JLab discusion on tracking priorities, March 5, 2009

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Discussion

General comment: We have three tracking efforts. How can we leverage the work to date? How do we move forward effectively?

  1. Short summary of current effort (~5 slides each)
  2. Issues impacting design/construction
    • Charge division in CDC
      • What does it buy us in pattern recognition or resolving L/R ambiguities?
      • How do connected wires add to ghost tracks?
      • Where and how many measurements are they needed?
      • On what time scale is this decision required (Jan 2010)?
    • sensitivity to B-field
      • Timeline - summer 2009
      • Generate new fields given "reasonable" variations in (coil positions, magnetic properties of iron, fringe fields downstream and iron cladding)
      • key discriminators: momentum resolution, extrapolation to tof
    • staggering wire configuration for FDCs
      • Timeline - summer 2009
      • help left-right assignment?(use fit to wire positions to see which configuration finds more L/R configurations)
      • note: impact is that the number of types of electronic boards doubles (x, x' are different)
    • Effective size of forward hole (nominally 1 deg)
      • What is the effective angle in the current design at 1 GeV?
      • efficiency around hole in prototype
      • impact: artwork on cathode boards
      • positions of packages impacts effective angle
      • timeline - December 2009
    • ...we need to complete this list
  3. Achieving a robust tracking program for single tracks (multiple scattering, energy loss and position resolution only)
    • Not necessarily the "final" or best resolution
    • High efficiency over all angles (~1-140, define definite boundaries in angle and momentum)
    • Efficiency defined based on a reasonable cut on tracking Chi2.
    • Studies must include transition between CDC and FDC.
    • Goal: create efficiency and momentum resolution plots on log scales (p vs theta) for pions and protons.
  4. Studies of multi-track events
    • Are there any developments here beyond improvements/refinement of 2.? as a function of events with multiple tracks?
    • constraining the vertex?
  5. Refinements/optimizations of the tracking code
    • Kalman filters
    • reference trajectory methods
    • ... work on these to the extent that they impact studies 1-3.

Proposal (Eugene)

  1. Finalizing existing methods
    • Get ideal hit assignment
      1. determine resolutions, including sensitivity to B-field
      2. understand irregularities in efficiency and resolution
      3. demonstrate resolutions with Kalman filter are better under ideal circumstances than brute force fitters
  2. Ambiguity cleaning (determining correct L/R assignment)
    • procedure for reassigning L/R hits
  3. Reconsider best strategy for Hall D tracking
    • Review procedures from other experiments and mathematically "rigorous" tracking methods

Assignments:

  1. David: With correct L/R assignments compute resolutions (then study effect of B-field uncertainties)
  2. Mark: Investigate irregularities in current resolution and efficiency plots
  3. Simon: Demonstrate that Kalman filter improves resolution (in p and/or angles) in ideal cases.
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