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25 //
26 // G4RToEConvForPositron class implementation
27 //
28 // Author: H.Kurashige, 05 October 2002 - First implementation
29 // --------------------------------------------------------------------
30
31 #include "G4RToEConvForPositron.hh"
32 #include "G4ParticleDefinition.hh"
33 #include "G4ParticleTable.hh"
34
35 #include "G4PhysicalConstants.hh"
36 #include "G4SystemOfUnits.hh"
37 #include "G4Pow.hh"
38 #include "G4Log.hh"
39 #include "G4Exp.hh"
40
41 // --------------------------------------------------------------------
42 G4RToEConvForPositron::G4RToEConvForPositron()
43 : G4VRangeToEnergyConverter()
44 {
45 theParticle = G4ParticleTable::GetParticleTable()->FindParticle("e+");
46 if (theParticle == nullptr)
47 {
48 #ifdef G4VERBOSE
49 if (GetVerboseLevel()>0)
50 {
51 G4cout << "G4RToEConvForPositron::G4RToEConvForPositron() - ";
52 G4cout << "Positron is not defined !!" << G4endl;
53 }
54 #endif
55 }
56 else
57 {
58 fPDG = theParticle->GetPDGEncoding();
59 }
60 }
61
62 // --------------------------------------------------------------------
63 G4RToEConvForPositron::~G4RToEConvForPositron()
64 {}
65
66 // --------------------------------------------------------------------
67 G4double G4RToEConvForPositron::ComputeValue(const G4int Z,
68 const G4double kinEnergy)
69 {
70 const G4double cbr1=0.02, cbr2=-5.7e-5, cbr3=1., cbr4=0.072;
71 const G4double Tlow=10.*CLHEP::keV, Thigh=1.*CLHEP::GeV;
72 const G4double taul = Tlow/CLHEP::electron_mass_c2;
73 const G4double logtaul = G4Log(taul);
74 const G4double taul12 = std::sqrt(taul);
75 const G4double bremfactor = 0.1;
76
77 G4double Zlog = G4Pow::GetInstance()->logZ(Z);
78 G4double ionpot =
79 1.6e-5*CLHEP::MeV*G4Exp(0.9*Zlog)/CLHEP::electron_mass_c2;
80 G4double ionpotlog = G4Log(ionpot);
81
82 G4double tau = kinEnergy/CLHEP::electron_mass_c2;
83 G4double dEdx = 0.0;
84
85
86 if(tau<taul)
87 {
88 G4double t1 = taul+1.;
89 G4double t2 = taul+2.;
90 G4double tsq = taul*taul;
91 G4double beta2 = taul*t2/(t1*t1);
92 G4double f = 2.*logtaul -
93 (6.*taul+1.5*tsq-taul*(1.-tsq/3.)/t2
94 -tsq*(0.5-tsq/12.)/(t2*t2))/(t1*t1);
95 dEdx = (G4Log(2.*taul+4.)-2.*ionpotlog+f)/beta2;
96 dEdx *= Z*taul12/std::sqrt(tau);
97 }
98 else
99 {
100 G4double t1 = tau+1.;
101 G4double t2 = tau+2.;
102 G4double tsq = tau*tau;
103 G4double beta2 = tau*t2/(t1*t1);
104 G4double f = 2.*G4Log(tau) - (6.*tau+1.5*tsq-tau*(1.-tsq/3.)/t2
105 -tsq*(0.5-tsq/12.)/(t2*t2))/(t1*t1);
106 dEdx = Z*(G4Log(2.*tau+4.)-2.*ionpotlog+f)/beta2;
107
108 // loss from bremsstrahlung follows
109 G4double cbrem = (cbr1+cbr2*Z)
110 * (cbr3+cbr4*G4Log(kinEnergy/Thigh));
111 dEdx += cbrem*Z*(Z+1.)*bremfactor*tau/beta2;
112 }
113 return dEdx*CLHEP::twopi_mc2_rcl2;
114 }
115
116 // --------------------------------------------------------------------
117