ExpoRandomPGunProducer.cc

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/*
 *  \author Jean-Roch Vlimant
 *  modified by S.Abdullin 04/02/2011 
 */

#include <ostream>

#include "IOMC/ParticleGuns/interface/ExpoRandomPGunProducer.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 "CLHEP/Random/RandFlat.h"

using namespace edm;
using namespace std;

ExpoRandomPGunProducer::ExpoRandomPGunProducer(const ParameterSet& pset) : BaseFlatGunProducer(pset) {
  ParameterSet defpset;
  ParameterSet pgun_params = pset.getParameter<ParameterSet>("PGunParameters");

  fMinP = pgun_params.getParameter<double>("MinP");
  fMaxP = pgun_params.getParameter<double>("MaxP");

  produces<HepMCProduct>("unsmeared");
  produces<GenEventInfoProduct>();
}

ExpoRandomPGunProducer::~ExpoRandomPGunProducer() {
  // no need to cleanup GenEvent memory - done in HepMCProduct
}

void ExpoRandomPGunProducer::produce(Event& e, const EventSetup& es) {
  edm::Service<edm::RandomNumberGenerator> rng;
  CLHEP::HepRandomEngine* engine = &rng->getEngine(e.streamID());

  if (fVerbosity > 0) {
    std::cout << " ExpoRandomPGunProducer : Begin New Event Generation" << std::endl;
  }
  // 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(CLHEP::HepLorentzVector(0.,0.,0.));
  HepMC::GenVertex* Vtx = new HepMC::GenVertex(HepMC::FourVector(0., 0., 0.));

  // loop over particles
  //
  int barcode = 1;
  for (unsigned int ip = 0; ip < fPartIDs.size(); ++ip) {
    double pmom = CLHEP::RandFlat::shoot(engine, fMinP, fMaxP);
    double y = (1. / fMinP) * CLHEP::RandFlat::shoot(engine, 0.0, 1.0);
    double f = 1. / pmom;
    bool accpt = (y < f);
    //shoot until in the designated range
    while ((pmom < fMinP || pmom > fMaxP) || !accpt) {
      pmom = CLHEP::RandFlat::shoot(engine, fMinP, fMaxP);
      y = (1. / fMinP) * CLHEP::RandFlat::shoot(engine, 0.0, 1.0);
      f = 1. / pmom;
      accpt = (y < f);
    }

    double eta = CLHEP::RandFlat::shoot(engine, fMinEta, fMaxEta);
    double phi = CLHEP::RandFlat::shoot(engine, fMinPhi, fMaxPhi);
    int PartID = fPartIDs[ip];
    const HepPDT::ParticleData* PData = fPDGTable->particle(HepPDT::ParticleID(abs(PartID)));
    double mass = PData->mass().value();
    double theta = 2. * atan(exp(-eta));
    double mom = pmom;
    double pt = mom * sin(theta);
    double px = pt * cos(phi);
    double py = pt * sin(phi);
    double pz = mom * cos(theta);
    double energy2 = mom * mom + mass * mass;
    double energy = sqrt(energy2);
    //CLHEP::Hep3Vector p(px,py,pz) ;
    //HepMC::GenParticle* Part =
    //    new HepMC::GenParticle(CLHEP::HepLorentzVector(p,energy),PartID,1);
    HepMC::FourVector p(px, py, pz, energy);
    HepMC::GenParticle* Part = new HepMC::GenParticle(p, PartID, 1);
    Part->suggest_barcode(barcode);
    barcode++;
    Vtx->add_particle_out(Part);

    if (fAddAntiParticle) {
      //CLHEP::Hep3Vector ap(-px,-py,-pz) ;
      HepMC::FourVector ap(-px, -py, -pz, energy);
      int APartID = -PartID;
      if (PartID == 22 || PartID == 23) {
        APartID = PartID;
      }
      //HepMC::GenParticle* APart =
      //   new HepMC::GenParticle(CLHEP::HepLorentzVector(ap,energy),APartID,1);
      HepMC::GenParticle* APart = new HepMC::GenParticle(ap, APartID, 1);
      APart->suggest_barcode(barcode);
      barcode++;
      Vtx->add_particle_out(APart);
    }
  }

  fEvt->add_vertex(Vtx);
  fEvt->set_event_number(e.id().event());
  fEvt->set_signal_process_id(20);

  if (fVerbosity > 0) {
    fEvt->print();
  }

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

  unique_ptr<GenEventInfoProduct> genEventInfo(new GenEventInfoProduct(fEvt));
  e.put(std::move(genEventInfo));

  if (fVerbosity > 0) {
    // for testing purpose only
    // fEvt->print() ; // prints empty info after it's made into edm::Event
    std::cout << " FlatRandomPGunProducer : Event Generation Done " << std::endl;
  }
}