There will be an analysis/diagnostics meeting Thursday 26th November, 14:00.

We will be in one of the usual meeting rooms in the Atlas building, using phone:

  • Optics review
  • Tracker resolution and efficiency - Tracker Group
  • Tracker-to-tracker alignment - Melissa/Chris Hunt/John Nugent
    • Tracker Survey
  • Tracker alignment to field - Chris Rogers/Sophie
  • Cut-based beam selection vs 2015/01 data - Tanaz/Scott Wilbur
  • Ckov momentum scan - Ao, Durga
  • Full PID vs 2015/01 data - Celeste
  • PID detector alignment - Francois
  • Detector Efficiencies - Jan/Francois
  • Paper: High precision measurement of emittance - Chris Hunt/Victoria
  • Date of next meeting
    • 10th December
    • 17th December - if we have data in the meantime


Durga Rajaram
Chris Rogers
Francois Drielsma
Adam Dobbs
Scott Wilbur
Chris Hunt
Tanaz Mohayai
John Nyugent
Ed Overton

Tracker resolution and efficiency (Chris Hunt)
  • Took a step back from the alignment stuff following CM due to tracker geometry issues
  • Fixing data structure, analysis scripts
  • Main issue is pz resolution and systematic mismeasurement
    • Bug that has been floating around for quite a while
    • On the order of 1-2 MeV/c in MC
    • Looks like energy loss calculations were incorrect for some reason
    • Gradient of energy loss was different in MC and MC recon
    • But the error is more significant in data
  • Likely causes
    • Field non-uniformity
      • Field drop-off is around the TRP
      • Rogers notes there is also a 1-2 mrad misalignment
      • Rogers notes there is a miscalculation in MAUS due to the iron
    • Subtle issues with Kalman algorithm
      • Kalman is inherently linear
      • Helix is inherently non-linear
      • Helix is correct to first order
      • SciFi is made of fibres
      • Energy loss in Kalman is done "outside" the algorithm and hacked into Kalman;
      • energy loss is not tied into the smoothing step due to the funny way the propagator is done
      • Paul Soler notes parameterising energy loss as a polynomial fit worked okay, paper written and published
  • Durga asks what is the effect in < 4 T data
  • Chris Hunt notes that he can do the work but could be helped by spreading round some of his other responsibilities
Tracker-to-tracker alignment
  • Tracker alignment meeting; update on how things are going
  • Some useful suggestions
PID plots (Scott)
  • See slides
  • Note that there is additionally a transverse (momentum dependent) distribution; try taking a fiducial cut on e.g. the central bar
PID plots (Tanaz)
  • Working on modifying existing code for cut-based analysis
  • Produce an output for the PID based on different detectors
  • Note TOF is not trivial

Updated by Rogers, Chris over 8 years ago ยท 7 revisions