source: trunk/source/processes/hadronic/models/high_energy/src/G4HEProtonInelastic.cc@ 1350

Last change on this file since 1350 was 1347, checked in by garnier, 15 years ago

geant4 tag 9.4
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25//
26// $Id: G4HEProtonInelastic.cc,v 1.16 2010/11/29 05:44:44 dennis Exp $
27// GEANT4 tag $Name: geant4-09-04-ref-00 $
28//
29
30#include "globals.hh"
31#include "G4ios.hh"
32
33// G4 Process: Gheisha High Energy Collision model.
34// This includes the high energy cascading model, the two-body-resonance model
35// and the low energy two-body model. Not included are the low energy stuff
36// like nuclear reactions, nuclear fission without any cascading and all
37// processes for particles at rest.
38// First work done by J.L.Chuma and F.W.Jones, TRIUMF, June 96.
39// H. Fesefeldt, RWTH-Aachen, 23-October-1996
40// Last modified: 29-July-1998.
41
42#include "G4HEProtonInelastic.hh"
43
44G4HadFinalState*
45G4HEProtonInelastic::ApplyYourself(const G4HadProjectile& aTrack,
46 G4Nucleus& targetNucleus)
47{
48 G4HEVector* pv = new G4HEVector[MAXPART];
49 const G4HadProjectile* aParticle = &aTrack;
50 const G4double A = targetNucleus.GetN();
51 const G4double Z = targetNucleus.GetZ();
52 G4HEVector incidentParticle(aParticle);
53
54 G4double atomicNumber = Z;
55 G4double atomicWeight = A;
56
57 if (verboseLevel > 1)
58 G4cout << "Z , A = " << atomicNumber << " " << atomicWeight << G4endl;
59
60 G4int incidentCode = incidentParticle.getCode();
61 G4double incidentMass = incidentParticle.getMass();
62 G4double incidentTotalEnergy = incidentParticle.getEnergy();
63 G4double incidentTotalMomentum = incidentParticle.getTotalMomentum();
64 G4double incidentKineticEnergy = incidentParticle.getKineticEnergy();
65
66 if (incidentKineticEnergy < 1.)
67 G4cout << "GHEProtonInelastic: incident energy < 1 GeV" << G4endl;
68
69 if (verboseLevel > 1) {
70 G4cout << "G4HEProtonInelastic::ApplyYourself" << G4endl;
71 G4cout << "incident particle " << incidentParticle.getName() << " "
72 << "mass " << incidentMass << " "
73 << "kinetic energy " << incidentKineticEnergy
74 << G4endl;
75 G4cout << "target material with (A,Z) = ("
76 << atomicWeight << "," << atomicNumber << ")" << G4endl;
77 }
78
79 G4double inelasticity = NuclearInelasticity(incidentKineticEnergy,
80 atomicWeight, atomicNumber);
81 if (verboseLevel > 1)
82 G4cout << "nuclear inelasticity = " << inelasticity << G4endl;
83
84 incidentKineticEnergy -= inelasticity;
85
86 G4double excitationEnergyGNP = 0.;
87 G4double excitationEnergyDTA = 0.;
88
89 G4double excitation = NuclearExcitation(incidentKineticEnergy,
90 atomicWeight, atomicNumber,
91 excitationEnergyGNP,
92 excitationEnergyDTA);
93
94 if (verboseLevel > 1)
95 G4cout << "nuclear excitation = " << excitation << " "
96 << excitationEnergyGNP << " " << excitationEnergyDTA << G4endl;
97
98 incidentKineticEnergy -= excitation;
99 incidentTotalEnergy = incidentKineticEnergy + incidentMass;
100 incidentTotalMomentum = std::sqrt( (incidentTotalEnergy-incidentMass)
101 *(incidentTotalEnergy+incidentMass));
102
103 G4HEVector targetParticle;
104 if (G4UniformRand() < atomicNumber/atomicWeight) {
105 targetParticle.setDefinition("Proton");
106 } else {
107 targetParticle.setDefinition("Neutron");
108 }
109
110 G4double targetMass = targetParticle.getMass();
111 G4double centerOfMassEnergy = std::sqrt(incidentMass*incidentMass
112 + targetMass*targetMass
113 + 2.0*targetMass*incidentTotalEnergy);
114 G4double availableEnergy = centerOfMassEnergy - targetMass - incidentMass;
115
116 // In the original Gheisha code, the inElastic flag was defined as follows:
117 // G4bool inElastic = InElasticCrossSectionInFirstInt
118 // (availableEnergy, incidentCode, incidentTotalMomentum);
119 // For unknown reasons, it was replaced by the following code in Geant???
120
121 G4bool inElastic = true;
122 // if (G4UniformRand() < elasticCrossSection/totalCrossSection) inElastic = false;
123
124 vecLength = 0;
125
126 if (verboseLevel > 1)
127 G4cout << "ApplyYourself: CallFirstIntInCascade for particle "
128 << incidentCode << G4endl;
129
130 G4bool successful = false;
131
132 FirstIntInCasProton(inElastic, availableEnergy, pv, vecLength,
133 incidentParticle, targetParticle, atomicWeight);
134
135 if (verboseLevel > 1)
136 G4cout << "ApplyYourself::StrangeParticlePairProduction" << G4endl;
137
138 if ((vecLength > 0) && (availableEnergy > 1.))
139 StrangeParticlePairProduction(availableEnergy, centerOfMassEnergy,
140 pv, vecLength,
141 incidentParticle, targetParticle);
142
143 HighEnergyCascading(successful, pv, vecLength,
144 excitationEnergyGNP, excitationEnergyDTA,
145 incidentParticle, targetParticle,
146 atomicWeight, atomicNumber);
147 if (!successful)
148 HighEnergyClusterProduction(successful, pv, vecLength,
149 excitationEnergyGNP, excitationEnergyDTA,
150 incidentParticle, targetParticle,
151 atomicWeight, atomicNumber);
152 if (!successful)
153 MediumEnergyCascading(successful, pv, vecLength,
154 excitationEnergyGNP, excitationEnergyDTA,
155 incidentParticle, targetParticle,
156 atomicWeight, atomicNumber);
157
158 if (!successful)
159 MediumEnergyClusterProduction(successful, pv, vecLength,
160 excitationEnergyGNP, excitationEnergyDTA,
161 incidentParticle, targetParticle,
162 atomicWeight, atomicNumber);
163 if (!successful)
164 QuasiElasticScattering(successful, pv, vecLength,
165 excitationEnergyGNP, excitationEnergyDTA,
166 incidentParticle, targetParticle,
167 atomicWeight, atomicNumber);
168 if (!successful)
169 ElasticScattering(successful, pv, vecLength,
170 incidentParticle,
171 atomicWeight, atomicNumber);
172
173 if (!successful)
174 G4cout << "GHEInelasticInteraction::ApplyYourself fails to produce final state particles"
175 << G4endl;
176
177 FillParticleChange(pv, vecLength);
178 delete [] pv;
179 theParticleChange.SetStatusChange(stopAndKill);
180 return &theParticleChange;
181}
182
183
184void
185G4HEProtonInelastic::FirstIntInCasProton(G4bool& inElastic,
186 const G4double availableEnergy,
187 G4HEVector pv[],
188 G4int& vecLen,
189 const G4HEVector& incidentParticle,
190 const G4HEVector& targetParticle,
191 const G4double atomicWeight)
192
193// Proton undergoes interaction with nucleon within a nucleus. Check if it is
194// energetically possible to produce pions/kaons. In not, assume nuclear excitation
195// occurs and input particle is degraded in energy. No other particles are produced.
196// If reaction is possible, find the correct number of pions/protons/neutrons
197// produced using an interpolation to multiplicity data. Replace some pions or
198// protons/neutrons by kaons or strange baryons according to the average
199// multiplicity per inelastic reaction.
200{
201 static const G4double expxu = std::log(MAXFLOAT); // upper bound for arg. of exp
202 static const G4double expxl = -expxu; // lower bound for arg. of exp
203
204 static const G4double protb = 0.7;
205 static const G4double neutb = 0.35;
206 static const G4double c = 1.25;
207
208 static const G4int numMul = 1200;
209 static const G4int numSec = 60;
210
211 G4int neutronCode = Neutron.getCode();
212 G4int protonCode = Proton.getCode();
213 G4double pionMass = PionPlus.getMass();
214
215 G4int targetCode = targetParticle.getCode();
216 G4double incidentTotalMomentum = incidentParticle.getTotalMomentum();
217
218 static G4bool first = true;
219 static G4double protmul[numMul], protnorm[numSec]; // proton constants
220 static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
221
222 // misc. local variables
223 // np = number of pi+, nm = number of pi-, nz = number of pi0
224
225 G4int i, counter, nt, np, nm, nz;
226
227 if (first) {
228 // compute normalization constants, this will only be done once
229 first = false;
230 for (i=0; i<numMul; i++) protmul[i] = 0.0;
231 for (i=0; i<numSec; i++) protnorm[i] = 0.0;
232 counter = -1;
233 for (np=0; np<(numSec/3); np++) {
234 for (nm=Imax(0,np-2); nm<=np; nm++) {
235 for (nz=0; nz<numSec/3; nz++) {
236 if (++counter < numMul) {
237 nt = np+nm+nz;
238 if ( (nt>0) && (nt<=numSec) ) {
239 protmul[counter] = pmltpc(np,nm,nz,nt,protb,c)
240 /(Factorial(2-np+nm)*Factorial(np-nm)) ;
241 protnorm[nt-1] += protmul[counter];
242 }
243 }
244 }
245 }
246 }
247
248 for( i=0; i<numMul; i++ )neutmul[i] = 0.0;
249 for( i=0; i<numSec; i++ )neutnorm[i] = 0.0;
250 counter = -1;
251 for (np=0; np<numSec/3; np++) {
252 for (nm=Imax(0,np-1); nm<=(np+1); nm++) {
253 for (nz=0; nz<numSec/3; nz++) {
254 if (++counter < numMul) {
255 nt = np+nm+nz;
256 if ( (nt>0) && (nt<=numSec) ) {
257 neutmul[counter] = pmltpc(np,nm,nz,nt,neutb,c)
258 /(Factorial(1-np+nm)*Factorial(1+np-nm));
259 neutnorm[nt-1] += neutmul[counter];
260 }
261 }
262 }
263 }
264 }
265 for (i=0; i<numSec; i++) {
266 if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
267 if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
268 }
269 } // end of initialization
270
271
272 // initialize the first two places
273 // the same as beam and target
274 pv[0] = incidentParticle;
275 pv[1] = targetParticle;
276 vecLen = 2;
277
278 if( !inElastic )
279 { // quasi-elastic scattering, no pions produced
280 if( targetCode == neutronCode )
281 {
282 G4double cech[] = {0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.06, 0.04, 0.005, 0.};
283 G4int iplab = G4int( Amin( 9.0, incidentTotalMomentum*2.5 ) );
284 if( G4UniformRand() < cech[iplab]/std::pow(atomicWeight,0.42) )
285 { // charge exchange pi+ n -> pi0 p
286 pv[0] = PionZero;
287 pv[1] = Proton;
288 }
289 }
290 return;
291 }
292 else if (availableEnergy <= pionMass)
293 return;
294
295 // inelastic scattering
296
297 np = 0, nm = 0, nz = 0;
298 G4double eab = availableEnergy;
299 G4int ieab = G4int( eab*5.0 );
300
301 G4double supp[] = {0., 0.4, 0.55, 0.65, 0.75, 0.82, 0.86, 0.90, 0.94, 0.98};
302 if( (ieab <= 9) && (G4UniformRand() >= supp[ieab]) )
303 {
304 // suppress high multiplicity events at low momentum
305 // only one additional pion will be produced
306 G4double w0, wp, wm, wt, ran;
307 if( targetCode == protonCode ) // target is a proton
308 {
309 w0 = - sqr(1.+protb)/(2.*c*c);
310 wp = w0 = std::exp(w0);
311 if( G4UniformRand() < w0/(w0+wp) )
312 { np = 0; nm = 0; nz = 1; }
313 else
314 { np = 1; nm = 0; nz = 0; }
315 }
316 else
317 { // target is a neutron
318 w0 = -sqr(1.+neutb)/(2.*c*c);
319 w0 = std::exp(w0);
320 wp = w0/2.;
321 wm = -sqr(-1.+neutb)/(2.*c*c);
322 wm = std::exp(wm)/2.;
323 wt = w0+wp+wm;
324 wp = w0+wp;
325 ran = G4UniformRand();
326 if( ran < w0/wt)
327 { np = 0; nm = 0; nz = 1; }
328 else if( ran < wp/wt)
329 { np = 1; nm = 0; nz = 0; }
330 else
331 { np = 0; nm = 1; nz = 0; }
332 }
333 }
334 else
335 {
336 // number of total particles vs. centre of mass Energy - 2*proton mass
337
338 G4double aleab = std::log(availableEnergy);
339 G4double n = 3.62567+aleab*(0.665843+aleab*(0.336514
340 + aleab*(0.117712+0.0136912*aleab))) - 2.0;
341
342 // normalization constant for kno-distribution.
343 // calculate first the sum of all constants, check for numerical problems.
344 G4double test, dum, anpn = 0.0;
345
346 for (nt=1; nt<=numSec; nt++) {
347 test = std::exp( Amin( expxu, Amax( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
348 dum = pi*nt/(2.0*n*n);
349 if (std::fabs(dum) < 1.0) {
350 if( test >= 1.0e-10 )anpn += dum*test;
351 } else {
352 anpn += dum*test;
353 }
354 }
355
356 G4double ran = G4UniformRand();
357 G4double excs = 0.0;
358 if( targetCode == protonCode )
359 {
360 counter = -1;
361 for (np=0; np<numSec/3; np++) {
362 for (nm=Imax(0,np-2); nm<=np; nm++) {
363 for (nz=0; nz<numSec/3; nz++) {
364 if (++counter < numMul) {
365 nt = np+nm+nz;
366 if ( (nt>0) && (nt<=numSec) ) {
367 test = std::exp( Amin( expxu, Amax( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
368 dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
369 if (std::fabs(dum) < 1.0) {
370 if( test >= 1.0e-10 )excs += dum*test;
371 } else {
372 excs += dum*test;
373 }
374 if (ran < excs) goto outOfLoop; //------------------>
375 }
376 }
377 }
378 }
379 }
380
381 // 3 previous loops continued to the end
382 inElastic = false; // quasi-elastic scattering
383 return;
384 }
385 else
386 { // target must be a neutron
387 counter = -1;
388 for (np=0; np<numSec/3; np++) {
389 for (nm=Imax(0,np-1); nm<=(np+1); nm++) {
390 for (nz=0; nz<numSec/3; nz++) {
391 if (++counter < numMul) {
392 nt = np+nm+nz;
393 if ( (nt>=1) && (nt<=numSec) ) {
394 test = std::exp( Amin( expxu, Amax( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
395 dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
396 if (std::fabs(dum) < 1.0) {
397 if( test >= 1.0e-10 )excs += dum*test;
398 } else {
399 excs += dum*test;
400 }
401 if (ran < excs) goto outOfLoop; // ------------->
402 }
403 }
404 }
405 }
406 }
407 // 3 previous loops continued to the end
408 inElastic = false; // quasi-elastic scattering.
409 return;
410 }
411 }
412 outOfLoop: // <-----------------------------------------------
413
414 if( targetCode == protonCode)
415 {
416 if( np == nm)
417 {
418 }
419 else if (np == (1+nm))
420 {
421 if( G4UniformRand() < 0.5)
422 {
423 pv[1] = Neutron;
424 }
425 else
426 {
427 pv[0] = Neutron;
428 }
429 }
430 else
431 {
432 pv[0] = Neutron;
433 pv[1] = Neutron;
434 }
435 }
436 else
437 {
438 if( np == nm)
439 {
440 if( G4UniformRand() < 0.25)
441 {
442 pv[0] = Neutron;
443 pv[1] = Proton;
444 }
445 else
446 {
447 }
448 }
449 else if ( np == (1+nm))
450 {
451 pv[0] = Neutron;
452 }
453 else
454 {
455 pv[1] = Proton;
456 }
457 }
458
459
460 nt = np + nm + nz;
461 while ( nt > 0)
462 {
463 G4double ran = G4UniformRand();
464 if ( ran < (G4double)np/nt)
465 {
466 if( np > 0 )
467 { pv[vecLen++] = PionPlus;
468 np--;
469 }
470 }
471 else if ( ran < (G4double)(np+nm)/nt)
472 {
473 if( nm > 0 )
474 {
475 pv[vecLen++] = PionMinus;
476 nm--;
477 }
478 }
479 else
480 {
481 if( nz > 0 )
482 {
483 pv[vecLen++] = PionZero;
484 nz--;
485 }
486 }
487 nt = np + nm + nz;
488 }
489 if (verboseLevel > 1)
490 {
491 G4cout << "Particles produced: " ;
492 G4cout << pv[0].getName() << " " ;
493 G4cout << pv[1].getName() << " " ;
494 for (i=2; i < vecLen; i++)
495 {
496 G4cout << pv[i].getName() << " " ;
497 }
498 G4cout << G4endl;
499 }
500 return;
501 }
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