NucleonDecay_module.cc

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// Class:       NucleonDecay
// Module Type: producer
// GENIE nucleon decay generator
//
// Converted from gNucleonDecayEvGen.cxx by
// tjyang@fnal.gov
//
// 2016 PDG numbering scheme in pp.8-10 of
// http://www-pdg.lbl.gov/2016/listings/rpp2016-list-p.pdf (tau1 through tau60)
//

#include "art/Framework/Core/EDProducer.h"
#include "art/Framework/Core/ModuleMacros.h"
#include "art/Framework/Principal/Event.h"
#include "art/Framework/Principal/Run.h"
#include "art/Framework/Services/Registry/ServiceHandle.h"
#include "fhiclcpp/ParameterSet.h"
#include "messagefacility/MessageLogger/MessageLogger.h"

// GENIE includes
#include "Framework/Algorithm/AlgFactory.h"
#include "Framework/EventGen/EventRecord.h"
#include "Framework/EventGen/EventRecordVisitorI.h"
#include "Framework/GHEP/GHepParticle.h"
#include "Framework/ParticleData/PDGLibrary.h"
#include "Framework/Utils/AppInit.h"
#include "Physics/NucleonDecay/NucleonDecayMode.h"
#include "Physics/NucleonDecay/NucleonDecayUtils.h"

// larsoft includes
#include "nusimdata/SimulationBase/MCParticle.h"
#include "nusimdata/SimulationBase/MCTruth.h"

#include "nugen/EventGeneratorBase/GENIE/GENIE2ART.h"

#include "larcore/Geometry/Geometry.h"
#include "larcoreobj/SummaryData/RunData.h"
#include "nurandom/RandomUtils/NuRandomService.h"

// c++ includes
#include <memory>
#include <string>

#include "CLHEP/Random/RandFlat.h"

namespace evgen {
  class NucleonDecay;
}

class evgen::NucleonDecay : public art::EDProducer {
public:
  explicit NucleonDecay(fhicl::ParameterSet const& p);
  // The destructor generated by the compiler is fine for classes
  // without bare pointers or other resource use.

  // Plugins should not be copied or assigned.
  NucleonDecay(NucleonDecay const&) = delete;
  NucleonDecay(NucleonDecay&&) = delete;
  NucleonDecay& operator=(NucleonDecay const&) = delete;
  NucleonDecay& operator=(NucleonDecay&&) = delete;

  // Required functions.
  void produce(art::Event& e) override;

  // Selected optional functions.
  void beginRun(art::Run& run) override;

private:
  // Declare member data here.
  const genie::EventRecordVisitorI* mcgen;
  genie::NucleonDecayMode_t gOptDecayMode = genie::kNDNull; // nucleon decay mode
  int dpdg = 0;
  CLHEP::RandFlat flatDist;
};

evgen::NucleonDecay::NucleonDecay(fhicl::ParameterSet const& p)
  : art::EDProducer{p}
  // create a default random engine; obtain the random seed from NuRandomService,
  // unless overridden in configuration with key "Seed"
  , flatDist{art::ServiceHandle<rndm::NuRandomService>{}
             -> registerAndSeedEngine(createEngine(0), p, "Seed")}
{
  string sname = "genie::EventGenerator";
  string sconfig = "NucleonDecay";
  // GENIE v3 needs a tune (even if irrelevant)
  evgb::SetEventGeneratorListAndTune("Default", "Default");

  genie::PDGLibrary::Instance(); //Ensure Messenger is started first in GENIE.

  genie::AlgFactory* algf = genie::AlgFactory::Instance();
  mcgen = dynamic_cast<const genie::EventRecordVisitorI*>(algf->GetAlgorithm(sname, sconfig));
  if (!mcgen) {
    throw cet::exception("NucleonDecay") << "Couldn't instantiate the nucleon decay generator";
  }
  int fDecayMode = p.get<int>("DecayMode");
  gOptDecayMode = (genie::NucleonDecayMode_t)fDecayMode;

  if (p.get<int>("DecayedNucleon") > 0) { dpdg = p.get<int>("DecayedNucleon"); }
  else {
    dpdg = genie::utils::nucleon_decay::DecayedNucleonPdgCode(gOptDecayMode);
  }

  produces<std::vector<simb::MCTruth>>();
  produces<sumdata::RunData, art::InRun>();

  unsigned int seed = art::ServiceHandle<rndm::NuRandomService>()->getSeed();
  genie::utils::app_init::RandGen(seed);
}

void evgen::NucleonDecay::produce(art::Event& e)
{
  // Implementation of required member function here.
  genie::EventRecord* event = new genie::EventRecord;
  int target = 1000180400; //Only use argon target
  int decay = (int)gOptDecayMode;
  genie::Interaction* interaction = genie::Interaction::NDecay(target, decay, dpdg);
  event->AttachSummary(interaction);

  // Simulate decay
  mcgen->ProcessEventRecord(event);

  //  genie::Interaction *inter = event->Summary();
  //  const genie::InitialState &initState = inter->InitState();
  //  std::cout<<"initState = "<<initState.AsString()<<std::endl;
  //  const genie::ProcessInfo &procInfo = inter->ProcInfo();
  //  std::cout<<"procInfo = "<<procInfo.AsString()<<std::endl;
  MF_LOG_DEBUG("NucleonDecay") << "Generated event: " << *event;

  std::unique_ptr<std::vector<simb::MCTruth>> truthcol(new std::vector<simb::MCTruth>);
  simb::MCTruth truth;

  art::ServiceHandle<geo::Geometry const> geo;

  // Find boundary of active volume
  double minx = 1e9;
  double maxx = -1e9;
  double miny = 1e9;
  double maxy = -1e9;
  double minz = 1e9;
  double maxz = -1e9;
  for (auto const& tpc : geo->Iterate<geo::TPCGeo>(geo::CryostatID{0})) {
    if (minx > tpc.MinX()) minx = tpc.MinX();
    if (maxx < tpc.MaxX()) maxx = tpc.MaxX();
    if (miny > tpc.MinY()) miny = tpc.MinY();
    if (maxy < tpc.MaxY()) maxy = tpc.MaxY();
    if (minz > tpc.MinZ()) minz = tpc.MinZ();
    if (maxz < tpc.MaxZ()) maxz = tpc.MaxZ();
  }

  // Assign vertice position
  double X0 = flatDist.fire(minx, maxx);
  double Y0 = flatDist.fire(miny, maxy);
  double Z0 = flatDist.fire(minz, maxz);

  TIter partitr(event);
  genie::GHepParticle* part = 0;
  // GHepParticles return units of GeV/c for p.  the V_i are all in fermis
  // and are relative to the center of the struck nucleus.
  // add the vertex X/Y/Z to the V_i for status codes 0 and 1
  int trackid = 0;
  std::string primary("primary");

  while ((part = dynamic_cast<genie::GHepParticle*>(partitr.Next()))) {

    simb::MCParticle tpart(
      trackid, part->Pdg(), primary, part->FirstMother(), part->Mass(), part->Status());

    TLorentzVector pos(X0, Y0, Z0, 0);
    TLorentzVector mom(part->Px(), part->Py(), part->Pz(), part->E());
    tpart.AddTrajectoryPoint(pos, mom);
    if (part->PolzIsSet()) {
      TVector3 polz;
      part->GetPolarization(polz);
      tpart.SetPolarization(polz);
    }
    tpart.SetRescatter(part->RescatterCode());
    truth.Add(tpart);

    ++trackid;
  } // end loop to convert GHepParticles to MCParticles
  truth.SetOrigin(simb::kUnknown);
  truthcol->push_back(truth);
  //FillHistograms(truth);
  e.put(std::move(truthcol));

  delete event;
}

void evgen::NucleonDecay::beginRun(art::Run& run)
{
  art::ServiceHandle<geo::Geometry const> geo;
  run.put(std::make_unique<sumdata::RunData>(geo->DetectorName()), art::fullRun());
}

DEFINE_ART_MODULE(evgen::NucleonDecay)