FlatRandomOneOverPtGunProducer.cc

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#include <ostream>

#include "IOMC/ParticleGuns/interface/FlatRandomOneOverPtGunProducer.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/MessageLogger/interface/MessageLogger.h"
#include "FWCore/ServiceRegistry/interface/Service.h"
#include "FWCore/Utilities/interface/RandomNumberGenerator.h"

#include <CLHEP/Random/RandFlat.h>
#include <CLHEP/Units/SystemOfUnits.h>
using namespace edm;

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

  fMinOneOverPt = pgun_params.getParameter<double>("MinOneOverPt");
  fMaxOneOverPt = pgun_params.getParameter<double>("MaxOneOverPt");

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

  edm::LogInfo("ParticleGun") << "FlatRandomOneOverPtGunProducer: initialized with minimum and maximum 1/pt "
                              << fMinOneOverPt << ":" << fMaxOneOverPt;
}

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

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

  LogDebug("ParticleGun") << " FlatRandomOneOverPtGunProducer : Begin New Event Generation";

  // 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 = 1;
  for (unsigned int ip = 0; ip < fPartIDs.size(); ++ip) {
    double xx = CLHEP::RandFlat::shoot(engine, 0.0, 1.0);
    double pt = std::exp((1. - xx) * std::log(fMinOneOverPt) + xx * std::log(fMaxOneOverPt));
    double eta = CLHEP::RandFlat::shoot(engine, fMinEta, fMaxEta);
    double phi = CLHEP::RandFlat::shoot(engine, fMinPhi, fMaxPhi);
    if (pt != 0)
      pt = 1. / pt;
    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 = pt / 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);
    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);
    LogDebug("ParticleGun") << "FlatRandomOneOverPtGunProducer: Event generated with pt:eta:phi " << pt << " " << eta
                            << " " << phi << " (" << theta / CLHEP::deg << ":" << phi / CLHEP::deg << ")";

    if (fAddAntiParticle) {
      HepMC::FourVector ap(-px, -py, -pz, energy);
      int APartID = -PartID;
      if (PartID == 22 || PartID == 23) {
        APartID = PartID;
      }
      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();
  }

  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));

  LogDebug("ParticleGun") << " FlatRandomOneOverPtGunProducer : Event Generation Done ";
}