/data/refman/pasoursint/CMSSW_4_1_8_patch12/src/RecoMuon/MuonIdentification/src/DTTimingExtractor.cc

Go to the documentation of this file.

// -*- C++ -*-
//
// Package:    MuonIdentification
// Class:      DTTimingExtractor
// 
//
// Original Author:  Traczyk Piotr
//         Created:  Thu Oct 11 15:01:28 CEST 2007
// $Id: DTTimingExtractor.cc,v 1.10 2010/12/15 11:07:40 ptraczyk Exp $
//
//

#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)
  :
  DTSegmentTags_(iConfig.getParameter<edm::InputTag>("DTsegments")),
  theHitsMin_(iConfig.getParameter<int>("HitsMin")),
  thePruneCut_(iConfig.getParameter<double>("PruneCut")),
  theTimeOffset_(iConfig.getParameter<double>("DTTimeOffset")),
  useSegmentT0_(iConfig.getParameter<bool>("UseSegmentT0")),
  doWireCorr_(iConfig.getParameter<bool>("DoWireCorr")),
  requireBothProjections_(iConfig.getParameter<bool>("RequireBothProjections")),
  debug(iConfig.getParameter<bool>("debug"))
{
  edm::ParameterSet serviceParameters = iConfig.getParameter<edm::ParameterSet>("ServiceParameters");
  theService = new MuonServiceProxy(serviceParameters);
  
  edm::ParameterSet matchParameters = iConfig.getParameter<edm::ParameterSet>("MatchParameters");

  theMatcher = new MuonSegmentMatcher(matchParameters, theService);
}


DTTimingExtractor::~DTTimingExtractor()
{
  if (theService) delete theService;
  if (theMatcher) delete theMatcher;
}


//
// member functions
//

// ------------ method called to produce the data  ------------
void
DTTimingExtractor::fillTiming(TimeMeasurementSequence &tmSequence, reco::TrackRef muonTrack, const edm::Event& iEvent, const edm::EventSetup& iSetup)
{

//  using reco::TrackCollection;

  if (debug) 
    std::cout << " *** Muon 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);
  
  edm::ESHandle<Propagator> propagator;
  iSetup.get<TrackingComponentsRecord>().get("SteppingHelixPropagatorAny", propagator);
  const Propagator *propag = propagator.product();

  double invbeta=0;
  double invbetaerr=0;
  int totalWeight=0;
  std::vector<TimeMeasurement> tms;

  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());

  // get the DT segments that were used to construct the muon
  std::vector<const DTRecSegment4D*> range = theMatcher->matchDT(*muonTrack,iEvent);

  // create a collection on TimeMeasurements for the track        
  for (std::vector<const DTRecSegment4D*>::iterator rechit = range.begin(); rechit!=range.end();++rechit) {

    // Create the ChamberId
    DetId id = (*rechit)->geographicalId();
    DTChamberId chamberId(id.rawId());
    int station = chamberId.station();

    // 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++) {

      const DTRecSegment2D* segm;
      if (phi) segm = dynamic_cast<const DTRecSegment2D*>((*rechit)->phiSegment()); 
        else segm = dynamic_cast<const DTRecSegment2D*>((*rechit)->zSegment());

      if(segm == 0) continue;
      if (!segm->specificRecHits().size()) continue;

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

      // store all the hits from the segment
      for (std::vector<DTRecHit1D>::const_iterator hiti=hits1d.begin(); hiti!=hits1d.end(); hiti++) {

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

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

        double dist;            
        if (tsos.first.isValid()) dist = tsos.second+posp.mag(); 
          else dist = dtcell->toGlobal(hiti->localPosition()).mag();

        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;
        } 
          
        tms.push_back(thisHit);
      }
    } // phi = (0,1)            
  } // rechit
      
  bool modified = false;
  std::vector <double> dstnc, dsegm, dtraj, hitWeight, left;
    
  // Now loop over the measurements, calculate 1/beta and cut away outliers
  do {    

    modified = false;
    dstnc.clear();
    dsegm.clear();
    dtraj.clear();
    hitWeight.clear();
    left.clear();
      
    std::vector <int> hit_idx;
    totalWeight=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 (std::vector<TimeMeasurement>::iterator tm=tms.begin(); tm!=tms.end(); ++tm) {
          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 (std::vector<TimeMeasurement>::iterator tm=seg.begin(); tm!=seg.end(); ++tm) {
 
          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.size()) || (!hityl.size())) continue;

        int segidx=0;
        for (std::vector<TimeMeasurement>::const_iterator tm=seg.begin(); tm!=seg.end(); ++tm) {

          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;
            
          dstnc.push_back(tm->distIP);
          dsegm.push_back(t0_segm);
          left.push_back(hitSide);
          hitWeight.push_back(((double)seg.size()-2.)/(double)seg.size());
          hit_idx.push_back(seg_idx.at(segidx));
          segidx++;
        }
          
        totalWeight+=seg.size()-2;
      }

    if (totalWeight==0) break;        

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

    // inverse beta - weighted average of the contributions from individual hits
    invbeta=0;
    for (unsigned int i=0;i<dstnc.size();i++) 
      invbeta+=(1.+dsegm.at(i)/dstnc.at(i)*30.)*hitWeight.at(i)/totalWeight;

    double chimax=0.;
    std::vector<TimeMeasurement>::iterator tmmax;
    
    // the dispersion of inverse beta
    double diff;
    for (unsigned int i=0;i<dstnc.size();i++) {
      diff=(1.+dsegm.at(i)/dstnc.at(i)*30.)-invbeta;
      diff=diff*diff*hitWeight.at(i);
      invbetaerr+=diff;
      if (diff/totalWeight>chimax) { 
        tmmax=tms.begin()+hit_idx.at(i);
        chimax=diff;
      }
    }
    
    invbetaerr=sqrt(invbetaerr/totalWeight); 
 
    // cut away the outliers
    if (chimax>thePruneCut_) {
      tms.erase(tmmax);
      modified=true;
    }    

    if (debug)
      std::cout << " Measured 1/beta: " << invbeta << " +/- " << invbetaerr << 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(dsegm.at(i));
    tmSequence.weight.push_back(hitWeight.at(i));
  }

  tmSequence.totalWeight=totalWeight;

}

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