1 / 8

Ghost Tracks

Ghost Tracks. Definition of ghost track Ghost track rate in MC Causes of ghosts Reco (mini) level ghost identification Remediation (ideas). Ghost Tracks. Ghost = 2nd track reconstructed from the same physical (charged) particle Not looper Not (necessarily) removed by GTL cuts

tuyet
Télécharger la présentation

Ghost Tracks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ghost Tracks David Nathan Brown Definition of ghost track Ghost track rate in MC Causes of ghosts Reco (mini) level ghost identification Remediation (ideas)

  2. Ghost Tracks • Ghost = 2nd track reconstructed from the same physical (charged) particle • Not looper • Not (necessarily) removed by GTL cuts • Some others removed in BAD633 cuts • Provides no insight into the cause David Nathan Brown 2 Tracking meeting Jan. 19, 2005

  3. MC Studies • 18.2.0 Moose + BetaMini • Cond18boot from July 12 • Identify duplicate tracks using MC truth • I find 4.5% of ‘Default’ TrkRecoTrk are duplicates • Separate loopers from ghosts with • Charge •  • Overlap between hit layers • Compute fraction = (# of layers in common)/(total # of layers hit) • Scan some ghost track events • http://costard.lbl.gov/~brownd/tracking/ghosts/ David Nathan Brown 3 Tracking meeting Jan. 19, 2005

  4. David Nathan Brown 4 Tracking meeting Jan. 19, 2005

  5. Ghost finding in TrkFixup • Same charge • DOCA < 3 cm • Transverse radius at POCA > 10 cm •  at POCA < /4 • Hit layer overlap fraction < 0.15 • Only 1 track with >1 Svt hits • Separate ghost cause based on transverse radius • 80% of ghosts are Dch pat-rec problems (>30cm) • 20% are due to material scatters or E-loss (<30cm) David Nathan Brown 5 Tracking meeting Jan. 19, 2005

  6. David Nathan Brown 6 Tracking meeting Jan. 19, 2005

  7. Ghost Selection Results • >70% efficient on MC true ghosts • Inefficiency from dch pat-rec problems with • Very poor POCA • Spurious Dch or Svt hits picked up • Selected sample composition (MC truth) • 80% ghosts • 7% ‘inelastic’ hadronic scattering • 10% decay-in-flight • 90% K, 10%  • 3% random combinations (fakes) • 1 Svt-only plus 1 dch-only, many ‘junk’ tracks • No lost particle decays David Nathan Brown 7 Tracking meeting Jan. 19, 2005

  8. Ghost Repair (ideas) • Merge both tracks into a new single track • If present, use svt-track as trajectory seed • Re-enable disabled hots • Add a KalScatterSite for hard scatters • Adds 10-times the normal multiple scattering allowance • Add more (?) dE/dx uncertainty • Filter hits as necessary • Disable hits with  > 5 • Add a KalDecaySite for decays • Allows angles and momentum to change • If merged track refit fails • throw away ‘outer’ track • Keep ‘inner’ track for physics David Nathan Brown 8 Tracking meeting Jan. 19, 2005

More Related