Generates a Geant4 event from particle gun, but can have many particles. More...

#include <MultiParticleGunPrimaryGenerator.h>

Public Member Functions
	MultiParticleGunPrimaryGenerator (const std::string &name, const framework::config::Parameters &parameters)
	Constructor.

virtual	~MultiParticleGunPrimaryGenerator ()
	Destructor.

void	GeneratePrimaryVertex (G4Event *anEvent) override
	Generate vertices in the Geant4 event.

void	RecordConfig (const std::string &id, ldmx::RunHeader &rh) override
	Record the configuration of the primary generator into the run header.

Public Member Functions inherited from simcore::PrimaryGenerator
	PrimaryGenerator (const std::string &name, const framework::config::Parameters &parameters)
	Constructor.

	DECLARE_FACTORY_WITH_WAREHOUSE (PrimaryGenerator, std::shared_ptr< PrimaryGenerator >, const std::string &, const framework::config::Parameters &)

virtual	~PrimaryGenerator ()=default
	Destructor.

std::string	name ()

Private Attributes
TRandom *	random_
	Random number generator.

G4ThreeVector	mpg_vertex_
	The vertex position from which to fire the particles.

G4ThreeVector	mpg_momentum_
	The initial momentum of the particles.

double	mpg_n_particles_ {1.}
	Number of particles that will be fired by the gun per event.

int	mpg_pdg_id_ {99999}
	PDG ID of the particle used by the gun.

bool	mpg_enable_poisson_ {false}
	Flag denoting whether the number of incident particles should be Poisson distributed.

Additional Inherited Members
Protected Attributes inherited from simcore::PrimaryGenerator
std::string	name_ {""}
	Name of the PrimaryGenerator.

Detailed Description

Generates a Geant4 event from particle gun, but can have many particles.

Definition at line 52 of file MultiParticleGunPrimaryGenerator.h.

Constructor & Destructor Documentation

◆ MultiParticleGunPrimaryGenerator()

simcore::generators::MultiParticleGunPrimaryGenerator::MultiParticleGunPrimaryGenerator	(	const std::string &	name,
		const framework::config::Parameters &	parameters )

Constructor.

Parameters

name	the name of this generator
parameters	the configuration parameters

Parameters: vertex : Position to shoot from (mm) momentum : 3-vector mometum of particles (MeV) nParticles : number of particles to shoot (mean if Poisson enabled) pdgID : pdgID of particle to shoot enablePoisson : whether to poisson distribute the number of particles

Definition at line 13 of file MultiParticleGunPrimaryGenerator.cxx.

    : PrimaryGenerator(name, parameters), random_(new TRandom) {
  auto stl_vertex{parameters.get<std::vector<double> >("vertex")};
  auto stl_momentum{parameters.get<std::vector<double> >("momentum")};
  mpg_n_particles_ = parameters.get<int>("nParticles");
  mpg_pdg_id_ = parameters.get<int>("pdgID");
  mpg_enable_poisson_ = parameters.get<bool>("enablePoisson");
 
  if (stl_vertex.size() != 3 or stl_momentum.size() != 3 or
      mpg_n_particles_ <= 0) {
    EXCEPTION_RAISE("InvalideConfig",
                    "Parameters pass to '" + name_ + "' are not valid.");
  }
 
  mpg_vertex_ = G4ThreeVector(stl_vertex.at(0) * mm, stl_vertex.at(1) * mm,
                              stl_vertex.at(2) * mm);
  mpg_momentum_ =
      G4ThreeVector(stl_momentum.at(0) * MeV, stl_momentum.at(1) * MeV,
                    stl_momentum.at(2) * MeV);
}

References framework::config::Parameters::get(), mpg_enable_poisson_, mpg_momentum_, mpg_n_particles_, mpg_pdg_id_, and mpg_vertex_.

◆ ~MultiParticleGunPrimaryGenerator()

simcore::generators::MultiParticleGunPrimaryGenerator::~MultiParticleGunPrimaryGenerator ( )

virtual

Destructor.

Definition at line 35 of file MultiParticleGunPrimaryGenerator.cxx.

                                                                    {
  delete random_;
}

References random_.

Member Function Documentation

◆ GeneratePrimaryVertex()

void simcore::generators::MultiParticleGunPrimaryGenerator::GeneratePrimaryVertex ( G4Event * anEvent )

overridevirtual

Generate vertices in the Geant4 event.

Parameters

anEvent The Geant4 event.

Implements simcore::PrimaryGenerator.

Definition at line 39 of file MultiParticleGunPrimaryGenerator.cxx.

                                                                             {
  int cur_mpg_pdgid = mpg_pdg_id_;
  G4ThreeVector cur_mpg_vertex = mpg_vertex_;
  G4ThreeVector cur_mpg_momentum = mpg_momentum_;
 
  // current number of vertices in the event!
  int cur_n_vertices = anEvent->GetNumberOfPrimaryVertex();
 
  double n_interactions_input = mpg_n_particles_;
  int n_interactions = n_interactions_input;
  if (mpg_enable_poisson_) {
    n_interactions = 0;
    while (n_interactions == 0) {  // keep generating a random poisson until >
                                   // 0, no point in generator 0 vertices...
      n_interactions = random_->Poisson(n_interactions_input);
    }
  }
 
  // make a for loop
  for (int i = 0; i < (n_interactions - cur_n_vertices); ++i) {
    G4PrimaryVertex* curvertex =
        new G4PrimaryVertex(cur_mpg_vertex, 0.);  // second input is t0
    // curvertex->SetPosition(0. * mm,0. * mm,-10. * mm);
    curvertex->SetWeight(1.);
 
    G4PrimaryParticle* primary =
        new G4PrimaryParticle(cur_mpg_pdgid, cur_mpg_momentum.x(),
                              cur_mpg_momentum.y(), cur_mpg_momentum.z());
 
    UserPrimaryParticleInformation* primary_info =
        new UserPrimaryParticleInformation();
    primary_info->setHepEvtStatus(1.);
    primary->SetUserInformation(primary_info);
 
    curvertex->SetPrimary(primary);
    anEvent->AddPrimaryVertex(curvertex);
  }
}

References mpg_enable_poisson_, mpg_momentum_, mpg_n_particles_, mpg_pdg_id_, mpg_vertex_, random_, and simcore::UserPrimaryParticleInformation::setHepEvtStatus().

◆ RecordConfig()

void simcore::generators::MultiParticleGunPrimaryGenerator::RecordConfig	(	const std::string &	id,
		ldmx::RunHeader &	rh )

overridevirtual

Record the configuration of the primary generator into the run header.

Note: you must include the id number in each entry into the run header just in case there are other generators

Implements simcore::PrimaryGenerator.

Definition at line 78 of file MultiParticleGunPrimaryGenerator.cxx.

                                                                       {
  rh.setStringParameter(
      id + " Class", "simcore::generators::MultiParticleGunPrimaryGenerator");
  rh.setIntParameter(id + " Poisson Enabled", mpg_enable_poisson_);
  rh.setFloatParameter(id + " N Particles", mpg_n_particles_);
  rh.setIntParameter(id + " PDG ID", mpg_pdg_id_);
  rh.setFloatParameter(id + " Vertex X [mm]", mpg_vertex_.x());
  rh.setFloatParameter(id + " Vertex Y [mm]", mpg_vertex_.y());
  rh.setFloatParameter(id + " Vertex Z [mm]", mpg_vertex_.z());
  rh.setFloatParameter(id + " Momentum X [MeV]", mpg_momentum_.x());
  rh.setFloatParameter(id + " Momentum Y [MeV]", mpg_momentum_.y());
  rh.setFloatParameter(id + " Momentum Z [MeV]", mpg_momentum_.z());
}