source: trunk/source/processes/hadronic/models/low_energy/src/G4LEAntiNeutronInelastic.cc@ 1036

Last change on this file since 1036 was 1007, checked in by garnier, 17 years ago

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27// $Id: G4LEAntiNeutronInelastic.cc,v 1.14 2006/06/29 20:44:43 gunter Exp $
28// GEANT4 tag $Name: geant4-09-02 $
29//
30 // Hadronic Process: AntiNeutron Inelastic Process
31 // J.L. Chuma, TRIUMF, 18-Feb-1997
32 // Last modified: 27-Mar-1997
33 // J.P.Wellisch: 23-Apr-97: Added theNucleus.SetParameters call
34 // J.P. Wellisch: 23-Apr-97: nm = np+1; in line 392
35 // Modified by J.L.Chuma 30-Apr-97: added originalTarget for CalculateMomenta
36
37#include "G4LEAntiNeutronInelastic.hh"
38#include "Randomize.hh"
39
40 G4HadFinalState *
41 G4LEAntiNeutronInelastic::ApplyYourself( const G4HadProjectile &aTrack,
42 G4Nucleus &targetNucleus )
43 {
44 const G4HadProjectile *originalIncident = &aTrack;
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 << "G4LEAntiNeutronInelastic::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
94 G4ReactionProduct currentParticle = modifiedOriginal;
95 G4ReactionProduct targetParticle;
96 targetParticle = *originalTarget;
97 currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
98 targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
99 G4bool incidentHasChanged = false;
100 G4bool targetHasChanged = false;
101 G4bool quasiElastic = false;
102 G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec; // vec will contain the secondary particles
103 G4int vecLen = 0;
104 vec.Initialize( 0 );
105
106 const G4double cutOff = 0.1*MeV;
107 const G4double anni = std::min( 1.3*currentParticle.GetTotalMomentum()/GeV, 0.4 );
108
109 if( (currentParticle.GetKineticEnergy()/MeV > cutOff) ||
110 (G4UniformRand() > anni) )
111 Cascade( vec, vecLen,
112 originalIncident, currentParticle, targetParticle,
113 incidentHasChanged, targetHasChanged, quasiElastic );
114 else
115 quasiElastic = true;
116
117 CalculateMomenta( vec, vecLen,
118 originalIncident, originalTarget, modifiedOriginal,
119 targetNucleus, currentParticle, targetParticle,
120 incidentHasChanged, targetHasChanged, quasiElastic );
121
122 SetUpChange( vec, vecLen,
123 currentParticle, targetParticle,
124 incidentHasChanged );
125
126 delete originalTarget;
127 return &theParticleChange;
128 }
129
130 void
131 G4LEAntiNeutronInelastic::Cascade(
132 G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
133 G4int& vecLen,
134 const G4HadProjectile *originalIncident,
135 G4ReactionProduct &currentParticle,
136 G4ReactionProduct &targetParticle,
137 G4bool &incidentHasChanged,
138 G4bool &targetHasChanged,
139 G4bool &quasiElastic )
140 {
141 // derived from original FORTRAN code CASNB by H. Fesefeldt (13-Sep-1987)
142 //
143 // AntiNeutron undergoes interaction with nucleon within a nucleus. Check if it is
144 // energetically possible to produce pions/kaons. In not, assume nuclear excitation
145 // occurs and input particle is degraded in energy. No other particles are produced.
146 // If reaction is possible, find the correct number of pions/protons/neutrons
147 // produced using an interpolation to multiplicity data. Replace some pions or
148 // protons/neutrons by kaons or strange baryons according to the average
149 // multiplicity per Inelastic reaction.
150 //
151 const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass()/MeV;
152 const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
153 const G4double pOriginal = originalIncident->GetTotalMomentum()/MeV;
154 const G4double targetMass = targetParticle.GetMass()/MeV;
155 G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
156 targetMass*targetMass +
157 2.0*targetMass*etOriginal );
158 G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
159
160 static G4bool first = true;
161 const G4int numMul = 1200;
162 const G4int numMulA = 400;
163 const G4int numSec = 60;
164 static G4double protmul[numMul], protnorm[numSec]; // proton constants
165 static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
166 static G4double protmulA[numMulA], protnormA[numSec]; // proton constants
167 static G4double neutmulA[numMulA], neutnormA[numSec]; // neutron constants
168 // np = number of pi+, nm = number of pi-, nz = number of pi0
169 G4int counter, nt=0, np=0, nm=0, nz=0;
170 G4double test;
171 const G4double c = 1.25;
172 const G4double b[] = { 0.70, 0.70 };
173 if( first ) // compute normalization constants, this will only be Done once
174 {
175 first = false;
176 G4int i;
177 for( i=0; i<numMul; ++i )protmul[i] = 0.0;
178 for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
179 counter = -1;
180 for( np=0; np<(numSec/3); ++np )
181 {
182 for( nm=std::max(0,np-2); nm<=np; ++nm )
183 {
184 for( nz=0; nz<numSec/3; ++nz )
185 {
186 if( ++counter < numMul )
187 {
188 nt = np+nm+nz;
189 if( nt>0 && nt<=numSec )
190 {
191 protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
192 protnorm[nt-1] += protmul[counter];
193 }
194 }
195 }
196 }
197 }
198 for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
199 for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
200 counter = -1;
201 for( np=0; np<numSec/3; ++np )
202 {
203 for( nm=std::max(0,np-1); nm<=(np+1); ++nm )
204 {
205 for( nz=0; nz<numSec/3; ++nz )
206 {
207 if( ++counter < numMul )
208 {
209 nt = np+nm+nz;
210 if( (nt>0) && (nt<=numSec) )
211 {
212 neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
213 neutnorm[nt-1] += neutmul[counter];
214 }
215 }
216 }
217 }
218 }
219 for( i=0; i<numSec; ++i )
220 {
221 if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
222 if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
223 }
224 //
225 // do the same for annihilation channels
226 //
227 for( i=0; i<numMulA; ++i )protmulA[i] = 0.0;
228 for( i=0; i<numSec; ++i )protnormA[i] = 0.0;
229 counter = -1;
230 for( np=1; np<(numSec/3); ++np )
231 {
232 nm = np-1;
233 for( nz=0; nz<numSec/3; ++nz )
234 {
235 if( ++counter < numMulA )
236 {
237 nt = np+nm+nz;
238 if( nt>1 && nt<=numSec )
239 {
240 protmulA[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
241 protnormA[nt-1] += protmulA[counter];
242 }
243 }
244 }
245 }
246 for( i=0; i<numMulA; ++i )neutmulA[i] = 0.0;
247 for( i=0; i<numSec; ++i )neutnormA[i] = 0.0;
248 counter = -1;
249 for( np=0; np<numSec/3; ++np )
250 {
251 nm = np;
252 for( nz=0; nz<numSec/3; ++nz )
253 {
254 if( ++counter < numMulA )
255 {
256 nt = np+nm+nz;
257 if( nt>1 && nt<=numSec )
258 {
259 neutmulA[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
260 neutnormA[nt-1] += neutmulA[counter];
261 }
262 }
263 }
264 }
265 for( i=0; i<numSec; ++i )
266 {
267 if( protnormA[i] > 0.0 )protnormA[i] = 1.0/protnormA[i];
268 if( neutnormA[i] > 0.0 )neutnormA[i] = 1.0/neutnormA[i];
269 }
270 } // end of initialization
271 const G4double expxu = 82.; // upper bound for arg. of exp
272 const G4double expxl = -expxu; // lower bound for arg. of exp
273 G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
274 G4ParticleDefinition *aProton = G4Proton::Proton();
275 G4ParticleDefinition *anAntiProton = G4AntiProton::AntiProton();
276 G4ParticleDefinition *aPiPlus = G4PionPlus::PionPlus();
277
278 // energetically possible to produce pion(s) --> inelastic scattering
279 // otherwise quasi-elastic scattering
280
281 const G4double anhl[] = {1.00,1.00,1.00,1.00,1.00,1.00,1.00,1.00,0.97,0.88,
282 0.85,0.81,0.75,0.64,0.64,0.55,0.55,0.45,0.47,0.40,
283 0.39,0.36,0.33,0.10,0.01};
284 G4int iplab = G4int( pOriginal/GeV*10.0 );
285 if( iplab > 9 )iplab = G4int( (pOriginal/GeV- 1.0)*5.0 ) + 10;
286 if( iplab > 14 )iplab = G4int( pOriginal/GeV- 2.0 ) + 15;
287 if( iplab > 22 )iplab = G4int( (pOriginal/GeV-10.0)/10.0 ) + 23;
288 if( iplab > 24 )iplab = 24;
289 if( G4UniformRand() > anhl[iplab] )
290 {
291 if( availableEnergy <= aPiPlus->GetPDGMass()/MeV )
292 {
293 quasiElastic = true;
294 return;
295 }
296 G4int ieab = static_cast<G4int>(availableEnergy*5.0/GeV);
297 const G4double supp[] = {0.,0.4,0.55,0.65,0.75,0.82,0.86,0.90,0.94,0.98};
298 G4double w0, wp, wt, wm;
299 if( (availableEnergy < 2.0*GeV) && (G4UniformRand() >= supp[ieab]) )
300 {
301 // suppress high multiplicity events at low momentum
302 // only one pion will be produced
303 //
304 np = nm = nz = 0;
305 if( targetParticle.GetDefinition() == aProton )
306 {
307 test = std::exp( std::min( expxu, std::max( expxl, -(1.0+b[0])*(1.0+b[0])/(2.0*c*c) ) ) );
308 w0 = test;
309 wp = test;
310 if( G4UniformRand() < w0/(w0+wp) )
311 nz = 1;
312 else
313 np = 1;
314 }
315 else // target is a neutron
316 {
317 test = std::exp( std::min( expxu, std::max( expxl, -(1.0+b[1])*(1.0+b[1])/(2.0*c*c) ) ) );
318 w0 = test;
319 wp = test;
320 test = std::exp( std::min( expxu, std::max( expxl, -(-1.0+b[1])*(-1.0+b[1])/(2.0*c*c) ) ) );
321 wm = test;
322 wt = w0+wp+wm;
323 wp += w0;
324 G4double ran = G4UniformRand();
325 if( ran < w0/wt )
326 nz = 1;
327 else if( ran < wp/wt )
328 np = 1;
329 else
330 nm = 1;
331 }
332 }
333 else // (availableEnergy >= 2.0*GeV) || (random number < supp[ieab])
334 {
335 G4double n, anpn;
336 GetNormalizationConstant( availableEnergy, n, anpn );
337 G4double ran = G4UniformRand();
338 G4double dum, excs = 0.0;
339 if( targetParticle.GetDefinition() == aProton )
340 {
341 counter = -1;
342 for( np=0; np<numSec/3 && ran>=excs; ++np )
343 {
344 for( nm=std::max(0,np-2); nm<=np && ran>=excs; ++nm )
345 {
346 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
347 {
348 if( ++counter < numMul )
349 {
350 nt = np+nm+nz;
351 if( nt > 0 )
352 {
353 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
354 dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
355 if( std::fabs(dum) < 1.0 )
356 {
357 if( test >= 1.0e-10 )excs += dum*test;
358 }
359 else
360 excs += dum*test;
361 }
362 }
363 }
364 }
365 }
366 if( ran >= excs ) // 3 previous loops continued to the end
367 {
368 quasiElastic = true;
369 return;
370 }
371 np--; nm--; nz--;
372 }
373 else // target must be a neutron
374 {
375 counter = -1;
376 for( np=0; np<numSec/3 && ran>=excs; ++np )
377 {
378 for( nm=std::max(0,np-1); nm<=(np+1) && ran>=excs; ++nm )
379 {
380 for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
381 {
382 if( ++counter < numMul )
383 {
384 nt = np+nm+nz;
385 if( (nt>=1) && (nt<=numSec) )
386 {
387 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
388 dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
389 if( std::fabs(dum) < 1.0 )
390 {
391 if( test >= 1.0e-10 )excs += dum*test;
392 }
393 else
394 excs += dum*test;
395 }
396 }
397 }
398 }
399 }
400 if( ran >= excs ) // 3 previous loops continued to the end
401 {
402 quasiElastic = true;
403 return;
404 }
405 np--; nm--; nz--;
406 }
407 }
408 if( targetParticle.GetDefinition() == aProton )
409 {
410 switch( np-nm )
411 {
412 case 1:
413 if( G4UniformRand() < 0.5 )
414 {
415 currentParticle.SetDefinitionAndUpdateE( anAntiProton );
416 incidentHasChanged = true;
417 }
418 else
419 {
420 targetParticle.SetDefinitionAndUpdateE( aNeutron );
421 targetHasChanged = true;
422 }
423 break;
424 case 2:
425 currentParticle.SetDefinitionAndUpdateE( anAntiProton );
426 targetParticle.SetDefinitionAndUpdateE( aNeutron );
427 incidentHasChanged = true;
428 targetHasChanged = true;
429 break;
430 default:
431 break;
432 }
433 }
434 else // target must be a neutron
435 {
436 switch( np-nm )
437 {
438 case 0:
439 if( G4UniformRand() < 0.33 )
440 {
441 currentParticle.SetDefinitionAndUpdateE( anAntiProton );
442 targetParticle.SetDefinitionAndUpdateE( aProton );
443 incidentHasChanged = true;
444 targetHasChanged = true;
445 }
446 break;
447 case 1:
448 currentParticle.SetDefinitionAndUpdateE( anAntiProton );
449 incidentHasChanged = true;
450 break;
451 default:
452 targetParticle.SetDefinitionAndUpdateE( aProton );
453 targetHasChanged = true;
454 break;
455 }
456 }
457 }
458 else // random number <= anhl[iplab]
459 {
460 if( centerofmassEnergy <= 2*aPiPlus->GetPDGMass()/MeV )
461 {
462 quasiElastic = true;
463 return;
464 }
465 //
466 // annihilation channels
467 //
468 G4double n, anpn;
469 GetNormalizationConstant( -centerofmassEnergy, n, anpn );
470 G4double ran = G4UniformRand();
471 G4double dum, excs = 0.0;
472 if( targetParticle.GetDefinition() == aProton )
473 {
474 counter = -1;
475 for( np=1; (np<numSec/3) && (ran>=excs); ++np )
476 {
477 nm = np-1;
478 for( nz=0; (nz<numSec/3) && (ran>=excs); ++nz )
479 {
480 if( ++counter < numMulA )
481 {
482 nt = np+nm+nz;
483 if( nt>1 && nt<=numSec )
484 {
485 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
486 dum = (pi/anpn)*nt*protmulA[counter]*protnormA[nt-1]/(2.0*n*n);
487 if( std::fabs(dum) < 1.0 )
488 {
489 if( test >= 1.0e-10 )excs += dum*test;
490 }
491 else
492 excs += dum*test;
493 }
494 }
495 }
496 }
497 }
498 else // target must be a neutron
499 {
500 counter = -1;
501 for( np=0; (np<numSec/3) && (ran>=excs); ++np )
502 {
503 nm = np;
504 for( nz=0; (nz<numSec/3) && (ran>=excs); ++nz )
505 {
506 if( ++counter < numMulA )
507 {
508 nt = np+nm+nz;
509 if( (nt>1) && (nt<=numSec) )
510 {
511 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
512 dum = (pi/anpn)*nt*neutmulA[counter]*neutnormA[nt-1]/(2.0*n*n);
513 if( std::fabs(dum) < 1.0 )
514 {
515 if( test >= 1.0e-10 )excs += dum*test;
516 }
517 else
518 excs += dum*test;
519 }
520 }
521 }
522 }
523 }
524 if( ran >= excs ) // 3 previous loops continued to the end
525 {
526 quasiElastic = true;
527 return;
528 }
529 np--; nz--;
530 currentParticle.SetMass( 0.0 );
531 targetParticle.SetMass( 0.0 );
532 }
533 while(np+nm+nz<3) nz++;
534 SetUpPions( np, nm, nz, vec, vecLen );
535 return;
536 }
537
538 /* end of file */
539
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