Simulation::ZeroLifetimePositioner Class Reference

This tool works around the issue of zero-lifetime particles in Geant4. More...

#include <ZeroLifetimePositioner.h>

Inheritance diagram for Simulation::ZeroLifetimePositioner:

Collaboration diagram for Simulation::ZeroLifetimePositioner:

Public Member Functions
	ZeroLifetimePositioner (const std::string &name, ISvcLocator *pSvcLocator)
	Constructor with parameters.
StatusCode	initialize () override final
	Athena algtool's Hooks.
StatusCode	finalize () override final
	Athena algtool's Hooks.
virtual StatusCode	applyWorkaround (HepMC::GenEvent &ge) const override final
	Applies the workaround for zero-lifetime particles to the GenEvent.
virtual StatusCode	removeWorkaround (HepMC::GenEvent &ge) const override final
	Removes the workaround for zero-lifetime particles from the GenEvent.

Private Member Functions
StatusCode	manipulate (HepMC::GenEvent &ge, bool applyPatch, bool removePatch) const
	modifies (displaces) the given GenEvent

Private Attributes
Gaudi::Property< bool >	m_applyPatch {this, "ApplyPatch", false}
Gaudi::Property< bool >	m_removePatch {this, "RemovePatch", false}
Gaudi::Property< std::vector< int > >	m_pdgCodesToCheck { this, "PDGCodesToCheck", {421,511,531} }

Detailed Description

This tool works around the issue of zero-lifetime particles in Geant4.

Definition at line 21 of file ZeroLifetimePositioner.h.

Constructor & Destructor Documentation

ZeroLifetimePositioner()

Simulation::ZeroLifetimePositioner::ZeroLifetimePositioner	(	const std::string &	name,
		ISvcLocator *	pSvcLocator )

Constructor with parameters.

Constructor.

Definition at line 19 of file ZeroLifetimePositioner.cxx.

  : base_class(name, pSvcLocator)
{
}

Member Function Documentation

applyWorkaround()

StatusCode Simulation::ZeroLifetimePositioner::applyWorkaround ( HepMC::GenEvent & ge ) const

finaloverridevirtual

Applies the workaround for zero-lifetime particles to the GenEvent.

Definition at line 47 of file ZeroLifetimePositioner.cxx.

{
  ATH_MSG_DEBUG("applyWorkaround");
  return this->manipulate(ge, m_applyPatch, false);
}

finalize()

StatusCode Simulation::ZeroLifetimePositioner::finalize ( )

finaloverride

Athena algtool's Hooks.

Definition at line 40 of file ZeroLifetimePositioner.cxx.

{
  ATH_MSG_VERBOSE("Finalizing ...");
  return StatusCode::SUCCESS;
}

initialize()

StatusCode Simulation::ZeroLifetimePositioner::initialize ( )

finaloverride

Athena algtool's Hooks.

Definition at line 27 of file ZeroLifetimePositioner.cxx.

{
  ATH_MSG_VERBOSE("Initializing ...");
  for(auto& pdgcode : m_pdgCodesToCheck) {
    pdgcode = std::abs(pdgcode);
    ATH_MSG_DEBUG("Will look for verices where " << pdgcode <<
                  " oscillates into -" << pdgcode << " (and vice versa).");
  }
  return StatusCode::SUCCESS;
}

manipulate()

StatusCode Simulation::ZeroLifetimePositioner::manipulate ( HepMC::GenEvent & ge, bool applyPatch, bool removePatch ) const

private

modifies (displaces) the given GenEvent

Definition at line 62 of file ZeroLifetimePositioner.cxx.

{
  // loop over the vertices in the event
 
  const auto pdgCodesBegin = m_pdgCodesToCheck.begin();
  const auto pdgCodesEnd = m_pdgCodesToCheck.end();
  for (auto& curVtx: ge.vertices()) {
    if (curVtx->particles_in().size()!=1 || curVtx->particles_out().size()!=1) { continue; }
    const int pdgIn=curVtx->particles_in().front()->pdg_id();
    const int pdgOut=curVtx->particles_out().front()->pdg_id();
    if (pdgIn!=-pdgOut ||
        std::find(pdgCodesBegin, pdgCodesEnd, std::abs(pdgIn))== pdgCodesEnd) {
      continue;
    }
    HepMC::GenVertexPtr nextVtx = curVtx->particles_out().front()->end_vertex();
    if(!nextVtx) { continue; }
    ATH_MSG_DEBUG("Found a vertex to correct with incoming PDG code = " << pdgIn);
    ATH_MSG_VERBOSE("Next Vertex:");
    if (ATH_UNLIKELY(this->msgLvl (MSG::VERBOSE))) {
      HepMC::Print::line(nextVtx);
    }
    // NB Doing this check to explicitly avoid the fallback mechanism in
    // HepMC3::GenVertex::position() to return the position of
    // another GenVertex in the event if the position isn't set (or is set to zero)!
    const HepMC::FourVector &nextVec = (nextVtx->has_set_position()) ? nextVtx->position() : HepMC::FourVector::ZERO_VECTOR();
    const CLHEP::HepLorentzVector nextPos( nextVec.x(), nextVec.y(), nextVec.z(), nextVec.t() );
    ATH_MSG_VERBOSE("Current Vertex:");
    if (ATH_UNLIKELY(this->msgLvl (MSG::VERBOSE))) {
       HepMC::Print::line(curVtx);
    }
    if (applyPatch) {
      HepMC::GenVertexPtr prevVtx = curVtx->particles_in().front()->production_vertex();
      ATH_MSG_VERBOSE("Previous Vertex:");
      if (ATH_UNLIKELY(this->msgLvl (MSG::VERBOSE))) {
        HepMC::Print::line(prevVtx);
      }
      // NB Doing this check to explicitly avoid the fallback mechanism in
      // HepMC3::GenVertex::position() to return the position of
      // another GenVertex in the event if the position isn't set (or is set to zero)!
      const HepMC::FourVector &prevVec = (prevVtx->has_set_position()) ? prevVtx->position() : HepMC::FourVector::ZERO_VECTOR();
      const CLHEP::HepLorentzVector prevPos( prevVec.x(), prevVec.y(), prevVec.z(), prevVec.t() );
      CLHEP::HepLorentzVector newPos = 0.5*(prevPos+nextPos);
      curVtx->set_position(HepMC::FourVector(newPos.x(),newPos.y(),newPos.z(),newPos.t()));
      ATH_MSG_DEBUG("Revised current Vertex");
      if (ATH_UNLIKELY(this->msgLvl (MSG::VERBOSE))) {
        HepMC::Print::line(curVtx);
      }
    }
    if (removePatch) {
      CLHEP::HepLorentzVector newPos = nextPos;
      curVtx->set_position(HepMC::FourVector(newPos.x(),newPos.y(),newPos.z(),newPos.t()));
      ATH_MSG_DEBUG("Revised current Vertex");
      if (ATH_UNLIKELY(this->msgLvl (MSG::VERBOSE))) {
        HepMC::Print::line(curVtx);
      }
    }
  }
 
  return StatusCode::SUCCESS;
}

removeWorkaround()

StatusCode Simulation::ZeroLifetimePositioner::removeWorkaround ( HepMC::GenEvent & ge ) const

finaloverridevirtual

Removes the workaround for zero-lifetime particles from the GenEvent.

Definition at line 54 of file ZeroLifetimePositioner.cxx.

{
  ATH_MSG_DEBUG("removeWorkaround");
  return this->manipulate(ge, false, m_removePatch);
}

Member Data Documentation

m_applyPatch

Gaudi::Property<bool> Simulation::ZeroLifetimePositioner::m_applyPatch {this, "ApplyPatch", false}

private

Definition at line 39 of file ZeroLifetimePositioner.h.

{this, "ApplyPatch", false};

m_pdgCodesToCheck

Gaudi::Property<std::vector<int> > Simulation::ZeroLifetimePositioner::m_pdgCodesToCheck { this, "PDGCodesToCheck", {421,511,531} }

private

Definition at line 41 of file ZeroLifetimePositioner.h.

{ this, "PDGCodesToCheck", {421,511,531} }; // Apply fix to neutral mesons with oscillations: B0, B0s, D0

m_removePatch

Gaudi::Property<bool> Simulation::ZeroLifetimePositioner::m_removePatch {this, "RemovePatch", false}

private

Definition at line 40 of file ZeroLifetimePositioner.h.

{this, "RemovePatch", false};

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

• ZeroLifetimePositioner.h
• ZeroLifetimePositioner.cxx