Mattione Update 09042013

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Revision as of 12:26, 4 September 2013 by Pmatt (Talk | contribs) (CDC Track Finding - Basics)

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CDC Track Finding - Basics

  • Note: Some steps (and many details) are omitted entirely in this brief overview.

Build Super Layer Seeds

  • In each ring, link adjacent hits together (DCDCRingSeed).
  • In each super layer, link each possible combination of adjacent DCDCRingSeed's together to form super layer seeds (DCDCSuperLayerSeed).
    • NEW: Do for both axial super layers and stereo super layers (previously just axial).
  • NEW: Identify which DCDCSuperLayerSeed's contain potential spiral turns (where a spiraling track turns back inward/outward).
b1pi Event
Spiral Event


Build Track Circles

  • HEAVILY MODIFIED: Link adjacent DCDCSuperLayerSeed's together to form tracks (DCDCTrackCircle).
    • Previously, the axial DCDCSuperLayerSeed's were linked by progressively fitting track circles and selecting the next axial super layers that were close to the track fit.
    • Start in super layer 1 (axial) and expand outwards towards super layer 7 (axial) (was previously in reverse direction)
    • For each unique combination of axial super layers, create a new DCDCTrackCircle object.
    • Keep track of which stereo DCDCSuperLayerSeed were used when linking the DCDCTrackCircle objects. There may be (many) more than one for each super layer.

Fit Track Circles & Truncate: Axial

b1pi Event
  • Fit the hits in the axial super layers (plus the beamline) to a circle with DHelicalFit.
    • Reject tracks for which half of the axial hits are not close to the circle fit.
  • NEW: Truncate and re-fit track circles that have picked up erroneous super layer seeds in the outer super layers.
    • This is used to save (for example) forward-going tracks that pick up bad hits from another track (e.g. a large-angle track near in φ)


Filter Track Circles: Axial

Spiral Track
  • If two track circles share >= 50% of their hits, reject the DCDCTrackCircle with the worse circle-fit weighted-chisq/ndf (weighted by #axial super layers squared)
  • NEW: If two track circles are spiral-linked in their last axial super layer, have opposite charges, and have similar circle centers, reject the DCDCTrackCircle with the worse circle-fit weighted-chisq/ndf.


Select Stereo Super Layer Seeds

b1pi Event
  • Previously, all stereo hits that intersected the circle and were nearby were lumped all together. Now, stereo super layer seeds are used instead.
  • Project all hits from all possible stereo super layers onto the circle.
  • For all possible combinations of stereo super layers:
    • Do a linear regression fit of the projected stereo hits to calculate θ & Vertex-Z
    • NEW: Select the combination of stereo super layer seeds that have the best chisq/ndf from the regression fit.


Filter Track Circles: Stereo

  • NEW: Find super layer seeds that are shared between DCDCTrackCircle's, and remove them from all DCDCTrackCircle's except the one with the best weighted chisq/ndf from the regression fit.
    • Like the axial truncation, this is used to save (for example) forward-going tracks that pick up bad hits from another track (e.g. a large-angle track near in φ).
    • However, do NOT remove the stereo super layer if it's the last one on the track.
  • NEW: If two track circles are spiral-linked in their last stereo super layer, have opposite charges, and have similar circle centers, reject the DCDCTrackCircle with the worse circle-fit weighted-chisq/ndf.

Refinement

b1pi Event
  • Find single, unused hits in the next (outward) super layer and add them to track circles if nearby.
    • This primarily helps tracks that exit the CDC early (e.g. forward going).
  • Redo circle fits, using both the new hits added just before, as well as the intersection points between the two stereo super layers (e.g. SL2 & SL3).
  • Re-project stereo hits onto the new circle fits.
  • Do a linear regression fit on a subset of the projected stereo hits to calculate θ & Vertex-Z
    • SEMI-NEW: A subset is chosen to optimize the final fit results. This is because there are regions/cases for which the projected stereo-hit-positions are bad.


Finalize

Spiral Events (2nd peak due to wrong charge)
  • Calculate the position and momentum of the track at a point outside of the target and the start counter.
    • This is because the track finding does not take energy-loss into account.
    • Note that this skews the comparison between the DTrackCandidate and DMCThrown kinematics, since they are reported at different positions (r ~= 9.5cm, r = 0cm, respectively).
  • Create DTrackCandidate objects.



Single π+ Track

Single π+ Reconstruction: Current (Trunk) Code, trackeff_hists plugin

  • The below plots show the track reconstruction efficiency and resolution for the trunk using the single-track scripts plugin (trackeff_hists).
  • However, this efficiency is extremely misleading:
    • If a track is reconstructed using any of the hits that were on the thrown track it is considered "found."
    • This is regardless of whether the reconstructed track momentum is anywhere close to the thrown values.
Current Code: Time-Based Tracks (trackeff_hists plugin)
Current Code: Momentum Resolution (trackeff_hists plugin)

Single π+ Reconstruction: Current (Trunk) Code, NEW trackeffv2 plugin

  • The below plots show the track candidate and time-based track reconstruction efficiency for the trunk using a new plugin (trackeff_hists).
  • This plugin compares matches all of the thrown and reconstructed particles in the event, and requires that their momentum be "close."
    • "Close" for track candidates is defined as: Δp/p < 20%, Δθ < 40 degrees, Δφ < 40 degrees, ΔVertex-Z < 1 km
      • For thrown tracks with θ < 5 degrees, there is no cut on the candidate Δφ
    • "Close" for time-based tracks is defined as: Δp/p < 10%, Δθ < 15 degrees, Δφ < 15 degrees, ΔVertex-Z < 10 cm
Current Code: Track Candidates (trackeffv2 plugin)
Current Code: Time-Based Tracks (trackeffv2 plugin)
  • Note that the degradation of the efficiency at forward angles matches the track resolution plot in the previous section.
    • If I expand the requirements for the "Close" window, the efficiency increases, and the chosen parameters were somewhat arbitrary.

Single π+ Reconstruction: NEW Spiral Code

  • The below plots show the track candidate and time-based track reconstruction efficiencies for the new spiral code.
  • Note: The trackeffv2 plugin compares matches all of the thrown and reconstructed particles in the event, and requires that their momentum be "close."
    • "Close" for track candidates is defined as: Δp/p < 20%, Δθ < 40 degrees, Δφ < 40 degrees, ΔVertex-Z < 1 km
      • For thrown tracks with θ < 5 degrees, there is no cut on the candidate Δφ
    • "Close" for time-based tracks is defined as: Δp/p < 10%, Δθ < 15 degrees, Δφ < 15 degrees, ΔVertex-Z < 10 cm
Spiral Code: Track Candidates Efficiency (Spiral Code)
Spiral Code: Time-Based Track Efficiency (Spiral Code)
  • Selected Track Candidate 1-D Kinematics Comparisons
Track Candidates (Forward Angle)
Track Candidates (Transition Region)
Track Candidates (Spirals)
  • The below plots show the improvements in the track candidate and time-based track reconstruction efficiencies with the new spiral code.
Track Candidate Efficiency Improvement
Zoomed Track Candidate Efficiency Improvement
Time-Based Track Efficiency Improvement
Zoomed Time-Based Track Efficiency Improvement


γp→π+π+π-(n)

  • The below plots show the track candidate and time-based track reconstruction efficiencies for both track finding codes, and the improvement.
  • The definition of closeness is the same as before (see the single-track section).
  • Events were generated at beam energy of 9 GeV and a t-slope of 5.0

Summary

  • Overall track reconstruction improvement percentages for all tracks in this topology with momentum LESS than 3 GeV/c.
    • WARNING: This is not the overall gain for the topology, as many pions have larger than 3 GeV/c of momentum (their overall gain will be smaller).
Particle Track Candidates Time-Based Tracks
π+ 10.3% 5.38%
π- 8.08% 4.47%


π+

  • Thrown, Track Candidate 1-D Kinematics
Thrown π+'s
π+ Track Candidate Kinematics


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement Improvement - Zoomed
Track Candidates
Mattione Update 09042013 Efficiency Candidates n3pi PiPlus Current.png
Mattione Update 09042013 Efficiency Candidates n3pi PiPlus Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates n3pi PiPlus.png
Mattione Update 09042013 EfficiencyDiffZoomed Candidates n3pi PiPlus.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased n3pi PiPlus Current.png
Mattione Update 09042013 Efficiency TimeBased n3pi PiPlus Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased n3pi PiPlus.png
Mattione Update 09042013 EfficiencyDiffZoomed TimeBased n3pi PiPlus.png


γp→π+π+π-π-π0(p) (b1pi)

  • The below plots show the track candidate and time-based track reconstruction efficiencies for both track finding codes, and the improvement.
  • The definition of closeness is the same as before (see the single-track section).
  • Events were generated with a beam energy of 9 GeV and a t-slope of 5.0

Summary

  • Overall track reconstruction improvement percentages for all tracks in this topology with momentum LESS than 3 GeV/c.
    • WARNING: This is not the overall gain for the topology, as many pions have larger than 3 GeV/c of momentum (their overall gain will be smaller).
Particle Track Candidates Time-Based Tracks
π+ 7.93% 5.21%
π- 12.5% 6.23%
p 23.7% 22.6%


π-

  • Thrown
Thrown π-'s


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement Improvement - Zoomed
Track Candidates
Mattione Update 09042013 Efficiency Candidates b1pi PiMinus Current.png
Mattione Update 09042013 Efficiency Candidates b1pi PiMinus Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates b1pi PiMinus.png
Mattione Update 09042013 EfficiencyDiffZoomed Candidates b1pi PiMinus.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased b1pi PiMinus Current.png
Mattione Update 09042013 Efficiency TimeBased b1pi PiMinus Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased b1pi PiMinus.png
Mattione Update 09042013 EfficiencyDiffZoomed TimeBased b1pi PiMinus.png


Proton

  • Thrown, Track Candidate 1-D Kinematics
Thrown Proton's
Track Candidates


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement
Track Candidates
Mattione Update 09042013 Efficiency Candidates b1pi Proton Current.png
Mattione Update 09042013 Efficiency Candidates b1pi Proton Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates b1pi Proton.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased b1pi Proton Current.png
Mattione Update 09042013 Efficiency TimeBased b1pi Proton Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased b1pi Proton.png


γp→K+K+Ξ-

  • The below plots show the track candidate and time-based track reconstruction efficiencies for both track finding codes, and the improvement.
  • The definition of closeness is the same as before (see the single-track section).
  • Events were generated with beam energies between 8.4 and 9 GeV

Summary

  • Overall track reconstruction improvement percentages for all tracks in this topology with momentum LESS than 3 GeV/c.
    • WARNING: This is not the overall gain for the topology, as some kaons have larger than 3 GeV/c of momentum (their overall gain will be slightly smaller).
Particle Track Candidates Time-Based Tracks
K+ 21.7% 14.1%
π- 35.1% 28.7%
p 12.8% 16.7%


Sample Event

Reconstructed Hits Truth + Reconstructed Hits Current (09/03/13) Code Track Candidates Spiral Code Track Candidates
Mattione Update 09042013 Cascade Event3 ReconHits.png
Mattione Update 09042013 Cascade Event3 TruthHits.png
Mattione Update 09042013 Cascade Event3 Current.png
Mattione Update 09042013 Cascade Event3 Spiral.png


π-

  • Thrown
Thrown π-'s


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement Improvement - Zoomed
Track Candidates
Mattione Update 09042013 Efficiency Candidates cascade PiMinus Current.png
Mattione Update 09042013 Efficiency Candidates cascade PiMinus Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates cascade PiMinus.png
Mattione Update 09042013 EfficiencyDiffZoomed Candidates cascade PiMinus.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased cascade PiMinus Current.png
Mattione Update 09042013 Efficiency TimeBased cascade PiMinus Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased cascade PiMinus.png
Mattione Update 09042013 EfficiencyDiffZoomed TimeBased cascade PiMinus.png


K+

  • Thrown
Thrown K+'s


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement Improvement - Zoomed
Track Candidates
Mattione Update 09042013 Efficiency Candidates cascade KPlus Current.png
Mattione Update 09042013 Efficiency Candidates cascade KPlus Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates cascade KPlus.png
Mattione Update 09042013 EfficiencyDiffZoomed Candidates cascade KPlus.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased cascade KPlus Current.png
Mattione Update 09042013 Efficiency TimeBased cascade KPlus Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased cascade KPlus.png
Mattione Update 09042013 EfficiencyDiffZoomed TimeBased cascade KPlus.png


Proton

  • Thrown
Thrown Proton's


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement
Track Candidates
Mattione Update 09042013 Efficiency Candidates cascade Proton Current.png
Mattione Update 09042013 Efficiency Candidates cascade Proton Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates cascade Proton.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased cascade Proton Current.png
Mattione Update 09042013 Efficiency TimeBased cascade Proton Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased cascade Proton.png


bggen (pythia)

  • The below plots show the track candidate and time-based track reconstruction efficiencies for both track finding codes, and the improvement.
  • The definition of closeness is the same as before (see the single-track section).
  • Events were generated with beam energies between 8.4 and 9 GeV

Summary

  • Overall track reconstruction improvement percentages for all tracks in this topology with momentum LESS than 3 GeV/c.
    • WARNING: This is not the overall gain for the topology, as many pions have larger than 3 GeV/c of momentum (their overall gain will be smaller).
Particle Track Candidates Time-Based Tracks
π+ 16.7% 11.3%
π- 21.8% 12.7%
p 12.4% 6.92%


π-

  • Thrown
Thrown π-'s


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement Improvement - Zoomed
Track Candidates
Mattione Update 09042013 Efficiency Candidates bggen PiMinus Current.png
Mattione Update 09042013 Efficiency Candidates bggen PiMinus Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates bggen PiMinus.png
Mattione Update 09042013 EfficiencyDiffZoomed Candidates bggen PiMinus.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased bggen PiMinus Current.png
Mattione Update 09042013 Efficiency TimeBased bggen PiMinus Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased bggen PiMinus.png
Mattione Update 09042013 EfficiencyDiffZoomed TimeBased bggen PiMinus.png


Proton

  • Thrown
    • Note this is in log-scale.
Thrown Proton's


  • Efficiencies
Stage Efficiency - Current Code Efficiency - Spiral Code Improvement Improvement - Zoomed
Track Candidates
Mattione Update 09042013 Efficiency Candidates bggen Proton Current.png
Mattione Update 09042013 Efficiency Candidates bggen Proton Spiral.png
Mattione Update 09042013 EfficiencyDiff Candidates bggen Proton.png
Mattione Update 09042013 EfficiencyDiffZoomed Candidates bggen Proton.png
Time-Based Tracks
Mattione Update 09042013 Efficiency TimeBased bggen Proton Current.png
Mattione Update 09042013 Efficiency TimeBased bggen Proton Spiral.png
Mattione Update 09042013 EfficiencyDiff TimeBased bggen Proton.png
Mattione Update 09042013 EfficiencyDiffZoomed TimeBased bggen Proton.png


Hit Selector - bggen (pythia) Events

  • New Code Only: Time-Based Track Efficiency improvements with hit selector disabled at all stages.
Protons π+'s π-'s
Mattione Update 09042013 Efficiency NoHitSelector bggen Proton.png
Mattione Update 09042013 Efficiency NoHitSelector bggen PiPlus.png
Mattione Update 09042013 Efficiency NoHitSelector bggen PiMinus.png