JLab group chat on tracking progress, March 13, 2009

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This was a followup discussion to the "JLab discusion on tracking priorities, March 5, 2009" discussion to report on and monitor the progress of the tracking.

Attendees: Simon Taylor, Elton Smith, Eugene C., Alex S. (partial), David L., Mark I, Beni Z.(partial)


Dave

Dave showed a scan of his notepad where values were tabulated for the left-right (LR) ambiguity resolution correctness under various configurations of inserting truth information. After some discussion, Dave was tasked with the following:

  • Post the table on the web for recording purposes
  • Add the number of tracks with 1 or more bad LR choices to the table since all of the bad choices may come from correlations within the same track
  • Use a particle gun to view some specific events in the "smile" band (see Mark's section below).


Simon

Simon showed some slides where the pull distributions of each of the 5 fit parameters used in the Kalman filter were plotted as a function of theta angle. The q/p parameter had the strongest dependence with a sigma as high as 3 for 20 degree tracks. After some discussion, Simon was tasked with the following:

  • Use cleaner conditions for the studies (i.e. turn off multiple scattering and energy loss)
  • Understand the apparent loss of events in small theta (<6 degrees) where the pull appears to be getting narrower.

Mark

Mark showed some comparison of tracking resolutions and efficiencies between the ALT1(Dave) fitter and the LSLM(Mark) fitter. They showed many of the same overall features, including the "smile" curve in the efficiency plot. Some discussion was had as to what exactly could be causing this and it was finally decided that some events needed to be scanned with the viewer to see what was going on.

direct links to Mark's plots

LSLM ALT1
pres_vs_p_vs_theta pres_vs_p_vs_theta
eff_vs_p_vs_theta eff_vs_p_vs_theta
dphi_vs_p_vs_theta dphi_vs_p_vs_theta
pion_pres pion_pres
dtheta_vs_p_vs_theta dtheta_vs_p_vs_theta