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G4RPGOmegaMinusInelastic.cc
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25 //
26 // $Id$
27 //
28 
30 #include "G4PhysicalConstants.hh"
31 #include "G4SystemOfUnits.hh"
32 #include "Randomize.hh"
33 
36  G4Nucleus &targetNucleus )
37 {
38  const G4HadProjectile *originalIncident = &aTrack;
39  if (originalIncident->GetKineticEnergy()<= 0.1*MeV)
40  {
44  return &theParticleChange;
45  }
46 
47  // create the target particle
48 
49  G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
50 // G4double targetMass = originalTarget->GetDefinition()->GetPDGMass();
51  G4ReactionProduct targetParticle( originalTarget->GetDefinition() );
52 
53  if( verboseLevel > 1 )
54  {
55  const G4Material *targetMaterial = aTrack.GetMaterial();
56  G4cout << "G4RPGOmegaMinusInelastic::ApplyYourself called" << G4endl;
57  G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy() << "MeV, ";
58  G4cout << "target material = " << targetMaterial->GetName() << ", ";
59  G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
60  << G4endl;
61  }
62  G4ReactionProduct currentParticle( const_cast<G4ParticleDefinition *>(originalIncident->GetDefinition() ));
63  currentParticle.SetMomentum( originalIncident->Get4Momentum().vect() );
64  currentParticle.SetKineticEnergy( originalIncident->GetKineticEnergy() );
65 
66  // Fermi motion and evaporation
67  // As of Geant3, the Fermi energy calculation had not been Done
68 
69  G4double ek = originalIncident->GetKineticEnergy();
70  G4double amas = originalIncident->GetDefinition()->GetPDGMass();
71 
72  G4double tkin = targetNucleus.Cinema( ek );
73  ek += tkin;
74  currentParticle.SetKineticEnergy( ek );
75  G4double et = ek + amas;
76  G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
77  G4double pp = currentParticle.GetMomentum().mag();
78  if( pp > 0.0 )
79  {
80  G4ThreeVector momentum = currentParticle.GetMomentum();
81  currentParticle.SetMomentum( momentum * (p/pp) );
82  }
83 
84  // calculate black track energies
85 
86  tkin = targetNucleus.EvaporationEffects( ek );
87  ek -= tkin;
88  currentParticle.SetKineticEnergy( ek );
89  et = ek + amas;
90  p = std::sqrt( std::abs((et-amas)*(et+amas)) );
91  pp = currentParticle.GetMomentum().mag();
92  if( pp > 0.0 )
93  {
94  G4ThreeVector momentum = currentParticle.GetMomentum();
95  currentParticle.SetMomentum( momentum * (p/pp) );
96  }
97 
98  G4ReactionProduct modifiedOriginal = currentParticle;
99 
100  currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
101  targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
102  G4bool incidentHasChanged = false;
103  G4bool targetHasChanged = false;
104  G4bool quasiElastic = false;
105  G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec; // vec will contain the secondary particles
106  G4int vecLen = 0;
107  vec.Initialize( 0 );
108 
109  const G4double cutOff = 0.1*MeV;
110  if( currentParticle.GetKineticEnergy() > cutOff )
111  Cascade( vec, vecLen,
112  originalIncident, currentParticle, targetParticle,
113  incidentHasChanged, targetHasChanged, quasiElastic );
114 
115  CalculateMomenta( vec, vecLen,
116  originalIncident, originalTarget, modifiedOriginal,
117  targetNucleus, currentParticle, targetParticle,
118  incidentHasChanged, targetHasChanged, quasiElastic );
119 
120  SetUpChange( vec, vecLen,
121  currentParticle, targetParticle,
122  incidentHasChanged );
123 
124  delete originalTarget;
125  return &theParticleChange;
126 }
127 
128 
129 void G4RPGOmegaMinusInelastic::Cascade(
131  G4int& vecLen,
132  const G4HadProjectile *originalIncident,
133  G4ReactionProduct &currentParticle,
134  G4ReactionProduct &targetParticle,
135  G4bool &incidentHasChanged,
136  G4bool &targetHasChanged,
137  G4bool &quasiElastic )
138 {
139  // Derived from H. Fesefeldt's original FORTRAN code CASOM
140  // OmegaMinus undergoes interaction with nucleon within a nucleus. Check if it is
141  // energetically possible to produce pions/kaons. In not, assume nuclear excitation
142  // occurs and input particle is degraded in energy. No other particles are produced.
143  // If reaction is possible, find the correct number of pions/protons/neutrons
144  // produced using an interpolation to multiplicity data. Replace some pions or
145  // protons/neutrons by kaons or strange baryons according to the average
146  // multiplicity per Inelastic reaction.
147 
148  const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass();
149  const G4double etOriginal = originalIncident->GetTotalEnergy();
150 // const G4double pOriginal = originalIncident->GetTotalMomentum();
151  const G4double targetMass = targetParticle.GetMass();
152  G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
153  targetMass*targetMass +
154  2.0*targetMass*etOriginal );
155  G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
156  if( availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass() )
157  {
158  quasiElastic = true;
159  return;
160  }
161  static G4bool first = true;
162  const G4int numMul = 1200;
163  const G4int numSec = 60;
164  static G4double protmul[numMul], protnorm[numSec]; // proton constants
165  static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
166  // np = number of pi+, nneg = number of pi-, nz = number of pi0
167  G4int counter, nt=0, np=0, nneg=0, nz=0;
168  G4double test;
169  const G4double c = 1.25;
170  const G4double b[] = { 0.70, 0.70 };
171  if( first ) // compute normalization constants, this will only be Done once
172  {
173  first = false;
174  G4int i;
175  for( i=0; i<numMul; ++i )protmul[i] = 0.0;
176  for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
177  counter = -1;
178  for( np=0; np<(numSec/3); ++np )
179  {
180  for( nneg=std::max(0,np-1); nneg<=(np+1); ++nneg )
181  {
182  for( nz=0; nz<numSec/3; ++nz )
183  {
184  if( ++counter < numMul )
185  {
186  nt = np+nneg+nz;
187  if( nt > 0 )
188  {
189  protmul[counter] = Pmltpc(np,nneg,nz,nt,b[0],c);
190  protnorm[nt-1] += protmul[counter];
191  }
192  }
193  }
194  }
195  }
196  for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
197  for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
198  counter = -1;
199  for( np=0; np<numSec/3; ++np )
200  {
201  for( nneg=np; nneg<=(np+2); ++nneg )
202  {
203  for( nz=0; nz<numSec/3; ++nz )
204  {
205  if( ++counter < numMul )
206  {
207  nt = np+nneg+nz;
208  if( (nt>0) && (nt<=numSec) )
209  {
210  neutmul[counter] = Pmltpc(np,nneg,nz,nt,b[1],c);
211  neutnorm[nt-1] += neutmul[counter];
212  }
213  }
214  }
215  }
216  }
217  for( i=0; i<numSec; ++i )
218  {
219  if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
220  if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
221  }
222  } // end of initialization
223 
224  const G4double expxu = 82.; // upper bound for arg. of exp
225  const G4double expxl = -expxu; // lower bound for arg. of exp
232 
233  // energetically possible to produce pion(s) --> inelastic scattering
234 
235  G4double n, anpn;
236  GetNormalizationConstant( availableEnergy, n, anpn );
237  G4double ran = G4UniformRand();
238  G4double dum, excs = 0.0;
239  if( targetParticle.GetDefinition() == aProton )
240  {
241  counter = -1;
242  for( np=0; np<numSec/3 && ran>=excs; ++np )
243  {
244  for( nneg=std::max(0,np-1); nneg<=(np+1) && ran>=excs; ++nneg )
245  {
246  for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
247  {
248  if( ++counter < numMul )
249  {
250  nt = np+nneg+nz;
251  if( nt > 0 )
252  {
253  test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
254  dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
255  if( std::fabs(dum) < 1.0 )
256  {
257  if( test >= 1.0e-10 )excs += dum*test;
258  }
259  else
260  excs += dum*test;
261  }
262  }
263  }
264  }
265  }
266  if( ran >= excs ) // 3 previous loops continued to the end
267  {
268  quasiElastic = true;
269  return;
270  }
271  np--; nneg--; nz--;
272  }
273  else // target must be a neutron
274  {
275  counter = -1;
276  for( np=0; np<numSec/3 && ran>=excs; ++np )
277  {
278  for( nneg=np; nneg<=(np+2) && ran>=excs; ++nneg )
279  {
280  for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
281  {
282  if( ++counter < numMul )
283  {
284  nt = np+nneg+nz;
285  if( (nt>=1) && (nt<=numSec) )
286  {
287  test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
288  dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
289  if( std::fabs(dum) < 1.0 )
290  {
291  if( test >= 1.0e-10 )excs += dum*test;
292  }
293  else
294  excs += dum*test;
295  }
296  }
297  }
298  }
299  }
300  if( ran >= excs ) // 3 previous loops continued to the end
301  {
302  quasiElastic = true;
303  return;
304  }
305  np--; nneg--; nz--;
306  }
307  // number of secondary mesons determined by kno distribution
308  // check for total charge of final state mesons to determine
309  // the kind of baryons to be produced, taking into account
310  // charge and strangeness conservation
311  //
312  G4int nvefix = 0;
313  if( targetParticle.GetDefinition() == aProton )
314  {
315  if( nneg > np )
316  {
317  if( nneg == np+1 )
318  {
319  currentParticle.SetDefinitionAndUpdateE( aXiZero );
320  nvefix = 1;
321  }
322  else
323  {
324  currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
325  nvefix = 2;
326  }
327  incidentHasChanged = true;
328  }
329  else if( nneg < np )
330  {
331  targetParticle.SetDefinitionAndUpdateE( aNeutron );
332  targetHasChanged = true;
333  }
334  }
335  else // target is a neutron
336  {
337  if( np+1 < nneg )
338  {
339  if( nneg == np+2 )
340  {
341  currentParticle.SetDefinitionAndUpdateE( aXiZero );
342  incidentHasChanged = true;
343  nvefix = 1;
344  }
345  else // charge mismatch
346  {
347  currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
348  incidentHasChanged = true;
349  nvefix = 2;
350  }
351  targetParticle.SetDefinitionAndUpdateE( aProton );
352  targetHasChanged = true;
353  }
354  else if( nneg == np+1 )
355  {
356  targetParticle.SetDefinitionAndUpdateE( aProton );
357  targetHasChanged = true;
358  }
359  }
360 
361  SetUpPions(np, nneg, nz, vec, vecLen);
362  for (G4int i = 0; i < vecLen && nvefix > 0; ++i) {
363  if (vec[i]->GetDefinition() == aPiMinus) {
364  if( nvefix >= 1 )vec[i]->SetDefinitionAndUpdateE(aKaonMinus);
365  --nvefix;
366  }
367  }
368 
369  return;
370 }
371 
372  /* end of file */
373