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27 // 27 // //
28 // File: G4BetaPlusDecay.cc 28 // File: G4BetaPlusDecay.cc //
29 // Author: D.H. Wright (SLAC) 29 // Author: D.H. Wright (SLAC) //
30 // Date: 14 November 2014 30 // Date: 14 November 2014 //
31 // Modifications: <<
32 // 23.08.2023 V.Ivanchenko <<
33 // 31 // //
34 ////////////////////////////////////////////// 32 ////////////////////////////////////////////////////////////////////////////////
35 33
36 #include "G4BetaPlusDecay.hh" 34 #include "G4BetaPlusDecay.hh"
37 #include "G4BetaDecayCorrections.hh" 35 #include "G4BetaDecayCorrections.hh"
38 #include "G4IonTable.hh" 36 #include "G4IonTable.hh"
39 #include "G4ThreeVector.hh" 37 #include "G4ThreeVector.hh"
40 #include "G4LorentzVector.hh" <<
41 #include "G4DynamicParticle.hh" 38 #include "G4DynamicParticle.hh"
42 #include "G4DecayProducts.hh" 39 #include "G4DecayProducts.hh"
43 #include "G4PhysicalConstants.hh" 40 #include "G4PhysicalConstants.hh"
44 #include "G4SystemOfUnits.hh" 41 #include "G4SystemOfUnits.hh"
45 #include "G4Positron.hh" <<
46 #include "G4NeutrinoE.hh" <<
47 #include "G4RandomDirection.hh" <<
48 #include "G4BetaSpectrumSampler.hh" <<
49 #include <iostream> 42 #include <iostream>
50 #include <iomanip> 43 #include <iomanip>
51 44
52 namespace { <<
53 const G4double eMass = CLHEP::electron_mass_ <<
54 } <<
55 <<
56 G4BetaPlusDecay::G4BetaPlusDecay(const G4Parti 45 G4BetaPlusDecay::G4BetaPlusDecay(const G4ParticleDefinition* theParentNucleus,
57 const G4doubl 46 const G4double& branch, const G4double& e0,
58 const G4doubl 47 const G4double& excitationE,
59 const G4Ions: 48 const G4Ions::G4FloatLevelBase& flb,
60 const G4BetaD 49 const G4BetaDecayType& betaType)
61 : G4NuclearDecay("beta+ decay", BetaPlus, exc 50 : G4NuclearDecay("beta+ decay", BetaPlus, excitationE, flb),
62 maxEnergy(e0/eMass - 2.0), << 51 endpointEnergy(e0 - 2.*CLHEP::electron_mass_c2)
63 estep(maxEnergy/(G4double)(npti - 1)) <<
64 { 52 {
65 SetParent(theParentNucleus); // Store name 53 SetParent(theParentNucleus); // Store name of parent nucleus, delete G4MT_parent
66 SetBR(branch); 54 SetBR(branch);
67 SetNumberOfDaughters(3); <<
68 <<
69 fPrimaryIon = theParentNucleus; <<
70 fLepton = G4Positron::Positron(); <<
71 fNeutrino = G4NeutrinoE::NeutrinoE(); <<
72 55
73 G4IonTable* theIonTable = G4ParticleTable::G << 56 SetNumberOfDaughters(3);
>> 57 G4IonTable* theIonTable =
>> 58 (G4IonTable*)(G4ParticleTable::GetParticleTable()->GetIonTable());
74 G4int daughterZ = theParentNucleus->GetAtomi 59 G4int daughterZ = theParentNucleus->GetAtomicNumber() - 1;
75 G4int daughterA = theParentNucleus->GetAtomi << 60 G4int daughterA = theParentNucleus->GetAtomicMass();
76 fResIon = const_cast<const G4ParticleDefinit << 61 SetDaughter(0, theIonTable->GetIon(daughterZ, daughterA, excitationE, flb) );
77 << 62 SetUpBetaSpectrumSampler(daughterZ, daughterA, betaType);
>> 63 SetDaughter(1, "e+");
>> 64 SetDaughter(2, "nu_e");
>> 65 }
78 66
79 parentMass = theParentNucleus->GetPDGMass(); <<
80 resMass = fResIon->GetPDGMass(); <<
81 67
82 SetUpBetaSpectrumSampler(daughterZ, daughter << 68 G4BetaPlusDecay::~G4BetaPlusDecay()
>> 69 {
>> 70 delete spectrumSampler;
>> 71 }
83 72
84 SetDaughter(0, fResIon); <<
85 SetDaughter(1, fLepton); <<
86 SetDaughter(2, fNeutrino); <<
87 73
>> 74 G4DecayProducts* G4BetaPlusDecay::DecayIt(G4double)
>> 75 {
88 // Fill G4MT_parent with theParentNucleus (s 76 // Fill G4MT_parent with theParentNucleus (stored by SetParent in ctor)
89 CheckAndFillParent(); 77 CheckAndFillParent();
90 78
91 // Fill G4MT_daughters with e+, nu and resid << 79 // Fill G4MT_daughters with e-, nu and residual nucleus (stored by SetDaughter)
92 CheckAndFillDaughters(); 80 CheckAndFillDaughters();
93 } <<
94 81
95 G4DecayProducts* G4BetaPlusDecay::DecayIt(G4do << 82 G4double parentMass = G4MT_parent->GetPDGMass();
96 { << 83 G4double eMass = G4MT_daughters[1]->GetPDGMass();
>> 84 G4double nucleusMass = G4MT_daughters[0]->GetPDGMass();
97 // Set up final state 85 // Set up final state
98 // parentParticle is set at rest here becaus 86 // parentParticle is set at rest here because boost with correct momentum
99 // is done later 87 // is done later
100 G4DynamicParticle prim(fPrimaryIon, G4ThreeV << 88 G4DynamicParticle parentParticle(G4MT_parent, G4ThreeVector(0,0,0), 0.0);
101 G4DecayProducts* products = new G4DecayProdu << 89 G4DecayProducts* products = new G4DecayProducts(parentParticle);
102 <<
103 // Generate positron isotropic in angle, wit <<
104 const G4double eKE = eMass*G4BetaSpectrumSam <<
105 90
106 G4double eMomentum = std::sqrt(eKE*(eKE + 2. << 91 if (spectrumSampler) {
107 G4ThreeVector dir = G4RandomDirection(); << 92 // Generate positron isotropic in angle, with energy from stored spectrum
108 G4DynamicParticle* dp = new G4DynamicParticl << 93 G4double eKE = endpointEnergy*spectrumSampler->shoot(G4Random::getTheEngine() );
109 products->PushProducts(dp); << 94 G4double eMomentum = std::sqrt(eKE*(eKE + 2.*eMass) );
110 /* << 95
111 G4cout << "G4BetaPlusDecay::DecayIt: " << fP << 96 G4double cosTheta = 2.*G4UniformRand() - 1.0;
112 << " -> " << fResIon->GetParticleName() << << 97 G4double sinTheta = std::sqrt(1.0 - cosTheta*cosTheta);
113 << " + " << fNeutrino->GetParticleName() << << 98 G4double phi = twopi*G4UniformRand()*rad;
114 << G4endl; << 99 G4double sinPhi = std::sin(phi);
115 */ << 100 G4double cosPhi = std::cos(phi);
116 // 4-momentum of residual ion and neutrino << 101
117 G4LorentzVector lv(-eMomentum*dir.x(), -eMom << 102 G4ParticleMomentum eDirection(sinTheta*cosPhi, sinTheta*sinPhi, cosTheta);
118 parentMass - eKE - eMass) << 103 G4DynamicParticle* dynamicPositron
119 << 104 = new G4DynamicParticle(G4MT_daughters[1], eDirection*eMomentum);
120 const G4double elim = CLHEP::eV; << 105 products->PushProducts(dynamicPositron);
121 // centrum of mass system << 106
122 G4double M = lv.mag(); << 107 // Generate neutrino with angle relative to positron, and energy from
123 G4double edel = M - resMass; << 108 // energy-momentum conservation using endpoint energy of reaction
124 // Free energy should be above limit << 109 G4double cosThetaENu = 2.*G4UniformRand() - 1.;
125 if (edel >= elim) { << 110 G4double eTE = eMass + eKE;
126 // neutrino << 111 G4double nuEnergy = ((endpointEnergy - eKE)*(parentMass + nucleusMass - eTE)
127 G4double eNu = 0.5*(M - resMass*resMass/M) << 112 - eMomentum*eMomentum)/(parentMass - eTE + eMomentum*cosThetaENu)/2.;
128 G4LorentzVector lvnu(eNu*G4RandomDirection << 113
129 lvnu.boost(lv.boostVector()); << 114 G4double sinThetaENu = std::sqrt(1.0 - cosThetaENu*cosThetaENu);
130 dir = lvnu.vect().unit(); << 115 phi = twopi*G4UniformRand()*rad;
131 dp = new G4DynamicParticle(fNeutrino, dir, << 116 G4double sinPhiNu = std::sin(phi);
132 products->PushProducts(dp); << 117 G4double cosPhiNu = std::cos(phi);
133 << 118
134 // residual << 119 G4ParticleMomentum nuDirection;
135 lv -= lvnu; << 120 nuDirection.setX(sinThetaENu*cosPhiNu*cosTheta*cosPhi -
136 dir = lv.vect().unit(); << 121 sinThetaENu*sinPhiNu*sinPhi + cosThetaENu*sinTheta*cosPhi);
137 G4double ekin = std::max(lv.e() - resMass, << 122 nuDirection.setY(sinThetaENu*cosPhiNu*cosTheta*sinPhi +
138 dp = new G4DynamicParticle(fResIon, dir, e << 123 sinThetaENu*sinPhiNu*cosPhi + cosThetaENu*sinTheta*sinPhi);
139 products->PushProducts(dp); << 124 nuDirection.setZ(-sinThetaENu*cosPhiNu*sinTheta + cosThetaENu*cosTheta);
>> 125
>> 126 G4DynamicParticle* dynamicNeutrino
>> 127 = new G4DynamicParticle(G4MT_daughters[2], nuDirection*nuEnergy);
>> 128 products->PushProducts(dynamicNeutrino);
>> 129
>> 130 // Generate daughter nucleus from sum of positron and neutrino 4-vectors:
>> 131 // p_D = - p_e - p_nu
>> 132 G4DynamicParticle* dynamicDaughter =
>> 133 new G4DynamicParticle(G4MT_daughters[0],
>> 134 -eDirection*eMomentum - nuDirection*nuEnergy);
>> 135 products->PushProducts(dynamicDaughter);
140 136
141 } else { 137 } else {
142 // neglecting relativistic kinematic and g << 138 // positron energy below threshold -> no decay
143 dp = new G4DynamicParticle(fNeutrino, G4Ra << 139 G4DynamicParticle* noDecay =
144 products->PushProducts(dp); << 140 new G4DynamicParticle(G4MT_parent, G4ThreeVector(0,0,0), 0.0);
145 dp = new G4DynamicParticle(fResIon, G4Thre << 141 products->PushProducts(noDecay);
146 products->PushProducts(dp); <<
147 } 142 }
148 143
>> 144 // Check energy conservation against endpoint value, not nuclear masses
>> 145 /*
>> 146 G4int nProd = products->entries();
>> 147 G4DynamicParticle* temp = 0;
>> 148 G4double Esum = 0.0;
>> 149 for (G4int i = 0; i < nProd; i++) {
>> 150 temp = products->operator[](i);
>> 151 Esum += temp->GetKineticEnergy();
>> 152 }
>> 153 G4double eCons = (endpointEnergy - Esum)/keV;
>> 154 if (eCons > 0.001) G4cout << " Beta+ check: eCons (keV) = " << eCons << G4endl;
>> 155 */
149 return products; 156 return products;
150 } 157 }
151 158
152 159
153 void 160 void
154 G4BetaPlusDecay::SetUpBetaSpectrumSampler(cons 161 G4BetaPlusDecay::SetUpBetaSpectrumSampler(const G4int& daughterZ,
155 cons 162 const G4int& daughterA,
156 cons 163 const G4BetaDecayType& betaType)
157 { 164 {
158 cdf[0] = 0.0; << 165 G4double e0 = endpointEnergy/CLHEP::electron_mass_c2;
>> 166 G4BetaDecayCorrections corrections(-daughterZ, daughterA);
>> 167 spectrumSampler = 0;
159 168
160 // Check for cases in which Q < 2Me (e.g. z6 169 // Check for cases in which Q < 2Me (e.g. z67.a162)
161 if (maxEnergy > 0.) { << 170 if (e0 > 0.) {
162 G4BetaDecayCorrections corrections(-daught << 171 // Array to store spectrum pdf
163 << 172 G4int npti = 100;
164 // Fill array to store cumulative spectrum << 173 G4double* pdf = new G4double[npti];
165 G4double ex; // Positron kinetic energy << 174
166 G4double p; // Positron momentum in unit << 175 G4double e; // Total positron energy in units of electron mass
167 G4double f; // Spectral shape function << 176 G4double p; // Positron momentum in units of electron mass
168 G4double f0 = 0.0; << 177 G4double f; // Spectral shap function
169 G4double sum = 0.0; << 178 for (G4int ptn = 0; ptn < npti; ptn++) {
170 for (G4int i = 1; i < npti-1; ++i) { << 179 // Calculate simple phase space
171 ex = estep*i; << 180 e = 1. + e0*(ptn + 0.5)/G4double(npti);
172 p = std::sqrt(ex*(ex + 2.)); << 181 p = std::sqrt(e*e - 1.);
173 f = p*(1. + ex)*(maxEnergy - ex)*(maxEne << 182 f = p*e*(e0 - e + 1.)*(e0 - e + 1.);
174 183
175 // Apply Fermi factor to get allowed sha 184 // Apply Fermi factor to get allowed shape
176 f *= corrections.FermiFunction(1. + ex); << 185 f *= corrections.FermiFunction(e);
177 186
178 // Apply shape factor for forbidden tran 187 // Apply shape factor for forbidden transitions
179 f *= corrections.ShapeFactor(betaType, p << 188 f *= corrections.ShapeFactor(betaType, p, e0-e+1.);
180 sum += f + f0; << 189 pdf[ptn] = f;
181 cdf[i] = sum; <<
182 f0 = f; <<
183 } 190 }
184 cdf[npti-1] = sum + f0; << 191 spectrumSampler = new G4RandGeneral(pdf, npti);
185 } else { << 192 delete[] pdf;
186 for (G4int i = 0; i < npti; ++i) { cdf[i] <<
187 } 193 }
188 } 194 }
189 195
>> 196
190 void G4BetaPlusDecay::DumpNuclearInfo() 197 void G4BetaPlusDecay::DumpNuclearInfo()
191 { 198 {
192 G4cout << " G4BetaPlusDecay " << fPrimaryIo << 199 G4cout << " G4BetaPlusDecay for parent nucleus " << GetParentName() << G4endl;
193 << " -> " << fResIon->GetParticleName() << << 200 G4cout << " decays to " << GetDaughterName(0) << " , " << GetDaughterName(1)
194 << " + " << fNeutrino->GetParticleName() << << 201 << " and " << GetDaughterName(2) << " with branching ratio " << GetBR()
195 << maxEnergy*eMass << " BR=" << GetBR() << << 202 << "% and endpoint energy " << endpointEnergy/keV << " keV " << G4endl;
196 } 203 }
>> 204
197 205