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*

** http://micewww.pp.rl.ac.uk/attachments/download/9161/2016-04_1-2_6mm_diag.pdf

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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.

h2. Code snippet of pattern recognition residual analysis

<pre><code class="cplusplus">

bool AnalyserTrackerMCPRResiduals::analyse(MAUS::ReconEvent* const aReconEvent,

                                           MAUS::MCEvent* const aMCEvent) {

  if (!aReconEvent || !aMCEvent) {

    return false;

  }

  // Find a hit from a muon in the tracker references plane for each tracker

  MAUS::SciFiHit* tku_ref_hit = nullptr;

  MAUS::SciFiHit* tkd_ref_hit = nullptr;

  for (auto&& hitref : *(aMCEvent->GetSciFiHits())) {

    MAUS::SciFiHit* hit = &hitref;

    int pid = hit->GetParticleId();

    if (pid != 13 && pid != -13)

      continue;

    if (hit->GetChannelId()->GetStationNumber() == 1 && \

        hit->GetChannelId()->GetPlaneNumber() == 0) {

      if (hit->GetChannelId()->GetTrackerNumber() == 0) {

        tku_ref_hit = hit;

      } else if (hit->GetChannelId()->GetTrackerNumber() == 1) {

        tkd_ref_hit = hit;

      }

    }

    if (tku_ref_hit && tkd_ref_hit)

      break;

  }

  if (!tku_ref_hit || !tkd_ref_hit) {

    return false;

  }

  // Access the SciFi Event

  MAUS::SciFiEvent* sfevt = aReconEvent->GetSciFiEvent();

  if (!sfevt) {

    return false;

  }

  // Loop over all the scifi tracks in this event

  int nTkURecTracks = 0;

  int nTkDRecTracks = 0;

  MAUS::SciFiHelicalPRTrack* tku_trk = nullptr;

  MAUS::SciFiHelicalPRTrack* tkd_trk = nullptr;

  for (auto trk : sfevt->helicalprtracks()) {

    if (trk->get_tracker() == 0) {

      ++nTkURecTracks;

      tku_trk = trk;

    } else if (trk->get_tracker() == 1) {

      ++nTkDRecTracks;

      tkd_trk = trk;

    }

  }

  // Require 1 recon track in each tracker

  if (nTkURecTracks != 1 || nTkDRecTracks != 1) {

    return false;

  }

  if (tku_trk->get_spacepoints_pointers().size() != 5 ||

      tkd_trk->get_spacepoints_pointers().size() != 5) {

    return false;

  }

  // At this point we should an event that is good to analyse

  // Calculate the recon postion at the reference station, and the recon momentum (average)

  double tku_x = 0.0;

  double tku_y = 0.0;

  for (auto sp : tku_trk->get_spacepoints_pointers()) {

    if (sp->get_station() == 1) {

      tku_x = sp->get_position().x();

      tku_y = sp->get_position().y();

    }

  }

  double tkd_x = 0.0;

  double tkd_y = 0.0;

  for (auto sp : tkd_trk->get_spacepoints_pointers()) {

    if (sp->get_station() == 1) {

      tkd_x = sp->get_position().x();

      tkd_y = sp->get_position().y();

    }

  }

  double tku_dx = tku_x + tku_ref_hit->GetPosition().x();

  double tku_dy = tku_y - tku_ref_hit->GetPosition().y();

  double tku_ptmc = sqrt(tku_ref_hit->GetMomentum().x()*tku_ref_hit->GetMomentum().x() +

                         tku_ref_hit->GetMomentum().y()*tku_ref_hit->GetMomentum().y());

  double tku_ptrec = 0.3*mBfield*tku_trk->get_R(); // 0.3 comes from mom being in MeV and rad in mm

  double tku_dpt = tku_ptrec - tku_ptmc;

  double tku_pzrec = tku_ptrec / tku_trk->get_dsdz();

  double tku_dpz =  tku_pzrec + tku_ref_hit->GetMomentum().z();

  double tkd_dx = tkd_x - tkd_ref_hit->GetPosition().x();

  double tkd_dy = tkd_y - tkd_ref_hit->GetPosition().y();

  double tkd_ptmc = sqrt(tkd_ref_hit->GetMomentum().x()*tkd_ref_hit->GetMomentum().x() +

                         tkd_ref_hit->GetMomentum().y()*tkd_ref_hit->GetMomentum().y());

  double tkd_ptrec = 0.3*mBfield*tkd_trk->get_R(); // 0.3 comes from mom being in MeV and rad in mm

  double tkd_dpt = tkd_ptrec - tkd_ptmc;

  double tkd_pzrec = tkd_ptrec / tkd_trk->get_dsdz();

  double tkd_dpz = tkd_pzrec + tkd_ref_hit->GetMomentum().z();

  // Fill the histograms

  mHTkUMCPositionX->Fill(tku_ref_hit->GetPosition().x());

  mHTkUMCPositionY->Fill(tku_ref_hit->GetPosition().y());

  mHTkUMCMomentumT->Fill(tku_ptmc);

  mHTkUMCMomentumZ->Fill(tku_ref_hit->GetMomentum().z());

  mHTkURecPositionX->Fill(tku_x);

  mHTkURecPositionY->Fill(tku_y);

  mHTkURecMomentumT->Fill(tku_ptrec);

  mHTkURecMomentumZ->Fill(tku_pzrec);

  mHTkUPositionResidualsX->Fill(tku_dx);

  mHTkUPositionResidualsY->Fill(tku_dy);

  mHTkUMomentumResidualsT->Fill(tku_dpt);

  mHTkUMomentumResidualsZ->Fill(tku_dpz);

  mHTkDMCPositionX->Fill(tkd_ref_hit->GetPosition().x());

  mHTkDMCPositionY->Fill(tkd_ref_hit->GetPosition().y());

  mHTkDMCMomentumT->Fill(tkd_ptmc);

  mHTkDMCMomentumZ->Fill(tkd_ref_hit->GetMomentum().z());

  mHTkDRecPositionX->Fill(tkd_x);

  mHTkDRecPositionY->Fill(tkd_y);

  mHTkDRecMomentumT->Fill(tkd_ptrec);

  mHTkDRecMomentumZ->Fill(tkd_pzrec);

  mHTkDPositionResidualsX->Fill(tkd_dx);

  mHTkDPositionResidualsY->Fill(tkd_dy);

  mHTkDMomentumResidualsT->Fill(tkd_dpt);

  mHTkDMomentumResidualsZ->Fill(tkd_dpz);

  return true;

}  

</code></pre>