source: trunk/source/processes/electromagnetic/standard/src/G4BetheBlochModel.cc@ 1036

Last change on this file since 1036 was 1007, checked in by garnier, 17 years ago

update to geant4.9.2
File size: 15.5 KB
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25//
26// $Id: G4BetheBlochModel.cc,v 1.24 2008/10/22 16:00:57 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02 $
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#include "G4NistManager.hh"
68
69//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
70
71using namespace std;
72
73G4BetheBlochModel::G4BetheBlochModel(const G4ParticleDefinition* p,
74 const G4String& nam)
75 : G4VEmModel(nam),
76 particle(0),
77 tlimit(DBL_MAX),
78 twoln10(2.0*log(10.0)),
79 bg2lim(0.0169),
80 taulim(8.4146e-3),
81 isIon(false),
82 isInitialised(false)
83{
84 fParticleChange = 0;
85 if(p) SetParticle(p);
86 theElectron = G4Electron::Electron();
87 corr = G4LossTableManager::Instance()->EmCorrections();
88 nist = G4NistManager::Instance();
89 SetLowEnergyLimit(2.0*MeV);
90}
91
92//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
93
94G4BetheBlochModel::~G4BetheBlochModel()
95{}
96
97//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
98
99G4double G4BetheBlochModel::MinEnergyCut(const G4ParticleDefinition*,
100 const G4MaterialCutsCouple* couple)
101{
102 return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy();
103}
104
105//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
106
107void G4BetheBlochModel::Initialise(const G4ParticleDefinition* p,
108 const G4DataVector&)
109{
110 if (!particle) SetParticle(p);
111
112 corrFactor = chargeSquare;
113
114 if(!isInitialised) {
115 isInitialised = true;
116
117 if(!fParticleChange) {
118 if (pParticleChange) {
119 fParticleChange = reinterpret_cast<G4ParticleChangeForLoss*>
120 (pParticleChange);
121 } else {
122 fParticleChange = new G4ParticleChangeForLoss();
123 }
124 }
125 }
126}
127
128//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
129
130void G4BetheBlochModel::SetParticle(const G4ParticleDefinition* p)
131{
132 if(particle != p) {
133 particle = p;
134 G4String pname = particle->GetParticleName();
135 if (particle->GetParticleType() == "nucleus" &&
136 pname != "deuteron" && pname != "triton") {
137 isIon = true;
138 }
139
140 mass = particle->GetPDGMass();
141 spin = particle->GetPDGSpin();
142 G4double q = particle->GetPDGCharge()/eplus;
143 chargeSquare = q*q;
144 ratio = electron_mass_c2/mass;
145 G4double magmom = particle->GetPDGMagneticMoment()
146 *mass/(0.5*eplus*hbar_Planck*c_squared);
147 magMoment2 = magmom*magmom - 1.0;
148 formfact = 0.0;
149 if(particle->GetLeptonNumber() == 0) {
150 G4double x = 0.8426*GeV;
151 if(spin == 0.0 && mass < GeV) {x = 0.736*GeV;}
152 else if(mass > GeV) {
153 x /= nist->GetZ13(mass/proton_mass_c2);
154 // tlimit = 51.2*GeV*A13[iz]*A13[iz];
155 }
156 formfact = 2.0*electron_mass_c2/(x*x);
157 tlimit = 2.0/formfact;
158 }
159 }
160}
161
162//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
163
164G4double G4BetheBlochModel::GetChargeSquareRatio(const G4ParticleDefinition* p,
165 const G4Material* mat,
166 G4double kineticEnergy)
167{
168 // this method is called only for ions
169 G4double q2 = corr->EffectiveChargeSquareRatio(p,mat,kineticEnergy);
170 corrFactor = q2*corr->EffectiveChargeCorrection(p,mat,kineticEnergy);
171 return corrFactor;
172}
173
174//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
175
176G4double G4BetheBlochModel::GetParticleCharge(const G4ParticleDefinition* p,
177 const G4Material* mat,
178 G4double kineticEnergy)
179{
180 // this method is called only for ions
181 return corr->GetParticleCharge(p,mat,kineticEnergy);
182}
183
184//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
185
186G4double
187G4BetheBlochModel::ComputeCrossSectionPerElectron(const G4ParticleDefinition* p,
188 G4double kineticEnergy,
189 G4double cutEnergy,
190 G4double maxKinEnergy)
191{
192 G4double cross = 0.0;
193 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
194 G4double maxEnergy = min(tmax,maxKinEnergy);
195 if(cutEnergy < maxEnergy) {
196
197 G4double totEnergy = kineticEnergy + mass;
198 G4double energy2 = totEnergy*totEnergy;
199 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2;
200
201 cross = 1.0/cutEnergy - 1.0/maxEnergy
202 - beta2*log(maxEnergy/cutEnergy)/tmax;
203
204 // +term for spin=1/2 particle
205 if( 0.5 == spin ) cross += 0.5*(maxEnergy - cutEnergy)/energy2;
206
207 // High order correction different for hadrons and ions
208 // nevetheless they are applied to reduce high energy transfers
209 // if(!isIon)
210 //cross += corr->FiniteSizeCorrectionXS(p,currentMaterial,
211 // kineticEnergy,cutEnergy);
212
213 cross *= twopi_mc2_rcl2*chargeSquare/beta2;
214 }
215
216 // G4cout << "BB: e= " << kineticEnergy << " tmin= " << cutEnergy
217 // << " tmax= " << tmax << " cross= " << cross << G4endl;
218
219 return cross;
220}
221
222//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
223
224G4double G4BetheBlochModel::ComputeCrossSectionPerAtom(
225 const G4ParticleDefinition* p,
226 G4double kineticEnergy,
227 G4double Z, G4double,
228 G4double cutEnergy,
229 G4double maxEnergy)
230{
231 G4double cross = Z*ComputeCrossSectionPerElectron
232 (p,kineticEnergy,cutEnergy,maxEnergy);
233 return cross;
234}
235
236//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
237
238G4double G4BetheBlochModel::CrossSectionPerVolume(
239 const G4Material* material,
240 const G4ParticleDefinition* p,
241 G4double kineticEnergy,
242 G4double cutEnergy,
243 G4double maxEnergy)
244{
245 currentMaterial = material;
246 G4double eDensity = material->GetElectronDensity();
247 G4double cross = eDensity*ComputeCrossSectionPerElectron
248 (p,kineticEnergy,cutEnergy,maxEnergy);
249 return cross;
250}
251
252//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
253
254G4double G4BetheBlochModel::ComputeDEDXPerVolume(const G4Material* material,
255 const G4ParticleDefinition* p,
256 G4double kineticEnergy,
257 G4double cut)
258{
259 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
260 G4double cutEnergy = min(cut,tmax);
261
262 G4double tau = kineticEnergy/mass;
263 G4double gam = tau + 1.0;
264 G4double bg2 = tau * (tau+2.0);
265 G4double beta2 = bg2/(gam*gam);
266
267 G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
268 G4double eexc2 = eexc*eexc;
269 G4double cden = material->GetIonisation()->GetCdensity();
270 G4double mden = material->GetIonisation()->GetMdensity();
271 G4double aden = material->GetIonisation()->GetAdensity();
272 G4double x0den = material->GetIonisation()->GetX0density();
273 G4double x1den = material->GetIonisation()->GetX1density();
274
275 G4double eDensity = material->GetElectronDensity();
276
277 G4double dedx = log(2.0*electron_mass_c2*bg2*cutEnergy/eexc2)
278 - (1.0 + cutEnergy/tmax)*beta2;
279
280 if(0.5 == spin) {
281 G4double del = 0.5*cutEnergy/(kineticEnergy + mass);
282 dedx += del*del;
283 }
284
285 // density correction
286 G4double x = log(bg2)/twoln10;
287 if ( x >= x0den ) {
288 dedx -= twoln10*x - cden ;
289 if ( x < x1den ) dedx -= aden*pow((x1den-x),mden) ;
290 }
291
292 // shell correction
293 dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy);
294
295 // now compute the total ionization loss
296
297 if (dedx < 0.0) dedx = 0.0 ;
298
299 dedx *= twopi_mc2_rcl2*chargeSquare*eDensity/beta2;
300
301 //High order correction different for hadrons and ions
302 if(isIon) {
303 dedx += corr->IonBarkasCorrection(p,material,kineticEnergy);
304 } else {
305 dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy);
306 }
307 return dedx;
308}
309
310//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
311
312void G4BetheBlochModel::CorrectionsAlongStep(const G4MaterialCutsCouple* couple,
313 const G4DynamicParticle* dp,
314 G4double& eloss,
315 G4double&,
316 G4double length)
317{
318 const G4ParticleDefinition* p = dp->GetDefinition();
319 const G4Material* mat = couple->GetMaterial();
320 G4double preKinEnergy = dp->GetKineticEnergy();
321 G4double e = preKinEnergy - eloss*0.5;
322 if(e < 0.0) e = preKinEnergy*0.5;
323
324 if(isIon) {
325 G4double q2 = corr->EffectiveChargeSquareRatio(p,mat,e);
326 GetModelOfFluctuations()->SetParticleAndCharge(p, q2);
327 eloss *= q2*corr->EffectiveChargeCorrection(p,mat,e)/corrFactor;
328 eloss += length*corr->IonHighOrderCorrections(p,couple,e);
329 }
330
331 if(nuclearStopping && preKinEnergy*proton_mass_c2/mass < chargeSquare*100.*MeV) {
332
333 G4double nloss = length*corr->NuclearDEDX(p,mat,e,false);
334
335 // too big energy loss
336 if(eloss + nloss > preKinEnergy) {
337 nloss *= (preKinEnergy/(eloss + nloss));
338 eloss = preKinEnergy;
339 } else {
340 eloss += nloss;
341 }
342 /*
343 G4cout << "G4ionIonisation::CorrectionsAlongStep: e= " << preKinEnergy
344 << " de= " << eloss << " NIEL= " << nloss
345 << " dynQ= " << dp->GetCharge()/eplus << G4endl;
346 */
347 fParticleChange->ProposeNonIonizingEnergyDeposit(nloss);
348 }
349
350}
351
352//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
353
354void G4BetheBlochModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp,
355 const G4MaterialCutsCouple*,
356 const G4DynamicParticle* dp,
357 G4double minKinEnergy,
358 G4double maxEnergy)
359{
360 G4double kineticEnergy = dp->GetKineticEnergy();
361 G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(),kineticEnergy);
362
363 G4double maxKinEnergy = std::min(maxEnergy,tmax);
364 if(minKinEnergy >= maxKinEnergy) return;
365
366 G4double totEnergy = kineticEnergy + mass;
367 G4double etot2 = totEnergy*totEnergy;
368 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
369
370 G4double deltaKinEnergy, f;
371 G4double f1 = 0.0;
372 G4double fmax = 1.0;
373 if( 0.5 == spin ) fmax += 0.5*maxKinEnergy*maxKinEnergy/etot2;
374
375 // sampling without nuclear size effect
376 do {
377 G4double q = G4UniformRand();
378 deltaKinEnergy = minKinEnergy*maxKinEnergy
379 /(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
380
381 f = 1.0 - beta2*deltaKinEnergy/tmax;
382 if( 0.5 == spin ) {
383 f1 = 0.5*deltaKinEnergy*deltaKinEnergy/etot2;
384 f += f1;
385 }
386
387 } while( fmax*G4UniformRand() > f);
388
389 // projectile formfactor - suppresion of high energy
390 // delta-electron production at high energy
391
392 G4double x = formfact*deltaKinEnergy;
393 if(x > 1.e-6) {
394
395 G4double x1 = 1.0 + x;
396 G4double g = 1.0/(x1*x1);
397 if( 0.5 == spin ) {
398 G4double x2 = 0.5*electron_mass_c2*deltaKinEnergy/(mass*mass);
399 g *= (1.0 + magMoment2*(x2 - f1/f)/(1.0 + x2));
400 }
401 if(g > 1.0) {
402 G4cout << "### G4BetheBlochModel WARNING: g= " << g
403 << dp->GetDefinition()->GetParticleName()
404 << " Ekin(MeV)= " << kineticEnergy
405 << " delEkin(MeV)= " << deltaKinEnergy
406 << G4endl;
407 }
408 if(G4UniformRand() > g) return;
409 }
410
411 // delta-electron is produced
412 G4double totMomentum = totEnergy*sqrt(beta2);
413 G4double deltaMomentum =
414 sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
415 G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
416 (deltaMomentum * totMomentum);
417 if(cost > 1.0) {
418 G4cout << "### G4BetheBlochModel WARNING: cost= "
419 << cost << " > 1 for "
420 << dp->GetDefinition()->GetParticleName()
421 << " Ekin(MeV)= " << kineticEnergy
422 << " p(MeV/c)= " << totMomentum
423 << " delEkin(MeV)= " << deltaKinEnergy
424 << " delMom(MeV/c)= " << deltaMomentum
425 << " tmin(MeV)= " << minKinEnergy
426 << " tmax(MeV)= " << maxKinEnergy
427 << " dir= " << dp->GetMomentumDirection()
428 << G4endl;
429 cost = 1.0;
430 }
431 G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
432
433 G4double phi = twopi * G4UniformRand() ;
434
435
436 G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost);
437 G4ThreeVector direction = dp->GetMomentumDirection();
438 deltaDirection.rotateUz(direction);
439
440 // create G4DynamicParticle object for delta ray
441 G4DynamicParticle* delta = new G4DynamicParticle(theElectron,
442 deltaDirection,deltaKinEnergy);
443
444 vdp->push_back(delta);
445
446 // Change kinematics of primary particle
447 kineticEnergy -= deltaKinEnergy;
448 G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum;
449 finalP = finalP.unit();
450
451 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
452 fParticleChange->SetProposedMomentumDirection(finalP);
453}
454
455//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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