Geant4 10.7.0
Toolkit for the simulation of the passage of particles through matter
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G4RPGNeutronInelastic.cc
Go to the documentation of this file.
1//
2// ********************************************************************
3// * License and Disclaimer *
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5// * The Geant4 software is copyright of the Copyright Holders of *
6// * the Geant4 Collaboration. It is provided under the terms and *
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24// ********************************************************************
25//
26//
27
30#include "G4SystemOfUnits.hh"
31#include "Randomize.hh"
32
35 G4Nucleus& targetNucleus)
36{
38 const G4HadProjectile* originalIncident = &aTrack;
39
40 // create the target particle
41 G4DynamicParticle* originalTarget = targetNucleus.ReturnTargetParticle();
42
43 G4ReactionProduct modifiedOriginal;
44 modifiedOriginal = *originalIncident;
45 G4ReactionProduct targetParticle;
46 targetParticle = *originalTarget;
47 if( originalIncident->GetKineticEnergy()/GeV < 0.01 + 2.*G4UniformRand()/9. )
48 {
49 SlowNeutron(originalIncident,modifiedOriginal,targetParticle,targetNucleus );
50 delete originalTarget;
51 return &theParticleChange;
52 }
53
54 // Fermi motion and evaporation
55 // As of Geant3, the Fermi energy calculation had not been Done
56 G4double ek = originalIncident->GetKineticEnergy()/MeV;
57 G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
58
59 G4double tkin = targetNucleus.Cinema( ek );
60 ek += tkin;
61 modifiedOriginal.SetKineticEnergy( ek*MeV );
62 G4double et = ek + amas;
63 G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
64 G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
65 if( pp > 0.0 )
66 {
67 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
68 modifiedOriginal.SetMomentum( momentum * (p/pp) );
69 }
70 //
71 // calculate black track energies
72 //
73 tkin = targetNucleus.EvaporationEffects( ek );
74 ek -= tkin;
75 modifiedOriginal.SetKineticEnergy(ek);
76 et = ek + amas;
77 p = std::sqrt( std::abs((et-amas)*(et+amas)) );
78 pp = modifiedOriginal.GetMomentum().mag();
79 if( pp > 0.0 )
80 {
81 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
82 modifiedOriginal.SetMomentum( momentum * (p/pp) );
83 }
84 const G4double cutOff = 0.1;
85 if( modifiedOriginal.GetKineticEnergy()/MeV <= cutOff )
86 {
87 SlowNeutron( originalIncident, modifiedOriginal, targetParticle, targetNucleus );
88 delete originalTarget;
89 return &theParticleChange;
90 }
91
92 G4ReactionProduct currentParticle = modifiedOriginal;
93 currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
94 targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
95 G4bool incidentHasChanged = false;
96 G4bool targetHasChanged = false;
97 G4bool quasiElastic = false;
98 G4FastVector<G4ReactionProduct,256> vec; // vec will contain sec. particles
99 G4int vecLen = 0;
100 vec.Initialize( 0 );
101
102 InitialCollision(vec, vecLen, currentParticle, targetParticle,
103 incidentHasChanged, targetHasChanged);
104
105 CalculateMomenta(vec, vecLen,
106 originalIncident, originalTarget, modifiedOriginal,
107 targetNucleus, currentParticle, targetParticle,
108 incidentHasChanged, targetHasChanged, quasiElastic);
109
110 SetUpChange(vec, vecLen,
111 currentParticle, targetParticle,
112 incidentHasChanged);
113
114 delete originalTarget;
115 return &theParticleChange;
116}
117
118void
119G4RPGNeutronInelastic::SlowNeutron(const G4HadProjectile* originalIncident,
120 G4ReactionProduct& modifiedOriginal,
121 G4ReactionProduct& targetParticle,
122 G4Nucleus& targetNucleus)
123{
124 const G4double A = targetNucleus.GetA_asInt(); // atomic weight
125 const G4double Z = targetNucleus.GetZ_asInt(); // atomic number
126
127 G4double currentKinetic = modifiedOriginal.GetKineticEnergy()/MeV;
128 G4double currentMass = modifiedOriginal.GetMass()/MeV;
129 if( A < 1.5 ) // Hydrogen
130 {
131 //
132 // very simple simulation of scattering angle and energy
133 // nonrelativistic approximation with isotropic angular
134 // distribution in the cms system
135 //
136 G4double cost1, eka = 0.0;
137 while (eka <= 0.0) { /* Loop checking, 01.09.2015, D.Wright */
138 cost1 = -1.0 + 2.0*G4UniformRand();
139 eka = 1.0 + 2.0*cost1*A + A*A;
140 }
141 G4double cost = std::min( 1.0, std::max( -1.0, (A*cost1+1.0)/std::sqrt(eka) ) );
142 eka /= (1.0+A)*(1.0+A);
143 G4double ek = currentKinetic*MeV/GeV;
144 G4double amas = currentMass*MeV/GeV;
145 ek *= eka;
146 G4double en = ek + amas;
147 G4double p = std::sqrt(std::abs(en*en-amas*amas));
148 G4double sint = std::sqrt(std::abs(1.0-cost*cost));
149 G4double phi = G4UniformRand()*twopi;
150 G4double px = sint*std::sin(phi);
151 G4double py = sint*std::cos(phi);
152 G4double pz = cost;
153 targetParticle.SetMomentum( px*GeV, py*GeV, pz*GeV );
154 G4double pxO = originalIncident->Get4Momentum().x()/GeV;
155 G4double pyO = originalIncident->Get4Momentum().y()/GeV;
156 G4double pzO = originalIncident->Get4Momentum().z()/GeV;
157 G4double ptO = pxO*pxO + pyO+pyO;
158 if( ptO > 0.0 )
159 {
160 G4double pO = std::sqrt(pxO*pxO+pyO*pyO+pzO*pzO);
161 cost = pzO/pO;
162 sint = 0.5*(std::sqrt(std::abs((1.0-cost)*(1.0+cost)))+std::sqrt(ptO)/pO);
163 G4double ph = pi/2.0;
164 if( pyO < 0.0 )ph = ph*1.5;
165 if( std::abs(pxO) > 0.000001 )ph = std::atan2(pyO,pxO);
166 G4double cosp = std::cos(ph);
167 G4double sinp = std::sin(ph);
168 px = cost*cosp*px - sinp*py+sint*cosp*pz;
169 py = cost*sinp*px + cosp*py+sint*sinp*pz;
170 pz = -sint*px + cost*pz;
171 }
172 else
173 {
174 if( pz < 0.0 )pz *= -1.0;
175 }
176 G4double pu = std::sqrt(px*px+py*py+pz*pz);
177 modifiedOriginal.SetMomentum( targetParticle.GetMomentum() * (p/pu) );
178 modifiedOriginal.SetKineticEnergy( ek*GeV );
179
180 targetParticle.SetMomentum(
181 originalIncident->Get4Momentum().vect() - modifiedOriginal.GetMomentum() );
182 G4double pp = targetParticle.GetMomentum().mag();
183 G4double tarmas = targetParticle.GetMass();
184 targetParticle.SetTotalEnergy( std::sqrt( pp*pp + tarmas*tarmas ) );
185
188 pd->SetDefinition( targetParticle.GetDefinition() );
189 pd->SetMomentum( targetParticle.GetMomentum() );
191 return;
192 }
193
194 G4FastVector<G4ReactionProduct,4> vec; // vec will contain the secondary particles
195 G4int vecLen = 0;
196 vec.Initialize( 0 );
197
198 G4double theAtomicMass = targetNucleus.AtomicMass( A, Z );
199 G4double massVec[9];
200 massVec[0] = targetNucleus.AtomicMass( A+1.0, Z );
201 massVec[1] = theAtomicMass;
202 massVec[2] = 0.;
203 if (Z > 1.0) massVec[2] = targetNucleus.AtomicMass(A, Z-1.0);
204 massVec[3] = 0.;
205 if (Z > 1.0 && A > 1.0) massVec[3] = targetNucleus.AtomicMass(A-1.0, Z-1.0 );
206 massVec[4] = 0.;
207 if (Z > 1.0 && A > 2.0 && A-2.0 > Z-1.0)
208 massVec[4] = targetNucleus.AtomicMass( A-2.0, Z-1.0 );
209 massVec[5] = 0.;
210 if (Z > 2.0 && A > 3.0 && A-3.0 > Z-2.0)
211 massVec[5] = targetNucleus.AtomicMass( A-3.0, Z-2.0 );
212 massVec[6] = 0.;
213 if (A > 1.0 && A-1.0 > Z) massVec[6] = targetNucleus.AtomicMass(A-1.0, Z);
214 massVec[7] = massVec[3];
215 massVec[8] = 0.;
216 if (Z > 2.0 && A > 1.0) massVec[8] = targetNucleus.AtomicMass( A-1.0,Z-2.0 );
217
218 twoBody.NuclearReaction(vec, vecLen, originalIncident,
219 targetNucleus, theAtomicMass, massVec );
220
223
225 for( G4int i=0; i<vecLen; ++i ) {
226 pd = new G4DynamicParticle();
227 pd->SetDefinition( vec[i]->GetDefinition() );
228 pd->SetMomentum( vec[i]->GetMomentum() );
230 delete vec[i];
231 }
232}
233
234
235// Initial Collision
236// selects the particle types arising from the initial collision of
237// the neutron and target nucleon. Secondaries are assigned to
238// forward and backward reaction hemispheres, but final state energies
239// and momenta are not calculated here.
240
241void
242G4RPGNeutronInelastic::InitialCollision(G4FastVector<G4ReactionProduct,256>& vec,
243 G4int& vecLen,
244 G4ReactionProduct& currentParticle,
245 G4ReactionProduct& targetParticle,
246 G4bool& incidentHasChanged,
247 G4bool& targetHasChanged)
248{
249 G4double KE = currentParticle.GetKineticEnergy()/GeV;
250
251 G4int mult;
252 G4int partType;
253 std::vector<G4int> fsTypes;
254 G4int part1;
255 G4int part2;
256
257 G4double testCharge;
258 G4double testBaryon;
259 G4double testStrange;
260
261 // Get particle types according to incident and target types
262
263 if (targetParticle.GetDefinition() == particleDef[neu]) {
264 mult = GetMultiplicityT1(KE);
265 fsTypes = GetFSPartTypesForNN(mult, KE);
266
267 part1 = fsTypes[0];
268 part2 = fsTypes[1];
269 currentParticle.SetDefinition(particleDef[part1]);
270 targetParticle.SetDefinition(particleDef[part2]);
271 if (part1 == pro) {
272 if (part2 == neu) {
273 if (G4UniformRand() > 0.5) {
274 incidentHasChanged = true;
275 } else {
276 targetHasChanged = true;
277 currentParticle.SetDefinition(particleDef[part2]);
278 targetParticle.SetDefinition(particleDef[part1]);
279 }
280 } else {
281 targetHasChanged = true;
282 incidentHasChanged = true;
283 }
284
285 } else { // neutron
286 if (part2 > neu && part2 < xi0) targetHasChanged = true;
287 }
288
289 testCharge = 0.0;
290 testBaryon = 2.0;
291 testStrange = 0.0;
292
293 } else { // target was a proton
294 mult = GetMultiplicityT0(KE);
295 fsTypes = GetFSPartTypesForNP(mult, KE);
296
297 part1 = fsTypes[0];
298 part2 = fsTypes[1];
299 currentParticle.SetDefinition(particleDef[part1]);
300 targetParticle.SetDefinition(particleDef[part2]);
301 if (part1 == pro) {
302 if (part2 == pro) {
303 incidentHasChanged = true;
304 } else if (part2 == neu) {
305 if (G4UniformRand() > 0.5) {
306 incidentHasChanged = true;
307 targetHasChanged = true;
308 } else {
309 currentParticle.SetDefinition(particleDef[part2]);
310 targetParticle.SetDefinition(particleDef[part1]);
311 }
312
313 } else if (part2 > neu && part2 < xi0) {
314 incidentHasChanged = true;
315 targetHasChanged = true;
316 }
317
318 } else { // neutron
319 targetHasChanged = true;
320 }
321
322 testCharge = 1.0;
323 testBaryon = 2.0;
324 testStrange = 0.0;
325 }
326
327 // if (mult == 2 && !incidentHasChanged && !targetHasChanged)
328 // quasiElastic = true;
329
330 // Remove incident and target from fsTypes
331
332 fsTypes.erase(fsTypes.begin());
333 fsTypes.erase(fsTypes.begin());
334
335 // Remaining particles are secondaries. Put them into vec.
336
337 G4ReactionProduct* rp(0);
338 for(G4int i=0; i < mult-2; ++i ) {
339 partType = fsTypes[i];
340 rp = new G4ReactionProduct();
341 rp->SetDefinition(particleDef[partType]);
342 (G4UniformRand() < 0.5) ? rp->SetSide(-1) : rp->SetSide(1);
343 vec.SetElement(vecLen++, rp);
344 }
345
346 // Check conservation of charge, strangeness, baryon number
347
348 CheckQnums(vec, vecLen, currentParticle, targetParticle,
349 testCharge, testBaryon, testStrange);
350
351 return;
352}
double A(double temperature)
@ stopAndKill
double G4double
Definition: G4Types.hh:83
bool G4bool
Definition: G4Types.hh:86
int G4int
Definition: G4Types.hh:85
#define G4UniformRand()
Definition: Randomize.hh:52
double mag() const
Hep3Vector vect() const
void SetDefinition(const G4ParticleDefinition *aParticleDefinition)
void SetMomentum(const G4ThreeVector &momentum)
void SetElement(G4int anIndex, Type *anElement)
Definition: G4FastVector.hh:72
void Initialize(G4int items)
Definition: G4FastVector.hh:59
void SetStatusChange(G4HadFinalStateStatus aS)
void AddSecondary(G4DynamicParticle *aP, G4int mod=-1)
void SetEnergyChange(G4double anEnergy)
const G4ParticleDefinition * GetDefinition() const
G4double GetKineticEnergy() const
const G4LorentzVector & Get4Momentum() const
G4int GetA_asInt() const
Definition: G4Nucleus.hh:109
G4int GetZ_asInt() const
Definition: G4Nucleus.hh:115
G4double EvaporationEffects(G4double kineticEnergy)
Definition: G4Nucleus.cc:278
G4double Cinema(G4double kineticEnergy)
Definition: G4Nucleus.cc:382
G4DynamicParticle * ReturnTargetParticle() const
Definition: G4Nucleus.cc:241
G4double AtomicMass(const G4double A, const G4double Z) const
Definition: G4Nucleus.cc:254
void CheckQnums(G4FastVector< G4ReactionProduct, 256 > &vec, G4int &vecLen, G4ReactionProduct &currentParticle, G4ReactionProduct &targetParticle, G4double Q, G4double B, G4double S)
void CalculateMomenta(G4FastVector< G4ReactionProduct, 256 > &vec, G4int &vecLen, const G4HadProjectile *originalIncident, const G4DynamicParticle *originalTarget, G4ReactionProduct &modifiedOriginal, G4Nucleus &targetNucleus, G4ReactionProduct &currentParticle, G4ReactionProduct &targetParticle, G4bool &incidentHasChanged, G4bool &targetHasChanged, G4bool quasiElastic)
G4RPGTwoBody twoBody
void SetUpChange(G4FastVector< G4ReactionProduct, 256 > &vec, G4int &vecLen, G4ReactionProduct &currentParticle, G4ReactionProduct &targetParticle, G4bool &incidentHasChanged)
G4ParticleDefinition * particleDef[18]
G4HadFinalState * ApplyYourself(const G4HadProjectile &aTrack, G4Nucleus &targetNucleus)
G4int GetMultiplicityT0(G4double KE) const
G4int GetMultiplicityT1(G4double KE) const
std::vector< G4int > GetFSPartTypesForNN(G4int mult, G4double KE) const
std::vector< G4int > GetFSPartTypesForNP(G4int mult, G4double KE) const
void NuclearReaction(G4FastVector< G4ReactionProduct, 4 > &vec, G4int &vecLen, const G4HadProjectile *originalIncident, const G4Nucleus &aNucleus, const G4double theAtomicMass, const G4double *massVec)
void SetMomentum(const G4double x, const G4double y, const G4double z)
void SetTotalEnergy(const G4double en)
G4double GetKineticEnergy() const
const G4ParticleDefinition * GetDefinition() const
G4ThreeVector GetMomentum() const
void SetSide(const G4int sid)
void SetDefinition(const G4ParticleDefinition *aParticleDefinition)
void SetKineticEnergy(const G4double en)
G4double GetMass() const
const G4double pi