| Geant4 Cross Reference |
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25 //
26 //
27 // Author: D.H. Wright
28 // Date: 1 February 2011
29 //
30 // Modified:
31 //
32 // 19 Aug 2011, V.Ivanchenko move to new design and make x-section per element
33
34 // Description: use Kokoulin's parameterized calculation of virtual
35 // photon production cross section and conversion to
36 // real photons.
37
38 #include "G4KokoulinMuonNuclearXS.hh"
39
40 #include "G4PhysicalConstants.hh"
41 #include "G4SystemOfUnits.hh"
42 #include "G4PhysicsLogVector.hh"
43 #include "G4PhysicsVector.hh"
44 #include "G4MuonMinus.hh"
45 #include "G4MuonPlus.hh"
46 #include "G4NucleiProperties.hh"
47 #include "G4NistManager.hh"
48 #include "G4Log.hh"
49 #include "G4Exp.hh"
50
51 // factory
52 #include "G4CrossSectionFactory.hh"
53 //
54 G4_DECLARE_XS_FACTORY(G4KokoulinMuonNuclearXS);
55
56 G4PhysicsVector* G4KokoulinMuonNuclearXS::theCrossSection[] = {0};
57
58 G4KokoulinMuonNuclearXS::G4KokoulinMuonNuclearXS()
59 :G4VCrossSectionDataSet(Default_Name()),
60 LowestKineticEnergy(1*GeV), HighestKineticEnergy(1*PeV),
61 TotBin(60), CutFixed(0.2*GeV), isInitialized(false), isMaster(false)
62 {}
63
64 G4KokoulinMuonNuclearXS::~G4KokoulinMuonNuclearXS()
65 {
66 if (isMaster) {
67 for(G4int i=0; i<MAXZMUN; ++i) {
68 delete theCrossSection[i];
69 theCrossSection[i] = 0;
70 }
71 }
72 }
73
74
75 void
76 G4KokoulinMuonNuclearXS::CrossSectionDescription(std::ostream& outFile) const
77 {
78 outFile << "G4KokoulinMuonNuclearXS provides the total inelastic\n"
79 << "cross section for mu- and mu+ interactions with nuclei.\n"
80 << "R. Kokoulin's approximation of the Borog and Petrukhin double\n"
81 << "differential cross section at high energy and low Q**2 is integrated\n"
82 << "over the muon energy loss to get the total cross section as a\n"
83 << "function of muon kinetic energy\n" ;
84 }
85
86
87 G4bool
88 G4KokoulinMuonNuclearXS::IsElementApplicable(const G4DynamicParticle*,
89 G4int, const G4Material*)
90 {
91 return true;
92 }
93
94 void
95 G4KokoulinMuonNuclearXS::BuildPhysicsTable(const G4ParticleDefinition&)
96 {
97 if(!isInitialized) {
98 isInitialized = true;
99 for(G4int i=0; i<MAXZMUN; ++i) {
100 if(theCrossSection[i]) { return; }
101 }
102 isMaster = true;
103 }
104 if(isMaster) { BuildCrossSectionTable(); }
105 }
106
107 void G4KokoulinMuonNuclearXS::BuildCrossSectionTable()
108 {
109 G4double energy, A, Value;
110 G4int Z;
111
112 std::size_t nEl = G4Element::GetNumberOfElements();
113 const G4ElementTable* theElementTable = G4Element::GetElementTable();
114 G4NistManager* nistManager = G4NistManager::Instance();
115
116 for (std::size_t j = 0; j < nEl; ++j) {
117 Z = G4lrint((*theElementTable)[j]->GetZ());
118
119 //AR-24Apr2018 Switch to treat transuranic elements as uranium
120 const G4bool isHeavyElementAllowed = true; if ( isHeavyElementAllowed && Z>92 ) Z=92;
121
122 A = nistManager->GetAtomicMassAmu(Z);
123 if(Z < MAXZMUN && !theCrossSection[Z]) {
124 theCrossSection[Z] = new G4PhysicsLogVector(LowestKineticEnergy,
125 HighestKineticEnergy,
126 TotBin);
127 for (G4int i = 0; i <= TotBin; ++i) {
128 energy = theCrossSection[Z]->Energy(i);
129 Value = ComputeMicroscopicCrossSection(energy, A);
130 theCrossSection[Z]->PutValue(i,Value);
131 }
132 }
133 }
134 }
135
136 G4double G4KokoulinMuonNuclearXS::
137 ComputeMicroscopicCrossSection(G4double KineticEnergy, G4double A)
138 {
139 // Calculate cross section (differential in muon incident kinetic energy) by
140 // integrating the double differential cross section over the energy loss
141
142 static const G4double xgi[] =
143 {0.0199,0.1017,0.2372,0.4083,0.5917,0.7628,0.8983,0.9801};
144 static const G4double wgi[] =
145 {0.0506,0.1112,0.1569,0.1813,0.1813,0.1569,0.1112,0.0506};
146 static const G4double ak1 = 6.9;
147 static const G4double ak2 = 1.0;
148
149 G4double Mass = G4MuonMinus::MuonMinus()->GetPDGMass();
150
151 G4double CrossSection = 0.0;
152 if (KineticEnergy <= CutFixed) return CrossSection;
153
154 G4double epmin = CutFixed;
155 G4double epmax = KineticEnergy + Mass - 0.5*proton_mass_c2;
156 if (epmax <= epmin) return CrossSection; // NaN bug correction
157
158 G4double aaa = G4Log(epmin);
159 G4double bbb = G4Log(epmax);
160 G4int kkk = std::max(1,G4int((bbb-aaa)/ak1 +ak2));
161 G4double hhh = (bbb-aaa)/kkk ;
162 G4double epln;
163 G4double ep;
164 G4double x;
165
166 for (G4int l = 0; l < kkk; ++l) {
167 x = aaa + hhh*l;
168 for (G4int ll = 0; ll < 8; ++ll) {
169 epln=x+xgi[ll]*hhh;
170 ep = G4Exp(epln);
171 CrossSection +=
172 ep*wgi[ll]*ComputeDDMicroscopicCrossSection(KineticEnergy, 0, A, ep);
173 }
174 }
175
176 CrossSection *= hhh ;
177 if (CrossSection < 0.) { CrossSection = 0.; }
178 return CrossSection;
179 }
180
181 G4double G4KokoulinMuonNuclearXS::
182 ComputeDDMicroscopicCrossSection(G4double KineticEnergy, G4double,
183 G4double A, G4double epsilon)
184 {
185 // Calculate the double-differential microscopic cross section (in muon
186 // incident kinetic energy and energy loss) using the cross section formula
187 // of R.P. Kokoulin (18/01/98)
188
189 static const G4double alam2 = 0.400*GeV*GeV;
190 static const G4double alam = 0.632456*GeV;
191 static const G4double coeffn = fine_structure_const/pi;
192
193 G4double ParticleMass = G4MuonMinus::MuonMinus()->GetPDGMass();
194 G4double TotalEnergy = KineticEnergy + ParticleMass;
195
196 G4double DCrossSection = 0.;
197
198 if ((epsilon >= TotalEnergy - 0.5*proton_mass_c2) ||
199 (epsilon <= CutFixed) ) { return DCrossSection; }
200
201 G4double ep = epsilon/GeV;
202 G4double aeff = 0.22*A+0.78*G4Exp(0.89*G4Log(A)); //shadowing
203 G4double sigph = (49.2+11.1*G4Log(ep)+151.8/std::sqrt(ep))*microbarn;
204
205 G4double v = epsilon/TotalEnergy;
206 G4double v1 = 1.-v;
207 G4double v2 = v*v;
208 G4double mass2 = ParticleMass*ParticleMass;
209
210 G4double up = TotalEnergy*TotalEnergy*v1/mass2*(1.+mass2*v2/(alam2*v1));
211 G4double down = 1.+epsilon/alam*(1.+alam/(2.*proton_mass_c2)+epsilon/alam);
212
213 DCrossSection = coeffn*aeff*sigph/epsilon*
214 (-v1+(v1+0.5*v2*(1.+2.*mass2/alam2))*G4Log(up/down));
215
216 if (DCrossSection < 0.) { DCrossSection = 0.; }
217 return DCrossSection;
218 }
219
220 G4double G4KokoulinMuonNuclearXS::
221 GetElementCrossSection(const G4DynamicParticle* aPart,
222 G4int ZZ, const G4Material*)
223 {
224 //AR-24Apr2018 Switch to treat transuranic elements as uranium
225 G4int Z = std::min(ZZ, 92);
226 return theCrossSection[Z]->LogVectorValue(aPart->GetKineticEnergy(),
227 aPart->GetLogKineticEnergy());
228 }
229
230