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26 //
27 // -------------------------------------------------------------------
28 //
29 //
30 // GEANT4 Class header file
31 //
32 //
33 // File name: G4WentzelOKandVIxSection
34 //
35 // Authors: V.Ivanchenko and O.Kadri
36 //
37 // Creation date: 21.05.2010
38 //
39 // Modifications:
40 //
41 //
42 // Class Description:
43 //
44 // Implementation of the computation of total and transport cross sections,
45 // sample scattering angle for the single scattering case.
46 // to be used by single and multiple scattering models. References:
47 // 1) G.Wentzel, Z. Phys. 40 (1927) 590.
48 // 2) J.M. Fernandez-Varea et al., NIM B73 (1993) 447.
49 //
50 // -------------------------------------------------------------------
51 //
52
53 #ifndef G4WentzelOKandVIxSection_h
54 #define G4WentzelOKandVIxSection_h 1
55
56 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
57
58 #include "globals.hh"
59 #include "G4Material.hh"
60 #include "G4Element.hh"
61 #include "G4ElementVector.hh"
62 #include "G4NistManager.hh"
63 #include "G4NuclearFormfactorType.hh"
64 #include "G4ThreeVector.hh"
65 #include "G4Pow.hh"
66
67 class G4ParticleDefinition;
68 class G4ScreeningMottCrossSection;
69
70 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
71
72 class G4WentzelOKandVIxSection
73 {
74
75 public:
76
77 explicit G4WentzelOKandVIxSection(G4bool combined=true);
78
79 virtual ~G4WentzelOKandVIxSection();
80
81 void Initialise(const G4ParticleDefinition*, G4double CosThetaLim);
82
83 void SetupParticle(const G4ParticleDefinition*);
84
85 // return cos(ThetaMax) for msc and cos(thetaMin) for single scattering
86 // cut = DBL_MAX means no scattering off electrons
87 virtual G4double SetupKinematic(G4double kinEnergy, const G4Material* mat);
88 G4double SetupTarget(G4int Z, G4double cut);
89
90 G4double ComputeTransportCrossSectionPerAtom(G4double CosThetaMax);
91
92 G4ThreeVector& SampleSingleScattering(G4double CosThetaMin,
93 G4double CosThetaMax,
94 G4double elecRatio);
95
96 G4double ComputeSecondTransportMoment(G4double CosThetaMax);
97
98 inline G4double ComputeNuclearCrossSection(G4double CosThetaMin,
99 G4double CosThetaMax);
100
101 inline G4double ComputeElectronCrossSection(G4double CosThetaMin,
102 G4double CosThetaMax);
103
104 inline void SetTargetMass(G4double value);
105
106 inline G4double GetMomentumSquare() const;
107
108 inline G4double GetCosThetaNuc() const;
109
110 inline G4double GetCosThetaElec() const;
111
112 // hide assignment operator
113 G4WentzelOKandVIxSection & operator=
114 (const G4WentzelOKandVIxSection &right) = delete;
115 G4WentzelOKandVIxSection(const G4WentzelOKandVIxSection&) = delete;
116
117 protected:
118
119 void ComputeMaxElectronScattering(G4double cut);
120
121 void InitialiseA();
122
123 inline G4double FlatFormfactor(G4double x);
124
125 const G4ParticleDefinition* theProton;
126 const G4ParticleDefinition* theElectron;
127 const G4ParticleDefinition* thePositron;
128 const G4ParticleDefinition* particle = nullptr;
129 const G4Material* currentMaterial = nullptr;
130
131 G4NistManager* fNistManager;
132 G4Pow* fG4pow;
133
134 G4ScreeningMottCrossSection* fMottXSection = nullptr;
135
136 G4ThreeVector temp;
137
138 // single scattering parameters
139 G4double coeff;
140 G4double cosTetMaxElec = 1.0;
141 G4double cosTetMaxNuc = 1.0;
142
143 // for the combined mode it is cos(thetaMax)
144 // for single scattering it is cos(thetaMin)
145 G4double cosThetaMax = 1.0;
146
147 G4double chargeSquare = 0.0;
148 G4double charge3 = 0.0;
149 G4double spin = 0.0;
150 G4double mass = 0.0;
151 G4double tkin = 0.0;
152 G4double mom2 = 0.0;
153 G4double momCM2 = 0.0;
154 G4double invbeta2 = 1.0;
155 G4double kinFactor = 1.0;
156 G4double etag = DBL_MAX;
157 G4double ecut = DBL_MAX;
158
159 // target
160 G4double targetMass;
161 G4double screenZ = 0.0;
162 G4double formfactA = 0.0;
163 G4double factorA2 = 0.0;
164 G4double factB = 0.0;
165 G4double factD = 0.0;
166 G4double fMottFactor = 1.0;
167 G4double gam0pcmp = 1.0;
168 G4double pcmp2 = 1.0;
169
170 // integer parameters
171 G4int targetZ = 0;
172 G4int nwarnings = 0;
173
174 G4NuclearFormfactorType fNucFormfactor = fExponentialNF;
175
176 G4bool isCombined;
177
178 static G4double ScreenRSquareElec[100];
179 static G4double ScreenRSquare[100];
180 static G4double FormFactor[100];
181 };
182
183 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
184
185 inline void G4WentzelOKandVIxSection::SetTargetMass(G4double value)
186 {
187 targetMass = value;
188 factD = std::sqrt(mom2)/value;
189 }
190
191 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
192
193 inline G4double G4WentzelOKandVIxSection::GetMomentumSquare() const
194 {
195 return mom2;
196 }
197
198 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
199
200 inline G4double G4WentzelOKandVIxSection::GetCosThetaNuc() const
201 {
202 return cosTetMaxNuc;
203 }
204
205 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
206
207 inline G4double G4WentzelOKandVIxSection::GetCosThetaElec() const
208 {
209 return cosTetMaxElec;
210 }
211
212 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
213
214 inline G4double
215 G4WentzelOKandVIxSection::ComputeNuclearCrossSection(G4double cosTMin,
216 G4double cosTMax)
217 {
218 return targetZ*kinFactor*fMottFactor*(cosTMin - cosTMax)/
219 ((1.0 - cosTMin + screenZ)*(1.0 - cosTMax + screenZ));
220 }
221
222 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
223
224 inline G4double
225 G4WentzelOKandVIxSection::ComputeElectronCrossSection(G4double cosTMin,
226 G4double cosTMax)
227 {
228 G4double cost1 = std::max(cosTMin,cosTetMaxElec);
229 G4double cost2 = std::max(cosTMax,cosTetMaxElec);
230 return (cost1 <= cost2) ? 0.0 : kinFactor*fMottFactor*(cost1 - cost2)/
231 ((1.0 - cost1 + screenZ)*(1.0 - cost2 + screenZ));
232 }
233
234 inline G4double G4WentzelOKandVIxSection::FlatFormfactor(G4double x)
235 {
236 return 3.0*(std::sin(x) - x*std::cos(x))/(x*x*x);
237 }
238
239 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
240
241 #endif
242
243