source: trunk/source/processes/hadronic/models/coherent_elastic/src/G4HadronElastic.cc @ 1055

Last change on this file since 1055 was 1007, checked in by garnier, 15 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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