Difference between revisions of "Mattione Update 09042013"

Revision as of 22:55, 3 September 2013

CDC Track Finding - Overview

Build Super Layer Seeds

• In each ring, link adjacent hits together (DCDCRingSeed).
  • NEW: Do for both axial super layers and stereo super layers (previously just axial).
• In each super layer, link each possible combination of adjacent DCDCRingSeed's together to form super layer seeds (DCDCSuperLayerSeed).
  • Note: There may be many combinations. For example, if two tracks cross in an "X" pattern, this will result in four DCDCSuperLayerSeed's.
  • NEW: Do for both axial super layers and stereo super layers (previously just axial).
  • NEW: Can skip up to 1 ring (in case the track did not deposit enough energy in one of the rings to register a hit).
  • Require a minimum of two hits to form a DCDCSuperLayerSeed (unmatched hits will be added later).
• NEW: In each super layer, identify regions with high hit density (> 60% in an area of ~24 straws) and reject all DCDCSuperLayerSeed's passing through those regions.
  • This occurs when a spiraling track loops around 6+ times before stopping.
  • This is necessary because in this new code, these events effectively freeze the program with millions of possible combinations of super layer seeds.
• NEW: Identify which DCDCSuperLayerSeed's contain potential spiral turns (where a spiraling track turns back inward/outward)
  • Primary signature is many adjacent hits in the same ring.

Link Super Layer Seeds

• Link adjacent DCDCSuperLayerSeed's together to form tracks (DCDCTrackCircle).
  • Note: 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.
  • Note: The projection of the stereo straws onto the X-Y (axial) plane are lines. Therefore, adjacent super layers are determined by checking whether a point (axial) is near a line (stereo), or a line (stereo) is near a line (stereo).
  • While the new method results in many more super layer combinations to disentangle, every possible combination is guaranteed to be considered.

• Start in super layer 1 (axial) and expand outwards towards super layer 7 (axial) (was previously in reverse direction)
• Each unique combination of axial super layers, create a new DCDCTrackCircle object.
  • Do not attempt seed link if the outer seed is definitely an outward-turning spiral, or if the inner seed is definitely an inward-turning spiral.

CDC Track Finding - Details

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)

• 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

π⁺

• Thrown

• Efficiencies

Stage	Efficiency - Current Code	Efficiency - Spiral Code	Improvement	Improvement - Zoomed
Track Candidates
Time-Based Tracks

γp→π⁺π⁺π^-π^-π⁰(p) (b1pi)

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

π^-

• Thrown

• Efficiencies

Stage	Efficiency - Current Code	Efficiency - Spiral Code	Improvement	Improvement - Zoomed
Track Candidates
Time-Based Tracks

Proton

• Thrown

• Efficiencies

Stage	Efficiency - Current Code	Efficiency - Spiral Code	Improvement	Improvement - Zoomed
Track Candidates
Time-Based Tracks

γp→K⁺K⁺Ξ^-