Nov 29, 2018 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

Action Items

  1. FCAL: Cross check MC changes by Richard to make sure that gains are not affected in both Geant3 and Geant4 (Matt/IHEP)
  2. Fix FCAL online monitoring plugin to properly plot low level digi quantities in 2D displays. 2D display of pedestal is hard to get because occupancy plot is filled in a different loop. (Tolga)

Complete after new launch

  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.

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%.

References

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

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Run Updates
    1. FCAL
    2. BCAL
  4. Calibrations
  5. Reconstruction and Simulation
  6. Monitoring
  7. NIM articles
  8. Any other business

Minutes

Attending: Elton, Mark, Matt, Colin (JLab); Sean (FSU); Zisis, Ahmed, Karthik, Tegan (UofR); Christina, George (Athens); Will (CMU).

  1. Announcements
  2. Action Items
    1. Matt: Cross check of Geant3 finds MC has changed (currently broken). Still need to recalibrate since Richard's changes. [Aside: Geant4 has not been checked systematically, but showed consistent deviations of the pi0 peak (~10 MeV) for both FCAL and BCAL. This needs to be rechecked.]
    2. From Tolga: Regrettably I may not be able to call in tomorrow. This week is equivalently my finals week and I’m swamped with coursework. As for my FCAL I have run over 100,000 events of a recent run in monitoring and am actively working the script. For good measure, and in the meantime I will post the pedestal and geometry plots im DocDB shortly.
  3. Run Updates
    1. FCAL
      • Four failure rates of bases have been identified: 1) communication board failures (fixed by rebooting bus) 2) Base drops HV periodically (fixed by standard updates made to boards by Chris and Nick) 3) High current draw with HV, but nominal current draw without HV (likely related to #2 above) 4) High current draw with and without HV applied. Three bases returned to IU with this problem for investigated were fixed by Paul Smith by replacing a particular logic gate.
      • Investigation of failure modes 3 and 4 above were in progress during the downtime but data was lost and needs to be retaken. Studies will continue during the CompCal commissioning.
      • Voltages for inner rings were adjusted using LED data before it was discovered that the skimmed files tossed much of the data (based on Ilya's work). The voltages are now restored to original values but will soon be updated based on the pi0 peaks that are seen in the data.
    2. BCAL
      • We have had a couple of weeks of confusion regarding the BCAL LED pulsing sequencer. Mark updated the sequencer script to clean the initialization and seems to be pulsing correctly now. However, it is still puzzling that we seemed to be taking LED data without the FP trigger firing.
      • Ahmed has been investigating this failure. It is important to investigate data where LED events are found (with large energy and many hits) even if the FP trigger bit is not on. This can be checked on data early in the run before the timing of the FP was adjusted (by Sasha) relative to the main trigger. During this period, the downstream pulser was pulsing, but the FP trigger bit was not being set. Evidence of the LED events (without FP trigger bit) is seen in timing plots of the main trigger.
  4. Calibrations
    1. FCAL (Colin) Periods of spring 2018 data do not seem to be corrected for the 4 ns FADC shifts. Sean and Colin are tracking down the problem since the offsets should have been fixed with existing calibrations. It appears that the offsets have not been generated correctly and the algorithm is being checked. There was some discussion regarding whether to rewrite the code to adjust for the timing offsets or debug existing code (by a student that is leaving soon). Sean has some ideas on how to use the present system in a slightly different way.
    2. BCAL (Sean asked about the status of other calibrations)
      • Mark: 4, 32 ns offsets have been found for the fall 2018 run. Need a monitoring launch for higher level calibrations.
      • Spring 2018: All TDC calibrations have been completed except for an overall timing calibration that seems to drift over the run period by 100-150 ns. Some of this drift might be attributed to other detectors (e.g. tracking) which are used in the calibrations. However, the drifts are also observed for neutrals, so that may point to the BCAL. Mark and Sean's software are not completely consistent, so Mark will make a log entry for reference and Sean can compare with his software. If the effect is not just due to BCAL, it would be good to understand the origin and make corrections at the source.
    3. FCAL. Matt reminded us that shifts in the pi0 peak due to high LED pulsing rate has not been understood. Matt looked at some waveforms in raw data mode but did not find any anomalous behavior. This item has been added to the action item list for followup.
  5. Reconstruction and Simulation
  6. Monitoring
  7. NIM articles
  8. Any other business
    • George is working on issues related to the eta/eta' working group and plans to present an update next Monday on the differential cross section for eta'(->eta pi0 pi0) production.