py8decayer/src/Py8DecayerPhysics.cc

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0026 //
0027 /// \file eventgenerator/pythia/pythia8decayer/src/Py8DecayerPhysics.cc
0028 /// \brief Implementation of the Py8DecayerPhysics class
0029 ///
0030 /// \author J. Yarba; FNAL
0031
0032 #include "Py8DecayerPhysics.hh"
0033
0034 #include "Py8Decayer.hh"
0035
0036 #include "G4Decay.hh"
0037 #include "G4DecayTable.hh"
0038 #include "G4ParticleDefinition.hh"
0039 #include "G4ProcessManager.hh"
0040
0041 // factory
0042 //
0043 #include "G4PhysicsConstructorFactory.hh"
0044 //
0045 // register it with contructor factory
0046 //
0047 G4_DECLARE_PHYSCONSTR_FACTORY(Py8DecayerPhysics);
0048
0049 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0050
0051 Py8DecayerPhysics::Py8DecayerPhysics(G4int) : G4VPhysicsConstructor("Py8DecayerPhysics") {}
0052
0053 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0054
0055 Py8DecayerPhysics::~Py8DecayerPhysics() {}
0056
0057 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0058
0059 void Py8DecayerPhysics::ConstructParticle()
0060 {
0061   // Nothing needs to be done here
0062 }
0063
0064 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0065
0066 void Py8DecayerPhysics::ConstructProcess()
0067 {
0068   // Adding external decayer to G4Decay process (per each thread).
0069   // G4Decay will use the external decayer if G4Decay process is
0070   // assigned to an unstable particle and that particle does not
0071   // have its decay table.
0072
0073   // Loop over all particles instantiated and remove already-assigned
0074   // decay table for tau's and B+/- so that they will decay through
0075   // the external decayer (Pythia8).
0076
0077   // NOTE: The extDecayer will be deleted in G4Decay destructor
0078
0079   Py8Decayer* extDecayer = new Py8Decayer();
0080   G4bool setOnce = true;
0081
0082   auto particleIterator = GetParticleIterator();
0083   particleIterator->reset();
0084   while ((*particleIterator)()) {
0085     G4ParticleDefinition* particle = particleIterator->value();
0086
0087     // remove native/existing decay table for
0088     // a)tau's
0089     // b) B+/-
0090     // so that G4Decay will use the external decayer
0091     if (std::abs(particle->GetPDGEncoding()) == 15 || std::abs(particle->GetPDGEncoding()) == 521) {
0092       if (particle->GetDecayTable()) {
0093         delete particle->GetDecayTable();
0094         particle->SetDecayTable(nullptr);
0095         /*
0096                   if ( verboseLevel > 1 ) {
0097                      G4cout << "Use ext decayer for: "
0098                         <<  particleIterator->value()->GetParticleName()
0099                         << G4endl;
0100                   }
0101         */
0102       }
0103     }
0104
0105     if (setOnce)
0106     // One G4Decay object is shared by all unstable particles (per thread).
0107     // Thus, we set the external decayer only once.
0108     {
0109       G4ProcessManager* pmanager = particle->GetProcessManager();
0110       G4ProcessVector* processVector = pmanager->GetProcessList();
0111       for (size_t i = 0; i < processVector->length(); ++i) {
0112         G4Decay* decay = dynamic_cast<G4Decay*>((*processVector)[i]);
0113         if (decay) {
0114           decay->SetExtDecayer(extDecayer);
0115           setOnce = false;
0116         }
0117       }
0118     }
0119   }
0120
0121   return;
0122 }
0123
0124 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......