MultiParticleInConeGunProducer.cc

/*
 *  \author Jean-Roch Vlimant
 */

#include <ostream>

#include "IOMC/ParticleGuns/interface/MultiParticleInConeGunProducer.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;

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

  fMinPt = pgun_params.getParameter<double>("MinPt");
  fMaxPt = pgun_params.getParameter<double>("MaxPt");

  fInConeIds = pgun_params.getParameter<vector<int> >("InConeID");
  fMinDeltaR = pgun_params.getParameter<double>("MinDeltaR");
  fMaxDeltaR = pgun_params.getParameter<double>("MaxDeltaR");
  fMinMomRatio = pgun_params.getParameter<double>("MinMomRatio");
  fMaxMomRatio = pgun_params.getParameter<double>("MaxMomRatio");

  fInConeMinEta = pgun_params.getParameter<double>("InConeMinEta");
  fInConeMaxEta = pgun_params.getParameter<double>("InConeMaxEta");
  fInConeMinPhi = pgun_params.getParameter<double>("InConeMinPhi");
  fInConeMaxPhi = pgun_params.getParameter<double>("InConeMaxPhi");
  fInConeMaxTry = pgun_params.getParameter<unsigned int>("InConeMaxTry");

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

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

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

  if (fVerbosity > 0) {
    cout << " MultiParticleInConeGunProducer : Begin New Event Generation" << 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 pt = CLHEP::RandFlat::shoot(engine, fMinPt, fMaxPt);
    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 = 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);

    if (fAddAntiParticle) {
    }

    // now add the particles in the cone
    for (unsigned iPic = 0; iPic != fInConeIds.size(); iPic++) {
      unsigned int nTry = 0;
      while (true) {
        //shoot flat Deltar
        double dR = CLHEP::RandFlat::shoot(engine, fMinDeltaR, fMaxDeltaR);
        //shoot flat eta/phi mixing
        double alpha = CLHEP::RandFlat::shoot(engine, -3.14159265358979323846, 3.14159265358979323846);
        double dEta = dR * cos(alpha);
        double dPhi = dR * sin(alpha);

        /*
	   //shoot Energy of associated particle	 
	   double energyIc = CLHEP::RandFlat::shoot(engine, fMinEInCone, fMaxEInCone);
	   if (mom2Ic>0){ momIC = sqrt(mom2Ic);}
	   */
        //	 get kinematics
        double etaIc = eta + dEta;
        double phiIc = phi + dPhi;
        //put it back in -Pi:Pi if necessary. multiple time might be necessary if dR > 3
        const unsigned int maxL = 100;
        unsigned int iL = 0;
        while (iL++ < maxL) {
          if (phiIc > 3.14159265358979323846)
            phiIc -= 2 * 3.14159265358979323846;
          else if (phiIc < -3.14159265358979323846)
            phiIc += 2 * 3.14159265358979323846;

          if (abs(phiIc) < 3.14159265358979323846)
            break;
        }

        //allow to skip it if you did not run out of possible drawing
        if (nTry++ <= fInConeMaxTry) {
          //draw another one if this one is not in acceptance
          if (etaIc < fInConeMinEta || etaIc > fInConeMaxEta)
            continue;
          if (phiIc < fInConeMinPhi || phiIc > fInConeMaxPhi)
            continue;
        } else {
          if (fVerbosity > 0) {
            cout << " MultiParticleInConeGunProducer : could not produce a particle " << fInConeIds[iPic] << " in cone "
                 << fMinDeltaR << " to " << fMaxDeltaR << " within the " << fInConeMaxTry << " allowed tries." << endl;
          }
          /*	     edm::LogError("MultiParticleInConeGunProducer")<< " MultiParticleInConeGunProducer : could not produce a particle "<<
	       fInConeIds[iPic]<<" in cone "<<
	       fMinDeltaR<<" to "<<fMaxDeltaR<<" within the "<<fInConeMaxTry<<" allowed tries.";*/
        }
        int PartIDIc = fInConeIds[iPic];
        const HepPDT::ParticleData* PDataIc = fPDGTable->particle(HepPDT::ParticleID(abs(PartIDIc)));

        //shoot momentum ratio
        double momR = CLHEP::RandFlat::shoot(engine, fMinMomRatio, fMaxMomRatio);
        double massIc = PDataIc->mass().value();
        double momIc = momR * mom;
        double energyIc = sqrt(momIc * momIc + massIc * massIc);

        double thetaIc = 2. * atan(exp(-etaIc));
        double pxIc = momIc * sin(thetaIc) * cos(phiIc);
        double pyIc = momIc * sin(thetaIc) * sin(phiIc);
        double pzIc = momIc * cos(thetaIc);

        HepMC::FourVector pIc(pxIc, pyIc, pzIc, energyIc);
        HepMC::GenParticle* PartIc = new HepMC::GenParticle(pIc, PartIDIc, 1);
        PartIc->suggest_barcode(barcode);
        barcode++;
        Vtx->add_particle_out(PartIc);
        break;
      }  //try many times while not in acceptance
    }  //loop over the particle Ids in the cone
  }

  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) {
    cout << " MultiParticleInConeGunProducer : Event Generation Done " << endl;
  }
}