DerivationFramework::MuonExtrapolationTool Class Reference

#include <MuonExtrapolationTool.h>

Inheritance diagram for DerivationFramework::MuonExtrapolationTool:

Collaboration diagram for DerivationFramework::MuonExtrapolationTool:

Public Member Functions
	MuonExtrapolationTool (const std::string &t, const std::string &n, const IInterface *p)
virtual StatusCode	initialize ()
virtual StatusCode	addBranches () const

Public Attributes
ToolHandle< Trk::IExtrapolator >	m_extrapolator

Private Member Functions
const Trk::TrackParameters *	extrapolateToTriggerPivotPlane (const xAOD::TrackParticle &track) const
	run the extrapolation - only available in full athena More...
bool	extrapolateAndDecorateTrackParticle (const xAOD::TrackParticle *particle, float &eta, float &phi) const
const xAOD::TrackParticle *	getPreferredTrackParticle (const xAOD::IParticle *probe) const

Private Attributes
double	m_endcapPivotPlaneZ
double	m_endcapPivotPlaneMinimumRadius
double	m_endcapPivotPlaneMaximumRadius
double	m_barrelPivotPlaneRadius
double	m_barrelPivotPlaneHalfLength
std::string	m_muonContainerName

Detailed Description

Definition at line 20 of file MuonExtrapolationTool.h.

Constructor & Destructor Documentation

MuonExtrapolationTool()

DerivationFramework::MuonExtrapolationTool::MuonExtrapolationTool	(	const std::string &	t,
		const std::string &	n,
		const IInterface *	p
	)

Definition at line 16 of file MuonExtrapolationTool.cxx.

  : 
    base_class(t, n, p),
    m_extrapolator("Trk::Extrapolator/AtlasExtrapolator")
{    
  declareProperty("EndcapPivotPlaneZ",             m_endcapPivotPlaneZ = 15525.);// z position of pivot plane in endcap region
  declareProperty("EndcapPivotPlaneMinimumRadius", m_endcapPivotPlaneMinimumRadius = 0.);// minimum radius of pivot plane in endcap region
  declareProperty("EndcapPivotPlaneMaximumRadius", m_endcapPivotPlaneMaximumRadius = 11977.); // maximum radius of pivot plane in endcap region
  declareProperty("BarrelPivotPlaneRadius",        m_barrelPivotPlaneRadius = 8000.);// radius of pivot plane in barrel region
  declareProperty("BarrelPivotPlaneHalfLength",    m_barrelPivotPlaneHalfLength = 9700.);// half length of pivot plane in barrel region
  declareProperty("Extrapolator", m_extrapolator);
  declareProperty("MuonCollection", m_muonContainerName = "Muons");
}

Member Function Documentation

addBranches()

StatusCode DerivationFramework::MuonExtrapolationTool::addBranches ( ) const

virtual

Definition at line 95 of file MuonExtrapolationTool.cxx.

{
    const xAOD::MuonContainer* muons = NULL;
    CHECK(evtStore()->retrieve(muons, m_muonContainerName));
    for(auto muon : *muons){
       const xAOD::TrackParticle* track = getPreferredTrackParticle(muon);
       float eta, phi = 0;
       if( !extrapolateAndDecorateTrackParticle( track, eta, phi )){
           if( muon->pt() > 3500.){
             //only complain if the muon has sufficient pT to actually reach the pivot plane
             //extrapolation will often fail for muons with pT < 3500 MeV
             ATH_MSG_WARNING("Failed to extrapolate+decorate muon with pivot plane coords - Muon params: pt "<<muon->pt()<<", eta "<< muon->eta()<<", phi "<< muon->phi());
           }
        }   
    }
    return StatusCode::SUCCESS;
}

extrapolateAndDecorateTrackParticle()

bool DerivationFramework::MuonExtrapolationTool::extrapolateAndDecorateTrackParticle ( const xAOD::TrackParticle *  particle, float &  eta, float &  phi  ) const

private

Definition at line 42 of file MuonExtrapolationTool.cxx.

{
 
  // decorators used to access or store the information 
  static const SG::AuxElement::Decorator< char > Decorated ("DecoratedPivotEtaPhi");
  static const SG::AuxElement::Decorator< float > Eta ("EtaTriggerPivot");
  static const SG::AuxElement::Decorator< float > Phi ("PhiTriggerPivot");
 
  if (! Decorated.isAvailable(*particle) || !Decorated(*particle)){
    // in the athena release, we can run the extrapolation if needed
      const Trk::TrackParameters* pTag = extrapolateToTriggerPivotPlane(*particle);
      if(!pTag) {
        Decorated(*particle) = false;
        return false;
      }
      Eta(*particle) = pTag->position().eta();
      Phi(*particle) = pTag->position().phi();
      Decorated(*particle) = true;
      delete pTag;
    }
    // if we get here, the decoration was either already present or just added by us
    // so we can finally read the values
    eta = Eta(*particle);
    phi = Phi(*particle);
    return true;
}

extrapolateToTriggerPivotPlane()

const Trk::TrackParameters * DerivationFramework::MuonExtrapolationTool::extrapolateToTriggerPivotPlane ( const xAOD::TrackParticle &  track ) const

private

run the extrapolation - only available in full athena

Definition at line 113 of file MuonExtrapolationTool.cxx.

{
  // BARREL
  const EventContext& ctx = Gaudi::Hive::currentContext();
  const Trk::Perigee& perigee = track.perigeeParameters();
  
  // create the barrel as a cylinder surface centered at 0,0,0
  Amg::Vector3D barrelCentre(0., 0., 0.);
  Amg::Transform3D matrix = Amg::Transform3D(Amg::RotationMatrix3D::Identity(), barrelCentre);
  
  Trk::CylinderSurface* cylinder = 
    new Trk::CylinderSurface(matrix,
                 m_barrelPivotPlaneRadius,
                 m_barrelPivotPlaneHalfLength);
  if (!cylinder) {
    ATH_MSG_WARNING("extrapolateToTriggerPivotPlane :: new Trk::CylinderSurface failed.");
    return 0;
  }
  // and then attempt to extrapolate our track to this surface, checking for the boundaries of the barrel
  bool boundaryCheck = true;
  const Trk::Surface* surface = cylinder;
  const Trk::TrackParameters* p = m_extrapolator->extrapolate(
    ctx, perigee, *surface, Trk::alongMomentum, boundaryCheck, Trk::muon).release();
  delete cylinder;
  // if the extrapolation worked out (so we are in the barrel) we are done and can return the 
  // track parameters at this surface. 
  if (p) return p;
 
  // if we get here, the muon did not cross the barrel surface
  // so we assume it is going into the endcap. 
  // ENDCAP
 
  // After 2 years of using this code, we realised that ATLAS actually has endcaps on both sides ;-)
  // So better make sure we place our endcap at the correct side of the detector!  
  // Hopefully no-one will ever read this comment... 
  float SignOfEta = track.eta() > 0 ? 1. : -1.;
 
  Amg::Vector3D endcapCentre(0., 0., m_endcapPivotPlaneZ);
  // much better!
  matrix = Amg::Transform3D(Amg::RotationMatrix3D::Identity(), SignOfEta * endcapCentre);
  
  Trk::DiscSurface* disc = 
    new Trk::DiscSurface(matrix,
             m_endcapPivotPlaneMinimumRadius,
             m_endcapPivotPlaneMaximumRadius);
  if (!disc) {
    ATH_MSG_WARNING("extrapolateToTriggerPivotPlane :: new Trk::DiscSurface failed."); 
    return 0;
  }
  
  // for the endcap, we turn off the boundary check, extending the EC infinitely to catch stuff heading for the transition region
  boundaryCheck = false;
  surface = disc;
  p = m_extrapolator->extrapolate(
    ctx, perigee, *surface, Trk::alongMomentum, boundaryCheck, Trk::muon).release();
  delete disc;
  return p;
}

getPreferredTrackParticle()

const xAOD::TrackParticle * DerivationFramework::MuonExtrapolationTool::getPreferredTrackParticle ( const xAOD::IParticle *  probe ) const

private

Definition at line 71 of file MuonExtrapolationTool.cxx.

{
  if (dynamic_cast<const xAOD::TruthParticle*>(muon)){
    ATH_MSG_WARNING("Pivot plane extrapolation not supported for Truth muons!");
    return 0;
  }
  const xAOD::TrackParticle* muonTrack = dynamic_cast<const xAOD::TrackParticle*>(muon);
  if(!muonTrack && dynamic_cast<const xAOD::Muon*>(muon)) {
    const xAOD::Muon* theMuon = dynamic_cast<const xAOD::Muon*>(muon);
    muonTrack = theMuon->trackParticle( xAOD::Muon::MuonSpectrometerTrackParticle );
    if(!muonTrack) {
      muonTrack = theMuon->primaryTrackParticle();
      if(!muonTrack) {
       muonTrack = theMuon->trackParticle( xAOD::Muon::InnerDetectorTrackParticle );
      }
    }
  }
  if(!muonTrack){
    ATH_MSG_WARNING("no valid track found for extrapolating the muon to the pivot plane!");
  }
  return muonTrack;
 
}

initialize()

StatusCode DerivationFramework::MuonExtrapolationTool::initialize ( )

virtual

Definition at line 33 of file MuonExtrapolationTool.cxx.

{
  ATH_CHECK(m_extrapolator.retrieve());
  return StatusCode::SUCCESS;
}

Member Data Documentation

m_barrelPivotPlaneHalfLength

double DerivationFramework::MuonExtrapolationTool::m_barrelPivotPlaneHalfLength

private

Definition at line 53 of file MuonExtrapolationTool.h.

m_barrelPivotPlaneRadius

double DerivationFramework::MuonExtrapolationTool::m_barrelPivotPlaneRadius

private

Definition at line 52 of file MuonExtrapolationTool.h.

m_endcapPivotPlaneMaximumRadius

double DerivationFramework::MuonExtrapolationTool::m_endcapPivotPlaneMaximumRadius

private

Definition at line 51 of file MuonExtrapolationTool.h.

m_endcapPivotPlaneMinimumRadius

double DerivationFramework::MuonExtrapolationTool::m_endcapPivotPlaneMinimumRadius

private

Definition at line 50 of file MuonExtrapolationTool.h.

m_endcapPivotPlaneZ

double DerivationFramework::MuonExtrapolationTool::m_endcapPivotPlaneZ

private

Definition at line 49 of file MuonExtrapolationTool.h.

m_extrapolator

ToolHandle<Trk::IExtrapolator> DerivationFramework::MuonExtrapolationTool::m_extrapolator

Definition at line 28 of file MuonExtrapolationTool.h.

m_muonContainerName

std::string DerivationFramework::MuonExtrapolationTool::m_muonContainerName

private

Definition at line 54 of file MuonExtrapolationTool.h.

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The documentation for this class was generated from the following files:

• MuonExtrapolationTool.h
• MuonExtrapolationTool.cxx