source: trunk/source/processes/hadronic/models/coherent_elastic/src/G4HadronElastic.cc@ 900

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25//
26// $Id: G4HadronElastic.cc,v 1.56.2.1 2008/04/23 14:14:55 gcosmo Exp $
27// GEANT4 tag $Name: geant4-09-01-patch-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
104G4HadronElastic::~G4HadronElastic()
105{
106 delete hElastic;
107}
108
109G4VQCrossSection* G4HadronElastic::GetCS()
110{
111 return qCManager;
112}
113
114G4ElasticHadrNucleusHE* G4HadronElastic::GetHElastic()
115{
116 return hElastic;
117}
118
119G4HadFinalState* G4HadronElastic::ApplyYourself(
120 const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
121{
122 theParticleChange.Clear();
123
124 const G4HadProjectile* aParticle = &aTrack;
125 G4double ekin = aParticle->GetKineticEnergy();
126 if(ekin <= lowestEnergyLimit) {
127 theParticleChange.SetEnergyChange(ekin);
128 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
129 return &theParticleChange;
130 }
131
132 G4double aTarget = targetNucleus.GetN();
133 G4double zTarget = targetNucleus.GetZ();
134
135 G4double plab = aParticle->GetTotalMomentum();
136 if (verboseLevel >1) {
137 G4cout << "G4HadronElastic::DoIt: Incident particle plab="
138 << plab/GeV << " GeV/c "
139 << " ekin(MeV) = " << ekin/MeV << " "
140 << aParticle->GetDefinition()->GetParticleName() << G4endl;
141 }
142 // Scattered particle referred to axis of incident particle
143 const G4ParticleDefinition* theParticle = aParticle->GetDefinition();
144 G4double m1 = theParticle->GetPDGMass();
145
146 G4int Z = static_cast<G4int>(zTarget+0.5);
147 G4int A = static_cast<G4int>(aTarget+0.5);
148 G4int N = A - Z;
149 G4int projPDG = theParticle->GetPDGEncoding();
150 if (verboseLevel>1)
151 G4cout << "G4HadronElastic for " << theParticle->GetParticleName()
152 << " PDGcode= " << projPDG << " on nucleus Z= " << Z
153 << " A= " << A << " N= " << N
154 << G4endl;
155
156 G4ParticleDefinition * theDef = 0;
157
158 if(Z == 1 && A == 1) theDef = theProton;
159 else if (Z == 1 && A == 2) theDef = theDeuteron;
160 else if (Z == 1 && A == 3) theDef = G4Triton::Triton();
161 else if (Z == 2 && A == 3) theDef = G4He3::He3();
162 else if (Z == 2 && A == 4) theDef = theAlpha;
163 else theDef = G4ParticleTable::GetParticleTable()->FindIon(Z,A,0,Z);
164
165 G4double m2 = theDef->GetPDGMass();
166 G4LorentzVector lv1 = aParticle->Get4Momentum();
167 G4LorentzVector lv(0.0,0.0,0.0,m2);
168 lv += lv1;
169
170 G4ThreeVector bst = lv.boostVector();
171 lv1.boost(-bst);
172
173 G4ThreeVector p1 = lv1.vect();
174 G4double ptot = p1.mag();
175 G4double tmax = 4.0*ptot*ptot;
176 G4double t = 0.0;
177
178 // Choose generator
179 G4ElasticGenerator gtype = fLElastic;
180
181 // Q-elastic for p,n scattering on H and He
182 if (theParticle == theProton || theParticle == theNeutron)
183 // && Z <= 2 && ekin >= lowEnergyLimitQ)
184 gtype = fQElastic;
185
186 else {
187 // S-wave for very low energy
188 if(plab < plabLowLimit) gtype = fSWave;
189 // HE-elastic for energetic projectile mesons
190 else if(ekin >= lowEnergyLimitHE && theParticle->GetBaryonNumber() == 0)
191 gtype = fHElastic;
192 }
193
194 //
195 // Sample t
196 //
197 if(gtype == fQElastic) {
198 if (verboseLevel >1) {
199 G4cout << "G4HadronElastic: Z= " << Z << " N= "
200 << N << " pdg= " << projPDG
201 << " mom(GeV)= " << plab/GeV << " " << qCManager << G4endl;
202 }
203 if(Z == 1 && N == 2) N = 1;
204 else if(Z == 2 && N == 1) N = 2;
205 G4double cs = qCManager->GetCrossSection(false,plab,Z,N,projPDG);
206
207 // check if cross section is reasonable
208 if(cs > 0.0) t = qCManager->GetExchangeT(Z,N,projPDG);
209 else if(plab > plabLowLimit) gtype = fLElastic;
210 else gtype = fSWave;
211 }
212
213 if(gtype == fLElastic) {
214 t = GeV*GeV*SampleT(ptot,m1,m2,aTarget);
215 }
216
217 // use mean atomic number
218 if(gtype == fHElastic) {
219 t = hElastic->SampleT(theParticle,plab,Z,A);
220 }
221
222 // NaN finder
223 if(!(t < 0.0 || t >= 0.0)) {
224 if (verboseLevel > 0) {
225 G4cout << "G4HadronElastic:WARNING: Z= " << Z << " N= "
226 << N << " pdg= " << projPDG
227 << " mom(GeV)= " << plab/GeV
228 << " the model type " << gtype;
229 if(gtype == fQElastic) G4cout << " CHIPS ";
230 else if(gtype == fLElastic) G4cout << " LElastic ";
231 else if(gtype == fHElastic) G4cout << " HElastic ";
232 G4cout << " S-wave will be sampled"
233 << G4endl;
234 }
235 t = 0.0;
236 }
237
238 if(gtype == fSWave) t = G4UniformRand()*tmax;
239
240 if(verboseLevel>1)
241 G4cout <<"type= " << gtype <<" t= " << t << " tmax= " << tmax
242 << " ptot= " << ptot << G4endl;
243
244 // Sampling in CM system
245 G4double phi = G4UniformRand()*twopi;
246 G4double cost = 1. - 2.0*t/tmax;
247 G4double sint;
248
249 if( cost >= 1.0 || cost < -1 )
250 {
251 cost = 1.0;
252 sint = 0.0;
253 }
254 else
255 {
256 sint = std::sqrt((1.0-cost)*(1.0+cost));
257 }
258 if (verboseLevel>1)
259 G4cout << "cos(t)=" << cost << " std::sin(t)=" << sint << G4endl;
260
261 G4ThreeVector v1(sint*std::cos(phi),sint*std::sin(phi),cost);
262 v1 *= ptot;
263 G4LorentzVector nlv1(v1.x(),v1.y(),v1.z(),std::sqrt(ptot*ptot + m1*m1));
264
265 nlv1.boost(bst);
266
267 G4double eFinal = nlv1.e() - m1;
268 if (verboseLevel > 1) {
269 G4cout << "Scattered: "
270 << nlv1<<" m= " << m1 << " ekin(MeV)= " << eFinal
271 << " Proj: 4-mom " << lv1
272 <<G4endl;
273 }
274 if(eFinal <= lowestEnergyLimit) {
275 if(eFinal < 0.0) {
276 G4cout << "G4HadronElastic WARNING ekin= " << eFinal
277 << " after scattering of "
278 << aParticle->GetDefinition()->GetParticleName()
279 << " p(GeV/c)= " << plab
280 << " on " << theDef->GetParticleName()
281 << G4endl;
282 }
283 theParticleChange.SetEnergyChange(0.0);
284 nlv1 = G4LorentzVector(0.0,0.0,0.0,m1);
285
286 } else {
287 theParticleChange.SetMomentumChange(nlv1.vect().unit());
288 theParticleChange.SetEnergyChange(eFinal);
289 }
290
291 G4LorentzVector nlv0 = lv - nlv1;
292 G4double erec = nlv0.e() - m2;
293 if (verboseLevel > 1) {
294 G4cout << "Recoil: "
295 << nlv0<<" m= " << m2 << " ekin(MeV)= " << erec
296 <<G4endl;
297 }
298 if(erec > lowEnergyRecoilLimit) {
299 G4DynamicParticle * aSec = new G4DynamicParticle(theDef, nlv0);
300 theParticleChange.AddSecondary(aSec);
301 } else {
302 if(erec < 0.0) erec = 0.0;
303 theParticleChange.SetLocalEnergyDeposit(erec);
304 }
305
306 return &theParticleChange;
307}
308
309G4double
310G4HadronElastic::SampleT(G4double, G4double, G4double, G4double atno2)
311{
312 // G4cout << "Entering elastic scattering 2"<<G4endl;
313 // Compute the direction of elastic scattering.
314 // It is planned to replace this code with a method based on
315 // parameterized functions and a Monte Carlo method to invert the CDF.
316
317 G4double ran = G4UniformRand();
318 G4double aa, bb, cc, dd, rr;
319 if (atno2 <= 62.) {
320 aa = std::pow(atno2, 1.63);
321 bb = 14.5*std::pow(atno2, 0.66);
322 cc = 1.4*std::pow(atno2, 0.33);
323 dd = 10.;
324 } else {
325 aa = std::pow(atno2, 1.33);
326 bb = 60.*std::pow(atno2, 0.33);
327 cc = 0.4*std::pow(atno2, 0.40);
328 dd = 10.;
329 }
330 aa = aa/bb;
331 cc = cc/dd;
332 rr = (aa + cc)*ran;
333 if (verboseLevel > 1) {
334 G4cout << "DoIt: aa,bb,cc,dd,rr" << G4endl;
335 G4cout << aa << " " << bb << " " << cc << " " << dd << " " << rr << G4endl;
336 }
337 G4double t1 = -std::log(ran)/bb;
338 G4double t2 = -std::log(ran)/dd;
339 if (verboseLevel > 1) {
340 G4cout << "t1,Fctcos " << t1 << " " << Fctcos(t1, aa, bb, cc, dd, rr) << G4endl;
341 G4cout << "t2,Fctcos " << t2 << " " << Fctcos(t2, aa, bb, cc, dd, rr) << G4endl;
342 }
343 G4double eps = 0.001;
344 G4int ind1 = 10;
345 G4double t = 0.0;
346 G4int ier1;
347 ier1 = Rtmi(&t, t1, t2, eps, ind1,
348 aa, bb, cc, dd, rr);
349 if (verboseLevel > 1) {
350 G4cout << "From Rtmi, ier1=" << ier1 << G4endl;
351 G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << G4endl;
352 }
353 if (ier1 != 0) t = 0.25*(3.*t1 + t2);
354 if (verboseLevel > 1) {
355 G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) <<
356 G4endl;
357 }
358 return t;
359}
360
361// The following is a "translation" of a root-finding routine
362// from GEANT3.21/GHEISHA. Some of the labelled block structure has
363// been retained for clarity. This routine will not be needed after
364// the planned revisions to DoIt().
365
366G4int
367G4HadronElastic::Rtmi(G4double* x, G4double xli, G4double xri, G4double eps,
368 G4int iend,
369 G4double aa, G4double bb, G4double cc, G4double dd,
370 G4double rr)
371{
372 G4int ier = 0;
373 G4double xl = xli;
374 G4double xr = xri;
375 *x = xl;
376 G4double tol = *x;
377 G4double f = Fctcos(tol, aa, bb, cc, dd, rr);
378 if (f == 0.) return ier;
379 G4double fl, fr;
380 fl = f;
381 *x = xr;
382 tol = *x;
383 f = Fctcos(tol, aa, bb, cc, dd, rr);
384 if (f == 0.) return ier;
385 fr = f;
386
387// Error return in case of wrong input data
388 if (fl*fr >= 0.) {
389 ier = 2;
390 return ier;
391 }
392
393// Basic assumption fl*fr less than 0 is satisfied.
394// Generate tolerance for function values.
395 G4int i = 0;
396 G4double tolf = 100.*eps;
397
398// Start iteration loop
399label4:
400 i++;
401
402// Start bisection loop
403 for (G4int k = 1; k <= iend; k++) {
404 *x = 0.5*(xl + xr);
405 tol = *x;
406 f = Fctcos(tol, aa, bb, cc, dd, rr);
407 if (f == 0.) return 0;
408 if (f*fr < 0.) { // Interchange xl and xr in order to get the
409 tol = xl; // same Sign in f and fr
410 xl = xr;
411 xr = tol;
412 tol = fl;
413 fl = fr;
414 fr = tol;
415 }
416 tol = f - fl;
417 G4double a = f*tol;
418 a = a + a;
419 if (a < fr*(fr - fl) && i <= iend) goto label17;
420 xr = *x;
421 fr = f;
422
423// Test on satisfactory accuracy in bisection loop
424 tol = eps;
425 a = std::abs(xr);
426 if (a > 1.) tol = tol*a;
427 if (std::abs(xr - xl) <= tol && std::abs(fr - fl) <= tolf) goto label14;
428 }
429// End of bisection loop
430
431// No convergence after iend iteration steps followed by iend
432// successive steps of bisection or steadily increasing function
433// values at right bounds. Error return.
434 ier = 1;
435
436label14:
437 if (std::abs(fr) > std::abs(fl)) {
438 *x = xl;
439 f = fl;
440 }
441 return ier;
442
443// Computation of iterated x-value by inverse parabolic interp
444label17:
445 G4double a = fr - f;
446 G4double dx = (*x - xl)*fl*(1. + f*(a - tol)/(a*(fr - fl)))/tol;
447 G4double xm = *x;
448 G4double fm = f;
449 *x = xl - dx;
450 tol = *x;
451 f = Fctcos(tol, aa, bb, cc, dd, rr);
452 if (f == 0.) return ier;
453
454// Test on satisfactory accuracy in iteration loop
455 tol = eps;
456 a = std::abs(*x);
457 if (a > 1) tol = tol*a;
458 if (std::abs(dx) <= tol && std::abs(f) <= tolf) return ier;
459
460// Preparation of next bisection loop
461 if (f*fl < 0.) {
462 xr = *x;
463 fr = f;
464 }
465 else {
466 xl = *x;
467 fl = f;
468 xr = xm;
469 fr = fm;
470 }
471 goto label4;
472}
473
474// Test function for root-finder
475G4double
476G4HadronElastic::Fctcos(G4double t,
477 G4double aa, G4double bb, G4double cc, G4double dd,
478 G4double rr)
479{
480 const G4double expxl = -82.;
481 const G4double expxu = 82.;
482
483 G4double test1 = -bb*t;
484 if (test1 > expxu) test1 = expxu;
485 if (test1 < expxl) test1 = expxl;
486
487 G4double test2 = -dd*t;
488 if (test2 > expxu) test2 = expxu;
489 if (test2 < expxl) test2 = expxl;
490
491 return aa*std::exp(test1) + cc*std::exp(test2) - rr;
492}
493
494
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