h1. Tracker Software Review: Meeting 7

h2. September 8, 2017: 1400 BST

h2. Agenda

# *Introduction* - K. Long

# *Actions from previous meetings*

* *PR*:

### AD: Handle errors correctly in MINUIT fits

### AD: Optimize Chi2 cut for “MINUIT” variant

### AD, CH: Check and implement MCS errors

### AD: Plot chisq per dof for 'perfect' events

### AD, KL: Define multi-track requirements

### -AD: Compare data/MC efficiencies for 8681- _Done_

### -AD: Show distributions with sign per station per tracker- _Done_

### -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*:

### Repeat study that was done to investigate whether field integration (e.g. using Runge Kutta) is required to compensate for magnetic field non-uniformity

### 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

### 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*:

## MU/EO: Understand reasons for shape of hits-per-station histogram - low-level

## PK: Check dead channel & noise handling in MC. 

## Tracker group: Summarize, show what has been studied so far for systematics (alignment, scattering, energy loss, field uniformity, etc).

# *Report on actions: Pattern recognition*: A. Dobbs

# *Report on actions: Track fit*: C. Hunt

# *Next Steps for review*

# *AoB*

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h2. Dial-in information

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

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h2. Attendance: KL, CR, PK, AD, CH, MU, DR

h2. 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.