[968] | 1 | // |
---|
| 2 | // ******************************************************************** |
---|
| 3 | // * License and Disclaimer * |
---|
| 4 | // * * |
---|
| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
---|
| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
---|
| 7 | // * conditions of the Geant4 Software License, included in the file * |
---|
| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
---|
| 9 | // * include a list of copyright holders. * |
---|
| 10 | // * * |
---|
| 11 | // * Neither the authors of this software system, nor their employing * |
---|
| 12 | // * institutes,nor the agencies providing financial support for this * |
---|
| 13 | // * work make any representation or warranty, express or implied, * |
---|
| 14 | // * regarding this software system or assume any liability for its * |
---|
| 15 | // * use. Please see the license in the file LICENSE and URL above * |
---|
| 16 | // * for the full disclaimer and the limitation of liability. * |
---|
| 17 | // * * |
---|
| 18 | // * This code implementation is the result of the scientific and * |
---|
| 19 | // * technical work of the GEANT4 collaboration. * |
---|
| 20 | // * By using, copying, modifying or distributing the software (or * |
---|
| 21 | // * any work based on the software) you agree to acknowledge its * |
---|
| 22 | // * use in resulting scientific publications, and indicate your * |
---|
| 23 | // * acceptance of all terms of the Geant4 Software license. * |
---|
| 24 | // ******************************************************************** |
---|
| 25 | // |
---|
| 26 | // $Id: G4hPairProductionModel.cc,v 1.1 2008/03/06 11:47:11 vnivanch Exp $ |
---|
[1228] | 27 | // GEANT4 tag $Name: geant4-09-03 $ |
---|
[968] | 28 | // |
---|
| 29 | // ------------------------------------------------------------------- |
---|
| 30 | // |
---|
| 31 | // GEANT4 Class file |
---|
| 32 | // |
---|
| 33 | // |
---|
| 34 | // File name: G4hPairProductionModel |
---|
| 35 | // |
---|
| 36 | // Author: Vladimir Ivanchenko on base of G4MuPairProductionModel |
---|
| 37 | // |
---|
| 38 | // Creation date: 28.02.2008 |
---|
| 39 | // |
---|
| 40 | // Modifications: |
---|
| 41 | // |
---|
| 42 | |
---|
| 43 | // |
---|
| 44 | // Class Description: |
---|
| 45 | // |
---|
| 46 | // |
---|
| 47 | // ------------------------------------------------------------------- |
---|
| 48 | // |
---|
| 49 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
| 50 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
| 51 | |
---|
| 52 | #include "G4hPairProductionModel.hh" |
---|
| 53 | |
---|
| 54 | using namespace std; |
---|
| 55 | |
---|
| 56 | G4hPairProductionModel::G4hPairProductionModel(const G4ParticleDefinition* p, |
---|
| 57 | const G4String& nam) |
---|
| 58 | : G4MuPairProductionModel(p, nam) |
---|
| 59 | {} |
---|
| 60 | |
---|
| 61 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
| 62 | |
---|
| 63 | G4hPairProductionModel::~G4hPairProductionModel() |
---|
| 64 | {} |
---|
| 65 | |
---|
| 66 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
| 67 | |
---|
| 68 | G4double G4hPairProductionModel::ComputeDMicroscopicCrossSection( |
---|
| 69 | G4double tkin, |
---|
| 70 | G4double Z, |
---|
| 71 | G4double pairEnergy) |
---|
| 72 | // differential cross section |
---|
| 73 | { |
---|
| 74 | G4double bbbtf= 183. ; |
---|
| 75 | G4double bbbh = 202.4 ; |
---|
| 76 | G4double g1tf = 1.95e-5 ; |
---|
| 77 | G4double g2tf = 5.3e-5 ; |
---|
| 78 | G4double g1h = 4.4e-5 ; |
---|
| 79 | G4double g2h = 4.8e-5 ; |
---|
| 80 | |
---|
| 81 | G4double totalEnergy = tkin + particleMass; |
---|
| 82 | G4double residEnergy = totalEnergy - pairEnergy; |
---|
| 83 | G4double massratio = particleMass/electron_mass_c2 ; |
---|
| 84 | G4double massratio2 = massratio*massratio ; |
---|
| 85 | G4double cross = 0.; |
---|
| 86 | |
---|
| 87 | SetCurrentElement(Z); |
---|
| 88 | |
---|
| 89 | G4double c3 = 0.75*sqrte*particleMass; |
---|
| 90 | if (residEnergy <= c3*z13) return cross; |
---|
| 91 | |
---|
| 92 | G4double c7 = 4.*electron_mass_c2; |
---|
| 93 | G4double c8 = 6.*particleMass*particleMass; |
---|
| 94 | G4double alf = c7/pairEnergy; |
---|
| 95 | G4double a3 = 1. - alf; |
---|
| 96 | if (a3 <= 0.) return cross; |
---|
| 97 | |
---|
| 98 | // zeta calculation |
---|
| 99 | G4double bbb,g1,g2; |
---|
| 100 | if( Z < 1.5 ) { bbb = bbbh ; g1 = g1h ; g2 = g2h ; } |
---|
| 101 | else { bbb = bbbtf; g1 = g1tf; g2 = g2tf; } |
---|
| 102 | |
---|
| 103 | G4double zeta = 0; |
---|
| 104 | G4double zeta1 = 0.073*log(totalEnergy/(particleMass+g1*z23*totalEnergy))-0.26; |
---|
| 105 | if ( zeta1 > 0.) |
---|
| 106 | { |
---|
| 107 | G4double zeta2 = 0.058*log(totalEnergy/(particleMass+g2*z13*totalEnergy))-0.14; |
---|
| 108 | zeta = zeta1/zeta2 ; |
---|
| 109 | } |
---|
| 110 | |
---|
| 111 | G4double z2 = Z*(Z+zeta); |
---|
| 112 | G4double screen0 = 2.*electron_mass_c2*sqrte*bbb/(z13*pairEnergy); |
---|
| 113 | G4double a0 = totalEnergy*residEnergy; |
---|
| 114 | G4double a1 = pairEnergy*pairEnergy/a0; |
---|
| 115 | G4double bet = 0.5*a1; |
---|
| 116 | G4double xi0 = 0.25*massratio2*a1; |
---|
| 117 | G4double del = c8/a0; |
---|
| 118 | |
---|
| 119 | G4double rta3 = sqrt(a3); |
---|
| 120 | G4double tmnexp = alf/(1. + rta3) + del*rta3; |
---|
| 121 | if(tmnexp >= 1.0) return cross; |
---|
| 122 | |
---|
| 123 | G4double tmn = log(tmnexp); |
---|
| 124 | G4double sum = 0.; |
---|
| 125 | |
---|
| 126 | // Gaussian integration in ln(1-ro) ( with 8 points) |
---|
| 127 | for (G4int i=0; i<8; i++) |
---|
| 128 | { |
---|
| 129 | G4double a4 = exp(tmn*xgi[i]); // a4 = (1.-asymmetry) |
---|
| 130 | G4double a5 = a4*(2.-a4) ; |
---|
| 131 | G4double a6 = 1.-a5 ; |
---|
| 132 | G4double a7 = 1.+a6 ; |
---|
| 133 | G4double a9 = 3.+a6 ; |
---|
| 134 | G4double xi = xi0*a5 ; |
---|
| 135 | G4double xii = 1./xi ; |
---|
| 136 | G4double xi1 = 1.+xi ; |
---|
| 137 | G4double screen = screen0*xi1/a5 ; |
---|
| 138 | G4double yeu = 5.-a6+4.*bet*a7 ; |
---|
| 139 | G4double yed = 2.*(1.+3.*bet)*log(3.+xii)-a6-a1*(2.-a6) ; |
---|
| 140 | G4double ye1 = 1.+yeu/yed ; |
---|
| 141 | G4double ale=log(bbb/z13*sqrt(xi1*ye1)/(1.+screen*ye1)) ; |
---|
| 142 | G4double cre = 0.5*log(1.+2.25*z23*xi1*ye1/massratio2) ; |
---|
| 143 | G4double be; |
---|
| 144 | |
---|
| 145 | if (xi <= 1.e3) be = ((2.+a6)*(1.+bet)+xi*a9)*log(1.+xii)+(a5-bet)/xi1-a9; |
---|
| 146 | else be = (3.-a6+a1*a7)/(2.*xi); |
---|
| 147 | |
---|
| 148 | G4double fe = (ale-cre)*be; |
---|
| 149 | if ( fe < 0.) fe = 0. ; |
---|
| 150 | |
---|
| 151 | G4double ymu = 4.+a6 +3.*bet*a7 ; |
---|
| 152 | G4double ymd = a7*(1.5+a1)*log(3.+xi)+1.-1.5*a6 ; |
---|
| 153 | G4double ym1 = 1.+ymu/ymd ; |
---|
| 154 | G4double alm_crm = log(bbb*massratio/(1.5*z23*(1.+screen*ym1))); |
---|
| 155 | G4double a10,bm; |
---|
| 156 | if ( xi >= 1.e-3) |
---|
| 157 | { |
---|
| 158 | a10 = (1.+a1)*a5 ; |
---|
| 159 | bm = (a7*(1.+1.5*bet)-a10*xii)*log(xi1)+xi*(a5-bet)/xi1+a10; |
---|
| 160 | } else { |
---|
| 161 | bm = (5.-a6+bet*a9)*(xi/2.); |
---|
| 162 | } |
---|
| 163 | |
---|
| 164 | G4double fm = alm_crm*bm; |
---|
| 165 | if ( fm < 0.) fm = 0. ; |
---|
| 166 | |
---|
| 167 | sum += wgi[i]*a4*(fe+fm/massratio2); |
---|
| 168 | } |
---|
| 169 | |
---|
| 170 | cross = -tmn*sum*factorForCross*z2*residEnergy/(totalEnergy*pairEnergy); |
---|
| 171 | |
---|
| 172 | return cross; |
---|
| 173 | } |
---|
| 174 | |
---|
| 175 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|