source: trunk/source/processes/electromagnetic/standard/src/G4BetheBlochModel.cc @ 1050

Last change on this file since 1050 was 1007, checked in by garnier, 15 years ago

update to geant4.9.2
File size: 15.5 KB
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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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