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G4TritonDecay.cc
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27 // //
28 // File: G4TritonDecay.cc based on G4AlphaDecay //
29 // Author: A.Mereagglia (CENBG), imported in G4repository by L.Desorgher //
30 // Date: 24 June 2019, imported in Geant4 on 31 October 2019 //
31 // Description: //
32 // //
33 // //
35 
36 #include "G4TritonDecay.hh"
37 #include "G4IonTable.hh"
38 #include "Randomize.hh"
39 #include "G4ThreeVector.hh"
40 #include "G4DynamicParticle.hh"
41 #include "G4DecayProducts.hh"
42 #include "G4PhysicalConstants.hh"
43 #include "G4SystemOfUnits.hh"
44 #include <iostream>
45 #include <iomanip>
46 
47 G4TritonDecay::G4TritonDecay(const G4ParticleDefinition* theParentNucleus,
48  const G4double& branch, const G4double& Qvalue,
49  const G4double& excitationE,
50  const G4Ions::G4FloatLevelBase& flb)
51  : G4NuclearDecay("triton decay", Triton, excitationE, flb), transitionQ(Qvalue)
52 {
53  SetParent(theParentNucleus); // Store name of parent nucleus, delete G4MT_parent
54  SetBR(branch);
55 
56  SetNumberOfDaughters(2);
57  G4IonTable* theIonTable =
58  (G4IonTable*)(G4ParticleTable::GetParticleTable()->GetIonTable());
59  G4int daughterZ = theParentNucleus->GetAtomicNumber() - 1;
60  G4int daughterA = theParentNucleus->GetAtomicMass() - 3;
61  SetDaughter(0, theIonTable->GetIon(daughterZ, daughterA, excitationE, flb) );
62  SetDaughter(1, "triton");
63 }
64 
65 
66 G4TritonDecay::~G4TritonDecay()
67 {}
68 
69 
70 G4DecayProducts* G4TritonDecay::DecayIt(G4double)
71 {
72  // Fill G4MT_parent with theParentNucleus (stored by SetParent in ctor)
73  CheckAndFillParent();
74 
75  // Fill G4MT_daughters with triton and residual nucleus (stored by SetDaughter)
76  CheckAndFillDaughters();
77 
78  G4double tritonMass = G4MT_daughters[1]->GetPDGMass();
79  // Excitation energy included in PDG mass
80  G4double nucleusMass = G4MT_daughters[0]->GetPDGMass();
81 
82  // Q value was calculated from atomic masses.
83  // Use it to get correct triton energy.
84  G4double cmMomentum = std::sqrt(transitionQ*(transitionQ + 2.*tritonMass)*
85  (transitionQ + 2.*nucleusMass)*
86  (transitionQ + 2.*tritonMass + 2.*nucleusMass) )/
87  (transitionQ + tritonMass + nucleusMass)/2.;
88 
89  // Set up final state
90  // parentParticle is set at rest here because boost with correct momentum
91  // is done later
92  G4DynamicParticle parentParticle(G4MT_parent, G4ThreeVector(0,0,0), 0.0);
93  G4DecayProducts* products = new G4DecayProducts(parentParticle);
94 
95  G4double costheta = 2.*G4UniformRand()-1.0;
96  G4double sintheta = std::sqrt(1.0 - costheta*costheta);
97  G4double phi = twopi*G4UniformRand()*rad;
98  G4ThreeVector direction(sintheta*std::cos(phi),sintheta*std::sin(phi),
99  costheta);
100 
101  G4double KE = std::sqrt(cmMomentum*cmMomentum + tritonMass*tritonMass)
102  - tritonMass;
103  G4DynamicParticle* daughterparticle =
104  new G4DynamicParticle(G4MT_daughters[1], direction, KE, tritonMass);
105  products->PushProducts(daughterparticle);
106 
107  KE = std::sqrt(cmMomentum*cmMomentum + nucleusMass*nucleusMass) - nucleusMass;
108  daughterparticle =
109  new G4DynamicParticle(G4MT_daughters[0], -1.0*direction, KE, nucleusMass);
110  products->PushProducts(daughterparticle);
111 
112  // Energy conservation check
113  // For triton decays, do final energy check against reaction Q value
114  // which is well-measured using atomic mass differences. Nuclear masses
115  // should not be used since they are not usually directly measured and we
116  // always decay atoms and not fully stripped nuclei.
117  /*
118  G4int nProd = products->entries();
119  G4DynamicParticle* temp = 0;
120  G4double Esum = 0.0;
121  for (G4int i = 0; i < nProd; i++) {
122  temp = products->operator[](i);
123  Esum += temp->GetKineticEnergy();
124  }
125  G4double eCons = (transitionQ - Esum)/keV;
126  if (eCons > 1.e-07) G4cout << " Triton decay check: Ediff (keV) = " << eCons << G4endl;
127  */
128  return products;
129 }
130 
131 
132 void G4TritonDecay::DumpNuclearInfo()
133 {
134  G4cout << " G4TritonDecay for parent nucleus " << GetParentName() << G4endl;
135  G4cout << " decays to " << GetDaughterName(0) << " + " << GetDaughterName(1)
136  << " with branching ratio " << GetBR() << "% and Q value "
137  << transitionQ << G4endl;
138 }
139