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25 //
26 // --------------------------------------------------------------------
27 //
28 //
29 // Author: A. Forti
30 // Maria Grazia Pia (Maria.Grazia.Pia@cern.ch)
31 //
32 // History:
33 // --------
34 // Added Livermore data table construction methods A. Forti
35 // Added BuildMeanFreePath A. Forti
36 // Added PostStepDoIt A. Forti
37 // Added SelectRandomAtom A. Forti
38 // Added map of the elements A.Forti
39 // 24.04.01 V.Ivanchenko remove RogueWave
40 // 11.08.2001 MGP - Major revision according to a design iteration
41 // 06.10.2001 MGP - Added strategy to test range for secondary generation
42 // 05.06.2002 F.Longo and G.Depaola - bug fixed in angular distribution
43 // 20.10.2002 G. Depaola - Change sampling method of theta
44 // 22.01.2003 V.Ivanchenko - Cut per region
45 // 24.04.2003 V.Ivanchenko - Cut per region mfpt
46 //
47 // --------------------------------------------------------------------
48
49 #include "G4LowEnergyRayleigh.hh"
50 #include "Randomize.hh"
51 #include "G4PhysicalConstants.hh"
52 #include "G4SystemOfUnits.hh"
53 #include "G4ParticleDefinition.hh"
54 #include "G4Track.hh"
55 #include "G4Step.hh"
56 #include "G4ForceCondition.hh"
57 #include "G4Gamma.hh"
58 #include "G4Electron.hh"
59 #include "G4DynamicParticle.hh"
60 #include "G4VParticleChange.hh"
61 #include "G4ThreeVector.hh"
62 #include "G4RDVCrossSectionHandler.hh"
63 #include "G4RDCrossSectionHandler.hh"
64 #include "G4RDVEMDataSet.hh"
65 #include "G4RDCompositeEMDataSet.hh"
66 #include "G4RDVDataSetAlgorithm.hh"
67 #include "G4RDLogLogInterpolation.hh"
68
69 #include "G4MaterialCutsCouple.hh"
70
71 G4LowEnergyRayleigh::G4LowEnergyRayleigh(const G4String& processName)
72 : G4VDiscreteProcess(processName),
73 lowEnergyLimit(250*eV),
74 highEnergyLimit(100*GeV),
75 intrinsicLowEnergyLimit(10*eV),
76 intrinsicHighEnergyLimit(100*GeV)
77 {
78 if (lowEnergyLimit < intrinsicLowEnergyLimit ||
79 highEnergyLimit > intrinsicHighEnergyLimit)
80 {
81 G4Exception("G4LowEnergyRayleigh::G4LowEnergyRayleigh()",
82 "OutOfRange", FatalException,
83 "Energy limit outside intrinsic process validity range!");
84 }
85
86 crossSectionHandler = new G4RDCrossSectionHandler();
87
88 G4RDVDataSetAlgorithm* ffInterpolation = new G4RDLogLogInterpolation;
89 G4String formFactorFile = "rayl/re-ff-";
90 formFactorData = new G4RDCompositeEMDataSet(ffInterpolation,1.,1.);
91 formFactorData->LoadData(formFactorFile);
92
93 meanFreePathTable = 0;
94
95 if (verboseLevel > 0)
96 {
97 G4cout << GetProcessName() << " is created " << G4endl
98 << "Energy range: "
99 << lowEnergyLimit / keV << " keV - "
100 << highEnergyLimit / GeV << " GeV"
101 << G4endl;
102 }
103 }
104
105 G4LowEnergyRayleigh::~G4LowEnergyRayleigh()
106 {
107 delete meanFreePathTable;
108 delete crossSectionHandler;
109 delete formFactorData;
110 }
111
112 void G4LowEnergyRayleigh::BuildPhysicsTable(const G4ParticleDefinition& )
113 {
114
115 crossSectionHandler->Clear();
116 G4String crossSectionFile = "rayl/re-cs-";
117 crossSectionHandler->LoadData(crossSectionFile);
118
119 delete meanFreePathTable;
120 meanFreePathTable = crossSectionHandler->BuildMeanFreePathForMaterials();
121 }
122
123 G4VParticleChange* G4LowEnergyRayleigh::PostStepDoIt(const G4Track& aTrack,
124 const G4Step& aStep)
125 {
126
127 aParticleChange.Initialize(aTrack);
128
129 const G4DynamicParticle* incidentPhoton = aTrack.GetDynamicParticle();
130 G4double photonEnergy0 = incidentPhoton->GetKineticEnergy();
131
132 if (photonEnergy0 <= lowEnergyLimit)
133 {
134 aParticleChange.ProposeTrackStatus(fStopAndKill);
135 aParticleChange.ProposeEnergy(0.);
136 aParticleChange.ProposeLocalEnergyDeposit(photonEnergy0);
137 return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep);
138 }
139
140 // G4double e0m = photonEnergy0 / electron_mass_c2 ;
141 G4ParticleMomentum photonDirection0 = incidentPhoton->GetMomentumDirection();
142
143 // Select randomly one element in the current material
144 const G4MaterialCutsCouple* couple = aTrack.GetMaterialCutsCouple();
145 G4int Z = crossSectionHandler->SelectRandomAtom(couple,photonEnergy0);
146
147 // Sample the angle of the scattered photon
148
149 G4double wlPhoton = h_Planck*c_light/photonEnergy0;
150
151 G4double gReject,x,dataFormFactor;
152 G4double randomFormFactor;
153 G4double cosTheta;
154 G4double sinTheta;
155 G4double fcostheta;
156
157 do
158 {
159 do
160 {
161 cosTheta = 2. * G4UniformRand() - 1.;
162 fcostheta = ( 1. + cosTheta*cosTheta)/2.;
163 } while (fcostheta < G4UniformRand());
164
165 G4double sinThetaHalf = std::sqrt((1. - cosTheta) / 2.);
166 x = sinThetaHalf / (wlPhoton/cm);
167 if (x > 1.e+005)
168 dataFormFactor = formFactorData->FindValue(x,Z-1);
169 else
170 dataFormFactor = formFactorData->FindValue(0.,Z-1);
171 randomFormFactor = G4UniformRand() * Z * Z;
172 sinTheta = std::sqrt(1. - cosTheta*cosTheta);
173 gReject = dataFormFactor * dataFormFactor;
174
175 } while( gReject < randomFormFactor);
176
177 // Scattered photon angles. ( Z - axis along the parent photon)
178 G4double phi = twopi * G4UniformRand() ;
179 G4double dirX = sinTheta*std::cos(phi);
180 G4double dirY = sinTheta*std::sin(phi);
181 G4double dirZ = cosTheta;
182
183 // Update G4VParticleChange for the scattered photon
184 G4ThreeVector photonDirection1(dirX, dirY, dirZ);
185
186 photonDirection1.rotateUz(photonDirection0);
187 aParticleChange.ProposeEnergy(photonEnergy0);
188 aParticleChange.ProposeMomentumDirection(photonDirection1);
189
190 aParticleChange.SetNumberOfSecondaries(0);
191
192 return G4VDiscreteProcess::PostStepDoIt(aTrack, aStep);
193 }
194
195 G4bool G4LowEnergyRayleigh::IsApplicable(const G4ParticleDefinition& particle)
196 {
197 return ( &particle == G4Gamma::Gamma() );
198 }
199
200 G4double G4LowEnergyRayleigh::GetMeanFreePath(const G4Track& track,
201 G4double, // previousStepSize
202 G4ForceCondition*)
203 {
204 const G4DynamicParticle* photon = track.GetDynamicParticle();
205 G4double energy = photon->GetKineticEnergy();
206 const G4MaterialCutsCouple* couple = track.GetMaterialCutsCouple();
207 size_t materialIndex = couple->GetIndex();
208
209 G4double meanFreePath;
210 if (energy > highEnergyLimit) meanFreePath = meanFreePathTable->FindValue(highEnergyLimit,materialIndex);
211 else if (energy < lowEnergyLimit) meanFreePath = DBL_MAX;
212 else meanFreePath = meanFreePathTable->FindValue(energy,materialIndex);
213 return meanFreePath;
214 }
215