source: trunk/source/processes/electromagnetic/standard/src/G4PEEffectModel.cc@ 969

Last change on this file since 969 was 961, checked in by garnier, 17 years ago

update processes
File size: 7.3 KB
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25//
26// $Id: G4PEEffectModel.cc,v 1.7 2009/02/20 12:06:37 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02-ref-02 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name: G4PEEffectModel
35//
36// Author: Vladimir Ivanchenko on base of Michel Maire code
37//
38// Creation date: 21.03.2005
39//
40// Modifications:
41//
42// 04.12.05 : SetProposedKineticEnergy(0.) for the killed photon (mma)
43// 20.02.09 : Added initialisation of deexcitation flag and method
44// CrossSectionPerVolume instead of mfp (V.Ivanchenko)
45//
46// Class Description:
47//
48// -------------------------------------------------------------------
49//
50//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
51//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
52
53#include "G4PEEffectModel.hh"
54#include "G4Electron.hh"
55#include "G4Gamma.hh"
56#include "Randomize.hh"
57#include "G4DataVector.hh"
58#include "G4ParticleChangeForGamma.hh"
59
60//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
61
62using namespace std;
63
64G4PEEffectModel::G4PEEffectModel(const G4ParticleDefinition*,
65 const G4String& nam)
66 : G4VEmModel(nam),isInitialized(false)
67{
68 theGamma = G4Gamma::Gamma();
69 theElectron = G4Electron::Electron();
70 fminimalEnergy = 1.0*eV;
71}
72
73//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
74
75G4PEEffectModel::~G4PEEffectModel()
76{}
77
78//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
79
80void G4PEEffectModel::Initialise(const G4ParticleDefinition*,
81 const G4DataVector&)
82{
83 // always false before the run
84 SetDeexcitationFlag(false);
85
86 if (isInitialized) return;
87 if (pParticleChange) {
88 fParticleChange = reinterpret_cast<G4ParticleChangeForGamma*>(pParticleChange);
89 } else {
90 fParticleChange = new G4ParticleChangeForGamma();
91 }
92 isInitialized = true;
93}
94
95//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
96
97G4double G4PEEffectModel::ComputeCrossSectionPerAtom(const G4ParticleDefinition*,
98 G4double energy,
99 G4double Z, G4double,
100 G4double, G4double)
101{
102 G4double* SandiaCof = G4SandiaTable::GetSandiaCofPerAtom((G4int)Z, energy);
103
104 G4double energy2 = energy*energy;
105 G4double energy3 = energy*energy2;
106 G4double energy4 = energy2*energy2;
107
108 return SandiaCof[0]/energy + SandiaCof[1]/energy2 +
109 SandiaCof[2]/energy3 + SandiaCof[3]/energy4;
110}
111
112//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
113
114G4double G4PEEffectModel::CrossSectionPerVolume(const G4Material* material,
115 const G4ParticleDefinition*,
116 G4double energy,
117 G4double, G4double)
118{
119 G4double* SandiaCof =
120 material->GetSandiaTable()->GetSandiaCofForMaterial(energy);
121
122 G4double energy2 = energy*energy;
123 G4double energy3 = energy*energy2;
124 G4double energy4 = energy2*energy2;
125
126 return SandiaCof[0]/energy + SandiaCof[1]/energy2 +
127 SandiaCof[2]/energy3 + SandiaCof[3]/energy4;
128}
129
130//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
131
132void G4PEEffectModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
133 const G4MaterialCutsCouple* couple,
134 const G4DynamicParticle* aDynamicPhoton,
135 G4double,
136 G4double)
137{
138 const G4Material* aMaterial = couple->GetMaterial();
139
140 G4double energy = aDynamicPhoton->GetKineticEnergy();
141 G4ParticleMomentum PhotonDirection = aDynamicPhoton->GetMomentumDirection();
142
143 // select randomly one element constituing the material.
144 const G4Element* anElement = SelectRandomAtom(aMaterial,theGamma,energy);
145
146 //
147 // Photo electron
148 //
149
150 // Select atomic shell
151 G4int nShells = anElement->GetNbOfAtomicShells();
152 G4int i = 0;
153 while ((i<nShells) && (energy<anElement->GetAtomicShell(i))) i++;
154
155 // no shell available
156 if (i == nShells) return;
157
158 G4double bindingEnergy = anElement->GetAtomicShell(i);
159 G4double ElecKineEnergy = energy - bindingEnergy;
160
161 if (ElecKineEnergy > fminimalEnergy)
162 {
163 // direction of the photo electron
164 //
165 G4double cosTeta = ElecCosThetaDistribution(ElecKineEnergy);
166 G4double sinTeta = sqrt(1.-cosTeta*cosTeta);
167 G4double Phi = twopi * G4UniformRand();
168 G4double dirx = sinTeta*cos(Phi),diry = sinTeta*sin(Phi),dirz = cosTeta;
169 G4ThreeVector ElecDirection(dirx,diry,dirz);
170 ElecDirection.rotateUz(PhotonDirection);
171 //
172 G4DynamicParticle* aParticle = new G4DynamicParticle (
173 theElectron,ElecDirection, ElecKineEnergy);
174 fvect->push_back(aParticle);
175 }
176
177 fParticleChange->SetProposedKineticEnergy(0.);
178 fParticleChange->ProposeTrackStatus(fStopAndKill);
179 fParticleChange->ProposeLocalEnergyDeposit(bindingEnergy);
180}
181
182//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
183
184G4double G4PEEffectModel::ElecCosThetaDistribution(G4double kineEnergy)
185{
186 // Compute Theta distribution of the emitted electron, with respect to the
187 // incident Gamma.
188 // The Sauter-Gavrila distribution for the K-shell is used.
189 //
190 G4double costeta = 1.;
191 G4double gamma = 1. + kineEnergy/electron_mass_c2;
192 if (gamma > 5.) return costeta;
193 G4double beta = sqrt(gamma*gamma-1.)/gamma;
194 G4double b = 0.5*gamma*(gamma-1.)*(gamma-2);
195
196 G4double rndm,term,greject,grejsup;
197 if (gamma < 2.) grejsup = gamma*gamma*(1.+b-beta*b);
198 else grejsup = gamma*gamma*(1.+b+beta*b);
199
200 do { rndm = 1.-2*G4UniformRand();
201 costeta = (rndm+beta)/(rndm*beta+1.);
202 term = 1.-beta*costeta;
203 greject = (1.-costeta*costeta)*(1.+b*term)/(term*term);
204 } while(greject < G4UniformRand()*grejsup);
205
206 return costeta;
207}
208
209//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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