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26 // 26 //
>> 27 // $Id: G4GammaConversionToMuons.cc 91869 2015-08-07 15:21:02Z gcosmo $
>> 28 //
27 // ------------ G4GammaConversionToMuo 29 // ------------ G4GammaConversionToMuons physics process ------
28 // by H.Burkhardt, S. Kelner and R. Ko 30 // by H.Burkhardt, S. Kelner and R. Kokoulin, April 2002
29 // 31 //
30 // 32 //
31 // 07-08-02: missprint in OR condition in DoIt 33 // 07-08-02: missprint in OR condition in DoIt : f1<0 || f1>f1_max ..etc ...
32 // 25-10-04: migrade to new interfaces of Part 34 // 25-10-04: migrade to new interfaces of ParticleChange (vi)
33 // ------------------------------------------- 35 // ---------------------------------------------------------------------------
34 36
35 #include "G4GammaConversionToMuons.hh" 37 #include "G4GammaConversionToMuons.hh"
36 <<
37 #include "G4BetheHeitler5DModel.hh" <<
38 #include "G4Electron.hh" <<
39 #include "G4EmParameters.hh" <<
40 #include "G4EmProcessSubType.hh" <<
41 #include "G4Exp.hh" <<
42 #include "G4Gamma.hh" <<
43 #include "G4Log.hh" <<
44 #include "G4LossTableManager.hh" <<
45 #include "G4MuonMinus.hh" <<
46 #include "G4MuonPlus.hh" <<
47 #include "G4NistManager.hh" <<
48 #include "G4PhysicalConstants.hh" 38 #include "G4PhysicalConstants.hh"
49 #include "G4Positron.hh" <<
50 #include "G4ProductionCutsTable.hh" <<
51 #include "G4SystemOfUnits.hh" 39 #include "G4SystemOfUnits.hh"
52 #include "G4UnitsTable.hh" 40 #include "G4UnitsTable.hh"
>> 41 #include "G4MuonPlus.hh"
>> 42 #include "G4MuonMinus.hh"
>> 43 #include "G4EmProcessSubType.hh"
>> 44 #include "G4NistManager.hh"
>> 45 #include "G4Log.hh"
>> 46 #include "G4Exp.hh"
53 47
54 //....oooOO0OOooo........oooOO0OOooo........oo 48 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
55 49
56 static const G4double sqrte = std::sqrt(std::e << 50 using namespace std;
57 static const G4double PowSat = -0.88; << 51
>> 52 static const G4double sqrte=sqrt(exp(1.));
>> 53 static const G4double PowSat=-0.88;
58 54
59 G4GammaConversionToMuons::G4GammaConversionToM 55 G4GammaConversionToMuons::G4GammaConversionToMuons(const G4String& processName,
60 G4ProcessType type) 56 G4ProcessType type)
61 : G4VDiscreteProcess (processName, type), 57 : G4VDiscreteProcess (processName, type),
62 Mmuon(G4MuonPlus::MuonPlus()->GetPDGMass() 58 Mmuon(G4MuonPlus::MuonPlus()->GetPDGMass()),
63 Rc(CLHEP::elm_coupling / Mmuon), << 59 Rc(elm_coupling/Mmuon),
64 LimitEnergy(5. * Mmuon), << 60 LowestEnergyLimit (4*Mmuon), // 4*Mmuon
65 LowestEnergyLimit(2. * Mmuon), << 61 HighestEnergyLimit(1e21*eV), // ok to 1e21eV=1e12GeV, then LPM suppression
66 HighestEnergyLimit(1e12 * CLHEP::GeV), // << 62 CrossSecFactor(1.)
67 theGamma(G4Gamma::Gamma()), << 63 {
68 theMuonPlus(G4MuonPlus::MuonPlus()), <<
69 theMuonMinus(G4MuonMinus::MuonMinus()) <<
70 { <<
71 SetProcessSubType(fGammaConversionToMuMu); 64 SetProcessSubType(fGammaConversionToMuMu);
72 fManager = G4LossTableManager::Instance(); << 65 MeanFreePath = DBL_MAX;
73 fManager->Register(this); <<
74 } 66 }
75 67
76 //....oooOO0OOooo........oooOO0OOooo........oo 68 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
77 69
78 G4GammaConversionToMuons::~G4GammaConversionTo << 70 // destructor
79 { << 71
80 fManager->DeRegister(this); << 72 G4GammaConversionToMuons::~G4GammaConversionToMuons()
81 } << 73 {}
82 74
83 //....oooOO0OOooo........oooOO0OOooo........oo 75 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
84 76
85 G4bool G4GammaConversionToMuons::IsApplicable( << 77 G4bool G4GammaConversionToMuons::IsApplicable(
>> 78 const G4ParticleDefinition& particle)
86 { 79 {
87 return (&part == theGamma); << 80 return ( &particle == G4Gamma::Gamma() );
88 } 81 }
89 82
90 //....oooOO0OOooo........oooOO0OOooo........oo 83 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
91 84
92 void G4GammaConversionToMuons::BuildPhysicsTab << 85 void G4GammaConversionToMuons::BuildPhysicsTable(const G4ParticleDefinition&)
93 { << 86 // Build cross section and mean free path tables
94 Energy5DLimit = G4EmParameters::Instance()-> << 87 { //here no tables, just calling PrintInfoDefinition
95 << 88 PrintInfoDefinition();
96 auto table = G4Material::GetMaterialTable(); <<
97 std::size_t nelm = 0; <<
98 for (auto const& mat : *table) { <<
99 std::size_t n = mat->GetNumberOfElements() <<
100 nelm = std::max(nelm, n); <<
101 } <<
102 temp.resize(nelm, 0); <<
103 <<
104 if (Energy5DLimit > 0.0 && nullptr != f5Dmod <<
105 f5Dmodel = new G4BetheHeitler5DModel(); <<
106 f5Dmodel->SetLeptonPair(theMuonPlus, theMu <<
107 const std::size_t numElems = G4ProductionC <<
108 const G4DataVector cuts(numElems); <<
109 f5Dmodel->Initialise(&p, cuts); <<
110 } <<
111 PrintInfoDefinition(); <<
112 } 89 }
113 90
114 //....oooOO0OOooo........oooOO0OOooo........oo 91 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
115 92
116 G4double G4GammaConversionToMuons::GetMeanFree << 93 G4double G4GammaConversionToMuons::GetMeanFreePath(const G4Track& aTrack,
117 << 94 G4double, G4ForceCondition*)
>> 95
118 // returns the photon mean free path in GEANT4 96 // returns the photon mean free path in GEANT4 internal units
>> 97 // (MeanFreePath is a private member of the class)
>> 98
119 { 99 {
120 const G4DynamicParticle* aDynamicGamma = aTr << 100 const G4DynamicParticle* aDynamicGamma = aTrack.GetDynamicParticle();
121 G4double GammaEnergy = aDynamicGamma->GetKin << 101 G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
122 const G4Material* aMaterial = aTrack.GetMate << 102 G4Material* aMaterial = aTrack.GetMaterial();
123 return ComputeMeanFreePath(GammaEnergy, aMat << 103
>> 104 if (GammaEnergy <= LowestEnergyLimit)
>> 105 MeanFreePath = DBL_MAX;
>> 106 else
>> 107 MeanFreePath = ComputeMeanFreePath(GammaEnergy,aMaterial);
>> 108
>> 109 return MeanFreePath;
124 } 110 }
125 111
126 //....oooOO0OOooo........oooOO0OOooo........oo 112 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
127 113
128 G4double << 114 G4double G4GammaConversionToMuons::ComputeMeanFreePath(G4double GammaEnergy,
129 G4GammaConversionToMuons::ComputeMeanFreePath( << 115 G4Material* aMaterial)
130 <<
131 116
132 // computes and returns the photon mean free p 117 // computes and returns the photon mean free path in GEANT4 internal units
133 { 118 {
134 if(GammaEnergy <= LowestEnergyLimit) { retur <<
135 const G4ElementVector* theElementVector = aM 119 const G4ElementVector* theElementVector = aMaterial->GetElementVector();
136 const G4double* NbOfAtomsPerVolume = aMateri 120 const G4double* NbOfAtomsPerVolume = aMaterial->GetVecNbOfAtomsPerVolume();
137 121
138 G4double SIGMA = 0.0; << 122 G4double SIGMA = 0 ;
139 G4double fact = 1.0; <<
140 G4double e = GammaEnergy; <<
141 // low energy approximation as in Bethe-Heit <<
142 if(e < LimitEnergy) { <<
143 G4double y = (e - LowestEnergyLimit)/(Limi <<
144 fact = y*y; <<
145 e = LimitEnergy; <<
146 } <<
147 123
148 for ( std::size_t i=0 ; i < aMaterial->GetNu << 124 for ( size_t i=0 ; i < aMaterial->GetNumberOfElements(); ++i)
149 { 125 {
150 SIGMA += NbOfAtomsPerVolume[i] * fact * << 126 G4double AtomicZ = (*theElementVector)[i]->GetZ();
151 ComputeCrossSectionPerAtom(e, (*theEleme << 127 G4double AtomicA = (*theElementVector)[i]->GetA()/(g/mole);
>> 128 SIGMA += NbOfAtomsPerVolume[i] *
>> 129 ComputeCrossSectionPerAtom(GammaEnergy,AtomicZ,AtomicA);
152 } 130 }
153 return (SIGMA > 0.0) ? 1./SIGMA : DBL_MAX; << 131 return SIGMA > DBL_MIN ? 1./SIGMA : DBL_MAX;
154 } 132 }
155 133
156 //....oooOO0OOooo........oooOO0OOooo........oo 134 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
157 135
158 G4double G4GammaConversionToMuons::GetCrossSec 136 G4double G4GammaConversionToMuons::GetCrossSectionPerAtom(
159 const G4Dyn 137 const G4DynamicParticle* aDynamicGamma,
160 const G4Ele << 138 G4Element* anElement)
161 139
162 // gives the total cross section per atom in G 140 // gives the total cross section per atom in GEANT4 internal units
163 { 141 {
164 return ComputeCrossSectionPerAtom(aDynamicG << 142 G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
165 anElement << 143 G4double AtomicZ = anElement->GetZ();
>> 144 G4double AtomicA = anElement->GetN();
>> 145 G4double crossSection =
>> 146 ComputeCrossSectionPerAtom(GammaEnergy,AtomicZ,AtomicA);
>> 147 return crossSection;
166 } 148 }
167 149
168 //....oooOO0OOooo........oooOO0OOooo........oo 150 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
169 151
170 G4double G4GammaConversionToMuons::ComputeCros 152 G4double G4GammaConversionToMuons::ComputeCrossSectionPerAtom(
171 G4double Egam, G4int << 153 G4double Egam, G4double ZZ, G4double)
172 154
173 // Calculates the microscopic cross section in 155 // Calculates the microscopic cross section in GEANT4 internal units.
174 // Total cross section parametrisation from H. 156 // Total cross section parametrisation from H.Burkhardt
175 // It gives a good description at any energy ( 157 // It gives a good description at any energy (from 0 to 10**21 eV)
176 { 158 {
177 if(Egam <= LowestEnergyLimit) { return 0.0; << 159 if(Egam <= LowestEnergyLimit) return 0 ; // below threshold return 0
178 160
>> 161 G4int Z = G4lrint(ZZ);
>> 162 G4double CrossSection = 0.0;
179 G4NistManager* nist = G4NistManager::Instanc 163 G4NistManager* nist = G4NistManager::Instance();
180 164
181 G4double PowThres, Ecor, B, Dn, Zthird, Winf << 165 G4double PowThres,Ecor,B,Dn,Zthird,Winfty,WMedAppr,
182 << 166 Wsatur,sigfac;
183 if (Z == 1) { // special case of Hydrogen << 167
184 B = 202.4; << 168 if(Z==1) // special case of Hydrogen
185 Dn = 1.49; << 169 { B=202.4;
186 } << 170 Dn=1.49;
187 else { << 171 }
188 B = 183.; << 172 else
189 Dn = 1.54 * nist->GetA27(Z); << 173 { B=183.;
190 } << 174 Dn=1.54*nist->GetA27(Z);
191 Zthird = 1. / nist->GetZ13(Z); // Z**(-1/3) << 175 }
192 Winfty = B * Zthird * Mmuon / (Dn * electron << 176 Zthird=1./nist->GetZ13(Z); // Z**(-1/3)
193 WMedAppr = 1. / (4. * Dn * sqrte * Mmuon); << 177 Winfty=B*Zthird*Mmuon/(Dn*electron_mass_c2);
194 Wsatur = Winfty / WMedAppr; << 178 WMedAppr=1./(4.*Dn*sqrte*Mmuon);
195 sigfac = 4. * fine_structure_const * Z * Z * << 179 Wsatur=Winfty/WMedAppr;
196 PowThres = 1.479 + 0.00799 * Dn; << 180 sigfac=4.*fine_structure_const*Z*Z*Rc*Rc;
197 Ecor = -18. + 4347. / (B * Zthird); << 181 PowThres=1.479+0.00799*Dn;
198 << 182 Ecor=-18.+4347./(B*Zthird);
199 G4double CorFuc = 1. + .04 * G4Log(1. + Ecor << 183
200 G4double Eg = << 184 G4double CorFuc=1.+.04*G4Log(1.+Ecor/Egam);
201 G4Exp(G4Log(1. - 4. * Mmuon / Egam) * PowT << 185 //G4double Eg=pow(1.-4.*Mmuon/Egam,PowThres)*pow( pow(Wsatur,PowSat)+
202 * G4Exp(G4Log(G4Exp(G4Log(Wsatur) * PowSat << 186 // pow(Egam,PowSat),1./PowSat); // threshold and saturation
203 << 187 G4double Eg=G4Exp(G4Log(1.-4.*Mmuon/Egam)*PowThres)*
204 G4double CrossSection = 7. / 9. * sigfac * G << 188 G4Exp(G4Log( G4Exp(G4Log(Wsatur)*PowSat)+G4Exp(G4Log(Egam)*PowSat))/PowSat);
205 CrossSection *= CrossSecFactor; // increase << 189 CrossSection=7./9.*sigfac*G4Log(1.+WMedAppr*CorFuc*Eg);
>> 190 CrossSection*=CrossSecFactor; // increase the CrossSection by (by default 1)
206 return CrossSection; 191 return CrossSection;
207 } 192 }
208 193
209 //....oooOO0OOooo........oooOO0OOooo........oo 194 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
210 195
211 void G4GammaConversionToMuons::SetCrossSecFact 196 void G4GammaConversionToMuons::SetCrossSecFactor(G4double fac)
212 // Set the factor to artificially increase the 197 // Set the factor to artificially increase the cross section
213 { << 198 {
214 if (fac < 0.0) return; << 199 CrossSecFactor=fac;
215 CrossSecFactor = fac; << 200 G4cout << "The cross section for GammaConversionToMuons is artificially "
216 if (verboseLevel > 1) { << 201 << "increased by the CrossSecFactor=" << CrossSecFactor << G4endl;
217 G4cout << "The cross section for GammaConv <<
218 << "increased by the CrossSecFactor <<
219 } <<
220 } 202 }
221 203
222 //....oooOO0OOooo........oooOO0OOooo........oo 204 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
223 205
224 G4VParticleChange* G4GammaConversionToMuons::P 206 G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
225 207 const G4Track& aTrack,
226 208 const G4Step& aStep)
227 // 209 //
228 // generation of gamma->mu+mu- 210 // generation of gamma->mu+mu-
229 // 211 //
230 { 212 {
231 aParticleChange.Initialize(aTrack); 213 aParticleChange.Initialize(aTrack);
232 const G4Material* aMaterial = aTrack.GetMate << 214 G4Material* aMaterial = aTrack.GetMaterial();
233 215
234 // current Gamma energy and direction, retur 216 // current Gamma energy and direction, return if energy too low
235 const G4DynamicParticle* aDynamicGamma = aTr << 217 const G4DynamicParticle *aDynamicGamma = aTrack.GetDynamicParticle();
236 G4double Egam = aDynamicGamma->GetKineticEne 218 G4double Egam = aDynamicGamma->GetKineticEnergy();
237 if (Egam <= LowestEnergyLimit) { 219 if (Egam <= LowestEnergyLimit) {
238 return G4VDiscreteProcess::PostStepDoIt(aT 220 return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep);
239 } 221 }
240 // <<
241 // Kill the incident photon <<
242 // <<
243 aParticleChange.ProposeMomentumDirection( 0. <<
244 aParticleChange.ProposeEnergy( 0. ) ; <<
245 aParticleChange.ProposeTrackStatus( fStopAnd <<
246 <<
247 if (Egam <= Energy5DLimit) { <<
248 std::vector<G4DynamicParticle*> fvect; <<
249 f5Dmodel->SampleSecondaries(&fvect, aTrack <<
250 aTrack.GetDynamicParticle(), 0.0, DBL_ <<
251 for(auto dp : fvect) { aParticleChange.Add <<
252 return G4VDiscreteProcess::PostStepDoIt(aT <<
253 } <<
254 <<
255 G4ParticleMomentum GammaDirection = aDynamic 222 G4ParticleMomentum GammaDirection = aDynamicGamma->GetMomentumDirection();
256 223
257 // select randomly one element constituting 224 // select randomly one element constituting the material
258 const G4Element* anElement = SelectRandomAto 225 const G4Element* anElement = SelectRandomAtom(aDynamicGamma, aMaterial);
259 G4int Z = anElement->GetZasInt(); << 226 G4int Z = G4lrint(anElement->GetZ());
260 G4NistManager* nist = G4NistManager::Instanc 227 G4NistManager* nist = G4NistManager::Instance();
261 228
262 G4double B, Dn; << 229 G4double B,Dn;
263 G4double A027 = nist->GetA27(Z); 230 G4double A027 = nist->GetA27(Z);
264 231
265 if (Z == 1) { // special case of Hydrogen << 232 if(Z==1) // special case of Hydrogen
266 B = 202.4; << 233 { B=202.4;
267 Dn = 1.49; << 234 Dn=1.49;
268 } << 235 }
269 else { << 236 else
270 B = 183.; << 237 { B=183.;
271 Dn = 1.54 * A027; << 238 Dn=1.54*A027;
272 } << 239 }
273 G4double Zthird = 1. / nist->GetZ13(Z); // << 240 G4double Zthird=1./nist->GetZ13(Z); // Z**(-1/3)
274 G4double Winfty = B * Zthird * Mmuon / (Dn * << 241 G4double Winfty=B*Zthird*Mmuon/(Dn*electron_mass_c2);
275 << 242 G4double C1Num=0.35*A027;
276 G4double C1Num = 0.138 * A027; << 243 G4double C1Num2=C1Num*C1Num;
277 G4double C1Num2 = C1Num * C1Num; << 244 G4double C2Term2=electron_mass_c2/(183.*Zthird*Mmuon);
278 G4double C2Term2 = electron_mass_c2 / (183. << 245
279 << 246 G4double GammaMuonInv=Mmuon/Egam;
280 G4double GammaMuonInv = Mmuon / Egam; << 247 G4double sqrtx=sqrt(.25-GammaMuonInv);
>> 248 G4double xmax=.5+sqrtx;
>> 249 G4double xmin=.5-sqrtx;
281 250
282 // generate xPlus according to the different 251 // generate xPlus according to the differential cross section by rejection
283 G4double xmin = (Egam <= LimitEnergy) ? 0.5 << 252 G4double Ds2=(Dn*sqrte-2.);
284 G4double xmax = 1. - xmin; << 253 G4double sBZ=sqrte*B*Zthird/electron_mass_c2;
285 << 254 G4double LogWmaxInv=1./G4Log(Winfty*(1.+2.*Ds2*GammaMuonInv)
286 G4double Ds2 = (Dn * sqrte - 2.); << 255 /(1.+2.*sBZ*Mmuon*GammaMuonInv));
287 G4double sBZ = sqrte * B * Zthird / electron << 256 G4double xPlus,xMinus,xPM,result,W;
288 G4double LogWmaxInv = <<
289 1. / G4Log(Winfty * (1. + 2. * Ds2 * Gamma <<
290 G4double xPlus = 0.5; <<
291 G4double xMinus = 0.5; <<
292 G4double xPM = 0.25; <<
293 <<
294 G4int nn = 0; 257 G4int nn = 0;
295 const G4int nmax = 1000; 258 const G4int nmax = 1000;
296 << 259 do
297 // sampling for Egam > LimitEnergy << 260 { xPlus=xmin+G4UniformRand()*(xmax-xmin);
298 if (xmin < 0.5) { << 261 xMinus=1.-xPlus;
299 G4double result, W; << 262 xPM=xPlus*xMinus;
300 do { << 263 G4double del=Mmuon*Mmuon/(2.*Egam*xPM);
301 xPlus = xmin + G4UniformRand() * (xmax - << 264 W=Winfty*(1.+Ds2*del/Mmuon)/(1.+sBZ*del);
302 xMinus = 1. - xPlus; << 265 if(W<=1. || nn > nmax) { break; } // to avoid negative cross section at xmin
303 xPM = xPlus * xMinus; << 266 G4double xxp=1.-4./3.*xPM; // the main xPlus dependence
304 G4double del = Mmuon * Mmuon / (2. * Ega << 267 result=xxp*G4Log(W)*LogWmaxInv;
305 W = Winfty * (1. + Ds2 * del / Mmuon) / << 268 if(result>1.) {
306 G4double xxp = 1. - 4. / 3. * xPM; // t << 269 G4cout << "G4GammaConversionToMuons::PostStepDoIt WARNING:"
307 result = (xxp > 0.) ? xxp * G4Log(W) * L << 270 << " in dSigxPlusGen, result=" << result << " > 1" << G4endl;
308 if (result > 1.) { <<
309 G4cout << "G4GammaConversionToMuons::P <<
310 << " in dSigxPlusGen, result=" <<
311 } <<
312 ++nn; <<
313 if(nn >= nmax) { break; } <<
314 } 271 }
315 // Loop checking, 07-Aug-2015, Vladimir Iv << 272 ++nn;
316 while (G4UniformRand() > result); << 273 if(nn >= nmax) { break; }
317 } 274 }
>> 275 // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
>> 276 while (G4UniformRand() > result);
318 277
319 // now generate the angular variables via th 278 // now generate the angular variables via the auxilary variables t,psi,rho
320 G4double t; 279 G4double t;
321 G4double psi; 280 G4double psi;
322 G4double rho; 281 G4double rho;
323 282
324 G4double a3 = (GammaMuonInv / (2. * xPM)); <<
325 G4double a33 = a3 * a3; <<
326 G4double f1; <<
327 G4double b1 = 1./(4.*C1Num2); <<
328 G4double b3 = b1*b1*b1; <<
329 G4double a21 = a33 + b1; <<
330 <<
331 G4double f1_max=-(1.-xPM)*(2.*b1+(a21+a33)*G <<
332 <<
333 G4double thetaPlus,thetaMinus,phiHalf; // fi 283 G4double thetaPlus,thetaMinus,phiHalf; // final angular variables
334 nn = 0; 284 nn = 0;
335 // t, psi, rho generation start (while angl << 285 do // t, psi, rho generation start (while angle < pi)
336 do { << 286 {
337 //generate t by the rejection method 287 //generate t by the rejection method
338 do { << 288 G4double C1=C1Num2* GammaMuonInv/xPM;
>> 289 G4double f1_max=(1.-xPM) / (1.+C1);
>> 290 G4double f1; // the probability density
>> 291 do
>> 292 {
339 ++nn; 293 ++nn;
340 t=G4UniformRand(); 294 t=G4UniformRand();
341 G4double a34=a33/(t*t); << 295 f1=(1.-2.*xPM+4.*xPM*t*(1.-t)) / (1.+C1/(t*t));
342 G4double a22 = a34 + b1; << 296 if(f1<0 || f1> f1_max) // should never happend
343 if(std::abs(b1)<0.0001*a34) { << 297 {
344 // special case of a34=a22 because of << 298 G4cout << "G4GammaConversionToMuons::PostStepDoIt WARNING:"
345 f1=(1.-2.*xPM+4.*xPM*t*(1.-t))/(12.*a3 << 299 << "outside allowed range f1=" << f1 << " is set to zero"
346 } << 300 << G4endl;
347 else { << 301 f1 = 0.0;
348 f1=-(1.-2.*xPM+4.*xPM*t*(1.-t))*(2.*b1 << 302 }
349 } <<
350 if (f1 < 0.0 || f1 > f1_max) { // shoul <<
351 G4cout << "G4GammaConversionToMuons::P <<
352 << "outside allowed range f1=" << f1 <<
353 << " is set to zero, a34 = "<< a34 << <<
354 << G4endl; <<
355 f1 = 0.0; <<
356 } <<
357 if(nn > nmax) { break; } 303 if(nn > nmax) { break; }
358 // Loop checking, 07-Aug-2015, Vladimir << 304 }
359 } while ( G4UniformRand()*f1_max > f1); << 305 // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
>> 306 while ( G4UniformRand()*f1_max > f1);
360 // generate psi by the rejection method 307 // generate psi by the rejection method
361 G4double f2_max=1.-2.*xPM*(1.-4.*t*(1.-t)) 308 G4double f2_max=1.-2.*xPM*(1.-4.*t*(1.-t));
>> 309
362 // long version 310 // long version
363 G4double f2; 311 G4double f2;
364 do { << 312 do
>> 313 {
365 ++nn; 314 ++nn;
366 psi=twopi*G4UniformRand(); << 315 psi=2.*pi*G4UniformRand();
367 f2=1.-2.*xPM+4.*xPM*t*(1.-t)*(1.+std::co << 316 f2=1.-2.*xPM+4.*xPM*t*(1.-t)*(1.+cos(2.*psi));
368 if(f2<0 || f2> f2_max) { // should never << 317 if(f2<0 || f2> f2_max) // should never happend
369 G4cout << "G4GammaConversionToMuons::P << 318 {
370 << "outside allowed range f2=" << 319 G4cout << "G4GammaConversionToMuons::PostStepDoIt WARNING:"
371 f2 = 0.0; << 320 << "outside allowed range f2=" << f2 << " is set to zero"
372 } << 321 << G4endl;
>> 322 f2 = 0.0;
>> 323 }
373 if(nn >= nmax) { break; } 324 if(nn >= nmax) { break; }
374 // Loop checking, 07-Aug-2015, Vladimir << 325 }
375 } while ( G4UniformRand()*f2_max > f2); << 326 // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
>> 327 while ( G4UniformRand()*f2_max > f2);
376 328
377 // generate rho by direct transformation 329 // generate rho by direct transformation
378 G4double C2Term1=GammaMuonInv/(2.*xPM*t); 330 G4double C2Term1=GammaMuonInv/(2.*xPM*t);
379 G4double C22 = C2Term1*C2Term1+C2Term2*C2T << 331 G4double C2=4./sqrt(xPM)*pow(C2Term1*C2Term1+C2Term2*C2Term2,2.);
380 G4double C2=4.*C22*C22/std::sqrt(xPM); << 332 G4double rhomax=1.9/A027*(1./t-1.);
381 G4double rhomax=(1./t-1.)*1.9/A027; <<
382 G4double beta=G4Log( (C2+rhomax*rhomax*rho 333 G4double beta=G4Log( (C2+rhomax*rhomax*rhomax*rhomax)/C2 );
383 rho=G4Exp(G4Log(C2 *( G4Exp(beta*G4Uniform 334 rho=G4Exp(G4Log(C2 *( G4Exp(beta*G4UniformRand())-1. ))*0.25);
384 335
385 //now get from t and psi the kinematical v 336 //now get from t and psi the kinematical variables
386 G4double u=std::sqrt(1./t-1.); << 337 G4double u=sqrt(1./t-1.);
387 G4double xiHalf=0.5*rho*std::cos(psi); << 338 G4double xiHalf=0.5*rho*cos(psi);
388 phiHalf=0.5*rho/u*std::sin(psi); << 339 phiHalf=0.5*rho/u*sin(psi);
389 340
390 thetaPlus =GammaMuonInv*(u+xiHalf)/xPlus; 341 thetaPlus =GammaMuonInv*(u+xiHalf)/xPlus;
391 thetaMinus=GammaMuonInv*(u-xiHalf)/xMinus; 342 thetaMinus=GammaMuonInv*(u-xiHalf)/xMinus;
392 343
393 // protection against infinite loop 344 // protection against infinite loop
394 if(nn > nmax) { 345 if(nn > nmax) {
395 if(std::abs(thetaPlus)>pi) { thetaPlus = 346 if(std::abs(thetaPlus)>pi) { thetaPlus = 0.0; }
396 if(std::abs(thetaMinus)>pi) { thetaMinus 347 if(std::abs(thetaMinus)>pi) { thetaMinus = 0.0; }
397 } 348 }
398 349
399 // Loop checking, 07-Aug-2015, Vladimir Iv 350 // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
400 } while ( std::abs(thetaPlus)>pi || std::abs 351 } while ( std::abs(thetaPlus)>pi || std::abs(thetaMinus) >pi);
401 352
402 // now construct the vectors 353 // now construct the vectors
403 // azimuthal symmetry, take phi0 at random b 354 // azimuthal symmetry, take phi0 at random between 0 and 2 pi
404 G4double phi0=twopi*G4UniformRand(); << 355 G4double phi0=2.*pi*G4UniformRand();
405 G4double EPlus=xPlus*Egam; 356 G4double EPlus=xPlus*Egam;
406 G4double EMinus=xMinus*Egam; 357 G4double EMinus=xMinus*Egam;
407 358
408 // mu+ mu- directions for gamma in z-directi 359 // mu+ mu- directions for gamma in z-direction
409 G4ThreeVector MuPlusDirection ( std::sin(th << 360 G4ThreeVector MuPlusDirection ( sin(thetaPlus) *cos(phi0+phiHalf),
410 std::sin(thetaPlus) *std:: << 361 sin(thetaPlus) *sin(phi0+phiHalf), cos(thetaPlus) );
411 G4ThreeVector MuMinusDirection (-std::sin(th << 362 G4ThreeVector MuMinusDirection (-sin(thetaMinus)*cos(phi0-phiHalf),
412 -std::sin(thetaMinus) *std:: << 363 -sin(thetaMinus) *sin(phi0-phiHalf), cos(thetaMinus) );
413 // rotate to actual gamma direction 364 // rotate to actual gamma direction
414 MuPlusDirection.rotateUz(GammaDirection); 365 MuPlusDirection.rotateUz(GammaDirection);
415 MuMinusDirection.rotateUz(GammaDirection); 366 MuMinusDirection.rotateUz(GammaDirection);
416 << 367 aParticleChange.SetNumberOfSecondaries(2);
417 // create G4DynamicParticle object for the p 368 // create G4DynamicParticle object for the particle1
418 auto aParticle1 = new G4DynamicParticle(theM << 369 G4DynamicParticle* aParticle1= new G4DynamicParticle(
>> 370 G4MuonPlus::MuonPlus(),MuPlusDirection,EPlus-Mmuon);
419 aParticleChange.AddSecondary(aParticle1); 371 aParticleChange.AddSecondary(aParticle1);
420 // create G4DynamicParticle object for the p 372 // create G4DynamicParticle object for the particle2
421 auto aParticle2 = new G4DynamicParticle(theM << 373 G4DynamicParticle* aParticle2= new G4DynamicParticle(
>> 374 G4MuonMinus::MuonMinus(),MuMinusDirection,EMinus-Mmuon);
422 aParticleChange.AddSecondary(aParticle2); 375 aParticleChange.AddSecondary(aParticle2);
>> 376 //
>> 377 // Kill the incident photon
>> 378 //
>> 379 aParticleChange.ProposeMomentumDirection( 0., 0., 0. ) ;
>> 380 aParticleChange.ProposeEnergy( 0. ) ;
>> 381 aParticleChange.ProposeTrackStatus( fStopAndKill ) ;
423 // Reset NbOfInteractionLengthLeft and retu 382 // Reset NbOfInteractionLengthLeft and return aParticleChange
424 return G4VDiscreteProcess::PostStepDoIt( aTr 383 return G4VDiscreteProcess::PostStepDoIt( aTrack, aStep );
425 } 384 }
426 385
427 //....oooOO0OOooo........oooOO0OOooo........oo 386 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
428 387
429 const G4Element* G4GammaConversionToMuons::Sel << 388 G4Element* G4GammaConversionToMuons::SelectRandomAtom(
430 const G4DynamicParticle* aDynamicGamma, 389 const G4DynamicParticle* aDynamicGamma,
431 const G4Material* aMaterial) << 390 G4Material* aMaterial)
432 { 391 {
433 // select randomly 1 element within the mate 392 // select randomly 1 element within the material, invoked by PostStepDoIt
434 393
435 const std::size_t NumberOfElements = aM << 394 const G4int NumberOfElements = aMaterial->GetNumberOfElements();
436 const G4ElementVector* theElementVector = aM 395 const G4ElementVector* theElementVector = aMaterial->GetElementVector();
437 const G4Element* elm = (*theElementVector)[0 << 396 if (NumberOfElements == 1) return (*theElementVector)[0];
438 397
439 if (NumberOfElements > 1) { << 398 const G4double* NbOfAtomsPerVolume = aMaterial->GetVecNbOfAtomsPerVolume();
440 G4double e = std::max(aDynamicGamma->GetKi << 399
441 const G4double* natom = aMaterial->GetVecN << 400 G4double PartialSumSigma = 0. ;
442 << 401 G4double rval = G4UniformRand()/MeanFreePath;
443 G4double sum = 0.; << 402
444 for (std::size_t i=0; i<NumberOfElements; << 403
445 elm = (*theElementVector)[i]; << 404 for ( G4int i=0 ; i < NumberOfElements ; ++i)
446 sum += natom[i]*ComputeCrossSectionPerAt << 405 { PartialSumSigma += NbOfAtomsPerVolume[i] *
447 temp[i] = sum; << 406 GetCrossSectionPerAtom(aDynamicGamma, (*theElementVector)[i]);
448 } << 407 if (rval <= PartialSumSigma) return ((*theElementVector)[i]);
449 sum *= G4UniformRand(); <<
450 for (std::size_t i=0; i<NumberOfElements; <<
451 if(sum <= temp[i]) { <<
452 elm = (*theElementVector)[i]; <<
453 break; <<
454 } 408 }
455 } << 409 G4cout << " WARNING !!! - The Material '"<< aMaterial->GetName()
456 } << 410 << "' has no elements, NULL pointer returned." << G4endl;
457 return elm; << 411 return NULL;
458 } 412 }
459 413
460 //....oooOO0OOooo........oooOO0OOooo........oo 414 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
461 415
462 void G4GammaConversionToMuons::PrintInfoDefini 416 void G4GammaConversionToMuons::PrintInfoDefinition()
463 { 417 {
464 G4String comments = "gamma->mu+mu- Bethe Hei << 418 G4String comments ="gamma->mu+mu- Bethe Heitler process, SubType= ";
465 G4cout << G4endl << GetProcessName() << ": << 419 G4cout << G4endl << GetProcessName() << ": " << comments
>> 420 << GetProcessSubType() << G4endl;
466 G4cout << " good cross section parame 421 G4cout << " good cross section parametrization from "
467 << G4BestUnit(LowestEnergyLimit, "Ene << 422 << G4BestUnit(LowestEnergyLimit,"Energy")
468 << " GeV for all Z." << G4endl; << 423 << " to " << HighestEnergyLimit/GeV << " GeV for all Z." << G4endl;
469 G4cout << " cross section factor: " < <<
470 } 424 }
471 425
472 //....oooOO0OOooo........oooOO0OOooo........oo 426 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
473 427