source: trunk/source/processes/hadronic/models/rpg/src/G4RPGOmegaMinusInelastic.cc@ 1347

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25//
26// $Id: G4RPGOmegaMinusInelastic.cc,v 1.1 2007/07/18 21:04:20 dennis Exp $
27// GEANT4 tag $Name: geant4-09-03-ref-09 $
28//
29
30#include "G4RPGOmegaMinusInelastic.hh"
31#include "Randomize.hh"
32
33G4HadFinalState*
34G4RPGOmegaMinusInelastic::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// G4double targetMass = originalTarget->GetDefinition()->GetPDGMass();
50 G4ReactionProduct targetParticle( originalTarget->GetDefinition() );
51
52 if( verboseLevel > 1 )
53 {
54 const G4Material *targetMaterial = aTrack.GetMaterial();
55 G4cout << "G4RPGOmegaMinusInelastic::ApplyYourself called" << G4endl;
56 G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy() << "MeV, ";
57 G4cout << "target material = " << targetMaterial->GetName() << ", ";
58 G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
59 << G4endl;
60 }
61 G4ReactionProduct currentParticle( const_cast<G4ParticleDefinition *>(originalIncident->GetDefinition() ));
62 currentParticle.SetMomentum( originalIncident->Get4Momentum().vect() );
63 currentParticle.SetKineticEnergy( originalIncident->GetKineticEnergy() );
64
65 // Fermi motion and evaporation
66 // As of Geant3, the Fermi energy calculation had not been Done
67
68 G4double ek = originalIncident->GetKineticEnergy();
69 G4double amas = originalIncident->GetDefinition()->GetPDGMass();
70
71 G4double tkin = targetNucleus.Cinema( ek );
72 ek += tkin;
73 currentParticle.SetKineticEnergy( ek );
74 G4double et = ek + amas;
75 G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
76 G4double pp = currentParticle.GetMomentum().mag();
77 if( pp > 0.0 )
78 {
79 G4ThreeVector momentum = currentParticle.GetMomentum();
80 currentParticle.SetMomentum( momentum * (p/pp) );
81 }
82
83 // calculate black track energies
84
85 tkin = targetNucleus.EvaporationEffects( ek );
86 ek -= tkin;
87 currentParticle.SetKineticEnergy( ek );
88 et = ek + amas;
89 p = std::sqrt( std::abs((et-amas)*(et+amas)) );
90 pp = currentParticle.GetMomentum().mag();
91 if( pp > 0.0 )
92 {
93 G4ThreeVector momentum = currentParticle.GetMomentum();
94 currentParticle.SetMomentum( momentum * (p/pp) );
95 }
96
97 G4ReactionProduct modifiedOriginal = currentParticle;
98
99 currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
100 targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
101 G4bool incidentHasChanged = false;
102 G4bool targetHasChanged = false;
103 G4bool quasiElastic = false;
104 G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec; // vec will contain the secondary particles
105 G4int vecLen = 0;
106 vec.Initialize( 0 );
107
108 const G4double cutOff = 0.1*MeV;
109 if( currentParticle.GetKineticEnergy() > cutOff )
110 Cascade( vec, vecLen,
111 originalIncident, currentParticle, targetParticle,
112 incidentHasChanged, targetHasChanged, quasiElastic );
113
114 CalculateMomenta( vec, vecLen,
115 originalIncident, originalTarget, modifiedOriginal,
116 targetNucleus, currentParticle, targetParticle,
117 incidentHasChanged, targetHasChanged, quasiElastic );
118
119 SetUpChange( vec, vecLen,
120 currentParticle, targetParticle,
121 incidentHasChanged );
122
123 delete originalTarget;
124 return &theParticleChange;
125}
126
127
128void G4RPGOmegaMinusInelastic::Cascade(
129 G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
130 G4int& vecLen,
131 const G4HadProjectile *originalIncident,
132 G4ReactionProduct &currentParticle,
133 G4ReactionProduct &targetParticle,
134 G4bool &incidentHasChanged,
135 G4bool &targetHasChanged,
136 G4bool &quasiElastic )
137{
138 // Derived from H. Fesefeldt's original FORTRAN code CASOM
139 // OmegaMinus undergoes interaction with nucleon within a nucleus. Check if it is
140 // energetically possible to produce pions/kaons. In not, assume nuclear excitation
141 // occurs and input particle is degraded in energy. No other particles are produced.
142 // If reaction is possible, find the correct number of pions/protons/neutrons
143 // produced using an interpolation to multiplicity data. Replace some pions or
144 // protons/neutrons by kaons or strange baryons according to the average
145 // multiplicity per Inelastic reaction.
146
147 const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass();
148 const G4double etOriginal = originalIncident->GetTotalEnergy();
149// const G4double pOriginal = originalIncident->GetTotalMomentum();
150 const G4double targetMass = targetParticle.GetMass();
151 G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
152 targetMass*targetMass +
153 2.0*targetMass*etOriginal );
154 G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
155 if( availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass() )
156 {
157 quasiElastic = true;
158 return;
159 }
160 static G4bool first = true;
161 const G4int numMul = 1200;
162 const G4int numSec = 60;
163 static G4double protmul[numMul], protnorm[numSec]; // proton constants
164 static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
165 // np = number of pi+, nm = number of pi-, nz = number of pi0
166 G4int counter, nt=0, np=0, nm=0, nz=0;
167 G4double test;
168 const G4double c = 1.25;
169 const G4double b[] = { 0.70, 0.70 };
170 if( first ) // compute normalization constants, this will only be Done once
171 {
172 first = false;
173 G4int i;
174 for( i=0; i<numMul; ++i )protmul[i] = 0.0;
175 for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
176 counter = -1;
177 for( np=0; np<(numSec/3); ++np )
178 {
179 for( nm=std::max(0,np-1); nm<=(np+1); ++nm )
180 {
181 for( nz=0; nz<numSec/3; ++nz )
182 {
183 if( ++counter < numMul )
184 {
185 nt = np+nm+nz;
186 if( nt > 0 )
187 {
188 protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
189 protnorm[nt-1] += protmul[counter];
190 }
191 }
192 }
193 }
194 }
195 for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
196 for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
197 counter = -1;
198 for( np=0; np<numSec/3; ++np )
199 {
200 for( nm=np; nm<=(np+2); ++nm )
201 {
202 for( nz=0; nz<numSec/3; ++nz )
203 {
204 if( ++counter < numMul )
205 {
206 nt = np+nm+nz;
207 if( (nt>0) && (nt<=numSec) )
208 {
209 neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
210 neutnorm[nt-1] += neutmul[counter];
211 }
212 }
213 }
214 }
215 }
216 for( i=0; i<numSec; ++i )
217 {
218 if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
219 if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
220 }
221 } // end of initialization
222
223 const G4double expxu = 82.; // upper bound for arg. of exp
224 const G4double expxl = -expxu; // lower bound for arg. of exp
225 G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
226 G4ParticleDefinition *aProton = G4Proton::Proton();
227 G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
228 G4ParticleDefinition *aPiMinus = G4PionMinus::PionMinus();
229 G4ParticleDefinition *aSigmaPlus = G4SigmaPlus::SigmaPlus();
230 G4ParticleDefinition *aXiZero = G4XiZero::XiZero();
231
232 // energetically possible to produce pion(s) --> inelastic scattering
233
234 G4double n, anpn;
235 GetNormalizationConstant( availableEnergy, n, anpn );
236 G4double ran = G4UniformRand();
237 G4double dum, excs = 0.0;
238 if( targetParticle.GetDefinition() == aProton )
239 {
240 counter = -1;
241 for( np=0; np<numSec/3 && ran>=excs; ++np )
242 {
243 for( nm=std::max(0,np-1); nm<=(np+1) && ran>=excs; ++nm )
244 {
245 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
246 {
247 if( ++counter < numMul )
248 {
249 nt = np+nm+nz;
250 if( nt > 0 )
251 {
252 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
253 dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
254 if( std::fabs(dum) < 1.0 )
255 {
256 if( test >= 1.0e-10 )excs += dum*test;
257 }
258 else
259 excs += dum*test;
260 }
261 }
262 }
263 }
264 }
265 if( ran >= excs ) // 3 previous loops continued to the end
266 {
267 quasiElastic = true;
268 return;
269 }
270 np--; nm--; nz--;
271 }
272 else // target must be a neutron
273 {
274 counter = -1;
275 for( np=0; np<numSec/3 && ran>=excs; ++np )
276 {
277 for( nm=np; nm<=(np+2) && ran>=excs; ++nm )
278 {
279 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
280 {
281 if( ++counter < numMul )
282 {
283 nt = np+nm+nz;
284 if( (nt>=1) && (nt<=numSec) )
285 {
286 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
287 dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
288 if( std::fabs(dum) < 1.0 )
289 {
290 if( test >= 1.0e-10 )excs += dum*test;
291 }
292 else
293 excs += dum*test;
294 }
295 }
296 }
297 }
298 }
299 if( ran >= excs ) // 3 previous loops continued to the end
300 {
301 quasiElastic = true;
302 return;
303 }
304 np--; nm--; nz--;
305 }
306 // number of secondary mesons determined by kno distribution
307 // check for total charge of final state mesons to determine
308 // the kind of baryons to be produced, taking into account
309 // charge and strangeness conservation
310 //
311 G4int nvefix = 0;
312 if( targetParticle.GetDefinition() == aProton )
313 {
314 if( nm > np )
315 {
316 if( nm == np+1 )
317 {
318 currentParticle.SetDefinitionAndUpdateE( aXiZero );
319 nvefix = 1;
320 }
321 else
322 {
323 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
324 nvefix = 2;
325 }
326 incidentHasChanged = true;
327 }
328 else if( nm < np )
329 {
330 targetParticle.SetDefinitionAndUpdateE( aNeutron );
331 targetHasChanged = true;
332 }
333 }
334 else // target is a neutron
335 {
336 if( np+1 < nm )
337 {
338 if( nm == np+2 )
339 {
340 currentParticle.SetDefinitionAndUpdateE( aXiZero );
341 incidentHasChanged = true;
342 nvefix = 1;
343 }
344 else // charge mismatch
345 {
346 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
347 incidentHasChanged = true;
348 nvefix = 2;
349 }
350 targetParticle.SetDefinitionAndUpdateE( aProton );
351 targetHasChanged = true;
352 }
353 else if( nm == np+1 )
354 {
355 targetParticle.SetDefinitionAndUpdateE( aProton );
356 targetHasChanged = true;
357 }
358 }
359 SetUpPions( np, nm, nz, vec, vecLen );
360 for( G4int i=0; i<vecLen && nvefix>0; ++i )
361 {
362 if( vec[i]->GetDefinition() == aPiMinus )
363 {
364 if( nvefix >= 1 )vec[i]->SetDefinitionAndUpdateE( aKaonMinus );
365 --nvefix;
366 }
367 }
368 return;
369}
370
371 /* end of file */
372
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