source: trunk/source/processes/hadronic/models/coherent_elastic/src/G4HadronElastic.cc @ 1198

Last change on this file since 1198 was 1196, checked in by garnier, 15 years ago

update CVS release candidate geant4.9.3.01
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25//
26// $Id: G4HadronElastic.cc,v 1.65 2009/10/08 18:56:57 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-03-cand-01 $
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
81G4VQCrossSection* G4HadronElastic::qCManager = 0;
82
83G4HadronElastic::G4HadronElastic(G4ElasticHadrNucleusHE* HModel) 
84  : G4HadronicInteraction("G4HadronElastic"), hElastic(HModel)
85{
86  SetMinEnergy( 0.0*GeV );
87  SetMaxEnergy( 100.*TeV );
88  verboseLevel= 0;
89  lowEnergyRecoilLimit = 100.*keV; 
90  lowEnergyLimitQ  = 0.0*GeV; 
91  lowEnergyLimitHE = 1.0*GeV; 
92  lowestEnergyLimit= 1.e-6*eV; 
93  plabLowLimit     = 20.0*MeV;
94
95  if(!qCManager) {qCManager = G4QElasticCrossSection::GetPointer();}
96  if(!hElastic) hElastic = new G4ElasticHadrNucleusHE();
97
98  theProton   = G4Proton::Proton();
99  theNeutron  = G4Neutron::Neutron();
100  theDeuteron = G4Deuteron::Deuteron();
101  theAlpha    = G4Alpha::Alpha();
102  thePionPlus = G4PionPlus::PionPlus();
103  thePionMinus= G4PionMinus::PionMinus();
104
105}
106
107G4HadronElastic::~G4HadronElastic()
108{
109  delete hElastic;
110}
111
112G4VQCrossSection* G4HadronElastic::GetCS()
113{
114  return qCManager;
115}
116
117G4ElasticHadrNucleusHE* G4HadronElastic::GetHElastic()
118{
119  return hElastic;
120}
121
122G4HadFinalState* G4HadronElastic::ApplyYourself(
123                 const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
124{
125  theParticleChange.Clear();
126
127  const G4HadProjectile* aParticle = &aTrack;
128  G4double ekin = aParticle->GetKineticEnergy();
129  if(ekin <= lowestEnergyLimit) {
130    theParticleChange.SetEnergyChange(ekin);
131    theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
132    return &theParticleChange;
133  }
134
135  G4double aTarget = targetNucleus.GetN();
136  G4double zTarget = targetNucleus.GetZ();
137
138  G4double plab = aParticle->GetTotalMomentum();
139  if (verboseLevel >1) {
140    G4cout << "G4HadronElastic::DoIt: Incident particle plab=" 
141           << plab/GeV << " GeV/c " 
142           << " ekin(MeV) = " << ekin/MeV << "  " 
143           << aParticle->GetDefinition()->GetParticleName() << G4endl;
144  }
145  // Scattered particle referred to axis of incident particle
146  const G4ParticleDefinition* theParticle = aParticle->GetDefinition();
147  G4double m1 = theParticle->GetPDGMass();
148
149  G4int Z = static_cast<G4int>(zTarget+0.5);
150  G4int A = static_cast<G4int>(aTarget+0.5);
151  G4int N = A - Z;
152  G4int projPDG = theParticle->GetPDGEncoding();
153  if (verboseLevel>1) {
154    G4cout << "G4HadronElastic for " << theParticle->GetParticleName()
155           << " PDGcode= " << projPDG << " on nucleus Z= " << Z
156           << " A= " << A << " N= " << N
157           << G4endl;
158  }
159  G4ParticleDefinition * theDef = 0;
160
161  if(Z == 1 && A == 1)       theDef = theProton;
162  else if (Z == 1 && A == 2) theDef = theDeuteron;
163  else if (Z == 1 && A == 3) theDef = G4Triton::Triton();
164  else if (Z == 2 && A == 3) theDef = G4He3::He3();
165  else if (Z == 2 && A == 4) theDef = theAlpha;
166  else theDef = G4ParticleTable::GetParticleTable()->FindIon(Z,A,0,Z);
167 
168  G4double m2 = theDef->GetPDGMass();
169  G4LorentzVector lv1 = aParticle->Get4Momentum();
170  G4LorentzVector lv(0.0,0.0,0.0,m2);   
171  lv += lv1;
172
173  G4ThreeVector bst = lv.boostVector();
174  lv1.boost(-bst);
175
176  G4ThreeVector p1 = lv1.vect();
177  G4double ptot = p1.mag();
178  G4double tmax = 4.0*ptot*ptot;
179  G4double t = 0.0;
180
181  // Choose generator
182  G4ElasticGenerator gtype = fLElastic;
183
184  // Q-elastic for p,n scattering on H and He
185  if (theParticle == theProton || theParticle == theNeutron) {
186    //     && Z <= 2 && ekin >= lowEnergyLimitQ) 
187    gtype = fQElastic;
188
189  } else {
190    // S-wave for very low energy
191    if(plab < plabLowLimit) gtype = fSWave;
192    // HE-elastic for energetic projectile mesons
193    else if(ekin >= lowEnergyLimitHE && theParticle->GetBaryonNumber() == 0) 
194      { gtype = fHElastic; }
195  }
196
197  //
198  // Sample t
199  //
200  if(gtype == fQElastic) {
201    if (verboseLevel >1) {
202      G4cout << "G4HadronElastic: Z= " << Z << " N= " 
203             << N << " pdg= " <<  projPDG
204             << " mom(GeV)= " << plab/GeV << "  " << qCManager << G4endl; 
205    }
206    if(Z == 1 && N == 2) N = 1;
207    else if(Z == 2 && N == 1) N = 2;
208    G4double cs = qCManager->GetCrossSection(false,plab,Z,N,projPDG);
209
210    // check if cross section is reasonable
211    if(cs > 0.0) t = qCManager->GetExchangeT(Z,N,projPDG);
212    else if(plab > plabLowLimit) gtype = fLElastic;
213    else gtype = fSWave;
214  }
215
216  if(gtype == fLElastic) {
217    G4double g2 = GeV*GeV; 
218    t = g2*SampleT(tmax/g2,m1,m2,aTarget);
219  }
220
221  // use mean atomic number
222  if(gtype == fHElastic) {
223    t = hElastic->SampleT(theParticle,plab,Z,A);
224  }
225
226  if(gtype == fSWave) t = G4UniformRand()*tmax;
227
228  if(verboseLevel>1) {
229    G4cout <<"type= " << gtype <<" t= " << t << " tmax= " << tmax
230           << " ptot= " << ptot << G4endl;
231  }
232  // Sampling in CM system
233  G4double phi  = G4UniformRand()*twopi;
234  G4double cost = 1. - 2.0*t/tmax;
235  G4double sint;
236
237  // problem in sampling
238  if(cost > 1.0 || cost < -1.0) {
239    if(verboseLevel > 0) {
240      G4cout << "G4HadronElastic:WARNING: Z= " << Z << " N= " 
241             << N << " " << aParticle->GetDefinition()->GetParticleName()
242             << " mom(GeV)= " << plab/GeV
243             << " the model type " << gtype;
244      if(gtype ==  fQElastic) G4cout << " CHIPS ";
245      else if(gtype ==  fLElastic) G4cout << " LElastic ";
246      else if(gtype ==  fHElastic) G4cout << " HElastic ";
247      G4cout << " cost= " << cost
248             << G4endl; 
249    }
250    cost = 1.0;
251    sint = 0.0;
252
253    // normal situation
254  } else  {
255    sint = std::sqrt((1.0-cost)*(1.0+cost));
256  }   
257  if (verboseLevel>1) {
258    G4cout << "cos(t)=" << cost << " std::sin(t)=" << sint << G4endl;
259  }
260  G4ThreeVector v1(sint*std::cos(phi),sint*std::sin(phi),cost);
261  v1 *= ptot;
262  G4LorentzVector nlv1(v1.x(),v1.y(),v1.z(),std::sqrt(ptot*ptot + m1*m1));
263
264  nlv1.boost(bst); 
265
266  G4double eFinal = nlv1.e() - m1;
267  if (verboseLevel > 1) {
268    G4cout << "Scattered: "
269           << nlv1<<" m= " << m1 << " ekin(MeV)= " << eFinal
270           << " Proj: 4-mom " << lv1
271           <<G4endl;
272  }
273  if(eFinal <= lowestEnergyLimit) {
274    if(eFinal < 0.0 && verboseLevel > 0) {
275      G4cout << "G4HadronElastic WARNING ekin= " << eFinal
276             << " after scattering of " 
277             << aParticle->GetDefinition()->GetParticleName()
278             << " p(GeV/c)= " << plab
279             << " on " << theDef->GetParticleName()
280             << G4endl;
281    }
282    theParticleChange.SetEnergyChange(0.0);
283    nlv1 = G4LorentzVector(0.0,0.0,0.0,m1);
284
285  } else {
286    theParticleChange.SetMomentumChange(nlv1.vect().unit());
287    theParticleChange.SetEnergyChange(eFinal);
288  } 
289
290  G4LorentzVector nlv0 = lv - nlv1;
291  G4double erec =  nlv0.e() - m2;
292  if (verboseLevel > 1) {
293    G4cout << "Recoil: "
294           << nlv0<<" m= " << m2 << " ekin(MeV)= " << erec
295           <<G4endl;
296  }
297  if(erec > lowEnergyRecoilLimit) {
298    G4DynamicParticle * aSec = new G4DynamicParticle(theDef, nlv0);
299    theParticleChange.AddSecondary(aSec);
300  } else {
301    if(erec < 0.0) erec = 0.0;
302    theParticleChange.SetLocalEnergyDeposit(erec);
303  }
304
305  return &theParticleChange;
306}
307
308G4double
309G4HadronElastic::SampleT(G4double tmax, G4double, G4double, G4double atno2)
310{
311  // G4cout << "Entering elastic scattering 2"<<G4endl;
312  // Compute the direction of elastic scattering.
313  // It is planned to replace this code with a method based on
314  // parameterized functions and a Monte Carlo method to invert the CDF.
315
316  //  G4double ran = G4UniformRand();
317  G4double aa, bb, cc, dd, rr;
318  if (atno2 <= 62.) {
319    aa = std::pow(atno2, 1.63);
320    bb = 14.5*std::pow(atno2, 0.66);
321    cc = 1.4*std::pow(atno2, 0.33);
322    dd = 10.;
323  } else {
324    aa = std::pow(atno2, 1.33);
325    bb = 60.*std::pow(atno2, 0.33);
326    cc = 0.4*std::pow(atno2, 0.40);
327    dd = 10.;
328  }
329  aa = aa/bb;
330  cc = cc/dd;
331  G4double ran, t1, t2;
332  do {
333    ran = G4UniformRand();
334    t1 = -std::log(ran)/bb;
335    t2 = -std::log(ran)/dd;
336  } while(t1 > tmax || t2 > tmax);
337
338  rr = (aa + cc)*ran;
339
340  if (verboseLevel > 1) {
341    G4cout << "DoIt: aa,bb,cc,dd,rr" << G4endl;
342    G4cout << aa << " " << bb << " " << cc << " " << dd << " " << rr << G4endl;
343    G4cout << "t1,Fctcos " << t1 << " " << Fctcos(t1, aa, bb, cc, dd, rr) << G4endl;
344    G4cout << "t2,Fctcos " << t2 << " " << Fctcos(t2, aa, bb, cc, dd, rr) << G4endl;
345  }
346  G4double eps = 0.001;
347  G4int ind1 = 10;
348  G4double t = 0.0;
349  G4int ier1;
350  ier1 = Rtmi(&t, t1, t2, eps, ind1,
351              aa, bb, cc, dd, rr);
352  if (verboseLevel > 1) {
353    G4cout << "From Rtmi, ier1=" << ier1 << " t= " << t << G4endl;
354    G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << G4endl;
355  }
356  if (ier1 != 0) t = 0.25*(3.*t1 + t2);
357  if (verboseLevel > 1) {
358      G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << 
359              G4endl;
360  }
361  return t;
362}
363
364// The following is a "translation" of a root-finding routine
365// from GEANT3.21/GHEISHA.  Some of the labelled block structure has
366// been retained for clarity.  This routine will not be needed after
367// the planned revisions to DoIt().
368
369G4int
370G4HadronElastic::Rtmi(G4double* x, G4double xli, G4double xri, G4double eps, 
371                      G4int iend, 
372                      G4double aa, G4double bb, G4double cc, G4double dd, 
373                      G4double rr)
374{
375   G4int ier = 0;
376   G4double xl = xli;
377   G4double xr = xri;
378   *x = xl;
379   G4double tol = *x;
380   G4double f = Fctcos(tol, aa, bb, cc, dd, rr);
381   if (f == 0.) return ier;
382   G4double fl, fr;
383   fl = f;
384   *x = xr;
385   tol = *x;
386   f = Fctcos(tol, aa, bb, cc, dd, rr);
387   if (f == 0.) return ier;
388   fr = f;
389
390// Error return in case of wrong input data
391   if (fl*fr >= 0.) {
392      ier = 2;
393      return ier;
394   }
395
396// Basic assumption fl*fr less than 0 is satisfied.
397// Generate tolerance for function values.
398   G4int i = 0;
399   G4double tolf = 100.*eps;
400
401// Start iteration loop
402label4:
403   i++;
404
405// Start bisection loop
406   for (G4int k = 1; k <= iend; k++) {
407      *x = 0.5*(xl + xr);
408      tol = *x;
409      f = Fctcos(tol, aa, bb, cc, dd, rr);
410      if (f == 0.) return 0;
411      if (f*fr < 0.) {      // Interchange xl and xr in order to get the
412         tol = xl;          // same Sign in f and fr
413         xl = xr;
414         xr = tol;
415         tol = fl;
416         fl = fr;
417         fr = tol;
418      }
419      tol = f - fl;
420      G4double a = f*tol;
421      a = a + a;
422      if (a < fr*(fr - fl) && i <= iend) goto label17;
423      xr = *x;
424      fr = f;
425
426// Test on satisfactory accuracy in bisection loop
427      tol = eps;
428      a = std::abs(xr);
429      if (a > 1.) tol = tol*a;
430      if (std::abs(xr - xl) <= tol && std::abs(fr - fl) <= tolf) goto label14;
431   }
432// End of bisection loop
433
434// No convergence after iend iteration steps followed by iend
435// successive steps of bisection or steadily increasing function
436// values at right bounds.  Error return.
437   ier = 1;
438
439label14:
440   if (std::abs(fr) > std::abs(fl)) {
441      *x = xl;
442      f = fl;
443   }
444   return ier;
445
446// Computation of iterated x-value by inverse parabolic interp
447label17:
448   G4double a = fr - f;
449   G4double dx = (*x - xl)*fl*(1. + f*(a - tol)/(a*(fr - fl)))/tol;
450   G4double xm = *x;
451   G4double fm = f;
452   *x = xl - dx;
453   tol = *x;
454   f = Fctcos(tol, aa, bb, cc, dd, rr);
455   if (f == 0.) return ier;
456
457// Test on satisfactory accuracy in iteration loop
458   tol = eps;
459   a = std::abs(*x);
460   if (a > 1) tol = tol*a;
461   if (std::abs(dx) <= tol && std::abs(f) <= tolf) return ier;
462
463// Preparation of next bisection loop
464   if (f*fl < 0.) {
465      xr = *x;
466      fr = f;
467   }
468   else {
469      xl = *x;
470      fl = f;
471      xr = xm;
472      fr = fm;
473   }
474   goto label4;
475}
476
477// Test function for root-finder
478G4double
479G4HadronElastic::Fctcos(G4double t, 
480                        G4double aa, G4double bb, G4double cc, G4double dd, 
481                        G4double rr)
482{
483   const G4double expxl = -82.;
484   const G4double expxu = 82.;
485
486   G4double test1 = -bb*t;
487   if (test1 > expxu) test1 = expxu;
488   if (test1 < expxl) test1 = expxl;
489
490   G4double test2 = -dd*t;
491   if (test2 > expxu) test2 = expxu;
492   if (test2 < expxl) test2 = expxl;
493
494   return aa*std::exp(test1) + cc*std::exp(test2) - rr;
495}
496
497
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