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26 ////////////////////////////////////////////////////////////////////////////////
27 // //
28 // File: G4LENDInelastic.cc //
29 // Date: 24 March 2020 //
30 // Author: Dennis Wright //
31 // //
32 // Description: model for inelastic scattering of neutrons, light ions and //
33 // gammas at energies of order 20 MeV and lower. //
34 // This model uses GIDI particle data which are stored mostly //
35 // in spectrum mode. In this mode, spectra are reproduced //
36 // for each possible particle type which can result from a //
37 // given interaction. Unlike Geant4, this is done without //
38 // consideration of event-by-event conservation rules. //
39 // Indeed, forcing such conservation on GIDI output products //
40 // introduces correlations and distortions in the resulting //
41 // spectra which are not present in the data. //
42 // //
43 // In order to use GIDI data within the Geant4 framework, a //
44 // minimal event-by-event baryon number conservation is //
45 // enforced which allows deviations of up to 1 GeV without //
46 // giving warnings. Neither charge, nor energy, nor momentum //
47 // conservation is enforced. Under this scheme, light //
48 // fragment (n, p, d, t, alpha) spectra are well reproduced //
49 // after a large number of events. Charge and energy //
50 // conservation also approach their event-by-event values in //
51 // this limit. The mass, charge and energy distributions of //
52 // large fragments, however, are not expected to reproduce the //
53 // data very well. This is a result of forcing the crude //
54 // baryon number conservation and ensuring that the light //
55 // fragment spectra are correct. //
56 // //
57 ////////////////////////////////////////////////////////////////////////////////
58
59 #include "G4LENDInelastic.hh"
60 #include "G4SystemOfUnits.hh"
61 #include "G4Nucleus.hh"
62 #include "G4IonTable.hh"
63 #include <algorithm>
64 #include <random>
65
66 G4HadFinalState* G4LENDInelastic::ApplyYourself(const G4HadProjectile& aTrack,
67 G4Nucleus& aTarg)
68 {
69 G4ThreeVector projMom = aTrack.Get4Momentum().vect();
70 G4double temp = aTrack.GetMaterial()->GetTemperature();
71
72 G4int iZ = aTarg.GetZ_asInt();
73 G4int iA = aTarg.GetA_asInt();
74 G4int iM = 0;
75 if (aTarg.GetIsotope() != nullptr) iM = aTarg.GetIsotope()->Getm();
76
77 G4double ke = aTrack.GetKineticEnergy();
78
79 G4HadFinalState* theResult = &theParticleChange;
80 theResult->Clear();
81
82 G4GIDI_target* aGIDITarget =
83 get_target_from_map(lend_manager->GetNucleusEncoding(iZ, iA, iM) );
84 if (aGIDITarget == nullptr) {
85 // G4cout << " No target found " << G4endl;
86 theParticleChange.Clear();
87 theParticleChange.SetStatusChange(isAlive);
88 theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
89 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
90 return &theParticleChange;
91 }
92 // return returnUnchanged(aTrack, theResult);
93
94 // Get GIDI final state products for givern target and projectile
95 G4int loop(0);
96 G4int loopMax = 1000;
97 std::vector<G4GIDI_Product>* products;
98 do {
99 products = aGIDITarget->getOthersFinalState(ke*MeV, temp, MyRNG, NULL);
100 loop++;
101 } while (products == nullptr && loop < loopMax);
102
103 // G4LENDInelastic accepts all light fragments and gammas from GIDI (A < 5)
104 // and removes any heavy fragments which cause large baryon number violation.
105 // Charge and energy non-conservation still occur, but over a large number
106 // of events, this improves on average.
107
108 if (loop > loopMax - 1) {
109 // G4cout << " too many loops, return initial state " << G4endl;
110
111 theParticleChange.Clear();
112 theParticleChange.SetStatusChange(isAlive);
113 theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
114 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
115 return &theParticleChange;
116
117 // if (aTrack.GetDefinition() == G4Proton::Proton() ||
118 // aTrack.GetDefinition() == G4Neutron::Neutron() ) {
119 // theResult = preco->ApplyYourself(aTrack, aTarg);
120 // } else {
121 // theResult = returnUnchanged(aTrack, theResult);
122 // }
123
124 } else {
125 G4int iTotZ = iZ + aTrack.GetDefinition()->GetAtomicNumber();
126 G4int iTotA = iA + aTrack.GetDefinition()->GetAtomicMass();
127
128 // Loop over GIDI products and separate light from heavy fragments
129 G4int GZtot(0);
130 G4int GAtot(0);
131 G4int productA(0);
132 G4int productZ(0);
133 std::vector<G4int> lightProductIndex;
134 std::vector<G4int> heavyProductIndex;
135 for (G4int i = 0; i < int( products->size() ); i++ ) {
136 productA = (*products)[i].A;
137 if (productA < 5) {
138 lightProductIndex.push_back(i);
139 GZtot += (*products)[i].Z;
140 GAtot += productA;
141 } else {
142 heavyProductIndex.push_back(i);
143 }
144 }
145
146 // Randomize order of heavies to correct somewhat for sampling bias
147 // std::random_shuffle(heavyProductIndex.begin(), heavyProductIndex.end() );
148 // std::cout << " Heavy product index before shuffle : " ;
149 // for (G4int i = 0; i < int(heavyProductIndex.size() ); i++) std::cout << heavyProductIndex[i] << ", " ;
150 // std::cout << std::endl;
151
152 auto rng = std::default_random_engine {};
153 std::shuffle(heavyProductIndex.begin(), heavyProductIndex.end(), rng);
154
155 // std::cout << " Heavy product index after shuffle : " ;
156 // for (G4int i = 0; i < int(heavyProductIndex.size() ); i++) std::cout << heavyProductIndex[i] << ", " ;
157 // std::cout << std::endl;
158
159 std::vector<G4int> savedHeavyIndex;
160 G4int itest(0);
161 for (G4int i = 0; i < int(heavyProductIndex.size() ); i++) {
162 itest = heavyProductIndex[i];
163 productA = (*products)[itest].A;
164 productZ = (*products)[itest].Z;
165 if ((GAtot + productA <= iTotA) && (GZtot + productZ <= iTotZ) ) {
166 savedHeavyIndex.push_back(itest);
167 GZtot += productZ;
168 GAtot += productA;
169 }
170 }
171
172 /*
173 G4cout << " saved light products = ";
174 for (G4int k = 0; k < int(lightProductIndex.size() ); k++ ) {
175 itest = lightProductIndex[k];
176 G4cout << "(" << (*products)[itest].Z << ", " << (*products)[itest].A << "), ";
177 }
178 G4cout << G4endl;
179
180 G4cout << " saved heavy products = ";
181 for (G4int k = 0; k < int(savedHeavyIndex.size() ); k++ ) {
182 itest = savedHeavyIndex[k];
183 G4cout << "(" << (*products)[itest].Z << ", " << (*products)[itest].A << "), ";
184 }
185 G4cout << G4endl;
186 */
187 // Now convert saved products to Geant4 particles
188 // Note that, at least for heavy fragments, GIDI masses and Geant4 masses
189 // have slightly different values.
190
191 G4DynamicParticle* theSec = nullptr;
192 G4ThreeVector Psum;
193 for (G4int i = 0; i < int(lightProductIndex.size() ); i++) {
194 itest = lightProductIndex[i];
195 productZ = (*products)[itest].Z;
196 productA = (*products)[itest].A;
197 theSec = new G4DynamicParticle();
198 if (productA == 1 && productZ == 0) {
199 theSec->SetDefinition(G4Neutron::Neutron() );
200 } else if (productA == 1 && productZ == 1) {
201 theSec->SetDefinition(G4Proton::Proton() );
202 } else if (productA == 2 && productZ == 1) {
203 theSec->SetDefinition(G4Deuteron::Deuteron() );
204 } else if (productA == 3 && productZ == 1) {
205 theSec->SetDefinition(G4Triton::Triton() );
206 } else if (productA == 4 && productZ == 2) {
207 theSec->SetDefinition(G4Alpha::Alpha() );
208 } else {
209 theSec->SetDefinition(G4Gamma::Gamma() );
210 }
211
212 G4ThreeVector momentum((*products)[itest].px*MeV,
213 (*products)[itest].py*MeV,
214 (*products)[itest].pz*MeV );
215 Psum += momentum;
216 theSec->SetMomentum(momentum);
217 // theResult->AddSecondary(theSec);
218 theParticleChange.AddSecondary(theSec, secID);
219 }
220
221 G4int productM(0);
222 for (G4int i = 0; i < int(savedHeavyIndex.size() ); i++) {
223 itest = savedHeavyIndex[i];
224 productZ = (*products)[itest].Z;
225 productA = (*products)[itest].A;
226 productM = (*products)[itest].m;
227 theSec = new G4DynamicParticle();
228 theSec->SetDefinition(G4IonTable::GetIonTable()->GetIon(productZ,
229 productA,
230 productM) );
231 G4ThreeVector momentum((*products)[itest].px*MeV,
232 (*products)[itest].py*MeV,
233 (*products)[itest].pz*MeV );
234 Psum += momentum;
235 theSec->SetMomentum(momentum);
236 // theResult->AddSecondary(theSec);
237 theParticleChange.AddSecondary(theSec, secID);
238 }
239
240 // Create heavy fragment if necessary to try to balance A, Z
241 // Note: this step is only required to prevent warnings at the process level
242 // where "catastrophic" non-conservation tolerances are set to 1 GeV.
243 // The residual generated will not necessarily be the one that would
244 // occur in the actual reaction.
245 if (iTotA - GAtot > 1) {
246 theSec = new G4DynamicParticle();
247 if (iTotZ == GZtot) {
248 // Special case when a nucleus of only neutrons is requested
249 // Violate charge conservation and set Z = 1
250 // G4cout << " Z = 1, A = "<< iTotA - GAtot << " created " << G4endl;
251 theSec->SetDefinition(G4IonTable::GetIonTable()->GetIon(1, iTotA-GAtot, 0) );
252 } else {
253 theSec->SetDefinition(G4IonTable::GetIonTable()->GetIon(iTotZ-GZtot, iTotA-GAtot, 0) );
254 }
255 theSec->SetMomentum(projMom - Psum);
256 // theResult->AddSecondary(theSec);
257 theParticleChange.AddSecondary(theSec, secID);
258 }
259 } // loop OK
260
261 delete products;
262 // theResult->SetStatusChange( stopAndKill );
263 theParticleChange.SetStatusChange( stopAndKill );
264 // return theResult;
265 return &theParticleChange;
266 }
267