source: trunk/source/processes/electromagnetic/standard/src/G4BetheBlochModel.cc@ 1330

Last change on this file since 1330 was 1315, checked in by garnier, 15 years ago

update geant4-09-04-beta-cand-01 interfaces-V09-03-09 vis-V09-03-08
File size: 15.0 KB
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25//
26// $Id: G4BetheBlochModel.cc,v 1.37 2010/05/27 10:25:59 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-04-beta-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, so no check if it is an ion
148 return corr->GetParticleCharge(p,mat,kineticEnergy);
149}
150
151//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
152
153void G4BetheBlochModel::SetupParameters()
154{
155 mass = particle->GetPDGMass();
156 spin = particle->GetPDGSpin();
157 G4double q = particle->GetPDGCharge()/eplus;
158 chargeSquare = q*q;
159 ratio = electron_mass_c2/mass;
160 G4double magmom =
161 particle->GetPDGMagneticMoment()*mass/(0.5*eplus*hbar_Planck*c_squared);
162 magMoment2 = magmom*magmom - 1.0;
163 formfact = 0.0;
164 if(particle->GetLeptonNumber() == 0) {
165 G4double x = 0.8426*GeV;
166 if(spin == 0.0 && mass < GeV) {x = 0.736*GeV;}
167 else if(mass > GeV) {
168 x /= nist->GetZ13(mass/proton_mass_c2);
169 // tlimit = 51.2*GeV*A13[iz]*A13[iz];
170 }
171 formfact = 2.0*electron_mass_c2/(x*x);
172 tlimit = 2.0/formfact;
173 }
174}
175
176//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
177
178G4double
179G4BetheBlochModel::ComputeCrossSectionPerElectron(const G4ParticleDefinition* p,
180 G4double kineticEnergy,
181 G4double cutEnergy,
182 G4double maxKinEnergy)
183{
184 G4double cross = 0.0;
185 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
186 G4double maxEnergy = min(tmax,maxKinEnergy);
187 if(cutEnergy < maxEnergy) {
188
189 G4double totEnergy = kineticEnergy + mass;
190 G4double energy2 = totEnergy*totEnergy;
191 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2;
192
193 cross = 1.0/cutEnergy - 1.0/maxEnergy
194 - beta2*log(maxEnergy/cutEnergy)/tmax;
195
196 // +term for spin=1/2 particle
197 if( 0.5 == spin ) { cross += 0.5*(maxEnergy - cutEnergy)/energy2; }
198
199 // High order correction different for hadrons and ions
200 // nevetheless they are applied to reduce high energy transfers
201 // if(!isIon)
202 //cross += corr->FiniteSizeCorrectionXS(p,currentMaterial,
203 // kineticEnergy,cutEnergy);
204
205 cross *= twopi_mc2_rcl2*chargeSquare/beta2;
206 }
207
208 // G4cout << "BB: e= " << kineticEnergy << " tmin= " << cutEnergy
209 // << " tmax= " << tmax << " cross= " << cross << G4endl;
210
211 return cross;
212}
213
214//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
215
216G4double G4BetheBlochModel::ComputeCrossSectionPerAtom(
217 const G4ParticleDefinition* p,
218 G4double kineticEnergy,
219 G4double Z, G4double,
220 G4double cutEnergy,
221 G4double maxEnergy)
222{
223 G4double cross = Z*ComputeCrossSectionPerElectron
224 (p,kineticEnergy,cutEnergy,maxEnergy);
225 return cross;
226}
227
228//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
229
230G4double G4BetheBlochModel::CrossSectionPerVolume(
231 const G4Material* material,
232 const G4ParticleDefinition* p,
233 G4double kineticEnergy,
234 G4double cutEnergy,
235 G4double maxEnergy)
236{
237 currentMaterial = material;
238 G4double eDensity = material->GetElectronDensity();
239 G4double cross = eDensity*ComputeCrossSectionPerElectron
240 (p,kineticEnergy,cutEnergy,maxEnergy);
241 return cross;
242}
243
244//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
245
246G4double G4BetheBlochModel::ComputeDEDXPerVolume(const G4Material* material,
247 const G4ParticleDefinition* p,
248 G4double kineticEnergy,
249 G4double cut)
250{
251 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
252 G4double cutEnergy = std::min(cut,tmax);
253
254 G4double tau = kineticEnergy/mass;
255 G4double gam = tau + 1.0;
256 G4double bg2 = tau * (tau+2.0);
257 G4double beta2 = bg2/(gam*gam);
258
259 G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
260 G4double eexc2 = eexc*eexc;
261
262 G4double eDensity = material->GetElectronDensity();
263
264 G4double dedx = log(2.0*electron_mass_c2*bg2*cutEnergy/eexc2)
265 - (1.0 + cutEnergy/tmax)*beta2;
266
267 if(0.5 == spin) {
268 G4double del = 0.5*cutEnergy/(kineticEnergy + mass);
269 dedx += del*del;
270 }
271
272 // density correction
273 G4double x = log(bg2)/twoln10;
274 dedx -= material->GetIonisation()->DensityCorrection(x);
275
276 // shell correction
277 dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy);
278
279 // now compute the total ionization loss
280
281 if (dedx < 0.0) dedx = 0.0 ;
282
283 dedx *= twopi_mc2_rcl2*chargeSquare*eDensity/beta2;
284
285 //High order correction different for hadrons and ions
286 if(isIon) {
287 dedx += corr->IonBarkasCorrection(p,material,kineticEnergy);
288 } else {
289 dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy);
290 }
291 return dedx;
292}
293
294//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
295
296void G4BetheBlochModel::CorrectionsAlongStep(const G4MaterialCutsCouple* couple,
297 const G4DynamicParticle* dp,
298 G4double& eloss,
299 G4double&,
300 G4double length)
301{
302 if(isIon) {
303 const G4ParticleDefinition* p = dp->GetDefinition();
304 const G4Material* mat = couple->GetMaterial();
305 G4double preKinEnergy = dp->GetKineticEnergy();
306 G4double e = preKinEnergy - eloss*0.5;
307 if(e < 0.0) e = preKinEnergy*0.5;
308
309 G4double q2 = corr->EffectiveChargeSquareRatio(p,mat,e);
310 GetModelOfFluctuations()->SetParticleAndCharge(p, q2);
311 G4double qfactor = q2*corr->EffectiveChargeCorrection(p,mat,e)/corrFactor;
312 G4double highOrder = length*corr->IonHighOrderCorrections(p,couple,e);
313 eloss *= qfactor;
314 eloss += highOrder;
315 //G4cout << "G4BetheBlochModel::CorrectionsAlongStep: e= " << preKinEnergy
316 // << " qfactor= " << qfactor
317 // << " highOrder= " << highOrder << " (" << highOrder/eloss << ")" << G4endl;
318 }
319}
320
321//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
322
323void G4BetheBlochModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp,
324 const G4MaterialCutsCouple*,
325 const G4DynamicParticle* dp,
326 G4double minKinEnergy,
327 G4double maxEnergy)
328{
329 G4double kineticEnergy = dp->GetKineticEnergy();
330 G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(),kineticEnergy);
331
332 G4double maxKinEnergy = std::min(maxEnergy,tmax);
333 if(minKinEnergy >= maxKinEnergy) return;
334
335 G4double totEnergy = kineticEnergy + mass;
336 G4double etot2 = totEnergy*totEnergy;
337 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
338
339 G4double deltaKinEnergy, f;
340 G4double f1 = 0.0;
341 G4double fmax = 1.0;
342 if( 0.5 == spin ) fmax += 0.5*maxKinEnergy*maxKinEnergy/etot2;
343
344 // sampling without nuclear size effect
345 do {
346 G4double q = G4UniformRand();
347 deltaKinEnergy = minKinEnergy*maxKinEnergy
348 /(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
349
350 f = 1.0 - beta2*deltaKinEnergy/tmax;
351 if( 0.5 == spin ) {
352 f1 = 0.5*deltaKinEnergy*deltaKinEnergy/etot2;
353 f += f1;
354 }
355
356 } while( fmax*G4UniformRand() > f);
357
358 // projectile formfactor - suppresion of high energy
359 // delta-electron production at high energy
360
361 G4double x = formfact*deltaKinEnergy;
362 if(x > 1.e-6) {
363
364 G4double x1 = 1.0 + x;
365 G4double g = 1.0/(x1*x1);
366 if( 0.5 == spin ) {
367 G4double x2 = 0.5*electron_mass_c2*deltaKinEnergy/(mass*mass);
368 g *= (1.0 + magMoment2*(x2 - f1/f)/(1.0 + x2));
369 }
370 if(g > 1.0) {
371 G4cout << "### G4BetheBlochModel WARNING: g= " << g
372 << dp->GetDefinition()->GetParticleName()
373 << " Ekin(MeV)= " << kineticEnergy
374 << " delEkin(MeV)= " << deltaKinEnergy
375 << G4endl;
376 }
377 if(G4UniformRand() > g) return;
378 }
379
380 // delta-electron is produced
381 G4double totMomentum = totEnergy*sqrt(beta2);
382 G4double deltaMomentum =
383 sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
384 G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
385 (deltaMomentum * totMomentum);
386 /*
387 if(cost > 1.0) {
388 G4cout << "### G4BetheBlochModel WARNING: cost= "
389 << cost << " > 1 for "
390 << dp->GetDefinition()->GetParticleName()
391 << " Ekin(MeV)= " << kineticEnergy
392 << " p(MeV/c)= " << totMomentum
393 << " delEkin(MeV)= " << deltaKinEnergy
394 << " delMom(MeV/c)= " << deltaMomentum
395 << " tmin(MeV)= " << minKinEnergy
396 << " tmax(MeV)= " << maxKinEnergy
397 << " dir= " << dp->GetMomentumDirection()
398 << G4endl;
399 cost = 1.0;
400 }
401 */
402 G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
403
404 G4double phi = twopi * G4UniformRand() ;
405
406
407 G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost);
408 G4ThreeVector direction = dp->GetMomentumDirection();
409 deltaDirection.rotateUz(direction);
410
411 // create G4DynamicParticle object for delta ray
412 G4DynamicParticle* delta = new G4DynamicParticle(theElectron,
413 deltaDirection,deltaKinEnergy);
414
415 vdp->push_back(delta);
416
417 // Change kinematics of primary particle
418 kineticEnergy -= deltaKinEnergy;
419 G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum;
420 finalP = finalP.unit();
421
422 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
423 fParticleChange->SetProposedMomentumDirection(finalP);
424}
425
426//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
427
428G4double G4BetheBlochModel::MaxSecondaryEnergy(const G4ParticleDefinition* pd,
429 G4double kinEnergy)
430{
431 // here particle type is checked for any method
432 SetParticle(pd);
433 G4double tau = kinEnergy/mass;
434 G4double tmax = 2.0*electron_mass_c2*tau*(tau + 2.) /
435 (1. + 2.0*(tau + 1.)*ratio + ratio*ratio);
436 return std::min(tmax,tlimit);
437}
438
439//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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