Tracker Software Review: Meeting 7¶

September 8, 2017: 1400 BST¶

Agenda¶

1. Introduction - K. Long
2. Actions from previous meetings
• PR:
  1. AD: Optimize Chi2 cut for “MINUIT” variant
  2. AD, CH: Check and implement MCS errors
  3. AD: Plot chisq per dof for 'perfect' events
  4. Define multi-track requirements
  5. AD: Compare data/MC efficiencies for 8681 Done
  6. AD: Show distributions with sign per station per tracker Done
  7. AD: Show individual residual distributions to understand details - is the station 1 distribution a binning artifact or a constraint from the fit? Done

• Track fit:
  1. Repeat study that was done to investigate whether field integration (e.g. using Runge Kutta) is required to compensate for magnetic field non-uniformity
  2. Make study of magnetic-field alignment with a view to establishing whether the present algorithm is sufficiently insensitive to reasonable assumptions of maximum field-misalignment
  3. Study p-value: split up contributions to p-value shape using MC and study shape in data, e.g. is there an error in the resolution per plane, handling of MCS, handing of energy loss, b field..
• Tracker, MC:
  1. MU/EO: Understand reasons for shape of hits-per-station histogram - low-level
  2. PK: Check dead channel & noise handling in MC.
  3. Tracker group: Summarize, show what has been studied so far for systematics (alignment, scattering, energy loss, field uniformity, etc).

1. Report on actions: Pattern recognition: A. Dobbs
2. Report on actions: Track fit: C. Hunt
3. Next Steps for review
4. AoB

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Dial-in information¶

http://mice.iit.edu/phonebridge.html

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Attendance: KL, CR, PK, AD, CH, MU, DR¶

Notes from Meeting 5: Aug 16, 2017:¶

• AD: Compare data/MC efficiencies for 8681
  • done. 8681, 2.8.5 MC reprocessed with 2.9.1-PatRec,Kalman -- results consistent with 2.9.1 reco
  • Illustrative plots added

• AD: Optimize Chi2 cut for “MINUIT” variant
  • pushing cuts lower gives higher efficiencies, though purity may be an issue. Noted that critical parameter is efficiency
  • Q: how loose should the LSQ cuts be? AD points to loosest cut in table from previous meeting.

• AD: Show residual distributions with sign per station per tracker
  • sent to email list, added to meeting wiki

• AD: Plot chisq per dof for 'perfect’ events
  • stands

• Define multi-track requirements
  • stands. Need discussion and inputs on how to define

• Adding errors:
  • for circle fit: suggestion is to define a mean error and apply to every station rather than station-by-station errors.
  • Q: how to define mean error? based on the geometric mean of the errors?
  • Q: does taking the chi^2/mean_error^2 bias the pr fit?
  • errors on the resulting circle fit parameters will feed into the longitudinal fit

• Discussion about aperture cut
  • CR notes that aperture cut should be standardized by tracker group. AD notes that the cut in PR is loose -- 150.
  • PK suggests a flag to indicate if track passed or failed an aperture cut
  • All agree that fiducial cut should be standardized,
  • Q: does the current aperture cut throw out any potential tracks? If it does, cut should be loosened, but consensus seems to be that tracking should not do any "analysis-style" cuts but rather optimize track-finding.

• Effect of magnetic field non-uniformity, alignment on track fit -- CH had issues reading mag field map from Joe Langland's program. CH will check against comsol map for 7469.