TOF issues¶

June 14, 2017¶

Issues¶

• 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
      • Positrons.pdf
• 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?

Dial-in:¶

• We'll try http://mice.iit.edu/phonebridge.html
  • If already taken, Chris please advise re alternate dial-in code

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Notes¶

• 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