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27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class file
30 //
31 //
32 // File name: G4EmElementSelector
33 //
34 // Author: Vladimir Ivanchenko
35 //
36 // Creation date: 29.05.2008
37 //
38 // Modifications:
39 //
40 // Class Description:
41 //
42 // Generic helper class for the random selection of an element
43
44 // -------------------------------------------------------------------
45 //
46
47 #include "G4EmElementSelector.hh"
48 #include "G4VEmModel.hh"
49 #include "G4SystemOfUnits.hh"
50
51 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
52 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
53
54 G4EmElementSelector::G4EmElementSelector(G4VEmModel* mod,
55 const G4Material* mat,
56 G4int bins,
57 G4double emin,
58 G4double emax,
59 G4bool):
60 model(mod), material(mat), nbins(bins), cutEnergy(-1.0),
61 lowEnergy(emin), highEnergy(emax)
62 {
63 G4int n = (G4int)material->GetNumberOfElements();
64 nElmMinusOne = n - 1;
65 theElementVector = material->GetElementVector();
66 if(nElmMinusOne > 0) {
67 xSections.reserve(n);
68 auto v0 = new G4PhysicsLogVector(lowEnergy,highEnergy,nbins,false);
69 xSections.push_back(v0);
70 for(G4int i=1; i<n; ++i) {
71 auto v = new G4PhysicsLogVector(*v0);
72 xSections.push_back(v);
73 }
74 }
75 /*
76 G4cout << "G4EmElementSelector for " << mat->GetName() << " n= " << n
77 << " nbins= " << nbins << " Emin= " << lowEnergy
78 << " Emax= " << highEnergy << G4endl;
79 */
80 }
81
82 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
83
84 G4EmElementSelector::~G4EmElementSelector()
85 {
86 if(nElmMinusOne > 0) {
87 for(G4int i=0; i<=nElmMinusOne; ++i) { delete xSections[i]; }
88 }
89 }
90
91 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
92
93 void G4EmElementSelector::Initialise(const G4ParticleDefinition* part,
94 G4double cut)
95 {
96 //G4cout << "G4EmElementSelector initialise for " << material->GetName()
97 // << G4endl;
98 if(0 == nElmMinusOne || cut == cutEnergy) { return; }
99
100 cutEnergy = cut;
101 //G4cout << "cut(keV)= " << cut/keV << G4endl;
102 G4double cross;
103
104 const G4double* theAtomNumDensityVector =
105 material->GetVecNbOfAtomsPerVolume();
106
107 // loop over bins
108 for(G4int j=0; j<=nbins; ++j) {
109 G4double e = (xSections[0])->Energy(j);
110 model->SetupForMaterial(part, material, e);
111 cross = 0.0;
112 //G4cout << "j= " << j << " e(MeV)= " << e/MeV << G4endl;
113 for (G4int i=0; i<=nElmMinusOne; ++i) {
114 cross += theAtomNumDensityVector[i]*
115 model->ComputeCrossSectionPerAtom(part, (*theElementVector)[i], e,
116 cutEnergy, e);
117 xSections[i]->PutValue(j, cross);
118 }
119 }
120 // xSections start from null, so use probabilities from the next bin
121 if(0.0 == (*xSections[nElmMinusOne])[0]) {
122 for (G4int i=0; i<=nElmMinusOne; ++i) {
123 xSections[i]->PutValue(0, (*xSections[i])[1]);
124 }
125 }
126 // xSections ends with null, so use probabilities from the previous bin
127 if(0.0 == (*xSections[nElmMinusOne])[nbins]) {
128 for (G4int i=0; i<=nElmMinusOne; ++i) {
129 xSections[i]->PutValue(nbins, (*xSections[i])[nbins-1]);
130 }
131 }
132 // perform normalization
133 for(G4int j=0; j<=nbins; ++j) {
134 cross = (*xSections[nElmMinusOne])[j];
135 // only for positive X-section
136 if(cross > 0.0) {
137 for (G4int i=0; i<nElmMinusOne; ++i) {
138 G4double x = (*xSections[i])[j]/cross;
139 xSections[i]->PutValue(j, x);
140 }
141 }
142 }
143 /*
144 G4cout << "======== G4EmElementSelector for the " << model->GetName()
145 << G4endl;
146 for (G4int i=0; i<=nElmMinusOne; ++i) {
147 G4cout << "#### i=" << i << G4endl;
148 G4cout << (*xSections[i]) << G4endl;
149 }
150 */
151 }
152
153 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
154
155 const G4Element*
156 G4EmElementSelector::SelectRandomAtom(const G4double e,
157 const G4double loge) const
158 {
159 const G4Element* element = (*theElementVector)[nElmMinusOne];
160 if (nElmMinusOne > 0) {
161 // 1. Determine energy index (only once)
162 // handle cases below/above the enrgy grid (by ekin, idx that gives a=0/1)
163 // ekin = x[0] if e<=x[0] and idx will be 0 ^ a=0 => so y=y0
164 // ekin = x[N-1] if e>=x[N-1] and idx will be N-2 ^ a=1 => so y=y_{N-1}
165 G4double ekin = e;
166 std::size_t idx = 0;
167 if(e <= (xSections[0])->Energy(0)) {
168 ekin = (xSections[0])->Energy(0);
169 } else if(e < (xSections[0])->GetMaxEnergy()) {
170 idx = (xSections[0])->ComputeLogVectorBin(loge);
171 } else {
172 ekin = (xSections[0])->GetMaxEnergy();
173 idx = (xSections[0])->GetVectorLength() - 2;
174 }
175 // 2. Do the linear interp.(corner cases are already excluded)
176 const G4double x1 = (xSections[0])->Energy(idx);
177 const G4double a = (ekin - x1)/((xSections[0])->Energy(idx+1) - x1);
178 const G4double urnd = G4UniformRand();
179 for (G4int i = 0; i < nElmMinusOne; ++i) {
180 const G4double y1 = (*xSections[i])[idx];
181 if (urnd <= y1 + a*((*xSections[i])[idx+1] - y1)) {
182 element = (*theElementVector)[i];
183 break;
184 }
185 }
186 }
187 return element;
188 }
189
190 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
191
192 void G4EmElementSelector::Dump(const G4ParticleDefinition* part)
193 {
194 G4cout << "======== G4EmElementSelector for the " << model->GetName();
195 if(part) G4cout << " and " << part->GetParticleName();
196 G4cout << " for " << material->GetName() << " ========" << G4endl;
197 if(0 < nElmMinusOne) {
198 for(G4int i=0; i<nElmMinusOne; i++) {
199 G4cout << " " << (*theElementVector)[i]->GetName() << " : " << G4endl;
200 G4cout << *(xSections[i]) << G4endl;
201 }
202 }
203 G4cout << "Last Element in element vector "
204 << (*theElementVector)[nElmMinusOne]->GetName()
205 << G4endl;
206 G4cout << G4endl;
207 }
208
209 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
210
211
212