source: trunk/source/processes/electromagnetic/standard/src/G4BetheBlochModel.cc@ 1199

Last change on this file since 1199 was 1196, checked in by garnier, 16 years ago

update CVS release candidate geant4.9.3.01
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25//
26// $Id: G4BetheBlochModel.cc,v 1.34 2009/11/11 23:22:27 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-03-cand-01 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class header file
32//
33//
34// File name: G4BetheBlochModel
35//
36// Author: Vladimir Ivanchenko on base of Laszlo Urban code
37//
38// Creation date: 03.01.2002
39//
40// Modifications:
41//
42// 04-12-02 Fix problem of G4DynamicParticle constructor (V.Ivanchenko)
43// 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko)
44// 27-01-03 Make models region aware (V.Ivanchenko)
45// 13-02-03 Add name (V.Ivanchenko)
46// 24-03-05 Add G4EmCorrections (V.Ivanchenko)
47// 11-04-05 Major optimisation of internal interfaces (V.Ivanchenko)
48// 11-02-06 ComputeCrossSectionPerElectron, ComputeCrossSectionPerAtom (mma)
49// 12-02-06 move G4LossTableManager::Instance()->EmCorrections()
50// in constructor (mma)
51// 12-08-08 Added methods GetParticleCharge, GetChargeSquareRatio,
52// CorrectionsAlongStep needed for ions(V.Ivanchenko)
53//
54// -------------------------------------------------------------------
55//
56
57
58//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
59//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
60
61#include "G4BetheBlochModel.hh"
62#include "Randomize.hh"
63#include "G4Electron.hh"
64#include "G4LossTableManager.hh"
65#include "G4EmCorrections.hh"
66#include "G4ParticleChangeForLoss.hh"
67
68//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
69
70using namespace std;
71
72G4BetheBlochModel::G4BetheBlochModel(const G4ParticleDefinition* p,
73 const G4String& nam)
74 : G4VEmModel(nam),
75 particle(0),
76 tlimit(DBL_MAX),
77 twoln10(2.0*log(10.0)),
78 bg2lim(0.0169),
79 taulim(8.4146e-3),
80 isIon(false),
81 isInitialised(false)
82{
83 fParticleChange = 0;
84 if(p) {
85 SetGenericIon(p);
86 SetParticle(p);
87 }
88 theElectron = G4Electron::Electron();
89 corr = G4LossTableManager::Instance()->EmCorrections();
90 nist = G4NistManager::Instance();
91 SetLowEnergyLimit(2.0*MeV);
92}
93
94//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
95
96G4BetheBlochModel::~G4BetheBlochModel()
97{}
98
99//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
100
101G4double G4BetheBlochModel::MinEnergyCut(const G4ParticleDefinition*,
102 const G4MaterialCutsCouple* couple)
103{
104 return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy();
105}
106
107//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
108
109void G4BetheBlochModel::Initialise(const G4ParticleDefinition* p,
110 const G4DataVector&)
111{
112 SetGenericIon(p);
113 SetParticle(p);
114
115 //G4cout << "G4BetheBlochModel::Initialise for " << p->GetParticleName()
116 // << " isIon= " << isIon
117 // << G4endl;
118
119 corrFactor = chargeSquare;
120 // always false before the run
121 SetDeexcitationFlag(false);
122
123 if(!isInitialised) {
124 isInitialised = true;
125 fParticleChange = GetParticleChangeForLoss();
126 }
127}
128
129//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
130
131G4double G4BetheBlochModel::GetChargeSquareRatio(const G4ParticleDefinition* p,
132 const G4Material* mat,
133 G4double kineticEnergy)
134{
135 // this method is called only for ions
136 G4double q2 = corr->EffectiveChargeSquareRatio(p,mat,kineticEnergy);
137 corrFactor = q2*corr->EffectiveChargeCorrection(p,mat,kineticEnergy);
138 return corrFactor;
139}
140
141//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
142
143G4double G4BetheBlochModel::GetParticleCharge(const G4ParticleDefinition* p,
144 const G4Material* mat,
145 G4double kineticEnergy)
146{
147 // this method is called only for ions
148 return corr->GetParticleCharge(p,mat,kineticEnergy);
149}
150
151//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
152
153G4double
154G4BetheBlochModel::ComputeCrossSectionPerElectron(const G4ParticleDefinition* p,
155 G4double kineticEnergy,
156 G4double cutEnergy,
157 G4double maxKinEnergy)
158{
159 G4double cross = 0.0;
160 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
161 G4double maxEnergy = min(tmax,maxKinEnergy);
162 if(cutEnergy < maxEnergy) {
163
164 G4double totEnergy = kineticEnergy + mass;
165 G4double energy2 = totEnergy*totEnergy;
166 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2;
167
168 cross = 1.0/cutEnergy - 1.0/maxEnergy
169 - beta2*log(maxEnergy/cutEnergy)/tmax;
170
171 // +term for spin=1/2 particle
172 if( 0.5 == spin ) cross += 0.5*(maxEnergy - cutEnergy)/energy2;
173
174 // High order correction different for hadrons and ions
175 // nevetheless they are applied to reduce high energy transfers
176 // if(!isIon)
177 //cross += corr->FiniteSizeCorrectionXS(p,currentMaterial,
178 // kineticEnergy,cutEnergy);
179
180 cross *= twopi_mc2_rcl2*chargeSquare/beta2;
181 }
182
183 // G4cout << "BB: e= " << kineticEnergy << " tmin= " << cutEnergy
184 // << " tmax= " << tmax << " cross= " << cross << G4endl;
185
186 return cross;
187}
188
189//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
190
191G4double G4BetheBlochModel::ComputeCrossSectionPerAtom(
192 const G4ParticleDefinition* p,
193 G4double kineticEnergy,
194 G4double Z, G4double,
195 G4double cutEnergy,
196 G4double maxEnergy)
197{
198 G4double cross = Z*ComputeCrossSectionPerElectron
199 (p,kineticEnergy,cutEnergy,maxEnergy);
200 return cross;
201}
202
203//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
204
205G4double G4BetheBlochModel::CrossSectionPerVolume(
206 const G4Material* material,
207 const G4ParticleDefinition* p,
208 G4double kineticEnergy,
209 G4double cutEnergy,
210 G4double maxEnergy)
211{
212 currentMaterial = material;
213 G4double eDensity = material->GetElectronDensity();
214 G4double cross = eDensity*ComputeCrossSectionPerElectron
215 (p,kineticEnergy,cutEnergy,maxEnergy);
216 return cross;
217}
218
219//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
220
221G4double G4BetheBlochModel::ComputeDEDXPerVolume(const G4Material* material,
222 const G4ParticleDefinition* p,
223 G4double kineticEnergy,
224 G4double cut)
225{
226 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
227 G4double cutEnergy = min(cut,tmax);
228
229 G4double tau = kineticEnergy/mass;
230 G4double gam = tau + 1.0;
231 G4double bg2 = tau * (tau+2.0);
232 G4double beta2 = bg2/(gam*gam);
233
234 G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
235 G4double eexc2 = eexc*eexc;
236 //G4double cden = material->GetIonisation()->GetCdensity();
237 //G4double mden = material->GetIonisation()->GetMdensity();
238 //G4double aden = material->GetIonisation()->GetAdensity();
239 //G4double x0den = material->GetIonisation()->GetX0density();
240 //G4double x1den = material->GetIonisation()->GetX1density();
241
242 G4double eDensity = material->GetElectronDensity();
243
244 G4double dedx = log(2.0*electron_mass_c2*bg2*cutEnergy/eexc2)
245 - (1.0 + cutEnergy/tmax)*beta2;
246
247 if(0.5 == spin) {
248 G4double del = 0.5*cutEnergy/(kineticEnergy + mass);
249 dedx += del*del;
250 }
251
252 // density correction
253 G4double x = log(bg2)/twoln10;
254 //if ( x >= x0den ) {
255 // dedx -= twoln10*x - cden ;
256 // if ( x < x1den ) dedx -= aden*pow((x1den-x),mden) ;
257 //}
258 dedx -= material->GetIonisation()->DensityCorrection(x);
259
260 // shell correction
261 dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy);
262
263 // now compute the total ionization loss
264
265 if (dedx < 0.0) dedx = 0.0 ;
266
267 dedx *= twopi_mc2_rcl2*chargeSquare*eDensity/beta2;
268
269 //High order correction different for hadrons and ions
270 if(isIon) {
271 dedx += corr->IonBarkasCorrection(p,material,kineticEnergy);
272 } else {
273 dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy);
274 }
275 return dedx;
276}
277
278//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
279
280void G4BetheBlochModel::CorrectionsAlongStep(const G4MaterialCutsCouple* couple,
281 const G4DynamicParticle* dp,
282 G4double& eloss,
283 G4double&,
284 G4double length)
285{
286 if(isIon) {
287 const G4ParticleDefinition* p = dp->GetDefinition();
288 const G4Material* mat = couple->GetMaterial();
289 G4double preKinEnergy = dp->GetKineticEnergy();
290 G4double e = preKinEnergy - eloss*0.5;
291 if(e < 0.0) e = preKinEnergy*0.5;
292
293 G4double q2 = corr->EffectiveChargeSquareRatio(p,mat,e);
294 GetModelOfFluctuations()->SetParticleAndCharge(p, q2);
295 eloss *= q2*corr->EffectiveChargeCorrection(p,mat,e)/corrFactor;
296 eloss += length*corr->IonHighOrderCorrections(p,couple,e);
297 }
298 /*
299 if(nuclearStopping && preKinEnergy*proton_mass_c2/mass < chargeSquare*100.*MeV) {
300
301 G4double nloss = length*corr->NuclearDEDX(p,mat,e,false);
302
303 // too big energy loss
304 if(eloss + nloss > preKinEnergy) {
305 nloss *= (preKinEnergy/(eloss + nloss));
306 eloss = preKinEnergy;
307 } else {
308 eloss += nloss;
309 }
310
311 G4cout << "G4ionIonisation::CorrectionsAlongStep: e= " << preKinEnergy
312 << " de= " << eloss << " NIEL= " << nloss
313 << " dynQ= " << dp->GetCharge()/eplus << G4endl;
314
315 fParticleChange->ProposeNonIonizingEnergyDeposit(nloss);
316 }
317 */
318}
319
320//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
321
322void G4BetheBlochModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp,
323 const G4MaterialCutsCouple*,
324 const G4DynamicParticle* dp,
325 G4double minKinEnergy,
326 G4double maxEnergy)
327{
328 G4double kineticEnergy = dp->GetKineticEnergy();
329 G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(),kineticEnergy);
330
331 G4double maxKinEnergy = std::min(maxEnergy,tmax);
332 if(minKinEnergy >= maxKinEnergy) return;
333
334 G4double totEnergy = kineticEnergy + mass;
335 G4double etot2 = totEnergy*totEnergy;
336 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
337
338 G4double deltaKinEnergy, f;
339 G4double f1 = 0.0;
340 G4double fmax = 1.0;
341 if( 0.5 == spin ) fmax += 0.5*maxKinEnergy*maxKinEnergy/etot2;
342
343 // sampling without nuclear size effect
344 do {
345 G4double q = G4UniformRand();
346 deltaKinEnergy = minKinEnergy*maxKinEnergy
347 /(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
348
349 f = 1.0 - beta2*deltaKinEnergy/tmax;
350 if( 0.5 == spin ) {
351 f1 = 0.5*deltaKinEnergy*deltaKinEnergy/etot2;
352 f += f1;
353 }
354
355 } while( fmax*G4UniformRand() > f);
356
357 // projectile formfactor - suppresion of high energy
358 // delta-electron production at high energy
359
360 G4double x = formfact*deltaKinEnergy;
361 if(x > 1.e-6) {
362
363 G4double x1 = 1.0 + x;
364 G4double g = 1.0/(x1*x1);
365 if( 0.5 == spin ) {
366 G4double x2 = 0.5*electron_mass_c2*deltaKinEnergy/(mass*mass);
367 g *= (1.0 + magMoment2*(x2 - f1/f)/(1.0 + x2));
368 }
369 if(g > 1.0) {
370 G4cout << "### G4BetheBlochModel WARNING: g= " << g
371 << dp->GetDefinition()->GetParticleName()
372 << " Ekin(MeV)= " << kineticEnergy
373 << " delEkin(MeV)= " << deltaKinEnergy
374 << G4endl;
375 }
376 if(G4UniformRand() > g) return;
377 }
378
379 // delta-electron is produced
380 G4double totMomentum = totEnergy*sqrt(beta2);
381 G4double deltaMomentum =
382 sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
383 G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
384 (deltaMomentum * totMomentum);
385 /*
386 if(cost > 1.0) {
387 G4cout << "### G4BetheBlochModel WARNING: cost= "
388 << cost << " > 1 for "
389 << dp->GetDefinition()->GetParticleName()
390 << " Ekin(MeV)= " << kineticEnergy
391 << " p(MeV/c)= " << totMomentum
392 << " delEkin(MeV)= " << deltaKinEnergy
393 << " delMom(MeV/c)= " << deltaMomentum
394 << " tmin(MeV)= " << minKinEnergy
395 << " tmax(MeV)= " << maxKinEnergy
396 << " dir= " << dp->GetMomentumDirection()
397 << G4endl;
398 cost = 1.0;
399 }
400 */
401 G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
402
403 G4double phi = twopi * G4UniformRand() ;
404
405
406 G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost);
407 G4ThreeVector direction = dp->GetMomentumDirection();
408 deltaDirection.rotateUz(direction);
409
410 // create G4DynamicParticle object for delta ray
411 G4DynamicParticle* delta = new G4DynamicParticle(theElectron,
412 deltaDirection,deltaKinEnergy);
413
414 vdp->push_back(delta);
415
416 // Change kinematics of primary particle
417 kineticEnergy -= deltaKinEnergy;
418 G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum;
419 finalP = finalP.unit();
420
421 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
422 fParticleChange->SetProposedMomentumDirection(finalP);
423}
424
425//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
426
427G4double G4BetheBlochModel::MaxSecondaryEnergy(const G4ParticleDefinition* pd,
428 G4double kinEnergy)
429{
430 // here particle type is checked for any method
431 SetParticle(pd);
432 G4double tau = kinEnergy/mass;
433 G4double tmax = 2.0*electron_mass_c2*tau*(tau + 2.) /
434 (1. + 2.0*(tau + 1.)*ratio + ratio*ratio);
435 return std::min(tmax,tlimit);
436}
437
438//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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