source: trunk/source/processes/hadronic/models/low_energy/src/G4LELambdaInelastic.cc@ 1201

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update CVS release candidate geant4.9.3.01
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27// $Id: G4LELambdaInelastic.cc,v 1.11 2006/06/29 20:45:05 gunter Exp $
28// GEANT4 tag $Name: geant4-09-03-cand-01 $
29//
30 // Hadronic Process: Lambda Inelastic Process
31 // J.L. Chuma, TRIUMF, 18-Feb-1997
32 // Last modified: 27-Mar-1997
33 // Modified by J.L.Chuma 30-Apr-97: added originalTarget for CalculateMomenta
34
35#include "G4LELambdaInelastic.hh"
36#include "Randomize.hh"
37
38 G4HadFinalState *
39 G4LELambdaInelastic::ApplyYourself( const G4HadProjectile &aTrack,
40 G4Nucleus &targetNucleus )
41 {
42 const G4HadProjectile *originalIncident = &aTrack;
43 //
44 // create the target particle
45 //
46 G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
47
48 if( verboseLevel > 1 )
49 {
50 const G4Material *targetMaterial = aTrack.GetMaterial();
51 G4cout << "G4LELambdaInelastic::ApplyYourself called" << G4endl;
52 G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
53 G4cout << "target material = " << targetMaterial->GetName() << ", ";
54 G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
55 << G4endl;
56 }
57 //
58 // Fermi motion and evaporation
59 // As of Geant3, the Fermi energy calculation had not been Done
60 //
61 G4double ek = originalIncident->GetKineticEnergy()/MeV;
62 G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
63 G4ReactionProduct modifiedOriginal;
64 modifiedOriginal = *originalIncident;
65
66 G4double tkin = targetNucleus.Cinema( ek );
67 ek += tkin;
68 modifiedOriginal.SetKineticEnergy( ek*MeV );
69 G4double et = ek + amas;
70 G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
71 G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
72 if( pp > 0.0 )
73 {
74 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
75 modifiedOriginal.SetMomentum( momentum * (p/pp) );
76 }
77 //
78 // calculate black track energies
79 //
80 tkin = targetNucleus.EvaporationEffects( ek );
81 ek -= tkin;
82 modifiedOriginal.SetKineticEnergy( ek*MeV );
83 et = ek + amas;
84 p = std::sqrt( std::abs((et-amas)*(et+amas)) );
85 pp = modifiedOriginal.GetMomentum().mag()/MeV;
86 if( pp > 0.0 )
87 {
88 G4ThreeVector momentum = modifiedOriginal.GetMomentum();
89 modifiedOriginal.SetMomentum( momentum * (p/pp) );
90 }
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
123 void
124 G4LELambdaInelastic::Cascade(
125 G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
126 G4int& vecLen,
127 const G4HadProjectile *originalIncident,
128 G4ReactionProduct &currentParticle,
129 G4ReactionProduct &targetParticle,
130 G4bool &incidentHasChanged,
131 G4bool &targetHasChanged,
132 G4bool &quasiElastic )
133 {
134 // derived from original FORTRAN code CASL0 by H. Fesefeldt (13-Sep-1987)
135 //
136 // Lambda undergoes interaction with nucleon within a nucleus. Check if it is
137 // energetically possible to produce pions/kaons. In not, assume nuclear excitation
138 // occurs and input particle is degraded in energy. No other particles are produced.
139 // If reaction is possible, find the correct number of pions/protons/neutrons
140 // produced using an interpolation to multiplicity data. Replace some pions or
141 // protons/neutrons by kaons or strange baryons according to the average
142 // multiplicity per Inelastic reaction.
143 //
144 const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass()/MeV;
145 const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
146 const G4double targetMass = targetParticle.GetMass()/MeV;
147 G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
148 targetMass*targetMass +
149 2.0*targetMass*etOriginal );
150 G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
151 if( availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass()/MeV )
152 {
153 quasiElastic = true;
154 return;
155 }
156 static G4bool first = true;
157 const G4int numMul = 1200;
158 const G4int numSec = 60;
159 static G4double protmul[numMul], protnorm[numSec]; // proton constants
160 static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
161 // np = number of pi+, nm = number of pi-, nz = number of pi0
162 G4int counter, nt=0, np=0, nm=0, nz=0;
163 G4double test;
164 const G4double c = 1.25;
165 const G4double b[] = { 0.70, 0.35 };
166 if( first ) { // compute normalization constants, this will only be Done once
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 for( nm=std::max(0,np-2); nm<=(np+1); ++nm ) {
174 for( nz=0; nz<numSec/3; ++nz ) {
175 if( ++counter < numMul ) {
176 nt = np+nm+nz;
177 if( nt>0 && nt<=numSec ) {
178 protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
179 protnorm[nt-1] += protmul[counter];
180 }
181 }
182 }
183 }
184 }
185 for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
186 for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
187 counter = -1;
188 for( np=0; np<numSec/3; ++np ) {
189 for( nm=std::max(0,np-1); nm<=(np+2); ++nm ) {
190 for( nz=0; nz<numSec/3; ++nz ) {
191 if( ++counter < numMul ) {
192 nt = np+nm+nz;
193 if( nt>0 && nt<=numSec ) {
194 neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
195 neutnorm[nt-1] += neutmul[counter];
196 }
197 }
198 }
199 }
200 }
201 for( i=0; i<numSec; ++i ) {
202 if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
203 if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
204 }
205 } // end of initialization
206
207 const G4double expxu = 82.; // upper bound for arg. of exp
208 const G4double expxl = -expxu; // lower bound for arg. of exp
209 G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
210 G4ParticleDefinition *aProton = G4Proton::Proton();
211 G4ParticleDefinition *aSigmaPlus = G4SigmaPlus::SigmaPlus();
212 G4ParticleDefinition *aSigmaMinus = G4SigmaMinus::SigmaMinus();
213 G4ParticleDefinition *aSigmaZero = G4SigmaZero::SigmaZero();
214
215 // energetically possible to produce pion(s) --> inelastic scattering
216 // otherwise quasi-elastic scattering
217
218 G4double n, anpn;
219 GetNormalizationConstant( availableEnergy, n, anpn );
220 G4double ran = G4UniformRand();
221 G4double dum, excs = 0.0;
222 if( targetParticle.GetDefinition() == aProton ) {
223 counter = -1;
224 for( np=0; np<numSec/3 && ran>=excs; ++np ) {
225 for( nm=std::max(0,np-2); nm<=(np+1) && ran>=excs; ++nm ) {
226 for( nz=0; nz<numSec/3 && ran>=excs; ++nz ) {
227 if( ++counter < numMul ) {
228 nt = np+nm+nz;
229 if( nt>0 && nt<=numSec ) {
230 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
231 dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
232 if( std::fabs(dum) < 1.0 ) {
233 if( test >= 1.0e-10 )excs += dum*test;
234 } else {
235 excs += dum*test;
236 }
237 }
238 }
239 }
240 }
241 }
242 if( ran >= excs ) // 3 previous loops continued to the end
243 {
244 quasiElastic = true;
245 return;
246 }
247 np--; nm--; nz--;
248 G4int ncht = std::max( 1, np-nm );
249 switch( ncht ) {
250 case 1:
251 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
252 incidentHasChanged = true;
253 break;
254 case 2:
255 if( G4UniformRand() < 0.5 ) {
256 if( G4UniformRand() < 0.5 ) {
257 currentParticle.SetDefinitionAndUpdateE( aSigmaZero );
258 incidentHasChanged = true;
259 }
260 } else {
261 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
262 incidentHasChanged = true;
263 targetParticle.SetDefinitionAndUpdateE( aNeutron );
264 targetHasChanged = true;
265 }
266 break;
267 case 3:
268 if( G4UniformRand() < 0.5 ) {
269 if( G4UniformRand() < 0.5 ) {
270 currentParticle.SetDefinitionAndUpdateE( aSigmaZero );
271 incidentHasChanged = true;
272 }
273 targetParticle.SetDefinitionAndUpdateE( aNeutron );
274 targetHasChanged = true;
275 } else {
276 currentParticle.SetDefinitionAndUpdateE( aSigmaMinus );
277 incidentHasChanged = true;
278 }
279 break;
280 default:
281 currentParticle.SetDefinitionAndUpdateE( aSigmaMinus );
282 incidentHasChanged = true;
283 targetParticle.SetDefinitionAndUpdateE( aNeutron );
284 targetHasChanged = true;
285 break;
286 }
287 }
288 else // target must be a neutron
289 {
290 counter = -1;
291 for( np=0; np<numSec/3 && ran>=excs; ++np ) {
292 for( nm=std::max(0,np-1); nm<=(np+2) && ran>=excs; ++nm ) {
293 for( nz=0; nz<numSec/3 && ran>=excs; ++nz ) {
294 if( ++counter < numMul ) {
295 nt = np+nm+nz;
296 if( nt>0 && nt<=numSec ) {
297 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
298 dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
299 if( std::fabs(dum) < 1.0 ) {
300 if( test >= 1.0e-10 )excs += dum*test;
301 } else {
302 excs += dum*test;
303 }
304 }
305 }
306 }
307 }
308 }
309 if( ran >= excs ) // 3 previous loops continued to the end
310 {
311 quasiElastic = true;
312 return;
313 }
314 np--; nm--; nz--;
315 G4int ncht = std::max( 1, np-nm+3 );
316 switch( ncht ) {
317 case 1:
318 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
319 incidentHasChanged = true;
320 targetParticle.SetDefinitionAndUpdateE( aProton );
321 targetHasChanged = true;
322 break;
323 case 2:
324 if( G4UniformRand() < 0.5 ) {
325 if( G4UniformRand() < 0.5 ) {
326 currentParticle.SetDefinitionAndUpdateE( aSigmaZero );
327 incidentHasChanged = true;
328 }
329 targetParticle.SetDefinitionAndUpdateE( aProton );
330 targetHasChanged = true;
331 } else {
332 currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
333 incidentHasChanged = true;
334 }
335 break;
336 case 3:
337 if( G4UniformRand() < 0.5 ) {
338 if( G4UniformRand() < 0.5 ) {
339 currentParticle.SetDefinitionAndUpdateE( aSigmaZero );
340 incidentHasChanged = true;
341 }
342 } else {
343 currentParticle.SetDefinitionAndUpdateE( aSigmaMinus );
344 incidentHasChanged = true;
345 targetParticle.SetDefinitionAndUpdateE( aProton );
346 targetHasChanged = true;
347 }
348 break;
349 default:
350 currentParticle.SetDefinitionAndUpdateE( aSigmaMinus );
351 incidentHasChanged = true;
352 break;
353 }
354 }
355 SetUpPions( np, nm, nz, vec, vecLen );
356 return;
357 }
358
359 /* end of file */
360
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