of the different (position ~ up - down) may be different, since correlations cancel in the difference
      • Andrei: The data show timing resolutions of between 200-300 ps. How can this be reconciled with sigma_t ~ 50 ps. Will: The mcsmear parameter sigma_t is only part of the time resolution beyond what is produced in hdgeant and we don't know the relative contributions.
   2. Michel Electrons
      • Compared Michel electron energy for different cuts in the ratio of (E in max cell relative to total shower).
      • Reasonable agreement is found when the threshold is set to 2.2 MeV (up from 1.2 MeV originally)
      • MC and data compare quite favorably for the ration < 0.7 and starts deviating after that. Worst agreement for the ratio 0.9-1.0.
      • Efficiencies computed for detection of Michel electrons as a function of the electron energy. Plot shows efficiencies ~ 95% for E_electron > 14 MeV.
      • Elton: Do not expect such high resolution at that low energy. However, tools seem to be in place to determine the efficiency. Will send questions offline.
8. Any other business
   1. BCAL Timing (Andrei)
      • Preparing documentation on procedure for determining timing resolution and associated constants. Expect it will be ready in about a week
      • Elton will be on vacation till mid August. At that time the document should be available and a meeting will be setup to go over details.
   2. Next meeting
      • Due to summer schedules, our next meeting will be in 4 weeks.