//=============================================================================
// Smearing function
//=============================================================================
StatusCode FlatSmearVertex::smearVertex( HepMC::GenEvent * theEvent ) {
double dx , dy , dz , dt ;
dx = m_xmin + m_flatDist( ) * ( m_xmax - m_xmin ) ;
dy = m_ymin + m_flatDist( ) * ( m_ymax - m_ymin ) ;
dz = m_zmin + m_flatDist( ) * ( m_zmax - m_zmin ) ;
dt = m_zDir * dz/Gaudi::Units::c_light ;
Gaudi::LorentzVector dpos( dx , dy , dz , dt ) ;
debug() << "Smearing vertices by " << dpos << endmsg;
for (auto vit = theEvent->vertices_begin(); vit != theEvent->vertices_end(); ++vit ) {
Gaudi::LorentzVector pos ( (*vit) -> position() ) ;
pos += dpos ;
(*vit)->set_position( HepMC::FourVector(pos.x(), pos.y(), pos.z(), pos.t() ) ) ;
}
return StatusCode::SUCCESS ;
}
//=============================================================================
// Main execution
//=============================================================================
StatusCode ParticleGunAlg::execute() {
StatusCode sc = StatusCode::SUCCESS ;
Gaudi::LorentzVector theFourMomentum ;
Gaudi::LorentzVector origin ;
int thePdgId ;
// prepare a new HepMC event
HepMC::GenEvent * theEvent = new HepMC::GenEvent() ;
m_particleGunTool->generateParticle( theFourMomentum , origin , thePdgId );
// create HepMC Vertex
HepMC::GenVertex * v = new HepMC::GenVertex( HepMC::FourVector( origin.X() ,
origin.Y() ,
origin.Z() ,
origin.T() ) ) ;
// create HepMC particle
HepMC::GenParticle * p = new HepMC::GenParticle( HepMC::FourVector( theFourMomentum.Px() ,
theFourMomentum.Py() ,
theFourMomentum.Pz() ,
theFourMomentum.E() ) ,
thePdgId ,
3 ) ;
v -> add_particle_out( p ) ;
theEvent -> add_vertex( v ) ;
theEvent -> set_signal_process_id( 0 ) ;
theEvent -> set_signal_process_vertex( v ) ;
if(m_vertexSmearTool != nullptr)
m_vertexSmearTool->smearVertex(theEvent);
HepMCEntry * entry = new HepMCEntry();
entry->setEvent(theEvent);
m_hepmchandle.put(entry);
return sc ;
}
/// Generate the particles
void ConstPtParticleGun::generateParticle(Gaudi::LorentzVector& momentum, Gaudi::LorentzVector& origin, int& pdgId) {
origin.SetCoordinates(0., 0., 0., 0.);
double px(0.), py(0.), pz(0.);
// Generate values for eta and phi
double phi = m_minPhi + m_flatGenerator() * (m_deltaPhi);
double eta = m_minEta + m_flatGenerator() * (m_deltaEta);
// Transform to x,y,z coordinates
double pt = 0;
if (m_ptList.size() > 0) {
int randIndex = m_flatGenerator() * m_ptList.size();
pt = m_ptList[randIndex];
} else {
if (m_logSpacedPt) {
double logPtMin = std::log10(m_minPt);
double logPtMax = std::log10(m_maxPt);
pt = pow(10, logPtMin + (logPtMax - logPtMin) * m_flatGenerator());
} else {
pt = m_minPt + m_flatGenerator() * (m_maxPt - m_minPt);
}
}
px = pt * cos(phi);
py = pt * sin(phi);
pz = pt * sinh(eta);
// randomly choose a particle type
unsigned int currentType = (unsigned int)(m_pdgCodes.size() * m_flatGenerator());
// protect against funnies
if (currentType >= m_pdgCodes.size()) currentType = 0;
momentum.SetPx(px);
momentum.SetPy(py);
momentum.SetPz(pz);
momentum.SetE(std::sqrt(m_masses[currentType] * m_masses[currentType] + momentum.P2()));
pdgId = m_pdgCodes[currentType];
debug() << " -> " << pdgId << endmsg << " P = " << momentum << endmsg;
}
StatusCode ConstPtParticleGun::getNextEvent(HepMC::GenEvent& theEvent) {
Gaudi::LorentzVector theFourMomentum;
Gaudi::LorentzVector origin;
// note: pgdid is set in function generateParticle
int thePdgId;
generateParticle(theFourMomentum, origin, thePdgId);
// create HepMC Vertex --
// by calling add_vertex(), the hepmc event is given ownership of the vertex
HepMC::GenVertex* v = new HepMC::GenVertex(HepMC::FourVector(origin.X(), origin.Y(), origin.Z(), origin.T()));
// create HepMC particle --
// by calling add_particle_out(), the hepmc vertex is given ownership of the particle
HepMC::GenParticle* p = new HepMC::GenParticle(
HepMC::FourVector(theFourMomentum.Px(), theFourMomentum.Py(), theFourMomentum.Pz(), theFourMomentum.E()),
thePdgId,
1); // hepmc status code for final state particle
v->add_particle_out(p);
theEvent.add_vertex(v);
theEvent.set_signal_process_vertex(v);
return StatusCode::SUCCESS;
}