Manages GenParticles and Secondaries from interactions. More...

#include <ParticleManager.h>

Public Member Functions
unsigned	addEndVertex (const Particle *particle)
	Necessary to add an end vertex to a particle. More...

void	addSecondaries (const math::XYZTLorentzVector &vertexPosition, int motherSimTrackId, std::vector< std::unique_ptr< Particle > > &secondaries, const SimplifiedGeometry *layer=nullptr)
	Adds secondaries that are produced by any of the interactions (or particle decay) to the buffer. More...

const SimVertex	getSimVertex (unsigned i)
	Returns the position of a given SimVertex. Needed for interfacing the code with the old calorimetry. More...

std::unique_ptr< Particle >	nextParticle (const RandomEngineAndDistribution &random)
	Returns the next particle that has to be propagated (secondary or genParticle). More...

	ParticleManager (const HepMC::GenEvent &genEvent, const HepPDT::ParticleDataTable &particleDataTable, double beamPipeRadius, double deltaRchargedMother, const ParticleFilter &particleFilter, std::vector< SimTrack > &simTracks, std::vector< SimVertex > &simVertices)
	Constructor. More...

	~ParticleManager ()
	Default destructor. More...

Private Member Functions
unsigned	addSimTrack (const Particle *particle)
	Add a simTrack (simTrack contains some basic info about the particle, e.g. pdgId). More...

unsigned	addSimVertex (const math::XYZTLorentzVector &position, int motherIndex)
	Add a simVertex (simVertex contains information about the track it was produced). More...

std::unique_ptr< Particle >	nextGenParticle ()
	Returns next particle from the GenEvent that has to be propagated. More...

Private Attributes
const double	beamPipeRadius2_
	(Radius of the beampipe)^2 More...

const double	deltaRchargedMother_
	For FastSim (cheat) tracking: cut on the angle between a charged mother and charged daughter. More...

const HepMC::GenEvent *const	genEvent_
	The GenEvent. More...

const HepMC::GenEvent::particle_const_iterator	genParticleEnd_
	The last particle of the GenEvent. More...

int	genParticleIndex_
	Index of particle in the GenEvent (if it is a GenParticle) More...

HepMC::GenEvent::particle_const_iterator	genParticleIterator_
	Iterator to keep track on which GenParticles where already considered. More...

double	lengthUnitConversionFactor2_
	Convert pythia unis to cm^2 (FastSim standard) More...

double	lengthUnitConversionFactor_
	Convert pythia unis to cm (FastSim standard) More...

double	momentumUnitConversionFactor_
	Convert pythia units to GeV (FastSim standard) More...

std::vector< std::unique_ptr< Particle > >	particleBuffer_
	The vector of all secondaries that are not yet propagated in the event. More...

const HepPDT::ParticleDataTable *const	particleDataTable_
	Necessary to get information like lifetime and charge of a particle if unknown. More...

const ParticleFilter *const	particleFilter_
	(Kinematic) cuts on the particles that have to be propagated. More...

std::vector< SimTrack > *	simTracks_
	The generated SimTrack of this event. More...

std::vector< SimVertex > *	simVertices_
	The generated SimVertices of this event. More...

double	timeUnitConversionFactor_
	Convert pythia unis to ns (FastSim standard) More...

Detailed Description

Manages GenParticles and Secondaries from interactions.

Manages which particle has to be propagated next, this includes GenParticles and secondaries from the interactions. Furthermore, checks if all necessary information is included with the GenParticles (charge, lifetime), otherwise reads information from HepPDT::ParticleDataTable. Also handles secondaries, including closestChargedDaughter algorithm which is used for FastSim (cheat) tracking: a charged daughter can continue the track of a charged mother, see addSecondaries(...).

Definition at line 39 of file ParticleManager.h.

Constructor & Destructor Documentation

fastsim::ParticleManager::ParticleManager	(	const HepMC::GenEvent &	genEvent,
		const HepPDT::ParticleDataTable &	particleDataTable,
		double	beamPipeRadius,
		double	deltaRchargedMother,
		const ParticleFilter &	particleFilter,
		std::vector< SimTrack > &	simTracks,
		std::vector< SimVertex > &	simVertices
	)

Constructor.

Parameters

genEvent	Get the GenEvent.
particleDataTable	Get information about particles, e.g. charge, lifetime.
beamPipeRadius	Radius of the beampipe.
deltaRchargedMother	For FastSim (cheat) tracking: cut on the angle between a charged mother and charged daughter.
particleFilter	Selects which particles have to be propagated.
simTracks	The SimTracks.
simVertices	The SimVertices.

Definition at line 17 of file ParticleManager.cc.

References addSimVertex(), genEvent_, lengthUnitConversionFactor_, position, and timeUnitConversionFactor_.

     : genEvent_(&genEvent)
     , genParticleIterator_(genEvent_->particles_begin())
     , genParticleEnd_(genEvent_->particles_end())
     , genParticleIndex_(1)
     , particleDataTable_(&particleDataTable)
     , beamPipeRadius2_(beamPipeRadius*beamPipeRadius)
     , deltaRchargedMother_(deltaRchargedMother)
     , particleFilter_(&particleFilter)
     , simTracks_(&simTracks)
     , simVertices_(&simVertices)
     // prepare unit convsersions
     //  --------------------------------------------
     // |          |      hepmc               |  cms |
     //  --------------------------------------------
     // | length   | genEvent_->length_unit   |  cm  |
     // | momentum | genEvent_->momentum_unit |  GeV |
     // | time     | length unit (t*c)        |  ns  |
     //  --------------------------------------------
     , momentumUnitConversionFactor_(conversion_factor( genEvent_->momentum_unit(), HepMC::Units::GEV ))
     , lengthUnitConversionFactor_(conversion_factor(genEvent_->length_unit(),HepMC::Units::LengthUnit::CM))
     , lengthUnitConversionFactor2_(lengthUnitConversionFactor_*lengthUnitConversionFactor_)
     , timeUnitConversionFactor_(lengthUnitConversionFactor_/fastsim::Constants::speedOfLight)
 
 {
 
     // add the main vertex from the signal event to the simvertex collection
     if(genEvent.vertices_begin() != genEvent_->vertices_end())
     {
         const HepMC::FourVector & position = (*genEvent.vertices_begin())->position();
         addSimVertex(math::XYZTLorentzVector(position.x()*lengthUnitConversionFactor_,
                              position.y()*lengthUnitConversionFactor_,
                              position.z()*lengthUnitConversionFactor_,
                              position.t()*timeUnitConversionFactor_)
                     ,-1);
     }
 }

fastsim::ParticleManager::~ParticleManager ( )

Default destructor.

Definition at line 62 of file ParticleManager.cc.

62 {}

Member Function Documentation

unsigned fastsim::ParticleManager::addEndVertex ( const Particle * particle )

Necessary to add an end vertex to a particle.

Needed if particle is no longer propagated for some reason (e.g. remaining energy below threshold) and no secondaries where produced at that point.

Returns: Index of that vertex.

Definition at line 196 of file ParticleManager.cc.

References addSimVertex(), fastsim::Particle::position(), and fastsim::Particle::simTrackIndex().

 {
     return this->addSimVertex(particle->position(), particle->simTrackIndex());
 }

void fastsim::ParticleManager::addSecondaries	(	const math::XYZTLorentzVector &	vertexPosition,
		int	motherSimTrackId,
		std::vector< std::unique_ptr< Particle > > &	secondaries,
		const SimplifiedGeometry *	layer = `nullptr`
	)

Adds secondaries that are produced by any of the interactions (or particle decay) to the buffer.

Also checks which charged daughter is closest to a charged mother (in deltaR) and assigns the same SimTrack ID.

Parameters

vertexPosition	The origin vertex (interaction or particle decay took place here).
motherSimTrackId	SimTrack ID of the mother particle, necessary for FastSim (cheat) tracking.
secondaries	All secondaries that where produced in a single particle decay or interaction.

Definition at line 129 of file ParticleManager.cc.

References fastsim::ParticleFilter::acceptsVtx(), addSimVertex(), deltaRchargedMother_, training_settings::idx, fastsim::SimplifiedGeometry::index(), fastsim::SimplifiedGeometry::isForward(), eostools::move(), particleBuffer_, and particleFilter_.

Referenced by FastSimProducer::createFSimTrack().

 {
 
     // vertex must be within the accepted volume
     if(!particleFilter_->acceptsVtx(vertexPosition))
     {
        return;
     }
 
     // no need to create vertex in case no particles are produced
     if(secondaries.empty()){
         return;
     }
 
     // add simVertex
     unsigned simVertexIndex = addSimVertex(vertexPosition,parentSimTrackIndex);
 
     // closest charged daughter continues the track of the mother particle
     // simplified tracking algorithm for fastSim
     double distMin = 99999.;
     int idx = -1;
     int idxMin = -1;
     for(auto & secondary : secondaries)
     {
         idx++;
         if(secondary->getMotherDeltaR() != -1){
             if(secondary->getMotherDeltaR() > deltaRchargedMother_){
                 // larger than max requirement on deltaR
                 secondary->resetMother();
             }else{
                 if(secondary->getMotherDeltaR() < distMin){
                     distMin = secondary->getMotherDeltaR();
                     idxMin = idx;
                 }
             }            
         }
     }
     
     // add secondaries to buffer
     idx = -1;
     for(auto & secondary : secondaries)
     {
         idx++;
         if(idxMin != -1){
             // reset all but the particle with the lowest deltaR (which is at idxMin)
             if(secondary->getMotherDeltaR() != -1 && idx != idxMin){
                 secondary->resetMother();
             }
         }
 
         // set origin vertex
         secondary->setSimVertexIndex(simVertexIndex);
         //
         if(layer)
         {
             secondary->setOnLayer(layer->isForward(), layer->index());
         }
         // ...and add particle to buffer
         particleBuffer_.push_back(std::move(secondary));
     }
 
 }

unsigned fastsim::ParticleManager::addSimTrack ( const Particle * particle )

private

Add a simTrack (simTrack contains some basic info about the particle, e.g. pdgId).

Add a simTrack for a given particle and assign an index for that track. This might also be the index of the track of the mother particle (FastSim cheat tracking).

Parameters

particle Particle that produces that simTrack.

Returns: Index of that simTrack.

Definition at line 213 of file ParticleManager.cc.

References fastsim::Particle::genParticleIndex(), fastsim::Particle::getMotherDeltaR(), fastsim::Particle::getMotherSimTrackIndex(), fastsim::Particle::momentum(), fastsim::Particle::pdgId(), simTracks_, and fastsim::Particle::simVertexIndex().

Referenced by nextParticle().

 {
     int simTrackIndex;
     // Again: FastSim cheat tracking -> continue track of mother
     if(particle->getMotherDeltaR() != -1){
         simTrackIndex = particle->getMotherSimTrackIndex();
     }
     // or create new SimTrack
     else
     {
         simTrackIndex = simTracks_->size();
         simTracks_->emplace_back(particle->pdgId(),
                     particle->momentum(),
                     particle->simVertexIndex(),
                     particle->genParticleIndex());
         simTracks_->back().setTrackId(simTrackIndex);
     }
     return simTrackIndex;
 }

unsigned fastsim::ParticleManager::addSimVertex	(	const math::XYZTLorentzVector &	position,
		int	motherIndex
	)

private

Add a simVertex (simVertex contains information about the track it was produced).

Add a origin vertex for any particle.

Parameters

position	Position of the vertex.
motherIndex	Index of the parent's simTrack.

Returns: Index of that simVertex.

Definition at line 201 of file ParticleManager.cc.

References simVertices_.

Referenced by addEndVertex(), addSecondaries(), and ParticleManager().

 {
     int simVertexIndex = simVertices_->size();
     simVertices_->emplace_back(position.Vect(),
                    position.T(),
                    parentSimTrackIndex,
                    simVertexIndex);
     return simVertexIndex;
 }

const SimVertex fastsim::ParticleManager::getSimVertex ( unsigned i )

inline

Returns the position of a given SimVertex. Needed for interfacing the code with the old calorimetry.

Definition at line 88 of file ParticleManager.h.

References objects.autophobj::motherIndex, and position.

Referenced by FastSimProducer::createFSimTrack().

88 { return simVertices_->at(i); }

mps_fire.i

i

Definition: mps_fire.py:269

fastsim::ParticleManager::simVertices_

std::vector< SimVertex > * simVertices_

The generated SimVertices of this event.

Definition: ParticleManager.h:135

std::unique_ptr< fastsim::Particle > fastsim::ParticleManager::nextGenParticle ( )

private

Returns next particle from the GenEvent that has to be propagated.

Tries to get some basic information about the status of the particle from the GenEvent and does some first rejection cuts based on them.

Definition at line 233 of file ParticleManager.cc.

References beamPipeRadius2_, GenParticle::GenParticle, genParticleEnd_, genParticleIndex_, genParticleIterator_, lengthUnitConversionFactor2_, lengthUnitConversionFactor_, momentumUnitConversionFactor_, fastsim::Constants::speedOfLight, and timeUnitConversionFactor_.

Referenced by nextParticle().

 {
     // only consider particles that start in the beam pipe and end outside the beam pipe
     // try to get the decay time from pythia
     // use hepmc units
     // make the link simtrack to simvertex
     // try not to change the simvertex structure
     
     // loop over gen particles
     for ( ; genParticleIterator_ != genParticleEnd_ ; ++genParticleIterator_,++genParticleIndex_ ) 
     {
         // some handy pointers and references
         const HepMC::GenParticle & particle = **genParticleIterator_;
         const HepMC::GenVertex * productionVertex = particle.production_vertex();
         const HepMC::GenVertex * endVertex = particle.end_vertex();
 
         // skip incoming particles
         if(!productionVertex){
             continue;
         }
 
         // particle must be produced within the beampipe
         if(productionVertex->position().perp2()*lengthUnitConversionFactor2_ > beamPipeRadius2_)
         {
             continue;
         }
         
         // particle must not decay before it reaches the beam pipe
         if(endVertex && endVertex->position().perp2()*lengthUnitConversionFactor2_ < beamPipeRadius2_)
         {
             continue;
         }
 
         // make the particle
         std::unique_ptr<Particle> newParticle(
             new Particle(particle.pdg_id(),
                  math::XYZTLorentzVector(productionVertex->position().x()*lengthUnitConversionFactor_,
                              productionVertex->position().y()*lengthUnitConversionFactor_,
                              productionVertex->position().z()*lengthUnitConversionFactor_,
                              productionVertex->position().t()*timeUnitConversionFactor_),
                  math::XYZTLorentzVector(particle.momentum().x()*momentumUnitConversionFactor_,
                              particle.momentum().y()*momentumUnitConversionFactor_,
                              particle.momentum().z()*momentumUnitConversionFactor_,
                              particle.momentum().e()*momentumUnitConversionFactor_)));
         newParticle->setGenParticleIndex(genParticleIndex_);
 
         // try to get the life time of the particle from the genEvent
         if(endVertex)
         {
             double labFrameLifeTime = (endVertex->position().t() - productionVertex->position().t())*timeUnitConversionFactor_;
             newParticle->setRemainingProperLifeTimeC(labFrameLifeTime / newParticle->gamma() * fastsim::Constants::speedOfLight);
         }
 
         // TODO: The products of a b-decay should point to that vertex and not to the primary vertex!
         // Seems like this information has to be taken from the genEvent. How to do this? Is this really neccessary?
         // See FBaseSimEvent::fill(..)
         newParticle->setSimVertexIndex(0);
 
         // iterator/index has to be increased in case of return (is not done by the loop then)
         ++genParticleIterator_; ++genParticleIndex_;
         // and return
         return newParticle;
     }
 
     return std::unique_ptr<Particle>();
 }

std::unique_ptr< fastsim::Particle > fastsim::ParticleManager::nextParticle ( const RandomEngineAndDistribution & random )

Returns the next particle that has to be propagated (secondary or genParticle).

Main method of this class. At first consideres particles from the buffer (secondaries) if there are none, then the next GenParticle is considered. Only returns particles that pass the (kinetic) cuts of the ParticleFilter. Furthermore, uses the ParticleDataTable to ensure all necessary information about the particle is stored (lifetime, charge).

Returns: The next particle that has to be propagated.

See also: ParticleFilter

Definition at line 64 of file ParticleManager.cc.

References fastsim::ParticleFilter::accepts(), addSimTrack(), MillePedeFileConverter_cfg::e, Exception, RandomEngineAndDistribution::flatShoot(), cmsBatch::log, eostools::move(), nextGenParticle(), particleBuffer_, particleDataTable_, particleFilter_, source_particleGun_cfi::ParticleID, and ApeEstimator_cff::width.

 {
     std::unique_ptr<fastsim::Particle> particle;
 
     // retrieve particle from buffer
     if(!particleBuffer_.empty())
     {
         particle = std::move(particleBuffer_.back());
         particleBuffer_.pop_back();
     }
     // or from genParticle list
     else
     {
        particle = nextGenParticle();
        if(!particle) return nullptr;
     }
 
     // if filter does not accept, skip particle
     if(!particleFilter_->accepts(*particle))
     {
         return nextParticle(random);
     }
 
     // lifetime or charge of particle are not yet set
     if(!particle->remainingProperLifeTimeIsSet() || !particle->chargeIsSet())
     {
         // retrieve the particle data
         const HepPDT::ParticleData * particleData = particleDataTable_->particle(HepPDT::ParticleID(particle->pdgId()));
         if(!particleData)
         {
             throw cms::Exception("fastsim::ParticleManager") << "unknown pdg id: " << particle->pdgId() << std::endl;
         }
 
         // set lifetime
         if(!particle->remainingProperLifeTimeIsSet())
         {
             // The lifetime is 0. in the Pythia Particle Data Table! Calculate from width instead (ct=hbar/width).
             // ct=particleData->lifetime().value();
             double width = particleData->totalWidth().value();
             if(width > 1.0e-35)
             {
                 particle->setRemainingProperLifeTimeC(-log(random.flatShoot())*6.582119e-25/width/10.); // ct in cm
             }
             else
             {
                 particle->setStable();
             }
         }
 
         // set charge
         if(!particle->chargeIsSet())
         {
             particle->setCharge(particleData->charge());
         }
     }
 
     // add corresponding simTrack to simTrack collection
     unsigned simTrackIndex = addSimTrack(particle.get());
     particle->setSimTrackIndex(simTrackIndex);
 
     // and return
     return particle;
 }