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1 //
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18 // * This code implementation is the result of the scientific and *
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24 // ********************************************************************
25 //
26 // ----------------------------------------------------------------------
27 // GEANT 4 class implementation file
28 //
29 // History: first implementation, based on object model of
30 // 4th April 1996, G.Cosmo
31 // **********************************************************************
32 // New impelemenataion as an utility class M.Asai, 26 July 2004
33 // ----------------------------------------------------------------------
34
35 #include "G4PionZero.hh"
36
37 #include "G4DalitzDecayChannel.hh"
38 #include "G4DecayTable.hh"
39 #include "G4ParticleTable.hh"
40 #include "G4PhaseSpaceDecayChannel.hh"
41 #include "G4PhysicalConstants.hh"
42 #include "G4String.hh"
43 #include "G4SystemOfUnits.hh"
44 #include "G4VDecayChannel.hh"
45
46 G4PionZero* G4PionZero::theInstance = nullptr;
47
48 G4PionZero* G4PionZero::Definition()
49 {
50 if (theInstance != nullptr) return theInstance;
51 const G4String name = "pi0";
52 // search in particle table]
53 G4ParticleTable* pTable = G4ParticleTable::GetParticleTable();
54 G4ParticleDefinition* anInstance = pTable->FindParticle(name);
55 if (anInstance == nullptr) {
56 // create particle
57 //
58 // Arguments for constructor are as follows
59 // name mass width charge
60 // 2*spin parity C-conjugation
61 // 2*Isospin 2*Isospin3 G-parity
62 // type lepton number baryon number PDG encoding
63 // stable lifetime decay table
64 // shortlived subType anti_encoding
65
66 // clang-format off
67 anInstance = new G4ParticleDefinition(
68 name, 0.1349766*GeV, 7.73e-06*MeV, 0.0,
69 0, -1, +1,
70 2, 0, -1,
71 "meson", 0, 0, 111,
72 false, 8.52e-8*ns, nullptr,
73 false, "pi", 111);
74 // clang-format on
75
76 // Life time is given from width
77 anInstance->SetPDGLifeTime(hbar_Planck / (anInstance->GetPDGWidth()));
78
79 // create Decay Table
80 auto table = new G4DecayTable();
81
82 // create a decay channel
83 G4VDecayChannel* mode;
84 // pi0 -> gamma + gamma
85 mode = new G4PhaseSpaceDecayChannel("pi0", 0.988, 2, "gamma", "gamma");
86 table->Insert(mode);
87 // pi0 -> gamma + e+ + e-
88 mode = new G4DalitzDecayChannel("pi0", 0.012, "e-", "e+");
89 table->Insert(mode);
90
91 anInstance->SetDecayTable(table);
92 }
93 theInstance = static_cast<G4PionZero*>(anInstance);
94 return theInstance;
95 }
96
97 G4PionZero* G4PionZero::PionZeroDefinition()
98 {
99 return Definition();
100 }
101
102 G4PionZero* G4PionZero::PionZero()
103 {
104 return Definition();
105 }
106