source: trunk/source/processes/hadronic/models/coherent_elastic/src/G4HadronElastic.cc @ 1340

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25//
26// $Id: G4HadronElastic.cc,v 1.66 2010/01/13 15:42:06 mkossov Exp $
27// GEANT4 tag $Name: geant4-09-03-ref-09 $
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// 13.01.10: M.Kosov: Use G4Q(Pr/Neut)ElasticCS instead of G4QElasticCS
65//
66
67#include "G4HadronElastic.hh"
68#include "G4ParticleTable.hh"
69#include "G4ParticleDefinition.hh"
70#include "G4IonTable.hh"
71#include "G4QProtonElasticCrossSection.hh"
72#include "G4QNeutronElasticCrossSection.hh"
73#include "G4VQCrossSection.hh"
74#include "G4ElasticHadrNucleusHE.hh"
75#include "Randomize.hh"
76#include "G4Proton.hh"
77#include "G4Neutron.hh"
78#include "G4Deuteron.hh"
79#include "G4Alpha.hh"
80#include "G4PionPlus.hh"
81#include "G4PionMinus.hh"
82
83G4VQCrossSection* G4HadronElastic::pCManager = 0;
84G4VQCrossSection* G4HadronElastic::nCManager = 0;
85
86G4HadronElastic::G4HadronElastic(G4ElasticHadrNucleusHE* HModel) 
87  : G4HadronicInteraction("G4HadronElastic"), hElastic(HModel)
88{
89  SetMinEnergy( 0.0*GeV );
90  SetMaxEnergy( 100.*TeV );
91  verboseLevel= 0;
92  lowEnergyRecoilLimit = 100.*keV; 
93  lowEnergyLimitQ  = 0.0*GeV; 
94  lowEnergyLimitHE = 1.0*GeV; 
95  lowestEnergyLimit= 1.e-6*eV; 
96  plabLowLimit     = 20.0*MeV;
97
98  if(!pCManager)
99  {
100    pCManager = G4QProtonElasticCrossSection::GetPointer();
101    nCManager = G4QNeutronElasticCrossSection::GetPointer();
102  }
103  if(!hElastic) hElastic = new G4ElasticHadrNucleusHE();
104
105  theProton   = G4Proton::Proton();
106  theNeutron  = G4Neutron::Neutron();
107  theDeuteron = G4Deuteron::Deuteron();
108  theAlpha    = G4Alpha::Alpha();
109  thePionPlus = G4PionPlus::PionPlus();
110  thePionMinus= G4PionMinus::PionMinus();
111
112}
113
114G4HadronElastic::~G4HadronElastic()
115{
116  delete hElastic;
117}
118
119G4VQCrossSection* G4HadronElastic::GetCS()
120{
121  return pCManager;
122  //if     (PDG==2212) return pCManager;
123  //else if(PDG==2112) return nCManager;
124  //return 0;
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= "  << N << " pdg= " <<  projPDG
213               << " mom(GeV)= " << plab/GeV<<", pC="<<pCManager<<", nC="<<nCManager<<G4endl; 
214    }
215    if(Z == 1 && N == 2) N = 1;
216    else if(Z == 2 && N == 1) N = 2;
217    G4double cs = 0.;
218    if     (projPDG==2212) cs = pCManager->GetCrossSection(false,plab,Z,N,projPDG);
219    else if(projPDG==2112) cs = nCManager->GetCrossSection(false,plab,Z,N,projPDG);
220
221    // check if cross section is reasonable
222    if(cs > 0.0)
223    {
224      if     (projPDG==2212) t = pCManager->GetExchangeT(Z,N,projPDG);
225      else if(projPDG==2112) t = nCManager->GetExchangeT(Z,N,projPDG);
226    }
227    else if(plab > plabLowLimit) gtype = fLElastic;
228    else gtype = fSWave;
229  }
230
231  if(gtype == fLElastic) {
232    G4double g2 = GeV*GeV; 
233    t = g2*SampleT(tmax/g2,m1,m2,aTarget);
234  }
235
236  // use mean atomic number
237  if(gtype == fHElastic) {
238    t = hElastic->SampleT(theParticle,plab,Z,A);
239  }
240
241  if(gtype == fSWave) t = G4UniformRand()*tmax;
242
243  if(verboseLevel>1) {
244    G4cout <<"type= " << gtype <<" t= " << t << " tmax= " << tmax
245           << " ptot= " << ptot << G4endl;
246  }
247  // Sampling in CM system
248  G4double phi  = G4UniformRand()*twopi;
249  G4double cost = 1. - 2.0*t/tmax;
250  G4double sint;
251
252  // problem in sampling
253  if(cost > 1.0 || cost < -1.0) {
254    if(verboseLevel > 0) {
255      G4cout << "G4HadronElastic:WARNING: Z= " << Z << " N= " 
256             << N << " " << aParticle->GetDefinition()->GetParticleName()
257             << " mom(GeV)= " << plab/GeV
258             << " the model type " << gtype;
259      if(gtype ==  fQElastic) G4cout << " CHIPS ";
260      else if(gtype ==  fLElastic) G4cout << " LElastic ";
261      else if(gtype ==  fHElastic) G4cout << " HElastic ";
262      G4cout << " cost= " << cost
263             << G4endl; 
264    }
265    cost = 1.0;
266    sint = 0.0;
267
268    // normal situation
269  } else  {
270    sint = std::sqrt((1.0-cost)*(1.0+cost));
271  }   
272  if (verboseLevel>1) {
273    G4cout << "cos(t)=" << cost << " std::sin(t)=" << sint << G4endl;
274  }
275  G4ThreeVector v1(sint*std::cos(phi),sint*std::sin(phi),cost);
276  v1 *= ptot;
277  G4LorentzVector nlv1(v1.x(),v1.y(),v1.z(),std::sqrt(ptot*ptot + m1*m1));
278
279  nlv1.boost(bst); 
280
281  G4double eFinal = nlv1.e() - m1;
282  if (verboseLevel > 1) {
283    G4cout << "Scattered: "
284           << nlv1<<" m= " << m1 << " ekin(MeV)= " << eFinal
285           << " Proj: 4-mom " << lv1
286           <<G4endl;
287  }
288  if(eFinal <= lowestEnergyLimit) {
289    if(eFinal < 0.0 && verboseLevel > 0) {
290      G4cout << "G4HadronElastic WARNING ekin= " << eFinal
291             << " after scattering of " 
292             << aParticle->GetDefinition()->GetParticleName()
293             << " p(GeV/c)= " << plab
294             << " on " << theDef->GetParticleName()
295             << G4endl;
296    }
297    theParticleChange.SetEnergyChange(0.0);
298    nlv1 = G4LorentzVector(0.0,0.0,0.0,m1);
299
300  } else {
301    theParticleChange.SetMomentumChange(nlv1.vect().unit());
302    theParticleChange.SetEnergyChange(eFinal);
303  } 
304
305  G4LorentzVector nlv0 = lv - nlv1;
306  G4double erec =  nlv0.e() - m2;
307  if (verboseLevel > 1) {
308    G4cout << "Recoil: "
309           << nlv0<<" m= " << m2 << " ekin(MeV)= " << erec
310           <<G4endl;
311  }
312  if(erec > lowEnergyRecoilLimit) {
313    G4DynamicParticle * aSec = new G4DynamicParticle(theDef, nlv0);
314    theParticleChange.AddSecondary(aSec);
315  } else {
316    if(erec < 0.0) erec = 0.0;
317    theParticleChange.SetLocalEnergyDeposit(erec);
318  }
319
320  return &theParticleChange;
321}
322
323G4double
324G4HadronElastic::SampleT(G4double tmax, G4double, G4double, G4double atno2)
325{
326  // G4cout << "Entering elastic scattering 2"<<G4endl;
327  // Compute the direction of elastic scattering.
328  // It is planned to replace this code with a method based on
329  // parameterized functions and a Monte Carlo method to invert the CDF.
330
331  //  G4double ran = G4UniformRand();
332  G4double aa, bb, cc, dd, rr;
333  if (atno2 <= 62.) {
334    aa = std::pow(atno2, 1.63);
335    bb = 14.5*std::pow(atno2, 0.66);
336    cc = 1.4*std::pow(atno2, 0.33);
337    dd = 10.;
338  } else {
339    aa = std::pow(atno2, 1.33);
340    bb = 60.*std::pow(atno2, 0.33);
341    cc = 0.4*std::pow(atno2, 0.40);
342    dd = 10.;
343  }
344  aa = aa/bb;
345  cc = cc/dd;
346  G4double ran, t1, t2;
347  do {
348    ran = G4UniformRand();
349    t1 = -std::log(ran)/bb;
350    t2 = -std::log(ran)/dd;
351  } while(t1 > tmax || t2 > tmax);
352
353  rr = (aa + cc)*ran;
354
355  if (verboseLevel > 1) {
356    G4cout << "DoIt: aa,bb,cc,dd,rr" << G4endl;
357    G4cout << aa << " " << bb << " " << cc << " " << dd << " " << rr << G4endl;
358    G4cout << "t1,Fctcos " << t1 << " " << Fctcos(t1, aa, bb, cc, dd, rr) << G4endl;
359    G4cout << "t2,Fctcos " << t2 << " " << Fctcos(t2, aa, bb, cc, dd, rr) << G4endl;
360  }
361  G4double eps = 0.001;
362  G4int ind1 = 10;
363  G4double t = 0.0;
364  G4int ier1;
365  ier1 = Rtmi(&t, t1, t2, eps, ind1,
366              aa, bb, cc, dd, rr);
367  if (verboseLevel > 1) {
368    G4cout << "From Rtmi, ier1=" << ier1 << " t= " << t << G4endl;
369    G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << G4endl;
370  }
371  if (ier1 != 0) t = 0.25*(3.*t1 + t2);
372  if (verboseLevel > 1) {
373      G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << 
374              G4endl;
375  }
376  return t;
377}
378
379// The following is a "translation" of a root-finding routine
380// from GEANT3.21/GHEISHA.  Some of the labelled block structure has
381// been retained for clarity.  This routine will not be needed after
382// the planned revisions to DoIt().
383
384G4int
385G4HadronElastic::Rtmi(G4double* x, G4double xli, G4double xri, G4double eps, 
386                      G4int iend, 
387                      G4double aa, G4double bb, G4double cc, G4double dd, 
388                      G4double rr)
389{
390   G4int ier = 0;
391   G4double xl = xli;
392   G4double xr = xri;
393   *x = xl;
394   G4double tol = *x;
395   G4double f = Fctcos(tol, aa, bb, cc, dd, rr);
396   if (f == 0.) return ier;
397   G4double fl, fr;
398   fl = f;
399   *x = xr;
400   tol = *x;
401   f = Fctcos(tol, aa, bb, cc, dd, rr);
402   if (f == 0.) return ier;
403   fr = f;
404
405// Error return in case of wrong input data
406   if (fl*fr >= 0.) {
407      ier = 2;
408      return ier;
409   }
410
411// Basic assumption fl*fr less than 0 is satisfied.
412// Generate tolerance for function values.
413   G4int i = 0;
414   G4double tolf = 100.*eps;
415
416// Start iteration loop
417label4:
418   i++;
419
420// Start bisection loop
421   for (G4int k = 1; k <= iend; k++) {
422      *x = 0.5*(xl + xr);
423      tol = *x;
424      f = Fctcos(tol, aa, bb, cc, dd, rr);
425      if (f == 0.) return 0;
426      if (f*fr < 0.) {      // Interchange xl and xr in order to get the
427         tol = xl;          // same Sign in f and fr
428         xl = xr;
429         xr = tol;
430         tol = fl;
431         fl = fr;
432         fr = tol;
433      }
434      tol = f - fl;
435      G4double a = f*tol;
436      a = a + a;
437      if (a < fr*(fr - fl) && i <= iend) goto label17;
438      xr = *x;
439      fr = f;
440
441// Test on satisfactory accuracy in bisection loop
442      tol = eps;
443      a = std::abs(xr);
444      if (a > 1.) tol = tol*a;
445      if (std::abs(xr - xl) <= tol && std::abs(fr - fl) <= tolf) goto label14;
446   }
447// End of bisection loop
448
449// No convergence after iend iteration steps followed by iend
450// successive steps of bisection or steadily increasing function
451// values at right bounds.  Error return.
452   ier = 1;
453
454label14:
455   if (std::abs(fr) > std::abs(fl)) {
456      *x = xl;
457      f = fl;
458   }
459   return ier;
460
461// Computation of iterated x-value by inverse parabolic interp
462label17:
463   G4double a = fr - f;
464   G4double dx = (*x - xl)*fl*(1. + f*(a - tol)/(a*(fr - fl)))/tol;
465   G4double xm = *x;
466   G4double fm = f;
467   *x = xl - dx;
468   tol = *x;
469   f = Fctcos(tol, aa, bb, cc, dd, rr);
470   if (f == 0.) return ier;
471
472// Test on satisfactory accuracy in iteration loop
473   tol = eps;
474   a = std::abs(*x);
475   if (a > 1) tol = tol*a;
476   if (std::abs(dx) <= tol && std::abs(f) <= tolf) return ier;
477
478// Preparation of next bisection loop
479   if (f*fl < 0.) {
480      xr = *x;
481      fr = f;
482   }
483   else {
484      xl = *x;
485      fl = f;
486      xr = xm;
487      fr = fm;
488   }
489   goto label4;
490}
491
492// Test function for root-finder
493G4double
494G4HadronElastic::Fctcos(G4double t, 
495                        G4double aa, G4double bb, G4double cc, G4double dd, 
496                        G4double rr)
497{
498   const G4double expxl = -82.;
499   const G4double expxu = 82.;
500
501   G4double test1 = -bb*t;
502   if (test1 > expxu) test1 = expxu;
503   if (test1 < expxl) test1 = expxl;
504
505   G4double test2 = -dd*t;
506   if (test2 > expxu) test2 = expxu;
507   if (test2 < expxl) test2 = expxl;
508
509   return aa*std::exp(test1) + cc*std::exp(test2) - rr;
510}
511
512
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