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26 //
27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class file
30 //
31 //
32 // File name: G4DeltaAngle
33 //
34 // Author: Vladimir Ivantcheko
35 //
36 // Creation date: 23 August 2013
37 //
38 // Modifications:
39 //
40 // Class Description:
41 //
42 // Delta-electron Angular Distribution Generation
43 //
44 // Class Description: End
45 //
46 // -------------------------------------------------------------------
47 //
48
49 #include "G4DeltaAngle.hh"
50 #include "G4PhysicalConstants.hh"
51 #include "Randomize.hh"
52 #include "G4ParticleDefinition.hh"
53 #include "G4Electron.hh"
54 #include "G4AtomicShells.hh"
55 #include "G4SystemOfUnits.hh"
56 #include "G4Log.hh"
57
58 using namespace std;
59
60 G4DeltaAngle::G4DeltaAngle(const G4String&)
61 : G4VEmAngularDistribution("deltaVI")
62 {
63 fElectron = G4Electron::Electron();
64 nprob = 26;
65 fShellIdx = -1;
66 prob.resize(nprob,0.0);
67 }
68
69 G4DeltaAngle::~G4DeltaAngle() = default;
70
71 G4ThreeVector&
72 G4DeltaAngle::SampleDirectionForShell(const G4DynamicParticle* dp,
73 G4double kinEnergyFinal, G4int Z, G4int idx,
74 const G4Material* mat)
75 {
76 fShellIdx = idx;
77 return SampleDirection(dp, kinEnergyFinal,Z, mat);
78 }
79
80 G4ThreeVector&
81 G4DeltaAngle::SampleDirection(const G4DynamicParticle* dp,
82 G4double kinEnergyFinal, G4int Z,
83 const G4Material*)
84 {
85 G4int nShells = G4AtomicShells::GetNumberOfShells(Z);
86 G4int idx = fShellIdx;
87
88 // if idx is not properly defined sample shell index
89 if(idx < 0 || idx >= nShells) {
90 if(nShells> nprob) {
91 nprob = nShells;
92 prob.resize(nprob,0.0);
93 }
94 G4double sum = 0.0;
95 for(idx=0; idx<nShells; ++idx) {
96 sum += G4AtomicShells::GetNumberOfElectrons(Z, idx)
97 /G4AtomicShells::GetBindingEnergy(Z, idx);
98 prob[idx] = sum;
99 }
100 sum *= G4UniformRand();
101 for(idx=0; idx<nShells; ++idx) {
102 if(sum <= prob[idx]) { break; }
103 }
104 }
105 G4double bindingEnergy = G4AtomicShells::GetBindingEnergy(Z, idx);
106 G4double cost;
107 /*
108 G4cout << "E(keV)= " << kinEnergyFinal/keV
109 << " Ebind(keV)= " << bindingEnergy
110 << " idx= " << idx << " nShells= " << nShells << G4endl;
111 */
112 G4int n = 0;
113 G4bool isOK = false;
114 static const G4int nmax = 100;
115 do {
116 ++n;
117 // the atomic electron
118 G4double x = -G4Log(G4UniformRand());
119 G4double eKinEnergy = bindingEnergy*x;
120 G4double ePotEnergy = bindingEnergy*(1.0 + x);
121 G4double e = kinEnergyFinal + ePotEnergy + electron_mass_c2;
122 G4double p = sqrt((e + electron_mass_c2)*(e - electron_mass_c2));
123
124 G4double totEnergy = dp->GetTotalEnergy();
125 G4double totMomentum = dp->GetTotalMomentum();
126 if(dp->GetParticleDefinition() == fElectron) {
127 totEnergy += ePotEnergy;
128 totMomentum = sqrt((totEnergy + electron_mass_c2)
129 *(totEnergy - electron_mass_c2));
130 }
131
132 G4double eTotEnergy = eKinEnergy + electron_mass_c2;
133 G4double eTotMomentum = sqrt(eKinEnergy*(eTotEnergy + electron_mass_c2));
134 G4double costet = 2*G4UniformRand() - 1;
135 G4double sintet = sqrt((1 - costet)*(1 + costet));
136
137 cost = 1.0;
138 if(n >= nmax) {
139 /*
140 G4ExceptionDescription ed;
141 ed << "### G4DeltaAngle Warning: " << n
142 << " iterations - stop the loop with cost= 1.0 "
143 << " for " << dp->GetDefinition()->GetParticleName() << "\n"
144 << " Ekin(MeV)= " << dp->GetKineticEnergy()/MeV
145 << " Efinal(MeV)= " << kinEnergyFinal/MeV
146 << " Ebinding(MeV)= " << bindingEnergy/MeV;
147 G4Exception("G4DeltaAngle::SampleDirection","em0044",
148 JustWarning, ed,"");
149 */
150 if(0.0 == bindingEnergy) { isOK = true; }
151 bindingEnergy = 0.0;
152 }
153
154 G4double x0 = p*(totMomentum + eTotMomentum*costet);
155 /*
156 G4cout << " x0= " << x0 << " p= " << p
157 << " ptot= " << totMomentum << " pe= " << eTotMomentum
158 << " e= " << e << " totMom= " << totMomentum
159 << G4endl;
160 */
161 if(x0 > 0.0) {
162 G4double x1 = p*eTotMomentum*sintet;
163 G4double x2 = totEnergy*(eTotEnergy - e) - e*eTotEnergy
164 - totMomentum*eTotMomentum*costet + electron_mass_c2*electron_mass_c2;
165 G4double y = -x2/x0;
166 if(std::abs(y) <= 1.0) {
167 cost = -(x2 + x1*sqrt(1. - y*y))/x0;
168 if(std::abs(cost) <= 1.0) { isOK = true; }
169 else { cost = 1.0; }
170 }
171
172 /*
173 G4cout << " Ekin(MeV)= " << dp->GetKineticEnergy()
174 << " e1(keV)= " << eKinEnergy/keV
175 << " e2(keV)= " << (e - electron_mass_c2)/keV
176 << " 1-cost= " << 1-cost
177 << " x0= " << x0 << " x1= " << x1 << " x2= " << x2
178 << G4endl;
179 */
180 }
181
182 // Loop checking, 03-Aug-2015, Vladimir Ivanchenko
183 } while(!isOK);
184
185 G4double sint = sqrt((1 - cost)*(1 + cost));
186 G4double phi = twopi*G4UniformRand();
187
188 fLocalDirection.set(sint*cos(phi), sint*sin(phi), cost);
189 fLocalDirection.rotateUz(dp->GetMomentumDirection());
190
191 return fLocalDirection;
192 }
193