TOF Review - Meeting 1

February 16, 2018, 11 a.m. GMT

Issues to address:

  • Efficiency
    • TOF2 is particularly critical
    • What is the efficiency for
      • Slab hits: i.e. given at least one PMT hit at either end, how often is a slab hit reconstructed?
      • Spacepoints: i.e. given at least one slab hit in the horizontal & vertical planes, how often is a spacepoint formed?
      • Need efficiency as a function of slabs (both horiz. & vert.)
      • Should we look at efficiency as a function of momentum?
    • Understand sources of inefficiency
      • 0.5ns cut --need to see distribution of tails.
        • relax cut?
      • "out-of-time" hits?
      • uncalibrated pixels? can we improve?
  • Calibration
    • improve calibration coverage
  • offset in dT
    • what is the source?

Efficiency plots

Run 9799: 10-140, LH2, flip
Run 9811: 3-200, LH2, solenoid
Run 10109: 3-140, LH2-empty, flip
Run 10123: 10-140, LH2-empty, flip
Run 10219: TOfCalib, LH2-empty, field-off
Run 10271: 3-240, LH2-empty, solenoid
Run 10447: 10-140, LiH-empty, flip
Run 10541: 6-140, LiH, flip

TOF2 10-140, LH2, flip TOF2 3-200, LH2, solenoid TOF2 3-140, LH2-empty, flip TOF2 10-140, LH2-empty, flip

TOF2 TOfCalib, LH2-empty, field-off TOF2 3-240, LH2-empty, solenoid TOF2 10-140, LiH-empty, flip TOF2 6-140, LiH, flip

Additional documentation

Dial-in information


Attendance: CR, PF, VP, SW, DR


  • Suspect that the dT cut is responsible for lower spacepoint efficiency. VP speculates relaxing the dT cut will raise efficiency especially of 'edge' slabs since they're less well calibrated. SW notes that the tail of the dT distribution goes out only to ~1ns or so.
  • All agree first action is to relax dT cut and study efficiency.
    • question: is the tof calibration map in CDB up to date?
    • Noted that TOF1 was last surveyed on May 25, 2017.
    • ACTION: SW to ensure that the CDB contains the latest, best calibrations for all 2017-02/03 runs
    • ACTION: VP will run reco with the dT cut relaxed (change from 0.5ns to 2 ns ) and study effect on efficiency
    • ACTION: DR will help / provide information to VP on how to run reco against raw
  • Study slab efficiency
    • How often do we get a PMT hit at one end but not the other end?
    • How often do we associate a noise PMT hit with a real hit?
    • VP will look at some pulser data to see noise rate & noise-created-slabhits and noise-created-spacepoints
    • ACTION: DR will provide a list of reconstructed pulser runs
  • MC
    • CR shows plots illustrating a ~100ps offset between MC and data in the dT distributions
      • VP asks if this is because the MC time is not calibrated. Ans: no, the MC digitizer adds calibration corrections to the digitized time, and then spacepoint reco corrects for this just like in real data
      • DR wonders if this offset is because the digitizer input time is not at the detector center but rather for e.g. at the front/rear
      • PF notes that the TOF true hit positions are consistent with the survey positions in the geometry
      • PF, DR to check that the survey position in the geometry is indeed at the detector center
    • Extrapolated dT-measured dT shows features on the tail -- periodic peaks. We wonder if it's a feature of the extrapolation, for instance with low pt / high radius tracks or wrong-turns in track reconstruction
  • Next meeting: at paper writing workshop in 2 weeks

Updated by Rajaram, Durga about 3 years ago ยท 13 revisions