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25 // 25 //
>> 26 // $Id: G4UniversalFluctuation.cc,v 1.28 2010-10-26 10:06:12 vnivanch Exp $
>> 27 // GEANT4 tag $Name: geant4-09-04-patch-02 $
26 // 28 //
27 // ------------------------------------------- 29 // -------------------------------------------------------------------
28 // 30 //
29 // GEANT4 Class file 31 // GEANT4 Class file
30 // 32 //
31 // 33 //
32 // File name: G4UniversalFluctuation 34 // File name: G4UniversalFluctuation
33 // 35 //
34 // Author: V. Ivanchenko for Laszlo Urb << 36 // Author: Laszlo Urban
35 // 37 //
36 // Creation date: 03.01.2002 38 // Creation date: 03.01.2002
37 // 39 //
38 // Modifications: 40 // Modifications:
39 // 41 //
>> 42 // 28-12-02 add method Dispersion (V.Ivanchenko)
>> 43 // 07-02-03 change signature (V.Ivanchenko)
>> 44 // 13-02-03 Add name (V.Ivanchenko)
>> 45 // 16-10-03 Changed interface to Initialisation (V.Ivanchenko)
>> 46 // 07-11-03 Fix problem of rounding of double in G4UniversalFluctuations
>> 47 // 06-02-04 Add control on big sigma > 2*meanLoss (V.Ivanchenko)
>> 48 // 26-04-04 Comment out the case of very small step (V.Ivanchenko)
>> 49 // 07-02-05 define problim = 5.e-3 (mma)
>> 50 // 03-05-05 conditions of Gaussian fluctuation changed (bugfix)
>> 51 // + smearing for very small loss (L.Urban)
>> 52 // 03-10-05 energy dependent rate -> cut dependence of the
>> 53 // distribution is much weaker (L.Urban)
>> 54 // 17-10-05 correction for very small loss (L.Urban)
>> 55 // 20-03-07 'GLANDZ' part rewritten completely, no 'very small loss'
>> 56 // regime any more (L.Urban)
>> 57 // 03-04-07 correction to get better width of eloss distr.(L.Urban)
>> 58 // 13-07-07 add protection for very small step or low-density material (VI)
>> 59 // 19-03-09 new width correction (does not depend on previous steps) (L.Urban)
>> 60 // 20-03-09 modification in the width correction (L.Urban)
>> 61 // 14-06-10 fixed tail distribution - do not use uniform function (L.Urban)
>> 62 // 08-08-10 width correction algorithm has bee modified -->
>> 63 // better results for thin targets (L.Urban)
40 // 64 //
41 65
42 //....oooOO0OOooo........oooOO0OOooo........oo 66 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
43 //....oooOO0OOooo........oooOO0OOooo........oo 67 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
44 68
45 #include "G4UniversalFluctuation.hh" 69 #include "G4UniversalFluctuation.hh"
46 #include "G4PhysicalConstants.hh" <<
47 #include "G4SystemOfUnits.hh" <<
48 #include "Randomize.hh" 70 #include "Randomize.hh"
49 #include "G4Poisson.hh" 71 #include "G4Poisson.hh"
>> 72 #include "G4Step.hh"
50 #include "G4Material.hh" 73 #include "G4Material.hh"
51 #include "G4MaterialCutsCouple.hh" <<
52 #include "G4DynamicParticle.hh" 74 #include "G4DynamicParticle.hh"
53 #include "G4ParticleDefinition.hh" 75 #include "G4ParticleDefinition.hh"
54 #include "G4Log.hh" <<
55 76
56 //....oooOO0OOooo........oooOO0OOooo........oo 77 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
57 78
>> 79 using namespace std;
>> 80
58 G4UniversalFluctuation::G4UniversalFluctuation 81 G4UniversalFluctuation::G4UniversalFluctuation(const G4String& nam)
59 :G4VEmFluctuationModel(nam), 82 :G4VEmFluctuationModel(nam),
60 minLoss(10.*CLHEP::eV) << 83 particle(0),
>> 84 minNumberInteractionsBohr(10.0),
>> 85 theBohrBeta2(50.0*keV/proton_mass_c2),
>> 86 minLoss(10.*eV),
>> 87 nmaxCont(16.),
>> 88 rate(0.55),
>> 89 fw(4.)
61 { 90 {
62 rndmarray = new G4double[sizearray]; << 91 lastMaterial = 0;
>> 92
>> 93 particleMass = chargeSquare = ipotFluct = electronDensity = f1Fluct = f2Fluct
>> 94 = e1Fluct = e2Fluct = e1LogFluct = e2LogFluct = ipotLogFluct = e0 = esmall
>> 95 = e1 = e2 = 0;
63 } 96 }
64 97
65 //....oooOO0OOooo........oooOO0OOooo........oo 98 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
66 99
67 G4UniversalFluctuation::~G4UniversalFluctuatio 100 G4UniversalFluctuation::~G4UniversalFluctuation()
68 { << 101 {}
69 delete [] rndmarray; <<
70 } <<
71 102
72 //....oooOO0OOooo........oooOO0OOooo........oo 103 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
73 104
74 void G4UniversalFluctuation::InitialiseMe(cons 105 void G4UniversalFluctuation::InitialiseMe(const G4ParticleDefinition* part)
75 { 106 {
76 particle = part; << 107 particle = part;
77 particleMass = part->GetPDGMass(); << 108 particleMass = part->GetPDGMass();
78 const G4double q = part->GetPDGCharge()/CLHE << 109 G4double q = part->GetPDGCharge()/eplus;
79 << 110 chargeSquare = q*q;
80 // Derived quantities <<
81 m_Inv_particleMass = 1.0 / particleMass; <<
82 m_massrate = CLHEP::electron_mass_c2 * m_Inv <<
83 chargeSquare = q*q; <<
84 } 111 }
85 112
86 //....oooOO0OOooo........oooOO0OOooo........oo 113 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
87 114
88 G4double << 115 G4double G4UniversalFluctuation::SampleFluctuations(const G4Material* material,
89 G4UniversalFluctuation::SampleFluctuations(con << 116 const G4DynamicParticle* dp,
90 con << 117 G4double& tmax,
91 con << 118 G4double& length,
92 con << 119 G4double& meanLoss)
93 con <<
94 con <<
95 { 120 {
96 // Calculate actual loss from the mean loss. << 121 // Calculate actual loss from the mean loss.
97 // The model used to get the fluctuations is << 122 // The model used to get the fluctuations is essentially the same
98 // as in Glandz in Geant3 (Cern program libr << 123 // as in Glandz in Geant3 (Cern program library W5013, phys332).
99 // L. Urban et al. NIM A362, p.416 (1995) an << 124 // L. Urban et al. NIM A362, p.416 (1995) and Geant4 Physics Reference Manual
100 125
101 // shortcut for very small loss or from a st << 126 // shortcut for very very small loss (out of validity of the model)
102 // (out of validity of the model) <<
103 // 127 //
104 if (averageLoss < minLoss) { return averageL << 128 if (meanLoss < minLoss) { return meanLoss; }
105 meanLoss = averageLoss; <<
106 const G4double tkin = dp->GetKineticEnergy( <<
107 //G4cout<< "Emean= "<< meanLoss<< " tmax= "< <<
108 <<
109 if(dp->GetDefinition() != particle) { Initia <<
110 <<
111 CLHEP::HepRandomEngine* rndmEngineF = G4Rand <<
112 <<
113 const G4double gam = tkin * m_Inv_particle <<
114 const G4double gam2 = gam*gam; <<
115 const G4double beta = dp->GetBeta(); <<
116 const G4double beta2 = beta*beta; <<
117 129
118 G4double loss(0.), siga(0.); << 130 if(!particle) { InitialiseMe(dp->GetDefinition()); }
>> 131
>> 132 G4double tau = dp->GetKineticEnergy()/particleMass;
>> 133 G4double gam = tau + 1.0;
>> 134 G4double gam2 = gam*gam;
>> 135 G4double beta2 = tau*(tau + 2.0)/gam2;
119 136
120 const G4Material* material = couple->GetMate << 137 G4double loss(0.), siga(0.);
121 138
122 // Gaussian regime 139 // Gaussian regime
123 // for heavy particles only and conditions 140 // for heavy particles only and conditions
124 // for Gauusian fluct. has been changed 141 // for Gauusian fluct. has been changed
125 // 142 //
126 if (particleMass > CLHEP::electron_mass_c2 & << 143 if ((particleMass > electron_mass_c2) &&
127 meanLoss >= minNumberInteractionsBohr*tc << 144 (meanLoss >= minNumberInteractionsBohr*tmax))
128 << 145 {
129 siga = std::sqrt((tmax/beta2 - 0.5*tcut)*C << 146 G4double massrate = electron_mass_c2/particleMass ;
130 length*chargeSquare*mate << 147 G4double tmaxkine = 2.*electron_mass_c2*beta2*gam2/
131 const G4double sn = meanLoss/siga; << 148 (1.+massrate*(2.*gam+massrate)) ;
132 << 149 if (tmaxkine <= 2.*tmax)
133 // thick target case << 150 {
134 if (sn >= 2.0) { << 151 electronDensity = material->GetElectronDensity();
135 << 152 siga = (1.0/beta2 - 0.5) * twopi_mc2_rcl2 * tmax * length
136 const G4double twomeanLoss = meanLoss + << 153 * electronDensity * chargeSquare;
137 do { << 154 siga = sqrt(siga);
138 loss = G4RandGauss::shoot(rndmEngineF, meanL << 155 G4double twomeanLoss = meanLoss + meanLoss;
139 // Loop checking, 03-Aug-2015, Vladimir Ivan << 156 if (twomeanLoss < siga) {
140 } while (0.0 > loss || twomeanLoss < lo << 157 G4double x;
141 << 158 do {
142 // Gamma distribution << 159 loss = twomeanLoss*G4UniformRand();
143 } else { << 160 x = (loss - meanLoss)/siga;
144 << 161 } while (1.0 - 0.5*x*x < G4UniformRand());
145 const G4double neff = sn*sn; << 162 } else {
146 loss = meanLoss*G4RandGamma::shoot(rndmE << 163 do {
>> 164 loss = G4RandGauss::shoot(meanLoss,siga);
>> 165 } while (loss < 0. || loss > twomeanLoss);
>> 166 }
>> 167 return loss;
147 } 168 }
148 //G4cout << "Gauss: " << loss << G4endl; <<
149 return loss; <<
150 } 169 }
151 170
152 auto ioni = material->GetIonisation(); << 171 // Glandz regime : initialisation
153 e0 = ioni->GetEnergy0fluct(); << 172 //
>> 173 if (material != lastMaterial) {
>> 174 f1Fluct = material->GetIonisation()->GetF1fluct();
>> 175 f2Fluct = material->GetIonisation()->GetF2fluct();
>> 176 e1Fluct = material->GetIonisation()->GetEnergy1fluct();
>> 177 e2Fluct = material->GetIonisation()->GetEnergy2fluct();
>> 178 e1LogFluct = material->GetIonisation()->GetLogEnergy1fluct();
>> 179 e2LogFluct = material->GetIonisation()->GetLogEnergy2fluct();
>> 180 ipotFluct = material->GetIonisation()->GetMeanExcitationEnergy();
>> 181 ipotLogFluct = material->GetIonisation()->GetLogMeanExcEnergy();
>> 182 e0 = material->GetIonisation()->GetEnergy0fluct();
>> 183 esmall = 0.5*sqrt(e0*ipotFluct);
>> 184 lastMaterial = material;
>> 185
>> 186 }
154 187
155 // very small step or low-density material 188 // very small step or low-density material
156 if(tcut <= e0) { return meanLoss; } << 189 if(tmax <= e0) return meanLoss;
157 <<
158 ipotFluct = ioni->GetMeanExcitationEnergy(); <<
159 ipotLogFluct = ioni->GetLogMeanExcEnergy(); <<
160 190
161 // width correction for small cuts << 191 G4double a1 = 0. , a2 = 0., a3 = 0. ;
162 const G4double scaling = std::min(1.+0.5*CLH <<
163 meanLoss /= scaling; <<
164 <<
165 w2 = (tcut > ipotFluct) ? <<
166 G4Log(2.*CLHEP::electron_mass_c2*beta2*gam <<
167 return SampleGlandz(rndmEngineF, material, t <<
168 } <<
169 192
170 //....oooOO0OOooo........oooOO0OOooo........oo << 193 if(tmax > ipotFluct) {
>> 194 G4double w2 = log(2.*electron_mass_c2*beta2*gam2)-beta2;
171 195
172 G4double << 196 if(w2 > ipotLogFluct && w2 > e2LogFluct && tmax> ipotFluct) {
173 G4UniversalFluctuation::SampleGlandz(CLHEP::He << 197 G4double C = meanLoss*(1.-rate)/(w2-ipotLogFluct);
174 const G4M << 198 a1 = C*f1Fluct*(w2-e1LogFluct)/e1Fluct;
175 const G4d << 199 a2 = C*f2Fluct*(w2-e2LogFluct)/e2Fluct;
176 { << 200
177 G4double a1(0.0), a3(0.0); << 201
178 G4double loss = 0.0; << 202 if(a1 < nmaxCont)
179 G4double e1 = ipotFluct; << 203 {
180 << 204 //small energy loss
181 if(tcut > e1) { << 205 G4double sa1 = sqrt(a1);
182 a1 = meanLoss*(1.-rate)/e1; << 206 if(G4UniformRand() < exp(-sa1))
183 if(a1 < a0) { << 207 {
184 const G4double fwnow = 0.1+(fw-0.1)*std: << 208 e1 = esmall;
185 a1 /= fwnow; << 209 a1 = meanLoss*(1.-rate)/e1;
186 e1 *= fwnow; << 210 a2 = 0.;
187 } else { << 211 e2 = e2Fluct;
>> 212 }
>> 213 else
>> 214 {
>> 215 a1 = sa1 ;
>> 216 e1 = sa1*e1Fluct;
>> 217 e2 = e2Fluct;
>> 218 }
>> 219 }
>> 220 else
>> 221 {
>> 222 //not small energy loss
>> 223 //correction to get better fwhm value
188 a1 /= fw; 224 a1 /= fw;
189 e1 *= fw; << 225 e1 = fw*e1Fluct;
190 } << 226 e2 = e2Fluct;
191 } << 227 }
>> 228 }
>> 229 }
>> 230
>> 231 G4double w1 = tmax/e0;
>> 232 if(tmax > e0)
>> 233 a3 = rate*meanLoss*(tmax-e0)/(e0*tmax*log(w1));
192 234
193 const G4double w1 = tcut/e0; <<
194 a3 = rate*meanLoss*(tcut - e0)/(e0*tcut*G4Lo <<
195 if(a1 <= 0.) { a3 /= rate; } <<
196 <<
197 //'nearly' Gaussian fluctuation if a1>nmaxCo 235 //'nearly' Gaussian fluctuation if a1>nmaxCont&&a2>nmaxCont&&a3>nmaxCont
198 G4double emean = 0.; 236 G4double emean = 0.;
199 G4double sig2e = 0.; << 237 G4double sig2e = 0., sige = 0.;
200 << 238 G4double p1 = 0., p2 = 0., p3 = 0.;
>> 239
201 // excitation of type 1 240 // excitation of type 1
202 if(a1 > 0.0) { AddExcitation(rndmEngineF, a1 << 241 if(a1 > nmaxCont)
>> 242 {
>> 243 emean += a1*e1;
>> 244 sig2e += a1*e1*e1;
>> 245 }
>> 246 else if(a1 > 0.)
>> 247 {
>> 248 p1 = G4double(G4Poisson(a1));
>> 249 loss += p1*e1;
>> 250 if(p1 > 0.)
>> 251 loss += (1.-2.*G4UniformRand())*e1;
>> 252 }
203 253
204 if(sig2e > 0.0) { SampleGauss(rndmEngineF, e << 254 // excitation of type 2
>> 255 if(a2 > nmaxCont)
>> 256 {
>> 257 emean += a2*e2;
>> 258 sig2e += a2*e2*e2;
>> 259 }
>> 260 else if(a2 > 0.)
>> 261 {
>> 262 p2 = G4double(G4Poisson(a2));
>> 263 loss += p2*e2;
>> 264 if(p2 > 0.)
>> 265 loss += (1.-2.*G4UniformRand())*e2;
>> 266 }
205 267
206 // ionisation 268 // ionisation
207 if(a3 > 0.) { << 269 G4double lossc = 0.;
208 emean = 0.; << 270 if(a3 > 0.)
209 sig2e = 0.; << 271 {
210 G4double p3 = a3; << 272 p3 = a3;
211 G4double alfa = 1.; 273 G4double alfa = 1.;
212 if(a3 > nmaxCont) { << 274 if(a3 > nmaxCont)
213 alfa = w1*(nmaxCont+a3)/(w1*nmaxCont+a3) << 275 {
214 const G4double alfa1 = alfa*G4Log(alfa) << 276 alfa = w1*(nmaxCont+a3)/(w1*nmaxCont+a3);
215 const G4double namean = a3*w1*(alfa-1.)/ << 277 G4double alfa1 = alfa*log(alfa)/(alfa-1.);
216 emean += namean*e0*alfa1; << 278 G4double namean = a3*w1*(alfa-1.)/((w1-1.)*alfa);
217 sig2e += e0*e0*namean*(alfa-alfa1*alfa1) << 279 emean += namean*e0*alfa1;
218 p3 = a3 - namean; << 280 sig2e += e0*e0*namean*(alfa-alfa1*alfa1);
>> 281 p3 = a3-namean;
219 } 282 }
220 283
221 const G4double w3 = alfa*e0; << 284 G4double w2 = alfa*e0;
222 if(tcut > w3) { << 285 G4double w = (tmax-w2)/tmax;
223 const G4double w = (tcut-w3)/tcut; << 286 G4int nb = G4Poisson(p3);
224 const G4int nnb = (G4int)G4Poisson(p3); << 287 if(nb > 0)
225 if(nnb > 0) { << 288 for (G4int k=0; k<nb; k++) lossc += w2/(1.-w*G4UniformRand());
226 if(nnb > sizearray) { <<
227 sizearray = nnb; <<
228 delete [] rndmarray; <<
229 rndmarray = new G4double[nnb]; <<
230 } <<
231 rndmEngineF->flatArray(nnb, rndmarray) <<
232 for (G4int k=0; k<nnb; ++k) { loss += <<
233 } <<
234 } <<
235 if(sig2e > 0.0) { SampleGauss(rndmEngineF, <<
236 } 289 }
237 //G4cout << "### loss=" << loss << G4endl; << 290
>> 291 if(emean > 0.)
>> 292 {
>> 293 sige = sqrt(sig2e);
>> 294 loss += max(0.,G4RandGauss::shoot(emean,sige));
>> 295 }
>> 296
>> 297 loss += lossc;
>> 298
238 return loss; 299 return loss;
>> 300
239 } 301 }
240 302
241 //....oooOO0OOooo........oooOO0OOooo........oo 303 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
242 304
243 305
244 G4double G4UniversalFluctuation::Dispersion( 306 G4double G4UniversalFluctuation::Dispersion(
245 const G4Material* ma 307 const G4Material* material,
246 const G4DynamicParti 308 const G4DynamicParticle* dp,
247 const G4double tcut, << 309 G4double& tmax,
248 const G4double tmax, << 310 G4double& length)
249 const G4double lengt <<
250 { 311 {
251 if(dp->GetDefinition() != particle) { Initia << 312 if(!particle) InitialiseMe(dp->GetDefinition());
252 const G4double beta = dp->GetBeta(); << 313
253 return (tmax/(beta*beta) - 0.5*tcut) * CLHEP << 314 electronDensity = material->GetElectronDensity();
254 * material->GetElectronDensity() * chargeS << 315
>> 316 G4double gam = (dp->GetKineticEnergy())/particleMass + 1.0;
>> 317 G4double beta2 = 1.0 - 1.0/(gam*gam);
>> 318
>> 319 G4double siga = (1.0/beta2 - 0.5) * twopi_mc2_rcl2 * tmax * length
>> 320 * electronDensity * chargeSquare;
>> 321
>> 322 return siga;
255 } 323 }
256 324
257 //....oooOO0OOooo........oooOO0OOooo........oo 325 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
258 326
259 void 327 void
260 G4UniversalFluctuation::SetParticleAndCharge(c 328 G4UniversalFluctuation::SetParticleAndCharge(const G4ParticleDefinition* part,
261 G << 329 G4double q2)
262 { 330 {
263 if(part != particle) { 331 if(part != particle) {
264 particle = part; << 332 particle = part;
265 particleMass = part->GetPDGMass(); << 333 particleMass = part->GetPDGMass();
266 <<
267 // Derived quantities <<
268 m_Inv_particleMass = 1.0 / particleMass; <<
269 m_massrate = CLHEP::electron_mass_c2 * m_I <<
270 } 334 }
271 chargeSquare = q2; 335 chargeSquare = q2;
272 } 336 }
273 337
274 //....oooOO0OOooo........oooOO0OOooo........oo 338 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
275 339