TOF issues

June 14, 2017


  • Efficiency:
    • #1912
    • Source of inefficiency?
      • Calibration coverage (TOF0 & TOF2)?
        • Inefficient PMTs?
      • Spacepoint reconstruction?
  • TOF-tracker discrepancy
    • Reported discrepancy of ~100ps (?) between TOF and tracker? [ any plots to show this? CR? ]
  • MC-vs-data
    • can’t reproduce pos of electron peak in data [ ? ]
    • Source of discrepancy?
      • related to calibration issues [ below ]?
      • Digitization-level?
  • Calibration systematics
    • TOF2 coverage has always been a problem
      • Should be able to combine recent [ May 2017 ] calibration data with ones from March and improve coverage [ ? ]
        • survey shows TOF1 moved by ~1mm
    • TOF2 dt offset by ~100ps
      • Suspect poor/bad automatic fits during calibration [ ? ]
  • Calibration assumes straight line path between TOFs
    • path length effect?
      • we took some data with Q789 turned off. Paolo couldn't see a difference in e peak
  • Is there a discrepancy between where the MC time is reported vs where the time is in real data?
    • note slabs are ~2.5 cm thick [ ~80 ps ]
    • spacepoint time = (time_plane0 + time_plane1)/2 ==> i.e. between the two planes
  • Others?



  • Attendance: Rogers, Wilbur, Rajaram
  • Efficiency
    • SW has new experimental calibrations which improve the coverage
    • 6% failed calibration (now) vs 15% (before)
    • SW is checking the calibrations before uploading
    • DR: Suggestions to improve coverage:
      • combine data from May and March runs
      • do timewalk calibration from a large sample (run conditions don't matter) and use this instead of doing tw calib each time
    • CR asks about the 500ps cut in spacepoint reconstruction -- notes it cuts out ~1% of events. Can it be expanded?
    • CR: can we have a new spacepoint structure to include the events which failed the cut?
    • Action: SW to look at expanding the data structure to include an e.g. tof0/1/2_all_spacepoints structure
    • Action: SW to upload new calibrations after verifying. Estimate ~end of this week
  • TOF tracker discrepancy
    • CR: Not clear if this is from tof or tracker, there is a ~3 MeV discrepancy in just trackers
    • Issue parked for now. Will revisit after vetting TOF MC
  • MC
    • SW: MC truth and reco agree now, there remains a small (??? ps) discrepancy in TOF1-2
    • Action: SW to add plots showing MC true vs reco
    • Action: SW to verify that the TOF0-1-2 distances in the calibration cards are consistent with survey geometry
    • Action: SW to compare MC and data for 140, 240 MeV to benchmark level of discrepancy between MC and data
    • Action: Try to add path length information to MC. the PathLength data member is currently unfilled in MAUS.
      • SW notes GEANT4 calculates the path length each time, which is potentially computationally intensive.
      • DR: Can we turn this on and do some test MC to see what the MC path length is and how it compares with the straightline distance?
  • Calibration systematics
    • TOF2 dt offset: SW notes that he still sees this with his new calibrations. It is not from fits to the 'wrong peak'. To be understood
  • Date of next meeting: Thurs, June 22, 1400 BST

Updated by Rajaram, Durga almost 7 years ago · 6 revisions