| Geant4 Cross Reference |
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 //
27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class header file
30 //
31 //
32 // File name: G4MuBetheBlochModel
33 //
34 // Author: Vladimir Ivanchenko on base of Laszlo Urban code
35 //
36 // Creation date: 09.08.2002
37 //
38 // Modifications:
39 //
40 // 04-12-02 Fix problem of G4DynamicParticle constructor (V.Ivanchenko)
41 // 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko)
42 // 27-01-03 Make models region aware (V.Ivanchenko)
43 // 13-02-03 Add name (V.Ivanchenko)
44 // 10-02-04 Calculation of radiative corrections using R.Kokoulin model (V.I)
45 // 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko)
46 // 12-04-05 Add usage of G4EmCorrections (V.Ivanchenko)
47 // 13-02-06 ComputeCrossSectionPerElectron, ComputeCrossSectionPerAtom (mma)
48 //
49
50 //
51 // -------------------------------------------------------------------
52 //
53
54 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
55 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
56
57 #include "G4MuBetheBlochModel.hh"
58 #include "G4PhysicalConstants.hh"
59 #include "G4SystemOfUnits.hh"
60 #include "Randomize.hh"
61 #include "G4Electron.hh"
62 #include "G4LossTableManager.hh"
63 #include "G4EmCorrections.hh"
64 #include "G4ParticleChangeForLoss.hh"
65 #include "G4Log.hh"
66 #include "G4Exp.hh"
67 #include "G4DeltaAngle.hh"
68
69 G4double G4MuBetheBlochModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083, 0.5917,
70 0.7628, 0.8983, 0.9801 };
71
72 G4double G4MuBetheBlochModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813, 0.1813,
73 0.1569, 0.1112, 0.0506 };
74
75 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
76
77 G4MuBetheBlochModel::G4MuBetheBlochModel(const G4ParticleDefinition* p,
78 const G4String& nam)
79 : G4VEmModel(nam),
80 limitRadCorrection(250.*CLHEP::MeV),
81 limitKinEnergy(100.*CLHEP::keV),
82 logLimitKinEnergy(G4Log(limitKinEnergy)),
83 twoln10(2.0*G4Log(10.0)),
84 alphaprime(CLHEP::fine_structure_const/CLHEP::twopi)
85 {
86 theElectron = G4Electron::Electron();
87 corr = G4LossTableManager::Instance()->EmCorrections();
88 if(nullptr != p) { SetParticle(p); }
89 }
90
91 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
92
93 G4double G4MuBetheBlochModel::MinEnergyCut(const G4ParticleDefinition*,
94 const G4MaterialCutsCouple* couple)
95 {
96 return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy();
97 }
98
99 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
100
101 G4double G4MuBetheBlochModel::MaxSecondaryEnergy(const G4ParticleDefinition*,
102 G4double kinEnergy)
103 {
104 G4double tau = kinEnergy/mass;
105 G4double tmax = 2.0*CLHEP::electron_mass_c2*tau*(tau + 2.) /
106 (1. + 2.0*(tau + 1.)*ratio + ratio*ratio);
107 return tmax;
108 }
109
110 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
111
112 void G4MuBetheBlochModel::SetParticle(const G4ParticleDefinition* p)
113 {
114 if(nullptr == particle) {
115 particle = p;
116 mass = particle->GetPDGMass();
117 massSquare = mass*mass;
118 ratio = CLHEP::electron_mass_c2/mass;
119 }
120 }
121
122 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
123
124 void G4MuBetheBlochModel::Initialise(const G4ParticleDefinition* p,
125 const G4DataVector&)
126 {
127 SetParticle(p);
128 if(nullptr == fParticleChange) {
129 fParticleChange = GetParticleChangeForLoss();
130 if(UseAngularGeneratorFlag() && nullptr == GetAngularDistribution()) {
131 SetAngularDistribution(new G4DeltaAngle());
132 }
133 }
134 }
135
136 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
137
138 G4double G4MuBetheBlochModel::ComputeCrossSectionPerElectron(
139 const G4ParticleDefinition* p,
140 G4double kineticEnergy,
141 G4double cutEnergy,
142 G4double maxKinEnergy)
143 {
144 G4double cross = 0.0;
145 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
146 G4double maxEnergy = std::min(tmax, maxKinEnergy);
147 if(cutEnergy < maxEnergy) {
148
149 G4double totEnergy = kineticEnergy + mass;
150 G4double energy2 = totEnergy*totEnergy;
151 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2;
152
153 cross = 1.0/cutEnergy - 1.0/maxEnergy -
154 beta2*G4Log(maxEnergy/cutEnergy)/tmax +
155 0.5*(maxEnergy - cutEnergy)/energy2;
156
157 // radiative corrections of R. Kokoulin
158 if (maxEnergy > limitKinEnergy && kineticEnergy > limitRadCorrection) {
159
160 G4double logtmax = G4Log(maxEnergy);
161 G4double logtmin = G4Log(std::max(cutEnergy,limitKinEnergy));
162 G4double logstep = logtmax - logtmin;
163 G4double dcross = 0.0;
164
165 for (G4int ll=0; ll<8; ++ll) {
166 G4double ep = G4Exp(logtmin + xgi[ll]*logstep);
167 G4double a1 = G4Log(1.0 + 2.0*ep/CLHEP::electron_mass_c2);
168 G4double a3 = G4Log(4.0*totEnergy*(totEnergy - ep)/massSquare);
169 dcross += wgi[ll]*(1.0/ep - beta2/tmax + 0.5*ep/energy2)*a1*(a3 - a1);
170 }
171 cross += dcross*logstep*alphaprime;
172 }
173 cross *= CLHEP::twopi_mc2_rcl2/beta2;
174 }
175 // G4cout << "tmin= " << cutEnergy << " tmax= " << tmax
176 // << " cross= " << cross << G4endl;
177 return cross;
178 }
179
180 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
181
182 G4double G4MuBetheBlochModel::ComputeCrossSectionPerAtom(
183 const G4ParticleDefinition* p,
184 G4double kineticEnergy,
185 G4double Z, G4double,
186 G4double cutEnergy,
187 G4double maxEnergy)
188 {
189 G4double cross = Z*ComputeCrossSectionPerElectron
190 (p,kineticEnergy,cutEnergy,maxEnergy);
191 return cross;
192 }
193
194 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
195
196 G4double G4MuBetheBlochModel::CrossSectionPerVolume(
197 const G4Material* material,
198 const G4ParticleDefinition* p,
199 G4double kineticEnergy,
200 G4double cutEnergy,
201 G4double maxEnergy)
202 {
203 G4double eDensity = material->GetElectronDensity();
204 G4double cross = eDensity*ComputeCrossSectionPerElectron
205 (p,kineticEnergy,cutEnergy,maxEnergy);
206 return cross;
207 }
208
209 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
210
211 G4double G4MuBetheBlochModel::ComputeDEDXPerVolume(const G4Material* material,
212 const G4ParticleDefinition* p,
213 G4double kineticEnergy,
214 G4double cut)
215 {
216 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
217 G4double tau = kineticEnergy/mass;
218 G4double cutEnergy = std::min(cut, tmax);
219 G4double gam = tau + 1.0;
220 G4double bg2 = tau * (tau+2.0);
221 G4double beta2 = bg2/(gam*gam);
222
223 G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
224 G4double eexc2 = eexc*eexc;
225
226 G4double eDensity = material->GetElectronDensity();
227
228 G4double dedx = G4Log(2.0*CLHEP::electron_mass_c2*bg2*cutEnergy/eexc2)
229 -(1.0 + cutEnergy/tmax)*beta2;
230
231 G4double totEnergy = kineticEnergy + mass;
232 G4double del = 0.5*cutEnergy/totEnergy;
233 dedx += del*del;
234
235 // density correction
236 G4double x = G4Log(bg2)/twoln10;
237 dedx -= material->GetIonisation()->DensityCorrection(x);
238
239 // shell and high order corrections
240 dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy);
241
242 // radiative corrections of R. Kokoulin
243 if (cutEnergy > limitKinEnergy && kineticEnergy > limitRadCorrection) {
244
245 G4double logtmax = G4Log(cutEnergy);
246 G4double logstep = logtmax - logLimitKinEnergy;
247 G4double dloss = 0.0;
248 G4double ftot2= 0.5/(totEnergy*totEnergy);
249
250 for (G4int ll=0; ll<8; ++ll) {
251 G4double ep = G4Exp(logLimitKinEnergy + xgi[ll]*logstep);
252 G4double a1 = G4Log(1.0 + 2.0*ep/CLHEP::electron_mass_c2);
253 G4double a3 = G4Log(4.0*totEnergy*(totEnergy - ep)/massSquare);
254 dloss += wgi[ll]*(1.0 - beta2*ep/tmax + ep*ep*ftot2)*a1*(a3 - a1);
255 }
256 dedx += dloss*logstep*alphaprime;
257 }
258 dedx *= CLHEP::twopi_mc2_rcl2*eDensity/beta2;
259
260 //High order corrections
261 dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy);
262 dedx = std::max(dedx, 0.);
263 return dedx;
264 }
265
266 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
267
268 void G4MuBetheBlochModel::SampleSecondaries(
269 std::vector<G4DynamicParticle*>* vdp,
270 const G4MaterialCutsCouple* couple,
271 const G4DynamicParticle* dp,
272 G4double minKinEnergy,
273 G4double maxEnergy)
274 {
275 G4double kineticEnergy = dp->GetKineticEnergy();
276 G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(), kineticEnergy);
277 G4double maxKinEnergy = std::min(maxEnergy, tmax);
278 if(minKinEnergy >= maxKinEnergy) { return; }
279
280 G4double totEnergy = kineticEnergy + mass;
281 G4double etot2 = totEnergy*totEnergy;
282 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
283
284 G4double grej = 1.;
285 G4bool radC = (tmax > limitKinEnergy && kineticEnergy > limitRadCorrection);
286 if(radC) {
287 G4double a0 = G4Log(2.*totEnergy/mass);
288 grej += alphaprime*a0*a0;
289 }
290
291 G4double tkin, f;
292
293 // sampling follows ...
294 do {
295 G4double q = G4UniformRand();
296 tkin = minKinEnergy*maxKinEnergy/(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
297 f = 1.0 - beta2*tkin/tmax + 0.5*tkin*tkin/etot2;
298
299 if(radC && tkin > limitKinEnergy) {
300 G4double a1 = G4Log(1.0 + 2.0*tkin/CLHEP::electron_mass_c2);
301 G4double a3 = G4Log(4.0*totEnergy*(totEnergy - tkin)/massSquare);
302 f *= (1. + alphaprime*a1*(a3 - a1));
303 }
304
305 if(f > grej) {
306 G4cout << "G4MuBetheBlochModel::SampleSecondary Warning! "
307 << "Majorant " << grej << " < "
308 << f << " for edelta= " << tkin
309 << " tmin= " << minKinEnergy << " max= " << maxKinEnergy
310 << G4endl;
311 }
312 // Loop checking, 03-Aug-2015, Vladimir Ivanchenko
313 } while( grej*G4UniformRand() > f );
314
315 G4ThreeVector deltaDirection;
316
317 if(UseAngularGeneratorFlag()) {
318 const G4Material* mat = couple->GetMaterial();
319 deltaDirection = GetAngularDistribution()->SampleDirection(dp, tkin,
320 SelectRandomAtomNumber(mat), mat);
321 } else {
322
323 G4double deltaMom = std::sqrt(tkin * (tkin + 2.0*CLHEP::electron_mass_c2));
324 G4double totalMom = totEnergy*std::sqrt(beta2);
325 G4double cost = tkin * (totEnergy + CLHEP::electron_mass_c2) /
326 (deltaMom * totalMom);
327 cost = std::min(cost, 1.0);
328 const G4double sint = std::sqrt((1.0 - cost)*(1.0 + cost));
329 const G4double phi = twopi*G4UniformRand();
330
331 deltaDirection.set(sint*std::cos(phi),sint*std::sin(phi), cost) ;
332 deltaDirection.rotateUz(dp->GetMomentumDirection());
333 }
334 // create G4DynamicParticle object for delta ray
335 auto delta = new G4DynamicParticle(theElectron, deltaDirection, tkin);
336 vdp->push_back(delta);
337
338 // primary change
339 kineticEnergy -= tkin;
340 G4ThreeVector dir = dp->GetMomentum() - delta->GetMomentum();
341 dir = dir.unit();
342 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
343 fParticleChange->SetProposedMomentumDirection(dir);
344 }
345
346 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
347