[1350] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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| 26 | // G4IonCoulombCrossSection.cc |
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| 27 | //------------------------------------------------------------------- |
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| 28 | // |
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| 29 | // GEANT4 Class header file |
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| 30 | // |
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| 31 | // File name: G4IonCoulombCrossSection |
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| 32 | // |
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| 33 | // Author: Cristina Consolandi |
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| 34 | // |
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| 35 | // Creation date: 05.10.2010 from G4eCoulombScatteringModel |
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| 36 | // |
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| 37 | // Class Description: |
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| 38 | // Computation of Screen-Coulomb Cross Section |
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| 39 | // for protons, alpha and heavy Ions |
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| 40 | // |
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| 41 | // |
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| 42 | // Reference: |
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| 43 | // M.J. Boschini et al. "Nuclear and Non-Ionizing Energy-Loss |
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| 44 | // for Coulomb Scattered Particles from Low Energy up to Relativistic |
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| 45 | // Regime in Space Radiation Environment" |
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| 46 | // Accepted for publication in the Proceedings of the ICATPP Conference |
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| 47 | // on Cosmic Rays for Particle and Astroparticle Physics, Villa Olmo, 7-8 |
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| 48 | // October, 2010, to be published by World Scientific (Singapore). |
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| 49 | // |
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| 50 | // Available for downloading at: |
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| 51 | // http://arxiv.org/abs/1011.4822 |
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| 52 | // |
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| 53 | // ------------------------------------------------------------------- |
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| 54 | // |
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| 55 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 56 | #include "G4IonCoulombCrossSection.hh" |
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| 57 | #include "Randomize.hh" |
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| 58 | #include "G4Proton.hh" |
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| 59 | #include "G4LossTableManager.hh" |
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| 60 | |
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| 61 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 62 | |
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| 63 | |
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| 64 | using namespace std; |
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| 65 | |
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| 66 | G4IonCoulombCrossSection::G4IonCoulombCrossSection(): |
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| 67 | cosThetaMin(1.0), |
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| 68 | cosThetaMax(-1.0), |
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| 69 | alpha2(fine_structure_const*fine_structure_const) |
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| 70 | { |
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| 71 | fNistManager = G4NistManager::Instance(); |
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| 72 | theProton = G4Proton::Proton(); |
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| 73 | particle=0; |
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| 74 | |
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| 75 | G4double p0 = electron_mass_c2*classic_electr_radius; |
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| 76 | coeff = twopi*p0*p0; |
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| 77 | |
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| 78 | cosTetMinNuc=0; |
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| 79 | cosTetMaxNuc=0; |
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| 80 | nucXSection =0; |
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| 81 | |
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| 82 | |
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| 83 | chargeSquare = spin = mass =0; |
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| 84 | tkinLab = momLab2 = invbetaLab2=0; |
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| 85 | tkin = mom2 = invbeta2=0; |
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| 86 | |
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| 87 | targetZ = targetMass = screenZ =0; |
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| 88 | ScreenRSquare=0.; |
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| 89 | |
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| 90 | etag = ecut = 0.0; |
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| 91 | |
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| 92 | } |
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| 93 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 94 | |
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| 95 | G4IonCoulombCrossSection::~G4IonCoulombCrossSection() |
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| 96 | {} |
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| 97 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 98 | |
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| 99 | void G4IonCoulombCrossSection::Initialise(const G4ParticleDefinition* p, |
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| 100 | G4double CosThetaLim) |
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| 101 | { |
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| 102 | |
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| 103 | SetupParticle(p); |
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| 104 | nucXSection = 0.0; |
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| 105 | tkin = targetZ = mom2 = DBL_MIN; |
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| 106 | ecut = etag = DBL_MAX; |
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| 107 | particle = p; |
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| 108 | |
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| 109 | |
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| 110 | cosThetaMin = CosThetaLim; |
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| 111 | |
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| 112 | } |
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| 113 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 114 | |
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| 115 | void G4IonCoulombCrossSection::SetupKinematic(G4double ekin, |
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| 116 | G4double cut,G4int iz ) |
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| 117 | { |
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| 118 | if(ekin != tkinLab || ecut != cut) { |
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| 119 | |
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| 120 | // lab |
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| 121 | tkinLab = ekin; |
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| 122 | momLab2 = tkinLab*(tkinLab + 2.0*mass); |
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| 123 | invbetaLab2 = 1.0 + mass*mass/momLab2; |
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| 124 | |
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| 125 | G4double etot = tkinLab + mass; |
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| 126 | G4double ptot = sqrt(momLab2); |
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| 127 | G4double m12 = mass*mass; |
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| 128 | |
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| 129 | targetMass=fNistManager->GetAtomicMassAmu(iz)*amu_c2; |
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| 130 | G4double m2 = targetMass; |
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| 131 | |
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| 132 | // relativistic reduced mass from publucation |
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| 133 | // A.P. Martynenko, R.N. Faustov, Teoret. mat. Fiz. 64 (1985) 179 |
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| 134 | |
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| 135 | //incident particle & target nucleus |
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| 136 | G4double Ecm=sqrt(m12 + m2*m2 + 2.0*etot*m2); |
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| 137 | G4double mu_rel=mass*m2/Ecm; |
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| 138 | G4double momCM= ptot*m2/Ecm; |
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| 139 | // relative system |
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| 140 | mom2 = momCM*momCM; |
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| 141 | invbeta2 = 1.0 + mu_rel*mu_rel/mom2; |
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| 142 | tkin = momCM*sqrt(invbeta2) - mu_rel;//Ekin of mu_rel |
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| 143 | //......................................................... |
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| 144 | |
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| 145 | cosTetMinNuc = cosThetaMin; |
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| 146 | cosTetMaxNuc = cosThetaMax; |
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| 147 | |
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| 148 | } |
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| 149 | |
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| 150 | } |
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| 151 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 152 | |
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| 153 | |
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| 154 | void G4IonCoulombCrossSection::SetupTarget(G4double Z, G4double e, G4int heavycorr) |
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| 155 | { |
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| 156 | if(Z != targetZ || e != etag) { |
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| 157 | etag = e; |
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| 158 | targetZ = Z; |
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| 159 | G4int iz= G4int(Z); |
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| 160 | |
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| 161 | SetScreenRSquare(iz); |
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| 162 | screenZ =0; |
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| 163 | screenZ = ScreenRSquare/mom2; |
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| 164 | |
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| 165 | // G4cout<< "heavycorr "<<heavycorr<<G4endl; |
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| 166 | |
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| 167 | if(heavycorr!=0 && particle != theProton){ |
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| 168 | G4double corr=5.*twopi*Z*std::sqrt(chargeSquare*alpha2); |
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| 169 | corr=std::pow(corr,0.12); |
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| 170 | screenZ *=(1.13 + corr*3.76*Z*Z*chargeSquare*invbeta2*alpha2)/2.; |
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| 171 | // G4cout<<" heavycorr Z e corr....2As "<< heavycorr << "\t" |
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| 172 | // <<Z <<"\t"<<e/MeV <<"\t"<<screenZ<<G4endl; |
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| 173 | |
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| 174 | }else{ screenZ *=(1.13 + 3.76*Z*Z*chargeSquare*invbeta2*alpha2)/2.; |
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| 175 | // G4cout<<" heavycorr Z e....2As "<< heavycorr << "\t" |
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| 176 | // <<Z <<"\t"<< e/MeV <<"\t" <<screenZ<<G4endl; |
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| 177 | } |
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| 178 | |
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| 179 | if(1 == iz && particle == theProton && cosTetMaxNuc < 0.0) { |
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| 180 | cosTetMaxNuc = 0.0; |
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| 181 | } |
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| 182 | |
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| 183 | } |
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| 184 | } |
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| 185 | |
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| 186 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 187 | void G4IonCoulombCrossSection::SetScreenRSquare(G4int iz){ |
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| 188 | |
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| 189 | G4double a0 = electron_mass_c2/0.88534; |
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| 190 | |
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| 191 | //target nucleus |
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| 192 | G4double Z1=std::sqrt(chargeSquare); |
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| 193 | G4double Z2=targetZ; |
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| 194 | |
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| 195 | G4double Z1023=std::pow(Z1,0.23); |
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| 196 | G4double Z2023=std::pow(Z2,0.23); |
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| 197 | |
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| 198 | // Universal screening length |
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| 199 | G4double x=a0*(Z1023+Z2023); |
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| 200 | |
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| 201 | //for proton Thomas-Fermi screening length |
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| 202 | if(particle == theProton){ |
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| 203 | x = a0*fNistManager->GetZ13(iz); |
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| 204 | } |
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| 205 | ScreenRSquare = alpha2*x*x; |
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| 206 | |
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| 207 | |
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| 208 | } |
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| 209 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 210 | |
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| 211 | G4double G4IonCoulombCrossSection::NuclearCrossSection() |
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| 212 | { |
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| 213 | // This method needs initialisation before be called |
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| 214 | |
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| 215 | // scattering with target nucleus |
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| 216 | G4double fac = coeff*targetZ*targetZ*chargeSquare*invbeta2/mom2; |
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| 217 | |
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| 218 | nucXSection = 0.0; |
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| 219 | |
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| 220 | G4double x = 1.0 - cosTetMinNuc; |
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| 221 | G4double x1 = x + screenZ; |
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| 222 | |
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| 223 | // scattering with nucleus |
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| 224 | if(cosTetMaxNuc < cosTetMinNuc) { |
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| 225 | |
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| 226 | nucXSection =fac*(cosTetMinNuc - cosTetMaxNuc)/ |
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| 227 | (x1*(1.0 - cosTetMaxNuc + screenZ)); |
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| 228 | |
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| 229 | } |
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| 230 | |
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| 231 | return nucXSection; |
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| 232 | } |
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| 233 | |
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| 234 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 235 | |
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| 236 | G4double G4IonCoulombCrossSection::SampleCosineTheta() |
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| 237 | { |
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| 238 | |
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| 239 | if(cosTetMaxNuc >= cosTetMinNuc) return 0.0; |
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| 240 | |
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| 241 | G4double x1 = 1. - cosTetMinNuc + screenZ; |
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| 242 | G4double x2 = 1. - cosTetMaxNuc + screenZ; |
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| 243 | G4double dx = cosTetMinNuc - cosTetMaxNuc; |
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| 244 | G4double grej, z1; |
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| 245 | |
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| 246 | z1 = x1*x2/(x1 + G4UniformRand()*dx) - screenZ; |
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| 247 | grej = 1.0/(1.0 + z1); |
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| 248 | |
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| 249 | |
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| 250 | return z1; |
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| 251 | } |
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| 252 | |
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| 253 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 254 | |
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| 255 | |
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| 256 | |
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| 257 | |
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