FlatRandomMultiParticlePGunProducer.cc

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#include <ostream>

#include "IOMC/ParticleGuns/interface/FlatRandomMultiParticlePGunProducer.h"

#include "SimDataFormats/GeneratorProducts/interface/HepMCProduct.h"
#include "SimDataFormats/GeneratorProducts/interface/GenEventInfoProduct.h"

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/ServiceRegistry/interface/Service.h"
#include "FWCore/Utilities/interface/RandomNumberGenerator.h"
#include "FWCore/Utilities/interface/EDMException.h"
#include "CLHEP/Random/RandFlat.h"

//#define DebugLog
using namespace edm;

FlatRandomMultiParticlePGunProducer::FlatRandomMultiParticlePGunProducer(const ParameterSet& pset) : BaseFlatGunProducer(pset) {

  ParameterSet pgunParams = pset.getParameter<ParameterSet>("PGunParameters");
  fProbParticle_ = pgunParams.getParameter<std::vector<double> >("ProbParts");
  fMinP_         = pgunParams.getParameter<double>("MinP");
  fMaxP_         = pgunParams.getParameter<double>("MaxP"); 
  if (fProbParticle_.size() != fPartIDs.size()) throw cms::Exception("Configuration") << "Not all probabilities given for all particle types " << fProbParticle_.size() << ":" << fPartIDs.size() << " need them to match\n";

  produces<HepMCProduct>("unsmeared");
  produces<GenEventInfoProduct>();
#ifdef DebugLog
  std::cout << "Internal FlatRandomPGun is initialzed for " << fPartIDs.size()
        << " particles in momentum range " << fMinP_ << ":" << fMaxP_
        << std::endl ;
  for (unsigned int k=0; k<fPartIDs.size(); ++k)
    std::cout << " [" << k << "] " << fPartIDs[k] << ":" << fProbParticle_[k];
  std::cout << std::endl;
#endif
  for (unsigned int k=1; k<fProbParticle_.size(); ++k)
    fProbParticle_[k] += fProbParticle_[k-1];
  for (unsigned int k=0; k<fProbParticle_.size(); ++k)
    fProbParticle_[k] /= fProbParticle_[fProbParticle_.size()-1];
#ifdef DebugLog
  std::cout << "Corrected probabilities:";
  for (unsigned int k=0; k<fProbParticle_.size(); ++k)
    std::cout << "  " << fProbParticle_[k];
  std::cout << std::endl;
#endif
}

FlatRandomMultiParticlePGunProducer::~FlatRandomMultiParticlePGunProducer() {}

void FlatRandomMultiParticlePGunProducer::produce(edm::Event & e, 
                          const edm::EventSetup& es) {

  edm::Service<edm::RandomNumberGenerator> rng;
  CLHEP::HepRandomEngine* engine = &rng->getEngine(e.streamID());

#ifdef DebugLog
  if (fVerbosity > 0)
    std::cout << "FlatRandomMultiParticlePGunProducer: Begin New Event Generation" << std::endl ; 
#endif
   
  // event loop (well, another step in it...)
  // no need to clean up GenEvent memory - done in HepMCProduct
  // here re-create fEvt (memory)
  //
  fEvt = new HepMC::GenEvent() ;
   
  // now actualy, cook up the event from PDGTable and gun parameters
  //

  // 1st, primary vertex
  //
  HepMC::GenVertex* Vtx = new HepMC::GenVertex( HepMC::FourVector(0.,0.,0.));
  
  // loop over particles
  //
  int    barcode(0), PartID(fPartIDs[0]);
  double r1      = CLHEP::RandFlat::shoot(engine, 0., 1.);
  for (unsigned int ip=0; ip<fPartIDs.size(); ip++) {
    if (r1 <= fProbParticle_[ip]) {
      PartID = fPartIDs[ip];
      break;
    }
  }
#ifdef DebugLog
  if (fVerbosity > 0) std::cout << "Random " << r1 << " PartID " << PartID
                << std::endl;
#endif
  double mom    = CLHEP::RandFlat::shoot(engine, fMinP_,  fMaxP_);
  double eta    = CLHEP::RandFlat::shoot(engine, fMinEta, fMaxEta);
  double phi    = CLHEP::RandFlat::shoot(engine, fMinPhi, fMaxPhi);
  const HepPDT::ParticleData* 
    PData = fPDGTable->particle(HepPDT::ParticleID(abs(PartID))) ;
  double mass   = PData->mass().value() ;
  double energy = sqrt(mom*mom + mass*mass);
  double theta  = 2.*atan(exp(-eta));
  double px     = mom*sin(theta)*cos(phi);
  double py     = mom*sin(theta)*sin(phi);
  double pz     = mom*cos(theta);

  HepMC::FourVector p(px,py,pz,energy) ;
  HepMC::GenParticle* Part = new HepMC::GenParticle(p,PartID,1);
  barcode++ ;
  Part->suggest_barcode(barcode);
  Vtx->add_particle_out(Part);

  if (fAddAntiParticle) {
    HepMC::FourVector ap(-px,-py,-pz,energy) ;
    int APartID = (PartID == 22 || PartID == 23) ? PartID : -PartID;
    HepMC::GenParticle* APart = new HepMC::GenParticle(ap,APartID,1);
    barcode++ ;
    APart->suggest_barcode(barcode);
    Vtx->add_particle_out(APart);
  }

  fEvt->add_vertex(Vtx) ;
  fEvt->set_event_number(e.id().event()) ;
  fEvt->set_signal_process_id(20) ;  
   
#ifdef DebugLog 
  if (fVerbosity > 0) fEvt->print() ;  
#endif

  std::unique_ptr<HepMCProduct> BProduct(new HepMCProduct()) ;
  BProduct->addHepMCData( fEvt );
  e.put(std::move(BProduct), "unsmeared");

  std::unique_ptr<GenEventInfoProduct> genEventInfo(new GenEventInfoProduct(fEvt));
  e.put(std::move(genEventInfo));
#ifdef DebugLog    
   if (fVerbosity > 0) 
     std::cout << " FlatRandomMultiParticlePGunProducer : Event Generation Done " << std::endl;
#endif
}