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 EventContext &ctx) const

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

Private Attributes
SG::ReadHandleKey< xAOD::MuonContainer >	m_muonContainerName {this, "MuonCollection", "Muons"}
PublicToolHandle< Trk::IExtrapolator >	m_extrapolator {this, "Extrapolator", "Trk::Extrapolator/AtlasExtrapolator"}
Gaudi::Property< double >	m_endcapPivotPlaneZ {this, "EndcapPivotPlaneZ", 15525., "z position of pivot plane in endcap region"}
Gaudi::Property< double >	m_endcapPivotPlaneMinimumRadius {this, "EndcapPivotPlaneMinimumRadius", 0., "minimum radius of pivot plane in endcap region"}
Gaudi::Property< double >	m_endcapPivotPlaneMaximumRadius {this, "EndcapPivotPlaneMaximumRadius", 11977., "maximum radius of pivot plane in endcap region"}
Gaudi::Property< double >	m_barrelPivotPlaneRadius {this, "BarrelPivotPlaneRadius", 8000., "radius of pivot plane in barrel region"}
Gaudi::Property< double >	m_barrelPivotPlaneHalfLength {this, "BarrelPivotPlaneHalfLength", 9700., "half length of pivot plane in barrel region"}

Detailed Description

Definition at line 18 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 17 of file MuonExtrapolationTool.cxx.

  :
    base_class(t, n, p)
{
}

Member Function Documentation

addBranches()

StatusCode DerivationFramework::MuonExtrapolationTool::addBranches ( const EventContext &  ctx ) const

virtual

Definition at line 89 of file MuonExtrapolationTool.cxx.

{
    SG::ReadHandle<xAOD::MuonContainer> muonContainer{m_muonContainerName, ctx};
    if (!muonContainer.isValid()) {
      ATH_MSG_ERROR("Failed to retrieve MuonContainer with name: " << m_muonContainerName.key());
      return StatusCode::FAILURE;
    }
    for (auto muon : *muonContainer) {
       const xAOD::TrackParticle* track = getPreferredTrackParticle(muon);
       float eta, phi = 0;
       if( !extrapolateAndDecorateTrackParticle( track, eta, phi, ctx )){
           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 EventContext &  ctx  ) const

private

Definition at line 36 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, ctx);
      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 EventContext &  ctx  ) const

private

run the extrapolation - only available in full athena

Definition at line 110 of file MuonExtrapolationTool.cxx.

{
  // BARREL
  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 nullptr;
  }
  // 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);
 
  std::unique_ptr<Trk::DiscSurface> disc =
    std::make_unique<Trk::DiscSurface>(matrix,
                                       m_endcapPivotPlaneMinimumRadius,
                                       m_endcapPivotPlaneMaximumRadius);
  if (!disc) {
    ATH_MSG_WARNING("extrapolateToTriggerPivotPlane :: new Trk::DiscSurface failed.");
    return nullptr;
  }
 
  // 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.get();
  p = m_extrapolator->extrapolate(
    ctx, perigee, *surface, Trk::alongMomentum, boundaryCheck, Trk::muon).release();
  return p;
}

getPreferredTrackParticle()

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

private

Definition at line 65 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 26 of file MuonExtrapolationTool.cxx.

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

Member Data Documentation

m_barrelPivotPlaneHalfLength

Gaudi::Property<double> DerivationFramework::MuonExtrapolationTool::m_barrelPivotPlaneHalfLength {this, "BarrelPivotPlaneHalfLength", 9700., "half length of pivot plane in barrel region"}

private

Definition at line 53 of file MuonExtrapolationTool.h.

m_barrelPivotPlaneRadius

Gaudi::Property<double> DerivationFramework::MuonExtrapolationTool::m_barrelPivotPlaneRadius {this, "BarrelPivotPlaneRadius", 8000., "radius of pivot plane in barrel region"}

private

Definition at line 52 of file MuonExtrapolationTool.h.

m_endcapPivotPlaneMaximumRadius

Gaudi::Property<double> DerivationFramework::MuonExtrapolationTool::m_endcapPivotPlaneMaximumRadius {this, "EndcapPivotPlaneMaximumRadius", 11977., "maximum radius of pivot plane in endcap region"}

private

Definition at line 51 of file MuonExtrapolationTool.h.

m_endcapPivotPlaneMinimumRadius

Gaudi::Property<double> DerivationFramework::MuonExtrapolationTool::m_endcapPivotPlaneMinimumRadius {this, "EndcapPivotPlaneMinimumRadius", 0., "minimum radius of pivot plane in endcap region"}

private

Definition at line 50 of file MuonExtrapolationTool.h.

m_endcapPivotPlaneZ

Gaudi::Property<double> DerivationFramework::MuonExtrapolationTool::m_endcapPivotPlaneZ {this, "EndcapPivotPlaneZ", 15525., "z position of pivot plane in endcap region"}

private

Definition at line 49 of file MuonExtrapolationTool.h.

m_extrapolator

PublicToolHandle<Trk::IExtrapolator> DerivationFramework::MuonExtrapolationTool::m_extrapolator {this, "Extrapolator", "Trk::Extrapolator/AtlasExtrapolator"}

private

Definition at line 45 of file MuonExtrapolationTool.h.

m_muonContainerName

SG::ReadHandleKey<xAOD::MuonContainer> DerivationFramework::MuonExtrapolationTool::m_muonContainerName {this, "MuonCollection", "Muons"}

private

Definition at line 44 of file MuonExtrapolationTool.h.

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

• MuonExtrapolationTool.h
• MuonExtrapolationTool.cxx