source: trunk/source/processes/hadronic/models/rpg/src/G4RPGXiZeroInelastic.cc@ 1038

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25//
26// $Id: G4RPGXiZeroInelastic.cc,v 1.1 2007/07/18 21:04:21 dennis Exp $
27//
28
29#include "G4RPGXiZeroInelastic.hh"
30#include "Randomize.hh"
31
32 G4HadFinalState *
33 G4RPGXiZeroInelastic::ApplyYourself( const G4HadProjectile &aTrack,
34 G4Nucleus &targetNucleus )
35 {
36 const G4HadProjectile *originalIncident = &aTrack;
37 if (originalIncident->GetKineticEnergy()<= 0.1*MeV)
38 {
39 theParticleChange.SetStatusChange(isAlive);
40 theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
41 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
42 return &theParticleChange;
43 }
44 //
45 // create the target particle
46 //
47 G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
48
49 if( verboseLevel > 1 )
50 {
51 const G4Material *targetMaterial = aTrack.GetMaterial();
52 G4cout << "G4RPGXiZeroInelastic::ApplyYourself called" << G4endl;
53 G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
54 G4cout << "target material = " << targetMaterial->GetName() << ", ";
55 G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
56 << G4endl;
57 }
58 //
59 // Fermi motion and evaporation
60 // As of Geant3, the Fermi energy calculation had not been Done
61 //
62 G4double ek = originalIncident->GetKineticEnergy()/MeV;
63 G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
64 G4ReactionProduct modifiedOriginal;
65 modifiedOriginal = *originalIncident;
66
67 G4double tkin = targetNucleus.Cinema( ek );
68 ek += tkin;
69 modifiedOriginal.SetKineticEnergy( ek*MeV );
70 G4double et = ek + amas;
71 G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
72 G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
73 if( pp > 0.0 )
74 {
75 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
76 modifiedOriginal.SetMomentum( momentum * (p/pp) );
77 }
78 //
79 // calculate black track energies
80 //
81 tkin = targetNucleus.EvaporationEffects( ek );
82 ek -= tkin;
83 modifiedOriginal.SetKineticEnergy( ek*MeV );
84 et = ek + amas;
85 p = std::sqrt( std::abs((et-amas)*(et+amas)) );
86 pp = modifiedOriginal.GetMomentum().mag()/MeV;
87 if( pp > 0.0 )
88 {
89 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
90 modifiedOriginal.SetMomentum( momentum * (p/pp) );
91 }
92 G4ReactionProduct currentParticle = modifiedOriginal;
93 G4ReactionProduct targetParticle;
94 targetParticle = *originalTarget;
95 currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
96 targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
97 G4bool incidentHasChanged = false;
98 G4bool targetHasChanged = false;
99 G4bool quasiElastic = false;
100 G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec; // vec will contain the secondary particles
101 G4int vecLen = 0;
102 vec.Initialize( 0 );
103
104 const G4double cutOff = 0.1;
105 if( currentParticle.GetKineticEnergy()/MeV > cutOff )
106 Cascade( vec, vecLen,
107 originalIncident, currentParticle, targetParticle,
108 incidentHasChanged, targetHasChanged, quasiElastic );
109
110 CalculateMomenta( vec, vecLen,
111 originalIncident, originalTarget, modifiedOriginal,
112 targetNucleus, currentParticle, targetParticle,
113 incidentHasChanged, targetHasChanged, quasiElastic );
114
115 SetUpChange( vec, vecLen,
116 currentParticle, targetParticle,
117 incidentHasChanged );
118
119 delete originalTarget;
120 return &theParticleChange;
121 }
122
123void G4RPGXiZeroInelastic::Cascade(
124 G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
125 G4int& vecLen,
126 const G4HadProjectile *originalIncident,
127 G4ReactionProduct &currentParticle,
128 G4ReactionProduct &targetParticle,
129 G4bool &incidentHasChanged,
130 G4bool &targetHasChanged,
131 G4bool &quasiElastic )
132{
133 // Derived from H. Fesefeldt's original FORTRAN code CASX0
134 //
135 // XiZero undergoes interaction with nucleon within a nucleus. Check if it is
136 // energetically possible to produce pions/kaons. In not, assume nuclear excitation
137 // occurs and input particle is degraded in energy. No other particles are produced.
138 // If reaction is possible, find the correct number of pions/protons/neutrons
139 // produced using an interpolation to multiplicity data. Replace some pions or
140 // protons/neutrons by kaons or strange baryons according to the average
141 // multiplicity per inelastic reaction.
142
143 const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass()/MeV;
144 const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
145 const G4double targetMass = targetParticle.GetMass()/MeV;
146 G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
147 targetMass*targetMass +
148 2.0*targetMass*etOriginal );
149 G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
150 if( availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass()/MeV )
151 {
152 quasiElastic = true;
153 return;
154 }
155 static G4bool first = true;
156 const G4int numMul = 1200;
157 const G4int numSec = 60;
158 static G4double protmul[numMul], protnorm[numSec]; // proton constants
159 static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
160 // np = number of pi+, nm = number of pi-, nz = number of pi0
161 G4int counter, nt=0, np=0, nm=0, nz=0;
162 G4double test;
163 const G4double c = 1.25;
164 const G4double b[] = { 0.7, 0.7 };
165 if( first ) // compute normalization constants, this will only be Done once
166 {
167 first = false;
168 G4int i;
169 for( i=0; i<numMul; ++i )protmul[i] = 0.0;
170 for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
171 counter = -1;
172 for( np=0; np<(numSec/3); ++np )
173 {
174 for( nm=std::max(0,np-2); nm<=(np+1); ++nm )
175 {
176 for( nz=0; nz<numSec/3; ++nz )
177 {
178 if( ++counter < numMul )
179 {
180 nt = np+nm+nz;
181 if( nt>0 && nt<=numSec )
182 {
183 protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
184 protnorm[nt-1] += protmul[counter];
185 }
186 }
187 }
188 }
189 }
190 for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
191 for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
192 counter = -1;
193 for( np=0; np<numSec/3; ++np )
194 {
195 for( nm=std::max(0,np-1); nm<=(np+2); ++nm )
196 {
197 for( nz=0; nz<numSec/3; ++nz )
198 {
199 if( ++counter < numMul )
200 {
201 nt = np+nm+nz;
202 if( nt>0 && nt<=numSec )
203 {
204 neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
205 neutnorm[nt-1] += neutmul[counter];
206 }
207 }
208 }
209 }
210 }
211 for( i=0; i<numSec; ++i )
212 {
213 if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
214 if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
215 }
216 } // end of initialization
217
218 const G4double expxu = 82.; // upper bound for arg. of exp
219 const G4double expxl = -expxu; // lower bound for arg. of exp
220 G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
221 G4ParticleDefinition *aProton = G4Proton::Proton();
222 G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
223 G4ParticleDefinition *aSigmaPlus = G4SigmaPlus::SigmaPlus();
224 G4ParticleDefinition *aXiMinus = G4XiMinus::XiMinus();
225 //
226 // energetically possible to produce pion(s) --> inelastic scattering
227 //
228 G4double n, anpn;
229 GetNormalizationConstant( availableEnergy, n, anpn );
230 G4double ran = G4UniformRand();
231 G4double dum, excs = 0.0;
232 if( targetParticle.GetDefinition() == aProton )
233 {
234 counter = -1;
235 for( np=0; np<numSec/3 && ran>=excs; ++np )
236 {
237 for( nm=std::max(0,np-2); nm<=(np+1) && ran>=excs; ++nm )
238 {
239 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
240 {
241 if( ++counter < numMul )
242 {
243 nt = np+nm+nz;
244 if( nt>0 && nt<=numSec )
245 {
246 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
247 dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
248 if( std::fabs(dum) < 1.0 )
249 {
250 if( test >= 1.0e-10 )excs += dum*test;
251 }
252 else
253 excs += dum*test;
254 }
255 }
256 }
257 }
258 }
259 if( ran >= excs ) // 3 previous loops continued to the end
260 {
261 quasiElastic = true;
262 return;
263 }
264 np--; nm--; nz--;
265 //
266 // number of secondary mesons determined by kno distribution
267 // check for total charge of final state mesons to determine
268 // the kind of baryons to be produced, taking into account
269 // charge and strangeness conservation
270 //
271 if( np < nm+1 )
272 {
273 if( np != nm ) // charge mismatch
274 {
275 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
276 incidentHasChanged = true;
277 //
278 // correct the strangeness by replacing a pi- by a kaon-
279 //
280 vec.Initialize( 1 );
281 G4ReactionProduct *p = new G4ReactionProduct;
282 p->SetDefinition( aKaonMinus );
283 (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
284 vec.SetElement( vecLen++, p );
285 --nm;
286 }
287 }
288 else if( np == nm+1 )
289 {
290 if( G4UniformRand() < 0.5 )
291 {
292 targetParticle.SetDefinitionAndUpdateE( aNeutron );
293 targetHasChanged = true;
294 }
295 else
296 {
297 currentParticle.SetDefinitionAndUpdateE( aXiMinus );
298 incidentHasChanged = true;
299 }
300 }
301 else
302 {
303 currentParticle.SetDefinitionAndUpdateE( aXiMinus );
304 incidentHasChanged = true;
305 targetParticle.SetDefinitionAndUpdateE( aNeutron );
306 targetHasChanged = true;
307 }
308 }
309 else // target must be a neutron
310 {
311 counter = -1;
312 for( np=0; np<numSec/3 && ran>=excs; ++np )
313 {
314 for( nm=std::max(0,np-1); nm<=(np+2) && ran>=excs; ++nm )
315 {
316 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
317 {
318 if( ++counter < numMul )
319 {
320 nt = np+nm+nz;
321 if( nt>0 && nt<=numSec )
322 {
323 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
324 dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
325 if( std::fabs(dum) < 1.0 )
326 {
327 if( test >= 1.0e-10 )excs += dum*test;
328 }
329 else
330 excs += dum*test;
331 }
332 }
333 }
334 }
335 }
336 if( ran >= excs ) // 3 previous loops continued to the end
337 {
338 quasiElastic = true;
339 return;
340 }
341 np--; nm--; nz--;
342 if( np < nm )
343 {
344 if( np+1 == nm )
345 {
346 targetParticle.SetDefinitionAndUpdateE( aProton );
347 targetHasChanged = true;
348 }
349 else // charge mismatch
350 {
351 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
352 incidentHasChanged = true;
353 targetParticle.SetDefinitionAndUpdateE( aProton );
354 targetHasChanged = true;
355 //
356 // correct the strangeness by replacing a pi- by a kaon-
357 //
358 vec.Initialize( 1 );
359 G4ReactionProduct *p = new G4ReactionProduct;
360 p->SetDefinition( aKaonMinus );
361 (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
362 vec.SetElement( vecLen++, p );
363 --nm;
364 }
365 }
366 else if( np == nm )
367 {
368 if( G4UniformRand() >= 0.5 )
369 {
370 currentParticle.SetDefinitionAndUpdateE( aXiMinus );
371 incidentHasChanged = true;
372 targetParticle.SetDefinitionAndUpdateE( aProton );
373 targetHasChanged = true;
374 }
375 }
376 else
377 {
378 currentParticle.SetDefinitionAndUpdateE( aXiMinus );
379 incidentHasChanged = true;
380 }
381 }
382 SetUpPions( np, nm, nz, vec, vecLen );
383 return;
384}
385
386 /* end of file */
387
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