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25 //
26
27 #include "G4XTRGammaRadModel.hh"
28
29 ////////////////////////////////////////////////////////////////////////////
30 // Constructor, destructor
31 G4XTRGammaRadModel::G4XTRGammaRadModel(G4LogicalVolume* anEnvelope,
32 G4double alphaPlate, G4double alphaGas,
33 G4Material* foilMat, G4Material* gasMat,
34 G4double a, G4double b, G4int n,
35 const G4String& processName)
36 : G4VXTRenergyLoss(anEnvelope, foilMat, gasMat, a, b, n, processName)
37 {
38 G4cout << "Gamma distributed X-ray TR radiator model is called" << G4endl;
39
40 // Build energy and angular integral spectra of X-ray TR photons from
41 // a radiator
42 fAlphaPlate = alphaPlate;
43 fAlphaGas = alphaGas;
44 G4cout << "fAlphaPlate = " << fAlphaPlate << " ; fAlphaGas = " << fAlphaGas
45 << G4endl;
46 fExitFlux = true;
47 }
48
49 ///////////////////////////////////////////////////////////////////////////
50 G4XTRGammaRadModel::~G4XTRGammaRadModel() = default;
51
52 void G4XTRGammaRadModel::ProcessDescription(std::ostream& out) const
53 {
54 out << "Rough model describing X-ray transition radiation. Thicknesses of "
55 "plates\n"
56 "and gas gaps are distributed according to gamma distributions.\n";
57 }
58
59 ///////////////////////////////////////////////////////////////////////////
60 // Rough approximation for radiator interference factor for the case of
61 // fully GamDistr radiator. The plate and gas gap thicknesses are distributed
62 // according to exponent. The mean values of the plate and gas gap thicknesses
63 // are supposed to be about XTR formation zones but much less than
64 // mean absorption length of XTR photons in coresponding material.
65 G4double G4XTRGammaRadModel::GetStackFactor(G4double energy, G4double gamma,
66 G4double varAngle)
67 {
68 G4double result, Qa, Qb, Q, Za, Zb, Ma, Mb;
69
70 Za = GetPlateFormationZone(energy, gamma, varAngle);
71 Zb = GetGasFormationZone(energy, gamma, varAngle);
72
73 Ma = GetPlateLinearPhotoAbs(energy);
74 Mb = GetGasLinearPhotoAbs(energy);
75
76 Qa = (1.0 + fPlateThick * Ma / fAlphaPlate);
77 Qa = std::pow(Qa, -fAlphaPlate);
78 Qb = (1.0 + fGasThick * Mb / fAlphaGas);
79 Qb = std::pow(Qb, -fAlphaGas);
80 Q = Qa * Qb;
81
82 G4complex Ca(1.0 + 0.5 * fPlateThick * Ma / fAlphaPlate,
83 fPlateThick / Za / fAlphaPlate);
84 G4complex Cb(1.0 + 0.5 * fGasThick * Mb / fAlphaGas,
85 fGasThick / Zb / fAlphaGas);
86
87 G4complex Ha = std::pow(Ca, -fAlphaPlate);
88 G4complex Hb = std::pow(Cb, -fAlphaGas);
89 G4complex H = Ha * Hb;
90
91 G4complex F1 = (0.5 * (1 + Qa) * (1.0 + H) - Ha - Qa * Hb) / (1.0 - H);
92
93 G4complex F2 = (1.0 - Ha) * (Qa - Ha) * Hb / (1.0 - H) / (Q - H);
94
95 F2 *= std::pow(Q, G4double(fPlateNumber)) - std::pow(H, fPlateNumber);
96
97 result = (1. - std::pow(Q, G4double(fPlateNumber))) / (1. - Q);
98
99 G4complex stack = result * F1;
100 stack += F2;
101 stack *= 2.0 * OneInterfaceXTRdEdx(energy, gamma, varAngle);
102
103 result = std::real(stack);
104
105 return result;
106 }
107