source: trunk/source/processes/electromagnetic/muons/src/G4MuBetheBlochModel.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: 12.8 KB
RevLine 
[819]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//
[1007]26// $Id: G4MuBetheBlochModel.cc,v 1.24 2008/03/25 12:31:04 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02 $
[819]28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class header file
32//
33//
34// File name: G4MuBetheBlochModel
35//
36// Author: Vladimir Ivanchenko on base of Laszlo Urban code
37//
38// Creation date: 09.08.2002
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// 10-02-04 Calculation of radiative corrections using R.Kokoulin model (V.I)
47// 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko)
48// 12-04-05 Add usage of G4EmCorrections (V.Ivanchenko)
49// 13-02-06 ComputeCrossSectionPerElectron, ComputeCrossSectionPerAtom (mma)
50//
51
52//
53// -------------------------------------------------------------------
54//
55
56
57//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
58//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
59
60#include "G4MuBetheBlochModel.hh"
61#include "Randomize.hh"
62#include "G4Electron.hh"
63#include "G4LossTableManager.hh"
64#include "G4EmCorrections.hh"
65#include "G4ParticleChangeForLoss.hh"
66
67G4double G4MuBetheBlochModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083, 0.5917,
68 0.7628, 0.8983, 0.9801 };
69
70G4double G4MuBetheBlochModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813, 0.1813,
71 0.1569, 0.1112, 0.0506 };
72
73//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
74
75using namespace std;
76
77G4MuBetheBlochModel::G4MuBetheBlochModel(const G4ParticleDefinition* p,
78 const G4String& nam)
79 : G4VEmModel(nam),
80 particle(0),
81 limitKinEnergy(100.*keV),
82 logLimitKinEnergy(log(limitKinEnergy)),
83 twoln10(2.0*log(10.0)),
84 bg2lim(0.0169),
85 taulim(8.4146e-3),
86 alphaprime(fine_structure_const/twopi)
87{
88 theElectron = G4Electron::Electron();
89 corr = G4LossTableManager::Instance()->EmCorrections();
90
91 if(p) SetParticle(p);
92}
93
94//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
95
96G4MuBetheBlochModel::~G4MuBetheBlochModel()
97{}
98
99//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
100
[1007]101void G4MuBetheBlochModel::SetParticle(const G4ParticleDefinition* p)
[819]102{
[1007]103 if(!particle) {
104 particle = p;
105 mass = particle->GetPDGMass();
106 massSquare = mass*mass;
107 ratio = electron_mass_c2/mass;
108 }
[819]109}
110
[1007]111//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
[819]112
[1007]113G4double G4MuBetheBlochModel::MinEnergyCut(const G4ParticleDefinition*,
114 const G4MaterialCutsCouple* couple)
[819]115{
[1007]116 return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy();
[819]117}
118
119//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
120
121void G4MuBetheBlochModel::Initialise(const G4ParticleDefinition* p,
122 const G4DataVector&)
123{
124 if(p) SetParticle(p);
125
[1007]126 if(pParticleChange)
127 fParticleChange = reinterpret_cast<G4ParticleChangeForLoss*>
128 (pParticleChange);
129 else
130 fParticleChange = new G4ParticleChangeForLoss();
[819]131}
132
133//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
134
135G4double G4MuBetheBlochModel::ComputeCrossSectionPerElectron(
136 const G4ParticleDefinition* p,
137 G4double kineticEnergy,
138 G4double cutEnergy,
139 G4double maxKinEnergy)
140{
141 G4double cross = 0.0;
142 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
143 G4double maxEnergy = min(tmax,maxKinEnergy);
144 if(cutEnergy < maxEnergy) {
145
146 G4double totEnergy = kineticEnergy + mass;
147 G4double energy2 = totEnergy*totEnergy;
148 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2;
149
150 cross = 1.0/cutEnergy - 1.0/maxEnergy - beta2*log(maxEnergy/cutEnergy)/tmax
151 + 0.5*(maxEnergy - cutEnergy)/energy2;
152
153 // radiative corrections of R. Kokoulin
154 if (maxEnergy > limitKinEnergy) {
155
156 G4double logtmax = log(maxEnergy);
157 G4double logtmin = log(max(cutEnergy,limitKinEnergy));
158 G4double logstep = logtmax - logtmin;
159 G4double dcross = 0.0;
160
161 for (G4int ll=0; ll<8; ll++)
162 {
163 G4double ep = exp(logtmin + xgi[ll]*logstep);
164 G4double a1 = log(1.0 + 2.0*ep/electron_mass_c2);
165 G4double a3 = log(4.0*totEnergy*(totEnergy - ep)/massSquare);
166 dcross += wgi[ll]*(1.0/ep - beta2/tmax + 0.5*ep/energy2)*a1*(a3 - a1);
167 }
168
169 cross += dcross*logstep*alphaprime;
170 }
171
172 cross *= twopi_mc2_rcl2/beta2;
173
174 }
175
176 // G4cout << "tmin= " << cutEnergy << " tmax= " << tmax
177 // << " cross= " << cross << G4endl;
178
179 return cross;
180}
181
182//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
183
184G4double G4MuBetheBlochModel::ComputeCrossSectionPerAtom(
185 const G4ParticleDefinition* p,
186 G4double kineticEnergy,
187 G4double Z, G4double,
188 G4double cutEnergy,
189 G4double maxEnergy)
190{
191 G4double cross = Z*ComputeCrossSectionPerElectron
192 (p,kineticEnergy,cutEnergy,maxEnergy);
193 return cross;
194}
195
196//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
197
198G4double G4MuBetheBlochModel::CrossSectionPerVolume(
199 const G4Material* material,
200 const G4ParticleDefinition* p,
201 G4double kineticEnergy,
202 G4double cutEnergy,
203 G4double maxEnergy)
204{
205 G4double eDensity = material->GetElectronDensity();
206 G4double cross = eDensity*ComputeCrossSectionPerElectron
207 (p,kineticEnergy,cutEnergy,maxEnergy);
208 return cross;
209}
210
211//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
212
213G4double G4MuBetheBlochModel::ComputeDEDXPerVolume(const G4Material* material,
214 const G4ParticleDefinition* p,
215 G4double kineticEnergy,
216 G4double cut)
217{
218 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
219 G4double tau = kineticEnergy/mass;
220 G4double cutEnergy = min(cut,tmax);
221 G4double gam = tau + 1.0;
222 G4double bg2 = tau * (tau+2.0);
223 G4double beta2 = bg2/(gam*gam);
224
225 G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
226 G4double eexc2 = eexc*eexc;
227 G4double cden = material->GetIonisation()->GetCdensity();
228 G4double mden = material->GetIonisation()->GetMdensity();
229 G4double aden = material->GetIonisation()->GetAdensity();
230 G4double x0den = material->GetIonisation()->GetX0density();
231 G4double x1den = material->GetIonisation()->GetX1density();
232
233 G4double eDensity = material->GetElectronDensity();
234
235 G4double dedx = log(2.0*electron_mass_c2*bg2*cutEnergy/eexc2)
236 -(1.0 + cutEnergy/tmax)*beta2;
237
238 G4double totEnergy = kineticEnergy + mass;
239 G4double del = 0.5*cutEnergy/totEnergy;
240 dedx += del*del;
241
242 // density correction
243 G4double x = log(bg2)/twoln10;
244 if ( x >= x0den ) {
245 dedx -= twoln10*x - cden ;
246 if ( x < x1den ) dedx -= aden*pow((x1den-x),mden) ;
247 }
248
249 // shell correction
250 dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy);
251
252 // now compute the total ionization loss
253
254 if (dedx < 0.0) dedx = 0.0 ;
255
256 // radiative corrections of R. Kokoulin
257 if (cutEnergy > limitKinEnergy) {
258
259 G4double logtmax = log(cutEnergy);
260 G4double logstep = logtmax - logLimitKinEnergy;
261 G4double dloss = 0.0;
262 G4double ftot2= 0.5/(totEnergy*totEnergy);
263
264 for (G4int ll=0; ll<8; ll++)
265 {
266 G4double ep = exp(logLimitKinEnergy + xgi[ll]*logstep);
267 G4double a1 = log(1.0 + 2.0*ep/electron_mass_c2);
268 G4double a3 = log(4.0*totEnergy*(totEnergy - ep)/massSquare);
269 dloss += wgi[ll]*(1.0 - beta2*ep/tmax + ep*ep*ftot2)*a1*(a3 - a1);
270 }
271 dedx += dloss*logstep*alphaprime;
272 }
273
274 dedx *= twopi_mc2_rcl2*eDensity/beta2;
275
276 //High order corrections
[961]277 dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy);
[819]278
279 return dedx;
280}
281
282//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
283
284void G4MuBetheBlochModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp,
285 const G4MaterialCutsCouple*,
286 const G4DynamicParticle* dp,
287 G4double minKinEnergy,
288 G4double maxEnergy)
289{
290 G4double tmax = MaxSecondaryKinEnergy(dp);
291 G4double maxKinEnergy = min(maxEnergy,tmax);
292 if(minKinEnergy >= maxKinEnergy) return;
293
294 G4double kineticEnergy = dp->GetKineticEnergy();
295 G4double totEnergy = kineticEnergy + mass;
296 G4double etot2 = totEnergy*totEnergy;
297 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
298
299 G4double grej = 1.;
300 if(tmax > limitKinEnergy) {
301 G4double a0 = log(2.*totEnergy/mass);
302 grej += alphaprime*a0*a0;
303 }
304
305 G4double deltaKinEnergy, f;
306
307 // sampling follows ...
308 do {
309 G4double q = G4UniformRand();
310 deltaKinEnergy = minKinEnergy*maxKinEnergy
311 /(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
312
313
314 f = 1.0 - beta2*deltaKinEnergy/tmax
315 + 0.5*deltaKinEnergy*deltaKinEnergy/etot2;
316
317 if(deltaKinEnergy > limitKinEnergy) {
318 G4double a1 = log(1.0 + 2.0*deltaKinEnergy/electron_mass_c2);
319 G4double a3 = log(4.0*totEnergy*(totEnergy - deltaKinEnergy)/massSquare);
320 f *= (1. + alphaprime*a1*(a3 - a1));
321 }
322
323 if(f > grej) {
324 G4cout << "G4MuBetheBlochModel::SampleSecondary Warning! "
325 << "Majorant " << grej << " < "
326 << f << " for edelta= " << deltaKinEnergy
327 << " tmin= " << minKinEnergy << " max= " << maxKinEnergy
328 << G4endl;
329 }
330
331
332 } while( grej*G4UniformRand() > f );
333
334 G4double deltaMomentum =
335 sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
336 G4double totalMomentum = totEnergy*sqrt(beta2);
337 G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
338 (deltaMomentum * totalMomentum);
339
340 G4double sint = sqrt(1.0 - cost*cost);
341
342 G4double phi = twopi * G4UniformRand() ;
343
344 G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost) ;
345 G4ThreeVector direction = dp->GetMomentumDirection();
346 deltaDirection.rotateUz(direction);
347
348 // primary change
349 kineticEnergy -= deltaKinEnergy;
350 G4ThreeVector dir = totalMomentum*direction - deltaMomentum*deltaDirection;
351 direction = dir.unit();
352 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
353 fParticleChange->SetProposedMomentumDirection(direction);
354
355 // create G4DynamicParticle object for delta ray
356 G4DynamicParticle* delta = new G4DynamicParticle(theElectron,
357 deltaDirection,deltaKinEnergy);
358 vdp->push_back(delta);
359}
360
361//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
Note: See TracBrowser for help on using the repository browser.