source: trunk/source/processes/hadronic/models/coherent_elastic/src/G4HadronElastic.cc@ 1036

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

update to geant4.9.2
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25//
26// $Id: G4HadronElastic.cc,v 1.61 2008/08/05 07:37:39 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02 $
28//
29//
30// Physics model class G4HadronElastic (derived from G4LElastic)
31//
32//
33// G4 Model: Low-energy Elastic scattering with 4-momentum balance
34// F.W. Jones, TRIUMF, 04-JUN-96
35// Uses G4ElasticHadrNucleusHE and G4VQCrossSection
36//
37//
38// 25-JUN-98 FWJ: replaced missing Initialize for ParticleChange.
39// 09-Set-05 V.Ivanchenko HARP version of the model: fix scattering
40// on hydrogen, use relativistic Lorentz transformation
41// 24-Nov-05 V.Ivanchenko sample cost in center of mass reference system
42// 03-Dec-05 V.Ivanchenko add protection to initial momentum 20 MeV/c in
43// center of mass system (before it was in lab system)
44// below model is not valid
45// 14-Dec-05 V.Ivanchenko change protection to cos(theta) < -1 and
46// rename the class
47// 13-Apr-06 V.Ivanchenko move to coherent_elastic subdirectory; remove
48// charge exchange; remove limitation on incident momentum;
49// add s-wave regim below some momentum
50// 24-Apr-06 V.Ivanchenko add neutron scattering on hydrogen from CHIPS
51// 07-Jun-06 V.Ivanchenko fix problem of rotation
52// 25-Jul-06 V.Ivanchenko add 19 MeV low energy, below which S-wave is sampled
53// 02-Aug-06 V.Ivanchenko introduce energy cut on the aria of S-wave for pions
54// 24-Aug-06 V.Ivanchenko switch on G4ElasticHadrNucleusHE
55// 31-Aug-06 V.Ivanchenko do not sample sacttering for particles with kinetic
56// energy below 10 keV
57// 16-Nov-06 V.Ivanchenko Simplify logic of choosing of the model for sampling
58// 30-Mar-07 V.Ivanchenko lowEnergyLimitQ=0, lowEnergyLimitHE = 1.0*GeV,
59// lowestEnergyLimit= 0
60// 04-May-07 V.Ivanchenko do not use HE model for hydrogen target to avoid NaN;
61// use QElastic for p, n incident for any energy for
62// p and He targets only
63// 11-May-07 V.Ivanchenko remove unused method Defs1
64//
65
66#include "G4HadronElastic.hh"
67#include "G4ParticleTable.hh"
68#include "G4ParticleDefinition.hh"
69#include "G4IonTable.hh"
70#include "G4QElasticCrossSection.hh"
71#include "G4VQCrossSection.hh"
72#include "G4ElasticHadrNucleusHE.hh"
73#include "Randomize.hh"
74#include "G4Proton.hh"
75#include "G4Neutron.hh"
76#include "G4Deuteron.hh"
77#include "G4Alpha.hh"
78#include "G4PionPlus.hh"
79#include "G4PionMinus.hh"
80
81G4HadronElastic::G4HadronElastic(G4ElasticHadrNucleusHE* HModel)
82 : G4HadronicInteraction("G4HadronElastic"), hElastic(HModel)
83{
84 SetMinEnergy( 0.0*GeV );
85 SetMaxEnergy( 100.*TeV );
86 verboseLevel= 0;
87 lowEnergyRecoilLimit = 100.*keV;
88 lowEnergyLimitQ = 0.0*GeV;
89 lowEnergyLimitHE = 1.0*GeV;
90 lowestEnergyLimit= 1.e-6*eV;
91 plabLowLimit = 20.0*MeV;
92
93 qCManager = G4QElasticCrossSection::GetPointer();
94 if(!hElastic) hElastic = new G4ElasticHadrNucleusHE();
95
96 theProton = G4Proton::Proton();
97 theNeutron = G4Neutron::Neutron();
98 theDeuteron = G4Deuteron::Deuteron();
99 theAlpha = G4Alpha::Alpha();
100 thePionPlus = G4PionPlus::PionPlus();
101 thePionMinus= G4PionMinus::PionMinus();
102
103 nnans = 0;
104 npos = 0;
105 nneg = 0;
106 neneg = 0;
107}
108
109G4HadronElastic::~G4HadronElastic()
110{
111 delete hElastic;
112 if( (nnans + npos + nneg + neneg) > 0 ) {
113 G4cout << "### G4HadronElastic destructor Warnings: ";
114 if(nnans > 0) G4cout << "### N(nans) = " << nnans;
115 if(npos > 0) G4cout << "### N(cost > 1)= " << npos;
116 if(nneg > 0) G4cout << "### N(cost <-1)= " << nneg;
117 if(neneg > 0) G4cout << "### N(E < 0)= " << neneg;
118 G4cout << "###" << G4endl;
119 }
120}
121
122G4VQCrossSection* G4HadronElastic::GetCS()
123{
124 return qCManager;
125}
126
127G4ElasticHadrNucleusHE* G4HadronElastic::GetHElastic()
128{
129 return hElastic;
130}
131
132G4HadFinalState* G4HadronElastic::ApplyYourself(
133 const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
134{
135 theParticleChange.Clear();
136
137 const G4HadProjectile* aParticle = &aTrack;
138 G4double ekin = aParticle->GetKineticEnergy();
139 if(ekin <= lowestEnergyLimit) {
140 theParticleChange.SetEnergyChange(ekin);
141 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
142 return &theParticleChange;
143 }
144
145 G4double aTarget = targetNucleus.GetN();
146 G4double zTarget = targetNucleus.GetZ();
147
148 G4double plab = aParticle->GetTotalMomentum();
149 if (verboseLevel >1) {
150 G4cout << "G4HadronElastic::DoIt: Incident particle plab="
151 << plab/GeV << " GeV/c "
152 << " ekin(MeV) = " << ekin/MeV << " "
153 << aParticle->GetDefinition()->GetParticleName() << G4endl;
154 }
155 // Scattered particle referred to axis of incident particle
156 const G4ParticleDefinition* theParticle = aParticle->GetDefinition();
157 G4double m1 = theParticle->GetPDGMass();
158
159 G4int Z = static_cast<G4int>(zTarget+0.5);
160 G4int A = static_cast<G4int>(aTarget+0.5);
161 G4int N = A - Z;
162 G4int projPDG = theParticle->GetPDGEncoding();
163 if (verboseLevel>1) {
164 G4cout << "G4HadronElastic for " << theParticle->GetParticleName()
165 << " PDGcode= " << projPDG << " on nucleus Z= " << Z
166 << " A= " << A << " N= " << N
167 << G4endl;
168 }
169 G4ParticleDefinition * theDef = 0;
170
171 if(Z == 1 && A == 1) theDef = theProton;
172 else if (Z == 1 && A == 2) theDef = theDeuteron;
173 else if (Z == 1 && A == 3) theDef = G4Triton::Triton();
174 else if (Z == 2 && A == 3) theDef = G4He3::He3();
175 else if (Z == 2 && A == 4) theDef = theAlpha;
176 else theDef = G4ParticleTable::GetParticleTable()->FindIon(Z,A,0,Z);
177
178 G4double m2 = theDef->GetPDGMass();
179 G4LorentzVector lv1 = aParticle->Get4Momentum();
180 G4LorentzVector lv(0.0,0.0,0.0,m2);
181 lv += lv1;
182
183 G4ThreeVector bst = lv.boostVector();
184 lv1.boost(-bst);
185
186 G4ThreeVector p1 = lv1.vect();
187 G4double ptot = p1.mag();
188 G4double tmax = 4.0*ptot*ptot;
189 G4double t = 0.0;
190
191 // Choose generator
192 G4ElasticGenerator gtype = fLElastic;
193
194 // Q-elastic for p,n scattering on H and He
195 if (theParticle == theProton || theParticle == theNeutron) {
196 // && Z <= 2 && ekin >= lowEnergyLimitQ)
197 gtype = fQElastic;
198
199 } else {
200 // S-wave for very low energy
201 if(plab < plabLowLimit) gtype = fSWave;
202 // HE-elastic for energetic projectile mesons
203 else if(ekin >= lowEnergyLimitHE && theParticle->GetBaryonNumber() == 0)
204 { gtype = fHElastic; }
205 }
206
207 //
208 // Sample t
209 //
210 if(gtype == fQElastic) {
211 if (verboseLevel >1) {
212 G4cout << "G4HadronElastic: Z= " << Z << " N= "
213 << N << " pdg= " << projPDG
214 << " mom(GeV)= " << plab/GeV << " " << qCManager << G4endl;
215 }
216 if(Z == 1 && N == 2) N = 1;
217 else if(Z == 2 && N == 1) N = 2;
218 G4double cs = qCManager->GetCrossSection(false,plab,Z,N,projPDG);
219
220 // check if cross section is reasonable
221 if(cs > 0.0) t = qCManager->GetExchangeT(Z,N,projPDG);
222 else if(plab > plabLowLimit) gtype = fLElastic;
223 else gtype = fSWave;
224 }
225
226 if(gtype == fLElastic) {
227 G4double g2 = GeV*GeV;
228 t = g2*SampleT(tmax/g2,m1,m2,aTarget);
229 }
230
231 // use mean atomic number
232 if(gtype == fHElastic) {
233 t = hElastic->SampleT(theParticle,plab,Z,A);
234 }
235
236 // NaN finder
237 if(!(t < 0.0 || t >= 0.0)) {
238 if (verboseLevel > 0) {
239 G4cout << "G4HadronElastic:WARNING: Z= " << Z << " N= "
240 << N << " pdg= " << projPDG
241 << " mom(GeV)= " << plab/GeV
242 << " the model type " << gtype;
243 if(gtype == fQElastic) G4cout << " CHIPS ";
244 else if(gtype == fLElastic) G4cout << " LElastic ";
245 else if(gtype == fHElastic) G4cout << " HElastic ";
246 G4cout << " S-wave will be sampled"
247 << G4endl;
248 }
249 t = 0.0;
250 nnans++;
251 }
252
253 if(gtype == fSWave) t = G4UniformRand()*tmax;
254
255 if(verboseLevel>1) {
256 G4cout <<"type= " << gtype <<" t= " << t << " tmax= " << tmax
257 << " ptot= " << ptot << G4endl;
258 }
259 // Sampling in CM system
260 G4double phi = G4UniformRand()*twopi;
261 G4double cost = 1. - 2.0*t/tmax;
262 G4double sint;
263
264 // problem in sampling
265 if(cost >= 1.0) {
266 cost = 1.0;
267 sint = 0.0;
268 npos++;
269 } else if(cost < -1 ) {
270 /*
271 G4cout << "G4HadronElastic:WARNING: Z= " << Z << " N= "
272 << N << " " << aParticle->GetDefinition()->GetParticleName()
273 << " mom(GeV)= " << plab/GeV
274 << " the model type " << gtype;
275 if(gtype == fQElastic) G4cout << " CHIPS ";
276 else if(gtype == fLElastic) G4cout << " LElastic ";
277 else if(gtype == fHElastic) G4cout << " HElastic ";
278 G4cout << " cost= " << cost
279 << G4endl;
280 */
281 cost = 1.0;
282 sint = 0.0;
283 nneg++;
284
285 // normal situation
286 } else {
287 sint = std::sqrt((1.0-cost)*(1.0+cost));
288 }
289 if (verboseLevel>1) {
290 G4cout << "cos(t)=" << cost << " std::sin(t)=" << sint << G4endl;
291 }
292 G4ThreeVector v1(sint*std::cos(phi),sint*std::sin(phi),cost);
293 v1 *= ptot;
294 G4LorentzVector nlv1(v1.x(),v1.y(),v1.z(),std::sqrt(ptot*ptot + m1*m1));
295
296 nlv1.boost(bst);
297
298 G4double eFinal = nlv1.e() - m1;
299 if (verboseLevel > 1) {
300 G4cout << "Scattered: "
301 << nlv1<<" m= " << m1 << " ekin(MeV)= " << eFinal
302 << " Proj: 4-mom " << lv1
303 <<G4endl;
304 }
305 if(eFinal <= lowestEnergyLimit) {
306 if(eFinal < 0.0 && verboseLevel > 0) {
307 neneg++;
308 G4cout << "G4HadronElastic WARNING ekin= " << eFinal
309 << " after scattering of "
310 << aParticle->GetDefinition()->GetParticleName()
311 << " p(GeV/c)= " << plab
312 << " on " << theDef->GetParticleName()
313 << G4endl;
314 }
315 theParticleChange.SetEnergyChange(0.0);
316 nlv1 = G4LorentzVector(0.0,0.0,0.0,m1);
317
318 } else {
319 theParticleChange.SetMomentumChange(nlv1.vect().unit());
320 theParticleChange.SetEnergyChange(eFinal);
321 }
322
323 G4LorentzVector nlv0 = lv - nlv1;
324 G4double erec = nlv0.e() - m2;
325 if (verboseLevel > 1) {
326 G4cout << "Recoil: "
327 << nlv0<<" m= " << m2 << " ekin(MeV)= " << erec
328 <<G4endl;
329 }
330 if(erec > lowEnergyRecoilLimit) {
331 G4DynamicParticle * aSec = new G4DynamicParticle(theDef, nlv0);
332 theParticleChange.AddSecondary(aSec);
333 } else {
334 if(erec < 0.0) erec = 0.0;
335 theParticleChange.SetLocalEnergyDeposit(erec);
336 }
337
338 return &theParticleChange;
339}
340
341G4double
342G4HadronElastic::SampleT(G4double tmax, G4double, G4double, G4double atno2)
343{
344 // G4cout << "Entering elastic scattering 2"<<G4endl;
345 // Compute the direction of elastic scattering.
346 // It is planned to replace this code with a method based on
347 // parameterized functions and a Monte Carlo method to invert the CDF.
348
349 // G4double ran = G4UniformRand();
350 G4double aa, bb, cc, dd, rr;
351 if (atno2 <= 62.) {
352 aa = std::pow(atno2, 1.63);
353 bb = 14.5*std::pow(atno2, 0.66);
354 cc = 1.4*std::pow(atno2, 0.33);
355 dd = 10.;
356 } else {
357 aa = std::pow(atno2, 1.33);
358 bb = 60.*std::pow(atno2, 0.33);
359 cc = 0.4*std::pow(atno2, 0.40);
360 dd = 10.;
361 }
362 aa = aa/bb;
363 cc = cc/dd;
364 G4double ran, t1, t2;
365 do {
366 ran = G4UniformRand();
367 t1 = -std::log(ran)/bb;
368 t2 = -std::log(ran)/dd;
369 } while(t1 > tmax || t2 > tmax);
370
371 rr = (aa + cc)*ran;
372
373 if (verboseLevel > 1) {
374 G4cout << "DoIt: aa,bb,cc,dd,rr" << G4endl;
375 G4cout << aa << " " << bb << " " << cc << " " << dd << " " << rr << G4endl;
376 G4cout << "t1,Fctcos " << t1 << " " << Fctcos(t1, aa, bb, cc, dd, rr) << G4endl;
377 G4cout << "t2,Fctcos " << t2 << " " << Fctcos(t2, aa, bb, cc, dd, rr) << G4endl;
378 }
379 G4double eps = 0.001;
380 G4int ind1 = 10;
381 G4double t = 0.0;
382 G4int ier1;
383 ier1 = Rtmi(&t, t1, t2, eps, ind1,
384 aa, bb, cc, dd, rr);
385 if (verboseLevel > 1) {
386 G4cout << "From Rtmi, ier1=" << ier1 << " t= " << t << G4endl;
387 G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << G4endl;
388 }
389 if (ier1 != 0) t = 0.25*(3.*t1 + t2);
390 if (verboseLevel > 1) {
391 G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) <<
392 G4endl;
393 }
394 return t;
395}
396
397// The following is a "translation" of a root-finding routine
398// from GEANT3.21/GHEISHA. Some of the labelled block structure has
399// been retained for clarity. This routine will not be needed after
400// the planned revisions to DoIt().
401
402G4int
403G4HadronElastic::Rtmi(G4double* x, G4double xli, G4double xri, G4double eps,
404 G4int iend,
405 G4double aa, G4double bb, G4double cc, G4double dd,
406 G4double rr)
407{
408 G4int ier = 0;
409 G4double xl = xli;
410 G4double xr = xri;
411 *x = xl;
412 G4double tol = *x;
413 G4double f = Fctcos(tol, aa, bb, cc, dd, rr);
414 if (f == 0.) return ier;
415 G4double fl, fr;
416 fl = f;
417 *x = xr;
418 tol = *x;
419 f = Fctcos(tol, aa, bb, cc, dd, rr);
420 if (f == 0.) return ier;
421 fr = f;
422
423// Error return in case of wrong input data
424 if (fl*fr >= 0.) {
425 ier = 2;
426 return ier;
427 }
428
429// Basic assumption fl*fr less than 0 is satisfied.
430// Generate tolerance for function values.
431 G4int i = 0;
432 G4double tolf = 100.*eps;
433
434// Start iteration loop
435label4:
436 i++;
437
438// Start bisection loop
439 for (G4int k = 1; k <= iend; k++) {
440 *x = 0.5*(xl + xr);
441 tol = *x;
442 f = Fctcos(tol, aa, bb, cc, dd, rr);
443 if (f == 0.) return 0;
444 if (f*fr < 0.) { // Interchange xl and xr in order to get the
445 tol = xl; // same Sign in f and fr
446 xl = xr;
447 xr = tol;
448 tol = fl;
449 fl = fr;
450 fr = tol;
451 }
452 tol = f - fl;
453 G4double a = f*tol;
454 a = a + a;
455 if (a < fr*(fr - fl) && i <= iend) goto label17;
456 xr = *x;
457 fr = f;
458
459// Test on satisfactory accuracy in bisection loop
460 tol = eps;
461 a = std::abs(xr);
462 if (a > 1.) tol = tol*a;
463 if (std::abs(xr - xl) <= tol && std::abs(fr - fl) <= tolf) goto label14;
464 }
465// End of bisection loop
466
467// No convergence after iend iteration steps followed by iend
468// successive steps of bisection or steadily increasing function
469// values at right bounds. Error return.
470 ier = 1;
471
472label14:
473 if (std::abs(fr) > std::abs(fl)) {
474 *x = xl;
475 f = fl;
476 }
477 return ier;
478
479// Computation of iterated x-value by inverse parabolic interp
480label17:
481 G4double a = fr - f;
482 G4double dx = (*x - xl)*fl*(1. + f*(a - tol)/(a*(fr - fl)))/tol;
483 G4double xm = *x;
484 G4double fm = f;
485 *x = xl - dx;
486 tol = *x;
487 f = Fctcos(tol, aa, bb, cc, dd, rr);
488 if (f == 0.) return ier;
489
490// Test on satisfactory accuracy in iteration loop
491 tol = eps;
492 a = std::abs(*x);
493 if (a > 1) tol = tol*a;
494 if (std::abs(dx) <= tol && std::abs(f) <= tolf) return ier;
495
496// Preparation of next bisection loop
497 if (f*fl < 0.) {
498 xr = *x;
499 fr = f;
500 }
501 else {
502 xl = *x;
503 fl = f;
504 xr = xm;
505 fr = fm;
506 }
507 goto label4;
508}
509
510// Test function for root-finder
511G4double
512G4HadronElastic::Fctcos(G4double t,
513 G4double aa, G4double bb, G4double cc, G4double dd,
514 G4double rr)
515{
516 const G4double expxl = -82.;
517 const G4double expxu = 82.;
518
519 G4double test1 = -bb*t;
520 if (test1 > expxu) test1 = expxu;
521 if (test1 < expxl) test1 = expxl;
522
523 G4double test2 = -dd*t;
524 if (test2 > expxu) test2 = expxu;
525 if (test2 < expxl) test2 = expxl;
526
527 return aa*std::exp(test1) + cc*std::exp(test2) - rr;
528}
529
530
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