#include <RecoMuon/MuonIdentification/src/DTTimingExtractor.cc>

Classes
class	TimeMeasurement
Public Member Functions
	DTTimingExtractor (const edm::ParameterSet &)
	Constructor.
void	fillTiming (TimeMeasurementSequence &tmSequence, reco::TrackRef muonTrack, const edm::Event &iEvent, const edm::EventSetup &iSetup)
	~DTTimingExtractor ()
	Destructor.
Private Member Functions
double	fitT0 (double &a, double &b, std::vector< double > xl, std::vector< double > yl, std::vector< double > xr, std::vector< double > yr)
Private Attributes
bool	debug
bool	doWireCorr_
bool	dropTheta_
edm::InputTag	DTSegmentTags_
bool	requireBothProjections_
double	theError_
unsigned int	theHitsMin_
MuonSegmentMatcher *	theMatcher
double	thePruneCut_
MuonServiceProxy *	theService
double	theTimeOffset_
bool	useSegmentT0_

Detailed Description

Extracts timing information associated to a muon track

Description: Produce timing information for a muon track using 1D DT hits from segments used to build the track

Definition at line 55 of file DTTimingExtractor.h.

Constructor & Destructor Documentation

DTTimingExtractor::DTTimingExtractor ( const edm::ParameterSet & iConfig )

Constructor.

Definition at line 76 of file DTTimingExtractor.cc.

References edm::ParameterSet::getParameter(), MuonSegmentMatcher_cff::MuonSegmentMatcher, MuonServiceProxy_cff::MuonServiceProxy, theMatcher, and theService.

  :
  DTSegmentTags_(iConfig.getParameter<edm::InputTag>("DTsegments")),
  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 = new MuonServiceProxy(serviceParameters);
  
  edm::ParameterSet matchParameters = iConfig.getParameter<edm::ParameterSet>("MatchParameters");

  theMatcher = new MuonSegmentMatcher(matchParameters, theService);
}

DTTimingExtractor::~DTTimingExtractor ( )

Destructor.

Definition at line 98 of file DTTimingExtractor.cc.

References theMatcher, and theService.

{
  if (theService) delete theService;
  if (theMatcher) delete theMatcher;
}

Member Function Documentation

void DTTimingExtractor::fillTiming	(	TimeMeasurementSequence &	tmSequence,
		reco::TrackRef	muonTrack,
		const edm::Event &	iEvent,
		const edm::EventSetup &	iSetup
	)

Definition at line 111 of file DTTimingExtractor.cc.

References a, b, gather_cfg::cout, debug, diffTreeTool::diff, DTTimingExtractor::TimeMeasurement::distIP, doWireCorr_, DTTimingExtractor::TimeMeasurement::driftCell, dropTheta_, TimeMeasurementSequence::dstnc, fitT0(), TrackingRecHit::geographicalId(), edm::EventSetup::get(), i, GlobalTrackingGeometry::idToDet(), DTTimingExtractor::TimeMeasurement::isLeft, DTTimingExtractor::TimeMeasurement::isPhi, DTRecSegment2D::ist0Valid(), DTEnums::Left, TimeMeasurementSequence::local_t0, mag(), MuonServiceProxy::magneticField(), MuonSegmentMatcher::matchDT(), phi, pos, DTTimingExtractor::TimeMeasurement::posInLayer, GeomDet::position(), GloballyPositioned< T >::position(), edm::ESHandle< T >::product(), Propagator::propagateWithPath(), LargeD0_PixelPairStep_cff::propagator, requireBothProjections_, DTRecSegment2D::specificRecHits(), mathSSE::sqrt(), DTTimingExtractor::TimeMeasurement::station, relativeConstraints::station, DTChamberId::station(), DTLayer::superLayer(), GeomDet::surface(), DTRecSegment2D::t0(), theError_, theHitsMin_, theMatcher, thePruneCut_, theService, theTimeOffset_, MuonServiceProxy::theTrackingGeometry, DTTimingExtractor::TimeMeasurement::timeCorr, GeomDet::toGlobal(), GeomDet::toLocal(), TimeMeasurementSequence::totalWeightInvbeta, TimeMeasurementSequence::totalWeightVertex, MuonServiceProxy::trackingGeometry(), MuonServiceProxy::update(), useSegmentT0_, TimeMeasurementSequence::weightInvbeta, TimeMeasurementSequence::weightVertex, PV3DBase< T, PVType, FrameType >::x(), detailsBasic3DVector::y, and z.

Referenced by MuonTimingFiller::fillTiming().

{

//  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;
  double totalWeightInvbeta=0;
  double totalWeightVertex=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++) {

      if (dropTheta_ && !phi) continue;

      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;            
        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;
        }

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

    modified = false;
    dstnc.clear();
    dsegm.clear();
    dtraj.clear();
    hitWeightVertex.clear();
    hitWeightInvbeta.clear();
    left.clear();
      
    std::vector <int> hit_idx;
    totalWeightInvbeta=0;
    totalWeightVertex=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);
          hitWeightInvbeta.push_back(((double)seg.size()-2.)*tm->distIP*tm->distIP/((double)seg.size()*30.*30.*theError_*theError_));
          hitWeightVertex.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_);
          totalWeightVertex+=((double)seg.size()-2.)/((double)seg.size()*theError_*theError_);
        }
      }

    if (totalWeightInvbeta==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.)*hitWeightInvbeta.at(i)/totalWeightInvbeta;

    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*hitWeightInvbeta.at(i);
      invbetaerr+=diff;
      if (diff>chimax) { 
        tmmax=tms.begin()+hit_idx.at(i);
        chimax=diff;
      }
    }
    
    invbetaerr=sqrt(invbetaerr/totalWeightInvbeta); 
 
    // 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.weightInvbeta.push_back(hitWeightInvbeta.at(i));
    tmSequence.weightVertex.push_back(hitWeightVertex.at(i));
  }

  tmSequence.totalWeightInvbeta=totalWeightInvbeta;
  tmSequence.totalWeightVertex=totalWeightVertex;

}

double DTTimingExtractor::fitT0	(	double &	a,
		double &	b,
		std::vector< double >	xl,
		std::vector< double >	yl,
		std::vector< double >	xr,
		std::vector< double >	yr
	)		`[private]`

Definition at line 370 of file DTTimingExtractor.cc.

References delta, i, and asciidump::s.

Referenced by fillTiming().

                                                                                                                                      {

  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;
}