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25 //
26 //
27 //
28 // Author: Vladimir Grichine
29 //
30 // History:
31 //
32 // 14.10.12 V.Grichine, update of xsc and angular distribution
33 // 25.05.2011 first implementation
34
35 #include "G4XrayRayleighModel.hh"
36 #include "G4PhysicalConstants.hh"
37 #include "G4SystemOfUnits.hh"
38
39 //////////////////////////////////////////////////////////////////////////////////
40
41 const G4double G4XrayRayleighModel::fCofA = 2.*pi2*Bohr_radius*Bohr_radius;
42
43 const G4double G4XrayRayleighModel::fCofR = 8.*pi*classic_electr_radius*classic_electr_radius/3.;
44
45 //////////////////////////////////////////////////////////////////////////////////
46
47 G4XrayRayleighModel::G4XrayRayleighModel(const G4ParticleDefinition*,
48 const G4String& nam)
49 :G4VEmModel(nam),isInitialised(false)
50 {
51 fParticleChange = nullptr;
52 lowEnergyLimit = 250*eV;
53 highEnergyLimit = 10.*MeV;
54 fFormFactor = 0.0;
55
56 // SetLowEnergyLimit(lowEnergyLimit);
57 SetHighEnergyLimit(highEnergyLimit);
58 //
59 verboseLevel= 0;
60 // Verbosity scale:
61 // 0 = nothing
62 // 1 = warning for energy non-conservation
63 // 2 = details of energy budget
64 // 3 = calculation of cross sections, file openings, sampling of atoms
65 // 4 = entering in methods
66
67 if(verboseLevel > 0)
68 {
69 G4cout << "Xray Rayleigh is constructed " << G4endl
70 << "Energy range: "
71 << lowEnergyLimit / eV << " eV - "
72 << highEnergyLimit / MeV << " MeV"
73 << G4endl;
74 }
75 }
76
77 //////////////////////////////////////////////////////////////////////////////////
78
79 G4XrayRayleighModel::~G4XrayRayleighModel() = default;
80
81 //////////////////////////////////////////////////////////////////////////////////
82
83 void G4XrayRayleighModel::Initialise(const G4ParticleDefinition* particle,
84 const G4DataVector& cuts)
85 {
86 if (verboseLevel > 3)
87 {
88 G4cout << "Calling G4XrayRayleighModel::Initialise()" << G4endl;
89 }
90
91 InitialiseElementSelectors(particle,cuts);
92
93
94 if(isInitialised) return;
95 fParticleChange = GetParticleChangeForGamma();
96 isInitialised = true;
97
98 }
99
100 //////////////////////////////////////////////////////////////////////////////////
101
102 G4double G4XrayRayleighModel::ComputeCrossSectionPerAtom(
103 const G4ParticleDefinition*,
104 G4double gammaEnergy,
105 G4double Z, G4double,
106 G4double, G4double)
107 {
108 if (verboseLevel > 3)
109 {
110 G4cout << "Calling CrossSectionPerAtom() of G4XrayRayleighModel" << G4endl;
111 }
112 if (gammaEnergy < lowEnergyLimit || gammaEnergy > highEnergyLimit)
113 {
114 return 0.0;
115 }
116 G4double k = gammaEnergy/hbarc;
117 k *= Bohr_radius;
118 G4double p0 = 0.680654;
119 G4double p1 = -0.0224188;
120 G4double lnZ = std::log(Z);
121
122 G4double lna = p0 + p1*lnZ;
123
124 G4double alpha = std::exp(lna);
125
126 G4double fo = std::pow(k, alpha);
127
128 p0 = 3.68455;
129 p1 = -0.464806;
130 lna = p0 + p1*lnZ;
131
132 fo *= 0.01*std::exp(lna);
133
134 fFormFactor = fo;
135
136 G4double b = 1. + 2.*fo;
137 G4double b2 = b*b;
138 G4double b3 = b*b2;
139
140 G4double xsc = fCofR*Z*Z/b3;
141 xsc *= fo*fo + (1. + fo)*(1. + fo);
142
143
144 return xsc;
145
146 }
147
148 //////////////////////////////////////////////////////////////////////////////////
149
150 void G4XrayRayleighModel::SampleSecondaries(std::vector<G4DynamicParticle*>* /*fvect*/,
151 const G4MaterialCutsCouple* couple,
152 const G4DynamicParticle* aDPGamma,
153 G4double,
154 G4double)
155 {
156 if ( verboseLevel > 3)
157 {
158 G4cout << "Calling SampleSecondaries() of G4XrayRayleighModel" << G4endl;
159 }
160 G4double photonEnergy0 = aDPGamma->GetKineticEnergy();
161
162 G4ParticleMomentum photonDirection0 = aDPGamma->GetMomentumDirection();
163
164
165 // Sample the angle of the scattered photon
166 // according to 1 + cosTheta*cosTheta distribution
167
168 G4double cosDipole, cosTheta, sinTheta;
169 G4double c, delta, cofA, signc = 1., a, power = 1./3.;
170
171 c = 4. - 8.*G4UniformRand();
172 a = c;
173
174 if( c < 0. )
175 {
176 signc = -1.;
177 a = -c;
178 }
179 delta = std::sqrt(a*a+4.);
180 delta += a;
181 delta *= 0.5;
182 cofA = -signc*std::pow(delta, power);
183 cosDipole = cofA - 1./cofA;
184
185 // select atom
186 const G4Element* elm = SelectTargetAtom(couple, aDPGamma->GetParticleDefinition(),
187 photonEnergy0,aDPGamma->GetLogKineticEnergy());
188 G4double Z = elm->GetZ();
189
190 G4double k = photonEnergy0/hbarc;
191 k *= Bohr_radius;
192 G4double p0 = 0.680654;
193 G4double p1 = -0.0224188;
194 G4double lnZ = std::log(Z);
195
196 G4double lna = p0 + p1*lnZ;
197
198 G4double alpha = std::exp(lna);
199
200 G4double fo = std::pow(k, alpha);
201
202 p0 = 3.68455;
203 p1 = -0.464806;
204 lna = p0 + p1*lnZ;
205
206 fo *= 0.01*pi*std::exp(lna);
207
208
209 G4double beta = fo/(1 + fo);
210
211 cosTheta = (cosDipole + beta)/(1. + cosDipole*beta);
212
213
214 if( cosTheta > 1.) cosTheta = 1.;
215 if( cosTheta < -1.) cosTheta = -1.;
216
217 sinTheta = std::sqrt( (1. - cosTheta)*(1. + cosTheta) );
218
219 // Scattered photon angles. ( Z - axis along the parent photon)
220
221 G4double phi = twopi * G4UniformRand() ;
222 G4double dirX = sinTheta*std::cos(phi);
223 G4double dirY = sinTheta*std::sin(phi);
224 G4double dirZ = cosTheta;
225
226 // Update G4VParticleChange for the scattered photon
227
228 G4ThreeVector photonDirection1(dirX, dirY, dirZ);
229 photonDirection1.rotateUz(photonDirection0);
230 fParticleChange->ProposeMomentumDirection(photonDirection1);
231
232 fParticleChange->SetProposedKineticEnergy(photonEnergy0);
233 }
234
235
236