| 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: G4mplIonisationWithDeltaModel
33 //
34 // Author: Vladimir Ivanchenko
35 //
36 // Creation date: 06.09.2005
37 //
38 // Modifications:
39 // 12.08.2007 Changing low energy approximation and extrapolation.
40 // Small bug fixing and refactoring (M. Vladymyrov)
41 // 13.11.2007 Use low-energy asymptotic from [3] (V.Ivanchenko)
42 //
43 //
44 // -------------------------------------------------------------------
45 // References
46 // [1] Steven P. Ahlen: Energy loss of relativistic heavy ionizing particles,
47 // S.P. Ahlen, Rev. Mod. Phys 52(1980), p121
48 // [2] K.A. Milton arXiv:hep-ex/0602040
49 // [3] S.P. Ahlen and K. Kinoshita, Phys. Rev. D26 (1982) 2347
50
51
52 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
53 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
54
55 #include "G4mplIonisationWithDeltaModel.hh"
56 #include "Randomize.hh"
57 #include "G4PhysicalConstants.hh"
58 #include "G4SystemOfUnits.hh"
59 #include "G4ParticleChangeForLoss.hh"
60 #include "G4Electron.hh"
61 #include "G4DynamicParticle.hh"
62 #include "G4ProductionCutsTable.hh"
63 #include "G4MaterialCutsCouple.hh"
64 #include "G4Log.hh"
65 #include "G4Pow.hh"
66
67 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
68
69 using namespace std;
70
71 std::vector<G4double>* G4mplIonisationWithDeltaModel::dedx0 = nullptr;
72
73 G4mplIonisationWithDeltaModel::G4mplIonisationWithDeltaModel(G4double mCharge,
74 const G4String& nam)
75 : G4VEmModel(nam),G4VEmFluctuationModel(nam),
76 magCharge(mCharge),
77 twoln10(std::log(100.0)),
78 betalow(0.01),
79 betalim(0.1),
80 beta2lim(betalim*betalim),
81 bg2lim(beta2lim*(1.0 + beta2lim))
82 {
83 nmpl = G4lrint(std::abs(magCharge) * 2 * fine_structure_const);
84 if(nmpl > 6) { nmpl = 6; }
85 else if(nmpl < 1) { nmpl = 1; }
86 pi_hbarc2_over_mc2 = pi * hbarc * hbarc / electron_mass_c2;
87 chargeSquare = magCharge * magCharge;
88 dedxlim = 45.*nmpl*nmpl*GeV*cm2/g;
89 fParticleChange = nullptr;
90 theElectron = G4Electron::Electron();
91 G4cout << "### Monopole ionisation model with d-electron production, Gmag= "
92 << magCharge/eplus << G4endl;
93 monopole = nullptr;
94 mass = 0.0;
95 }
96
97 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
98
99 G4mplIonisationWithDeltaModel::~G4mplIonisationWithDeltaModel()
100 {
101 if(IsMaster()) { delete dedx0; }
102 }
103
104 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
105
106 void G4mplIonisationWithDeltaModel::SetParticle(const G4ParticleDefinition* p)
107 {
108 monopole = p;
109 mass = monopole->GetPDGMass();
110 G4double emin =
111 std::min(LowEnergyLimit(),0.1*mass*(1./sqrt(1. - betalow*betalow) - 1.));
112 G4double emax =
113 std::max(HighEnergyLimit(),10*mass*(1./sqrt(1. - beta2lim) - 1.));
114 SetLowEnergyLimit(emin);
115 SetHighEnergyLimit(emax);
116 }
117
118 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
119
120 void
121 G4mplIonisationWithDeltaModel::Initialise(const G4ParticleDefinition* p,
122 const G4DataVector&)
123 {
124 if(!monopole) { SetParticle(p); }
125 if(!fParticleChange) { fParticleChange = GetParticleChangeForLoss(); }
126 if(IsMaster()) {
127 if(!dedx0) { dedx0 = new std::vector<G4double>; }
128 G4ProductionCutsTable* theCoupleTable=
129 G4ProductionCutsTable::GetProductionCutsTable();
130 G4int numOfCouples = (G4int)theCoupleTable->GetTableSize();
131 G4int n = (G4int)dedx0->size();
132 if(n < numOfCouples) { dedx0->resize(numOfCouples); }
133 G4Pow* g4calc = G4Pow::GetInstance();
134
135 // initialise vector assuming low conductivity
136 for(G4int i=0; i<numOfCouples; ++i) {
137
138 const G4Material* material =
139 theCoupleTable->GetMaterialCutsCouple(i)->GetMaterial();
140 G4double eDensity = material->GetElectronDensity();
141 G4double vF2 = 2*electron_Compton_length*g4calc->A13(3.*pi*pi*eDensity);
142 (*dedx0)[i] = pi_hbarc2_over_mc2*eDensity*nmpl*nmpl*
143 (G4Log(vF2/fine_structure_const) - 0.5)/vF2;
144 }
145 }
146 }
147
148 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
149
150 G4double
151 G4mplIonisationWithDeltaModel::MinEnergyCut(const G4ParticleDefinition*,
152 const G4MaterialCutsCouple* couple)
153 {
154 return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy();
155 }
156
157 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
158
159 G4double
160 G4mplIonisationWithDeltaModel::ComputeDEDXPerVolume(const G4Material* material,
161 const G4ParticleDefinition* p,
162 G4double kineticEnergy,
163 G4double maxEnergy)
164 {
165 if(!monopole) { SetParticle(p); }
166 G4double tmax = MaxSecondaryEnergy(p,kineticEnergy);
167 G4double cutEnergy = std::min(tmax, maxEnergy);
168 cutEnergy = std::max(LowEnergyLimit(), cutEnergy);
169 G4double tau = kineticEnergy / mass;
170 G4double gam = tau + 1.0;
171 G4double bg2 = tau * (tau + 2.0);
172 G4double beta2 = bg2 / (gam * gam);
173 G4double beta = sqrt(beta2);
174
175 // low-energy asymptotic formula
176 G4double dedx = (*dedx0)[CurrentCouple()->GetIndex()]*beta;
177
178 // above asymptotic
179 if(beta > betalow) {
180
181 // high energy
182 if(beta >= betalim) {
183 dedx = ComputeDEDXAhlen(material, bg2, cutEnergy);
184
185 } else {
186 G4double dedx1 = (*dedx0)[CurrentCouple()->GetIndex()]*betalow;
187 G4double dedx2 = ComputeDEDXAhlen(material, bg2lim, cutEnergy);
188
189 // extrapolation between two formula
190 G4double kapa2 = beta - betalow;
191 G4double kapa1 = betalim - beta;
192 dedx = (kapa1*dedx1 + kapa2*dedx2)/(kapa1 + kapa2);
193 }
194 }
195 return dedx;
196 }
197
198 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
199
200 G4double
201 G4mplIonisationWithDeltaModel::ComputeDEDXAhlen(const G4Material* material,
202 G4double bg2,
203 G4double cutEnergy)
204 {
205 G4double eDensity = material->GetElectronDensity();
206 G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
207
208 // Ahlen's formula for nonconductors, [1]p157, f(5.7)
209 G4double dedx =
210 0.5*(G4Log(2.0*electron_mass_c2*bg2*cutEnergy/(eexc*eexc)) -1.0);
211
212 // Kazama et al. cross-section correction
213 G4double k = 0.406;
214 if(nmpl > 1) { k = 0.346; }
215
216 // Bloch correction
217 const G4double B[7] = { 0.0, 0.248, 0.672, 1.022, 1.243, 1.464, 1.685};
218
219 dedx += 0.5 * k - B[nmpl];
220
221 // density effect correction
222 G4double x = G4Log(bg2)/twoln10;
223 dedx -= material->GetIonisation()->DensityCorrection(x);
224
225 // now compute the total ionization loss
226 dedx *= pi_hbarc2_over_mc2 * eDensity * nmpl * nmpl;
227
228 dedx = std::max(dedx, 0.0);
229 return dedx;
230 }
231
232 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
233
234 G4double
235 G4mplIonisationWithDeltaModel::ComputeCrossSectionPerElectron(
236 const G4ParticleDefinition* p,
237 G4double kineticEnergy,
238 G4double cut,
239 G4double maxKinEnergy)
240 {
241 if(!monopole) { SetParticle(p); }
242 G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
243 G4double maxEnergy = std::min(tmax, maxKinEnergy);
244 G4double cutEnergy = std::max(LowEnergyLimit(), cut);
245 G4double cross = (cutEnergy < maxEnergy)
246 ? (0.5/cutEnergy - 0.5/maxEnergy)*pi_hbarc2_over_mc2 * nmpl * nmpl : 0.0;
247 return cross;
248 }
249
250 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
251
252 G4double
253 G4mplIonisationWithDeltaModel::ComputeCrossSectionPerAtom(
254 const G4ParticleDefinition* p,
255 G4double kineticEnergy,
256 G4double Z, G4double,
257 G4double cutEnergy,
258 G4double maxEnergy)
259 {
260 G4double cross =
261 Z*ComputeCrossSectionPerElectron(p,kineticEnergy,cutEnergy,maxEnergy);
262 return cross;
263 }
264
265 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
266
267 void
268 G4mplIonisationWithDeltaModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp,
269 const G4MaterialCutsCouple*,
270 const G4DynamicParticle* dp,
271 G4double minKinEnergy,
272 G4double maxEnergy)
273 {
274 G4double kineticEnergy = dp->GetKineticEnergy();
275 G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(),kineticEnergy);
276
277 G4double maxKinEnergy = std::min(maxEnergy,tmax);
278 if(minKinEnergy >= maxKinEnergy) { return; }
279
280 //G4cout << "G4mplIonisationWithDeltaModel::SampleSecondaries: E(GeV)= "
281 // << kineticEnergy/GeV << " M(GeV)= " << mass/GeV
282 // << " tmin(MeV)= " << minKinEnergy/MeV << G4endl;
283
284 G4double totEnergy = kineticEnergy + mass;
285 G4double etot2 = totEnergy*totEnergy;
286 G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
287
288 // sampling without nuclear size effect
289 G4double q = G4UniformRand();
290 G4double deltaKinEnergy = minKinEnergy*maxKinEnergy
291 /(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
292
293 // delta-electron is produced
294 G4double totMomentum = totEnergy*sqrt(beta2);
295 G4double deltaMomentum =
296 sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
297 G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
298 (deltaMomentum * totMomentum);
299 cost = std::min(cost, 1.0);
300
301 G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
302
303 G4double phi = twopi * G4UniformRand() ;
304
305 G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost);
306 G4ThreeVector direction = dp->GetMomentumDirection();
307 deltaDirection.rotateUz(direction);
308
309 // create G4DynamicParticle object for delta ray
310 G4DynamicParticle* delta =
311 new G4DynamicParticle(theElectron,deltaDirection,deltaKinEnergy);
312
313 vdp->push_back(delta);
314
315 // Change kinematics of primary particle
316 kineticEnergy -= deltaKinEnergy;
317 G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum;
318 finalP = finalP.unit();
319
320 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
321 fParticleChange->SetProposedMomentumDirection(finalP);
322 }
323
324 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
325
326 G4double G4mplIonisationWithDeltaModel::SampleFluctuations(
327 const G4MaterialCutsCouple* couple,
328 const G4DynamicParticle* dp,
329 const G4double tcut,
330 const G4double tmax,
331 const G4double length,
332 const G4double meanLoss)
333 {
334 G4double siga = Dispersion(couple->GetMaterial(),dp,tcut,tmax,length);
335 G4double loss = meanLoss;
336 siga = std::sqrt(siga);
337 G4double twomeanLoss = meanLoss + meanLoss;
338
339 if(twomeanLoss < siga) {
340 G4double x;
341 do {
342 loss = twomeanLoss*G4UniformRand();
343 x = (loss - meanLoss)/siga;
344 // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
345 } while (1.0 - 0.5*x*x < G4UniformRand());
346 } else {
347 do {
348 loss = G4RandGauss::shoot(meanLoss,siga);
349 // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
350 } while (0.0 > loss || loss > twomeanLoss);
351 }
352 return loss;
353 }
354
355 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
356
357 G4double
358 G4mplIonisationWithDeltaModel::Dispersion(const G4Material* material,
359 const G4DynamicParticle* dp,
360 const G4double tcut,
361 const G4double tmax,
362 const G4double length)
363 {
364 G4double siga = 0.0;
365 G4double tau = dp->GetKineticEnergy()/mass;
366 if(tau > 0.0) {
367 const G4double beta = dp->GetBeta();
368 siga = (tmax/(beta*beta) - 0.5*tcut) * twopi_mc2_rcl2 * length
369 * material->GetElectronDensity() * chargeSquare;
370 }
371 return siga;
372 }
373
374 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
375
376 G4double
377 G4mplIonisationWithDeltaModel::MaxSecondaryEnergy(const G4ParticleDefinition*,
378 G4double kinEnergy)
379 {
380 G4double tau = kinEnergy/mass;
381 return 2.0*electron_mass_c2*tau*(tau + 2.);
382 }
383
384 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
385