DTTimingExtractor.cc

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// -*- C++ -*-
//
// Package:    MuonIdentification
// Class:      DTTimingExtractor
// 
//
// Original Author:  Traczyk Piotr
//         Created:  Thu Oct 11 15:01:28 CEST 2007
//
//

#include "RecoMuon/MuonIdentification/interface/DTTimingExtractor.h"


// user include files
#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/EDProducer.h"

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/MakerMacros.h"

#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include "RecoMuon/TrackingTools/interface/MuonServiceProxy.h"

#include "Geometry/Records/interface/MuonGeometryRecord.h"
#include "DataFormats/MuonDetId/interface/MuonSubdetId.h"
#include "Geometry/DTGeometry/interface/DTGeometry.h"
#include "Geometry/DTGeometry/interface/DTLayer.h"
#include "Geometry/DTGeometry/interface/DTChamber.h"
#include "Geometry/DTGeometry/interface/DTSuperLayer.h"
#include "DataFormats/DTRecHit/interface/DTSLRecSegment2D.h"
#include "DataFormats/DTRecHit/interface/DTRecSegment2D.h"

#include "Geometry/Records/interface/GlobalTrackingGeometryRecord.h"
#include "Geometry/CommonDetUnit/interface/GlobalTrackingGeometry.h"
#include "TrackingTools/Records/interface/TrackingComponentsRecord.h"

#include "DataFormats/MuonReco/interface/Muon.h"
#include "DataFormats/MuonReco/interface/MuonFwd.h"
#include "DataFormats/DTRecHit/interface/DTRecSegment2D.h"
#include "DataFormats/DTRecHit/interface/DTRecSegment4DCollection.h"
#include "DataFormats/DTRecHit/interface/DTRecSegment2DCollection.h"
#include "DataFormats/TrackingRecHit/interface/TrackingRecHitFwd.h"
#include "RecoMuon/TransientTrackingRecHit/interface/MuonTransientTrackingRecHit.h"

#include "DataFormats/TrackReco/interface/Track.h"
#include "DataFormats/TrackReco/interface/TrackFwd.h"
#include "DataFormats/TrackReco/interface/TrackExtra.h"
#include "DataFormats/TrackReco/interface/TrackExtraFwd.h"


// system include files
#include <memory>
#include <vector>
#include <string>
#include <iostream>

namespace edm {
  class ParameterSet;
  class EventSetup;
  class InputTag;
}

class MuonServiceProxy;

//
// constructors and destructor
//
DTTimingExtractor::DTTimingExtractor(const edm::ParameterSet& iConfig, MuonSegmentMatcher *segMatcher)
  :
  theHitsMin_(iConfig.getParameter<int>("HitsMin")),
  thePruneCut_(iConfig.getParameter<double>("PruneCut")),
  theTimeOffset_(iConfig.getParameter<double>("DTTimeOffset")),
  theError_(iConfig.getParameter<double>("HitError")),
  useSegmentT0_(iConfig.getParameter<bool>("UseSegmentT0")),
  doWireCorr_(iConfig.getParameter<bool>("DoWireCorr")),
  dropTheta_(iConfig.getParameter<bool>("DropTheta")),
  requireBothProjections_(iConfig.getParameter<bool>("RequireBothProjections")),
  debug(iConfig.getParameter<bool>("debug"))
{
  edm::ParameterSet serviceParameters = iConfig.getParameter<edm::ParameterSet>("ServiceParameters");
  theService = std::make_unique<MuonServiceProxy>(serviceParameters);
  theMatcher = segMatcher;
}


DTTimingExtractor::~DTTimingExtractor()
{
}


//
// member functions
//
void DTTimingExtractor::fillTiming(TimeMeasurementSequence &tmSequence, 
                   const std::vector<const DTRecSegment4D*> &segments,
                   reco::TrackRef muonTrack,
                   const edm::Event& iEvent, const edm::EventSetup& iSetup)
{
  if (debug) 
    std::cout << " *** DT Timimng Extractor ***" << std::endl;

  theService->update(iSetup);

  const GlobalTrackingGeometry *theTrackingGeometry = &*theService->trackingGeometry();

  // get the DT geometry
  edm::ESHandle<DTGeometry> theDTGeom;
  iSetup.get<MuonGeometryRecord>().get(theDTGeom);

  // get the propagator  
  edm::ESHandle<Propagator> propagator;
  iSetup.get<TrackingComponentsRecord>().get("SteppingHelixPropagatorAny", propagator);
  const Propagator *propag = propagator.product();

  math::XYZPoint  pos=muonTrack->innerPosition();
  math::XYZVector mom=muonTrack->innerMomentum();
  GlobalPoint  posp(pos.x(), pos.y(), pos.z());
  GlobalVector momv(mom.x(), mom.y(), mom.z());
  FreeTrajectoryState muonFTS(posp, momv, (TrackCharge)muonTrack->charge(), theService->magneticField().product());

  // create a collection on TimeMeasurements for the track        
  std::vector<TimeMeasurement> tms;
  for (const auto& rechit : segments ) {

    // Create the ChamberId
    DetId id = rechit->geographicalId();
    DTChamberId chamberId(id.rawId());
    int station = chamberId.station();
    if (debug) std::cout << "Matched DT segment in station " << station << std::endl;

    // use only segments with both phi and theta projections present (optional)
    bool bothProjections = ( (rechit->hasPhi()) && (rechit->hasZed()) );
    if (requireBothProjections_ && !bothProjections) continue;

    // loop over (theta, phi) segments
    for (int phi=0; phi<2; phi++) {

      if (dropTheta_ && !phi) continue;

      const DTRecSegment2D* segm;
      if (phi) { 
        segm = dynamic_cast<const DTRecSegment2D*>(rechit->phiSegment()); 
        if (debug) std::cout << " *** Segment t0: " << segm->t0() << std::endl;
      }    
        else segm = dynamic_cast<const DTRecSegment2D*>(rechit->zSegment());

      if(segm == nullptr) continue;
      if (segm->specificRecHits().empty()) continue;

      const GeomDet* geomDet = theTrackingGeometry->idToDet(segm->geographicalId());
      const std::vector<DTRecHit1D>& hits1d(segm->specificRecHits());

      // store all the hits from the segment
      for (const auto& hiti : hits1d) {

    const GeomDet* dtcell = theTrackingGeometry->idToDet(hiti.geographicalId());
    TimeMeasurement thisHit;

    std::pair< TrajectoryStateOnSurface, double> tsos;
    tsos=propag->propagateWithPath(muonFTS,dtcell->surface());

        double dist;            
        double dist_straight = dtcell->toGlobal(hiti.localPosition()).mag(); 
    if (tsos.first.isValid()) { 
      dist = tsos.second+posp.mag(); 
//    std::cout << "Propagate distance: " << dist << " ( innermost: " << posp.mag() << ")" << std::endl; 
    } else { 
      dist = dist_straight;
//    std::cout << "Geom distance: " << dist << std::endl; 
    }

    thisHit.driftCell = hiti.geographicalId();
    if (hiti.lrSide()==DTEnums::Left) thisHit.isLeft=true; else thisHit.isLeft=false;
    thisHit.isPhi = phi;
    thisHit.posInLayer = geomDet->toLocal(dtcell->toGlobal(hiti.localPosition())).x();
    thisHit.distIP = dist;
    thisHit.station = station;
    if (useSegmentT0_ && segm->ist0Valid()) thisHit.timeCorr=segm->t0();
    else thisHit.timeCorr=0.;
    thisHit.timeCorr += theTimeOffset_;
      
    // signal propagation along the wire correction for unmached theta or phi segment hits
    if (doWireCorr_ && !bothProjections && tsos.first.isValid()) {
      const DTLayer* layer = theDTGeom->layer(hiti.wireId());
      float propgL = layer->toLocal( tsos.first.globalPosition() ).y();
      float wirePropCorr = propgL/24.4*0.00543; // signal propagation speed along the wire
      if (thisHit.isLeft) wirePropCorr=-wirePropCorr;
      thisHit.posInLayer += wirePropCorr;
      const DTSuperLayer *sl = layer->superLayer();
      float tofCorr = sl->surface().position().mag()-tsos.first.globalPosition().mag();
      tofCorr = (tofCorr/29.979)*0.00543;
      if (thisHit.isLeft) tofCorr=-tofCorr;
      thisHit.posInLayer += tofCorr;
    } else {
          // non straight-line path correction
          float slCorr = (dist_straight-dist)/29.979*0.00543;
      if (thisHit.isLeft) slCorr=-slCorr;
      thisHit.posInLayer += slCorr;
    }

        if (debug) std::cout << " dist: " << dist << "  t0: " << thisHit.posInLayer << std::endl;
 
    tms.push_back(thisHit);
      }
    } // phi = (0,1)            
  } // rechit
      
  bool modified = false;
  std::vector <double> dstnc, local_t0, hitWeightTimeVtx, hitWeightInvbeta, left;
  double totalWeightInvbeta=0;
  double totalWeightTimeVtx=0;
    
  // Now loop over the measurements, calculate 1/beta and time at vertex and cut away outliers
  do {    

    modified = false;
    dstnc.clear();
    local_t0.clear();
    hitWeightTimeVtx.clear();
    hitWeightInvbeta.clear();
    left.clear();
      
    std::vector <int> hit_idx;
    totalWeightInvbeta=0;
    totalWeightTimeVtx=0;
      
    // Rebuild segments
    for (int sta=1;sta<5;sta++)
      for (int phi=0;phi<2;phi++) {
        std::vector <TimeMeasurement> seg;
        std::vector <int> seg_idx;
    int tmpos=0;
    for (auto& tm : tms) {
      if ((tm.station==sta) && (tm.isPhi==phi)) {
        seg.push_back(tm);
        seg_idx.push_back(tmpos);
      }
      tmpos++;  
    }

    unsigned int segsize = seg.size();
    if (segsize<theHitsMin_) continue;

    double a=0, b=0;
        std::vector <double> hitxl,hitxr,hityl,hityr;

    for (auto& tm : seg) {
 
      DetId id = tm.driftCell;
      const GeomDet* dtcell = theTrackingGeometry->idToDet(id);
      DTChamberId chamberId(id.rawId());
      const GeomDet* dtcham = theTrackingGeometry->idToDet(chamberId);

      double celly=dtcham->toLocal(dtcell->position()).z();
            
      if (tm.isLeft) {
        hitxl.push_back(celly);
        hityl.push_back(tm.posInLayer);
      } else {
        hitxr.push_back(celly);
        hityr.push_back(tm.posInLayer);
      }    
    }

    if (!fitT0(a,b,hitxl,hityl,hitxr,hityr)) {
      if (debug)
        std::cout << "     t0 = zero, Left hits: " << hitxl.size() << " Right hits: " << hitxr.size() << std::endl;
      continue;
    }

    // a segment must have at least one left and one right hit
    if ((hitxl.empty()) || (hityl.empty())) continue;

    int segidx=0;
    for (const auto& tm : seg) {

      DetId id = tm.driftCell;
      const GeomDet* dtcell = theTrackingGeometry->idToDet(id);
      DTChamberId chamberId(id.rawId());
      const GeomDet* dtcham = theTrackingGeometry->idToDet(chamberId);

      double layerZ  = dtcham->toLocal(dtcell->position()).z();
      double segmLocalPos = b+layerZ*a;
      double hitLocalPos = tm.posInLayer;
      int hitSide = -tm.isLeft*2+1;
      double t0_segm = (-(hitSide*segmLocalPos)+(hitSide*hitLocalPos))/0.00543+tm.timeCorr;
      
      if (debug) std::cout << "   Segm hit.  dstnc: " << tm.distIP << "   t0: " << t0_segm << std::endl;
            
      dstnc.push_back(tm.distIP);
      local_t0.push_back(t0_segm);
      left.push_back(hitSide);
      hitWeightInvbeta.push_back(((double)seg.size()-2.)*tm.distIP*tm.distIP/((double)seg.size()*30.*30.*theError_*theError_));
          hitWeightTimeVtx.push_back(((double)seg.size()-2.)/((double)seg.size()*theError_*theError_));
      hit_idx.push_back(seg_idx.at(segidx));
      segidx++;
      totalWeightInvbeta+=((double)seg.size()-2.)*tm.distIP*tm.distIP/((double)seg.size()*30.*30.*theError_*theError_);
      totalWeightTimeVtx+=((double)seg.size()-2.)/((double)seg.size()*theError_*theError_);
    }
      }

    if (totalWeightInvbeta==0) break;        

    // calculate the value and error of 1/beta and timeVtx from the complete set of 1D hits
    if (debug)
      std::cout << " Points for global fit: " << dstnc.size() << std::endl;

    double invbeta=0,invbetaErr=0;
    double timeVtx=0,timeVtxErr=0;

    for (unsigned int i=0;i<dstnc.size();i++) {
      invbeta+=(1.+local_t0.at(i)/dstnc.at(i)*30.)*hitWeightInvbeta.at(i)/totalWeightInvbeta;
      timeVtx+=local_t0.at(i)*hitWeightTimeVtx.at(i)/totalWeightTimeVtx;
    }
    
    double chimax=0.;
    std::vector<TimeMeasurement>::iterator tmmax;
    
    // Calculate the inv beta and time at vertex dispersion
    double diff_ibeta,diff_tvtx;
    for (unsigned int i=0;i<dstnc.size();i++) {
      diff_ibeta=(1.+local_t0.at(i)/dstnc.at(i)*30.)-invbeta;
      diff_ibeta=diff_ibeta*diff_ibeta*hitWeightInvbeta.at(i);
      diff_tvtx=local_t0.at(i)-timeVtx;
      diff_tvtx=diff_tvtx*diff_tvtx*hitWeightTimeVtx.at(i);
      invbetaErr+=diff_ibeta;
      timeVtxErr+=diff_tvtx;
      
      // decide if we cut away time at vertex outliers or inverse beta outliers
      // currently not configurable.
      if (diff_tvtx>chimax) { 
    tmmax=tms.begin()+hit_idx.at(i);
    chimax=diff_tvtx;
      }
    }
    
    // cut away the outliers
    if (chimax>thePruneCut_) {
      tms.erase(tmmax);
      modified=true;
    }    

    if (debug) {
      double cf = 1./(dstnc.size()-1);
      invbetaErr=sqrt(invbetaErr/totalWeightInvbeta*cf); 
      timeVtxErr=sqrt(timeVtxErr/totalWeightTimeVtx*cf); 
      std::cout << " Measured 1/beta: " << invbeta << " +/- " << invbetaErr << std::endl;
      std::cout << " Measured time: " << timeVtx << " +/- " << timeVtxErr << std::endl;
    }  

  } while (modified);

  for (unsigned int i=0;i<dstnc.size();i++) {
    tmSequence.dstnc.push_back(dstnc.at(i));
    tmSequence.local_t0.push_back(local_t0.at(i));
    tmSequence.weightInvbeta.push_back(hitWeightInvbeta.at(i));
    tmSequence.weightTimeVtx.push_back(hitWeightTimeVtx.at(i));
  }

  tmSequence.totalWeightInvbeta=totalWeightInvbeta;
  tmSequence.totalWeightTimeVtx=totalWeightTimeVtx;
}

// ------------ method called to produce the data  ------------
void
DTTimingExtractor::fillTiming(TimeMeasurementSequence &tmSequence, reco::TrackRef muonTrack,
                              const edm::Event& iEvent, const edm::EventSetup& iSetup)
{
  // get the DT segments that were used to construct the muon
  std::vector<const DTRecSegment4D*> range = theMatcher->matchDT(*muonTrack,iEvent);
  
  if (debug) 
    std::cout << " The muon track matches " << range.size() << " segments." << std::endl;
  fillTiming(tmSequence,range,muonTrack,iEvent,iSetup);
}

double
DTTimingExtractor::fitT0(double &a, double &b, const std::vector<double>& xl, const std::vector<double>& yl, const std::vector<double>& xr, const std::vector<double>& yr ) {

  double sx=0,sy=0,sxy=0,sxx=0,ssx=0,ssy=0,s=0,ss=0;

  for (unsigned int i=0; i<xl.size(); i++) {
    sx+=xl[i];
    sy+=yl[i];
    sxy+=xl[i]*yl[i];
    sxx+=xl[i]*xl[i];
    s++;
    ssx+=xl[i];
    ssy+=yl[i];
    ss++;
  } 

  for (unsigned int i=0; i<xr.size(); i++) {
    sx+=xr[i];
    sy+=yr[i];
    sxy+=xr[i]*yr[i];
    sxx+=xr[i]*xr[i];
    s++;
    ssx-=xr[i];
    ssy-=yr[i];
    ss--;
  } 

  double delta = ss*ss*sxx+s*sx*sx+s*ssx*ssx-s*s*sxx-2*ss*sx*ssx;
  
  double t0_corr=0.;

  if (delta) {
    a=(ssy*s*ssx+sxy*ss*ss+sy*sx*s-sy*ss*ssx-ssy*sx*ss-sxy*s*s)/delta;
    b=(ssx*sy*ssx+sxx*ssy*ss+sx*sxy*s-sxx*sy*s-ssx*sxy*ss-sx*ssy*ssx)/delta;
    t0_corr=(ssx*s*sxy+sxx*ss*sy+sx*sx*ssy-sxx*s*ssy-sx*ss*sxy-ssx*sx*sy)/delta;
  }

  // convert drift distance to time
  t0_corr/=-0.00543;

  return t0_corr;
}


//define this as a plug-in
//DEFINE_FWK_MODULE(DTTimingExtractor);