G4PionZero.cc

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//
// ----------------------------------------------------------------------
//      GEANT 4 class implementation file
//
//      History: first implementation, based on object model of
//      4th April 1996, G.Cosmo
// **********************************************************************
//  New impelemenataion as an utility class  M.Asai, 26 July 2004
// ----------------------------------------------------------------------
 
#include "G4PionZero.hh"
 
#include "G4DalitzDecayChannel.hh"
#include "G4DecayTable.hh"
#include "G4ParticleTable.hh"
#include "G4PhaseSpaceDecayChannel.hh"
#include "G4PhysicalConstants.hh"
#include "G4String.hh"
#include "G4SystemOfUnits.hh"
#include "G4VDecayChannel.hh"
 
G4PionZero* G4PionZero::theInstance = nullptr;
 
G4PionZero* G4PionZero::Definition()
{
  if (theInstance != nullptr) return theInstance;
  const G4String name = "pi0";
  // search in particle table]
  G4ParticleTable* pTable = G4ParticleTable::GetParticleTable();
  G4ParticleDefinition* anInstance = pTable->FindParticle(name);
  if (anInstance == nullptr) {
    // create particle
    //
    //    Arguments for constructor are as follows
    //               name             mass          width         charge
    //             2*spin           parity  C-conjugation
    //          2*Isospin       2*Isospin3       G-parity
    //               type    lepton number  baryon number   PDG encoding
    //             stable         lifetime    decay table
    //             shortlived      subType    anti_encoding
 
    // clang-format off
   anInstance = new G4ParticleDefinition(
                 name,   0.1349766*GeV,  7.73e-06*MeV,         0.0,
                    0,              -1,            +1,
                    2,               0,            -1,
              "meson",               0,             0,         111,
                false,      8.52e-8*ns,          nullptr,
                false,            "pi",          111);
    // clang-format on
 
    // Life time is given from width
    anInstance->SetPDGLifeTime(hbar_Planck / (anInstance->GetPDGWidth()));
 
    // create Decay Table
    auto table = new G4DecayTable();
 
    // create a decay channel
    G4VDecayChannel* mode;
    // pi0 -> gamma + gamma
    mode = new G4PhaseSpaceDecayChannel("pi0", 0.988, 2, "gamma", "gamma");
    table->Insert(mode);
    // pi0 -> gamma + e+ + e-
    mode = new G4DalitzDecayChannel("pi0", 0.012, "e-", "e+");
    table->Insert(mode);
 
    anInstance->SetDecayTable(table);
  }
  theInstance = static_cast<G4PionZero*>(anInstance);
  return theInstance;
}
 
G4PionZero* G4PionZero::PionZeroDefinition()
{
  return Definition();
}
 
G4PionZero* G4PionZero::PionZero()
{
  return Definition();
}