source: trunk/source/processes/hadronic/models/rpg/src/G4RPGXiMinusInelastic.cc@ 1347

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25//
26// $Id: G4RPGXiMinusInelastic.cc,v 1.1 2007/07/18 21:04:21 dennis Exp $
27// GEANT4 tag $Name: geant4-09-03-ref-09 $
28//
29
30#include "G4RPGXiMinusInelastic.hh"
31#include "Randomize.hh"
32
33G4HadFinalState*
34G4RPGXiMinusInelastic::ApplyYourself( const G4HadProjectile &aTrack,
35 G4Nucleus &targetNucleus )
36{
37 const G4HadProjectile *originalIncident = &aTrack;
38 if (originalIncident->GetKineticEnergy()<= 0.1*MeV)
39 {
40 theParticleChange.SetStatusChange(isAlive);
41 theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
42 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
43 return &theParticleChange;
44 }
45
46 // create the target particle
47
48 G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
49
50 if( verboseLevel > 1 )
51 {
52 const G4Material *targetMaterial = aTrack.GetMaterial();
53 G4cout << "G4RPGXiMinusInelastic::ApplyYourself called" << G4endl;
54 G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
55 G4cout << "target material = " << targetMaterial->GetName() << ", ";
56 G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
57 << G4endl;
58 }
59
60 // Fermi motion and evaporation
61 // As of Geant3, the Fermi energy calculation had not been Done
62
63 G4double ek = originalIncident->GetKineticEnergy()/MeV;
64 G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
65 G4ReactionProduct modifiedOriginal;
66 modifiedOriginal = *originalIncident;
67
68 G4double tkin = targetNucleus.Cinema( ek );
69 ek += tkin;
70 modifiedOriginal.SetKineticEnergy( ek*MeV );
71 G4double et = ek + amas;
72 G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
73 G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
74 if( pp > 0.0 )
75 {
76 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
77 modifiedOriginal.SetMomentum( momentum * (p/pp) );
78 }
79 //
80 // calculate black track energies
81 //
82 tkin = targetNucleus.EvaporationEffects( ek );
83 ek -= tkin;
84 modifiedOriginal.SetKineticEnergy( ek*MeV );
85 et = ek + amas;
86 p = std::sqrt( std::abs((et-amas)*(et+amas)) );
87 pp = modifiedOriginal.GetMomentum().mag()/MeV;
88 if( pp > 0.0 )
89 {
90 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
91 modifiedOriginal.SetMomentum( momentum * (p/pp) );
92 }
93 G4ReactionProduct currentParticle = modifiedOriginal;
94 G4ReactionProduct targetParticle;
95 targetParticle = *originalTarget;
96 currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
97 targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
98 G4bool incidentHasChanged = false;
99 G4bool targetHasChanged = false;
100 G4bool quasiElastic = false;
101 G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec; // vec will contain the secondary particles
102 G4int vecLen = 0;
103 vec.Initialize( 0 );
104
105 const G4double cutOff = 0.1;
106 if( currentParticle.GetKineticEnergy()/MeV > cutOff )
107 Cascade( vec, vecLen,
108 originalIncident, currentParticle, targetParticle,
109 incidentHasChanged, targetHasChanged, quasiElastic );
110
111 CalculateMomenta( vec, vecLen,
112 originalIncident, originalTarget, modifiedOriginal,
113 targetNucleus, currentParticle, targetParticle,
114 incidentHasChanged, targetHasChanged, quasiElastic );
115
116 SetUpChange( vec, vecLen,
117 currentParticle, targetParticle,
118 incidentHasChanged );
119
120 delete originalTarget;
121 return &theParticleChange;
122}
123
124
125void G4RPGXiMinusInelastic::Cascade(
126 G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
127 G4int& vecLen,
128 const G4HadProjectile *originalIncident,
129 G4ReactionProduct &currentParticle,
130 G4ReactionProduct &targetParticle,
131 G4bool &incidentHasChanged,
132 G4bool &targetHasChanged,
133 G4bool &quasiElastic )
134{
135 // Derived from H. Fesefeldt's original FORTRAN code CASXM
136 //
137 // XiMinus undergoes interaction with nucleon within a nucleus. Check if it is
138 // energetically possible to produce pions/kaons. In not, assume nuclear excitation
139 // occurs and input particle is degraded in energy. No other particles are produced.
140 // If reaction is possible, find the correct number of pions/protons/neutrons
141 // produced using an interpolation to multiplicity data. Replace some pions or
142 // protons/neutrons by kaons or strange baryons according to the average
143 // multiplicity per inelastic reaction.
144
145 const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass()/MeV;
146 const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
147 const G4double targetMass = targetParticle.GetMass()/MeV;
148 G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
149 targetMass*targetMass +
150 2.0*targetMass*etOriginal );
151 G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
152 if( availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass()/MeV )
153 {
154 quasiElastic = true;
155 return;
156 }
157 static G4bool first = true;
158 const G4int numMul = 1200;
159 const G4int numSec = 60;
160 static G4double protmul[numMul], protnorm[numSec]; // proton constants
161 static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
162 // np = number of pi+, nm = number of pi-, nz = number of pi0
163 G4int counter, nt=0, np=0, nm=0, nz=0;
164 G4double test;
165 const G4double c = 1.25;
166 const G4double b[] = { 0.7, 0.7 };
167 if( first ) // compute normalization constants, this will only be Done once
168 {
169 first = false;
170 G4int i;
171 for( i=0; i<numMul; ++i )protmul[i] = 0.0;
172 for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
173 counter = -1;
174 for( np=0; np<(numSec/3); ++np )
175 {
176 for( nm=std::max(0,np-1); nm<=(np+1); ++nm )
177 {
178 for( nz=0; nz<numSec/3; ++nz )
179 {
180 if( ++counter < numMul )
181 {
182 nt = np+nm+nz;
183 if( nt>0 && nt<=numSec )
184 {
185 protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
186 protnorm[nt-1] += protmul[counter];
187 }
188 }
189 }
190 }
191 }
192 for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
193 for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
194 counter = -1;
195 for( np=0; np<numSec/3; ++np )
196 {
197 for( nm=np; nm<=(np+2); ++nm )
198 {
199 for( nz=0; nz<numSec/3; ++nz )
200 {
201 if( ++counter < numMul )
202 {
203 nt = np+nm+nz;
204 if( nt>0 && nt<=numSec )
205 {
206 neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
207 neutnorm[nt-1] += neutmul[counter];
208 }
209 }
210 }
211 }
212 }
213 for( i=0; i<numSec; ++i )
214 {
215 if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
216 if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
217 }
218 } // end of initialization
219
220 const G4double expxu = 82.; // upper bound for arg. of exp
221 const G4double expxl = -expxu; // lower bound for arg. of exp
222 G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
223 G4ParticleDefinition *aProton = G4Proton::Proton();
224 G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
225 G4ParticleDefinition *aSigmaPlus = G4SigmaPlus::SigmaPlus();
226 G4ParticleDefinition *aXiZero = G4XiZero::XiZero();
227 //
228 // energetically possible to produce pion(s) --> inelastic scattering
229 //
230 G4double n, anpn;
231 GetNormalizationConstant( availableEnergy, n, anpn );
232 G4double ran = G4UniformRand();
233 G4double dum, excs = 0.0;
234 if( targetParticle.GetDefinition() == aProton )
235 {
236 counter = -1;
237 for( np=0; np<numSec/3 && ran>=excs; ++np )
238 {
239 for( nm=std::max(0,np-1); nm<=(np+1) && ran>=excs; ++nm )
240 {
241 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
242 {
243 if( ++counter < numMul )
244 {
245 nt = np+nm+nz;
246 if( nt>0 && nt<=numSec )
247 {
248 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
249 dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
250 if( std::fabs(dum) < 1.0 )
251 {
252 if( test >= 1.0e-10 )excs += dum*test;
253 }
254 else
255 excs += dum*test;
256 }
257 }
258 }
259 }
260 }
261 if( ran >= excs ) // 3 previous loops continued to the end
262 {
263 quasiElastic = true;
264 return;
265 }
266 np--; nm--; nz--;
267 //
268 // number of secondary mesons determined by kno distribution
269 // check for total charge of final state mesons to determine
270 // the kind of baryons to be produced, taking into account
271 // charge and strangeness conservation
272 //
273 if( np < nm )
274 {
275 if( np+1 == nm )
276 {
277 currentParticle.SetDefinitionAndUpdateE( aXiZero );
278 incidentHasChanged = true;
279 }
280 else // charge mismatch
281 {
282 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
283 incidentHasChanged = true;
284 //
285 // correct the strangeness by replacing a pi- by a kaon-
286 //
287 vec.Initialize( 1 );
288 G4ReactionProduct *p = new G4ReactionProduct;
289 p->SetDefinition( aKaonMinus );
290 (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
291 vec.SetElement( vecLen++, p );
292 --nm;
293 }
294 }
295 else if( np == nm )
296 {
297 if( G4UniformRand() >= 0.5 )
298 {
299 currentParticle.SetDefinitionAndUpdateE( aXiZero );
300 incidentHasChanged = true;
301 targetParticle.SetDefinitionAndUpdateE( aNeutron );
302 targetHasChanged = true;
303 }
304 }
305 else
306 {
307 targetParticle.SetDefinitionAndUpdateE( aNeutron );
308 targetHasChanged = true;
309 }
310 }
311 else // target must be a neutron
312 {
313 counter = -1;
314 for( np=0; np<numSec/3 && ran>=excs; ++np )
315 {
316 for( nm=np; nm<=(np+2) && ran>=excs; ++nm )
317 {
318 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
319 {
320 if( ++counter < numMul )
321 {
322 nt = np+nm+nz;
323 if( nt>0 && nt<=numSec )
324 {
325 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
326 dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
327 if( std::fabs(dum) < 1.0 )
328 {
329 if( test >= 1.0e-10 )excs += dum*test;
330 }
331 else
332 excs += dum*test;
333 }
334 }
335 }
336 }
337 }
338 if( ran >= excs ) // 3 previous loops continued to the end
339 {
340 quasiElastic = true;
341 return;
342 }
343 np--; nm--; nz--;
344 if( np+1 < nm )
345 {
346 if( np+2 == nm )
347 {
348 currentParticle.SetDefinitionAndUpdateE( aXiZero );
349 incidentHasChanged = true;
350 targetParticle.SetDefinitionAndUpdateE( aProton );
351 targetHasChanged = true;
352 }
353 else // charge mismatch
354 {
355 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
356 incidentHasChanged = true;
357 targetParticle.SetDefinitionAndUpdateE( aProton );
358 targetHasChanged = true;
359 //
360 // correct the strangeness by replacing a pi- by a kaon-
361 //
362 vec.Initialize( 1 );
363 G4ReactionProduct *p = new G4ReactionProduct;
364 p->SetDefinition( aKaonMinus );
365 (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
366 vec.SetElement( vecLen++, p );
367 --nm;
368 }
369 }
370 else if( np+1 == nm )
371 {
372 if( G4UniformRand() < 0.5 )
373 {
374 currentParticle.SetDefinitionAndUpdateE( aXiZero );
375 incidentHasChanged = true;
376 }
377 else
378 {
379 targetParticle.SetDefinitionAndUpdateE( aProton );
380 targetHasChanged = true;
381 }
382 }
383 }
384 SetUpPions( np, nm, nz, vec, vecLen );
385 return;
386}
387
388 /* end of file */
389
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