[1350] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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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 | // $Id: G4mplIonisationWithDeltaModel.cc,v 1.1 2010/10/26 15:40:03 vnivanch Exp $ |
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| 27 | // GEANT4 tag $Name: emhighenergy-V09-03-02 $ |
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| 28 | // |
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| 29 | // ------------------------------------------------------------------- |
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| 30 | // |
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| 31 | // GEANT4 Class header file |
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| 32 | // |
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| 33 | // |
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| 34 | // File name: G4mplIonisationWithDeltaModel |
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| 35 | // |
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| 36 | // Author: Vladimir Ivanchenko |
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| 37 | // |
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| 38 | // Creation date: 06.09.2005 |
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| 39 | // |
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| 40 | // Modifications: |
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| 41 | // 12.08.2007 Changing low energy approximation and extrapolation. |
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| 42 | // Small bug fixing and refactoring (M. Vladymyrov) |
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| 43 | // 13.11.2007 Use low-energy asymptotic from [3] (V.Ivanchenko) |
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| 44 | // |
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| 45 | // |
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| 46 | // ------------------------------------------------------------------- |
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| 47 | // References |
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| 48 | // [1] Steven P. Ahlen: Energy loss of relativistic heavy ionizing particles, |
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| 49 | // S.P. Ahlen, Rev. Mod. Phys 52(1980), p121 |
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| 50 | // [2] K.A. Milton arXiv:hep-ex/0602040 |
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| 51 | // [3] S.P. Ahlen and K. Kinoshita, Phys. Rev. D26 (1982) 2347 |
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| 52 | |
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| 53 | |
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| 54 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 55 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 56 | |
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| 57 | #include "G4mplIonisationWithDeltaModel.hh" |
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| 58 | #include "Randomize.hh" |
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| 59 | #include "G4LossTableManager.hh" |
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| 60 | #include "G4ParticleChangeForLoss.hh" |
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| 61 | #include "G4Electron.hh" |
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| 62 | #include "G4DynamicParticle.hh" |
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| 63 | |
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| 64 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 65 | |
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| 66 | using namespace std; |
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| 67 | |
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| 68 | G4mplIonisationWithDeltaModel::G4mplIonisationWithDeltaModel(G4double mCharge, const G4String& nam) |
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| 69 | : G4VEmModel(nam),G4VEmFluctuationModel(nam), |
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| 70 | magCharge(mCharge), |
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| 71 | twoln10(log(100.0)), |
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| 72 | betalow(0.01), |
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| 73 | betalim(0.1), |
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| 74 | beta2lim(betalim*betalim), |
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| 75 | bg2lim(beta2lim*(1.0 + beta2lim)) |
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| 76 | { |
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| 77 | nmpl = G4int(abs(magCharge) * 2 * fine_structure_const + 0.5); |
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| 78 | if(nmpl > 6) { nmpl = 6; } |
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| 79 | else if(nmpl < 1) { nmpl = 1; } |
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| 80 | pi_hbarc2_over_mc2 = pi * hbarc * hbarc / electron_mass_c2; |
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| 81 | chargeSquare = magCharge * magCharge; |
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| 82 | dedxlim = 45.*nmpl*nmpl*GeV*cm2/g; |
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| 83 | fParticleChange = 0; |
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| 84 | theElectron = G4Electron::Electron(); |
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| 85 | G4cout << "### Monopole ionisation model with d-electron production, Gmag= " |
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| 86 | << magCharge/eplus << G4endl; |
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| 87 | mass = 0.0; |
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| 88 | } |
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| 89 | |
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| 90 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 91 | |
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| 92 | G4mplIonisationWithDeltaModel::~G4mplIonisationWithDeltaModel() |
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| 93 | {} |
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| 94 | |
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| 95 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 96 | |
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| 97 | void |
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| 98 | G4mplIonisationWithDeltaModel::Initialise(const G4ParticleDefinition* p, |
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| 99 | const G4DataVector&) |
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| 100 | { |
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| 101 | monopole = p; |
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| 102 | mass = monopole->GetPDGMass(); |
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| 103 | if(!fParticleChange) { fParticleChange = GetParticleChangeForLoss(); } |
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| 104 | } |
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| 105 | |
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| 106 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 107 | |
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| 108 | G4double |
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| 109 | G4mplIonisationWithDeltaModel::ComputeDEDXPerVolume(const G4Material* material, |
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| 110 | const G4ParticleDefinition* p, |
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| 111 | G4double kineticEnergy, |
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| 112 | G4double maxEnergy) |
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| 113 | { |
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| 114 | G4double tmax = MaxSecondaryEnergy(p,kineticEnergy); |
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| 115 | G4double cutEnergy = std::min(tmax, maxEnergy); |
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| 116 | G4double tau = kineticEnergy / mass; |
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| 117 | G4double gam = tau + 1.0; |
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| 118 | G4double bg2 = tau * (tau + 2.0); |
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| 119 | G4double beta2 = bg2 / (gam * gam); |
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| 120 | G4double beta = sqrt(beta2); |
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| 121 | |
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| 122 | // low-energy asymptotic formula |
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| 123 | G4double dedx = dedxlim*beta*material->GetDensity(); |
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| 124 | |
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| 125 | // above asymptotic |
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| 126 | if(beta > betalow) { |
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| 127 | |
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| 128 | // high energy |
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| 129 | if(beta >= betalim) { |
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| 130 | dedx = ComputeDEDXAhlen(material, bg2, cutEnergy); |
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| 131 | |
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| 132 | } else { |
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| 133 | |
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| 134 | G4double dedx1 = dedxlim*betalow*material->GetDensity(); |
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| 135 | G4double dedx2 = ComputeDEDXAhlen(material, bg2lim, cutEnergy); |
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| 136 | |
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| 137 | // extrapolation between two formula |
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| 138 | G4double kapa2 = beta - betalow; |
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| 139 | G4double kapa1 = betalim - beta; |
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| 140 | dedx = (kapa1*dedx1 + kapa2*dedx2)/(kapa1 + kapa2); |
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| 141 | } |
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| 142 | } |
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| 143 | return dedx; |
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| 144 | } |
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| 145 | |
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| 146 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 147 | |
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| 148 | G4double |
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| 149 | G4mplIonisationWithDeltaModel::ComputeDEDXAhlen(const G4Material* material, |
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| 150 | G4double bg2, |
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| 151 | G4double cutEnergy) |
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| 152 | { |
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| 153 | G4double eDensity = material->GetElectronDensity(); |
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| 154 | G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy(); |
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| 155 | |
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| 156 | // Ahlen's formula for nonconductors, [1]p157, f(5.7) |
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| 157 | G4double dedx = |
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| 158 | 0.5*(log(2.0 * electron_mass_c2 * bg2*cutEnergy / (eexc*eexc)) - 1.0); |
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| 159 | |
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| 160 | // Kazama et al. cross-section correction |
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| 161 | G4double k = 0.406; |
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| 162 | if(nmpl > 1) { k = 0.346; } |
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| 163 | |
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| 164 | // Bloch correction |
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| 165 | const G4double B[7] = { 0.0, 0.248, 0.672, 1.022, 1.243, 1.464, 1.685}; |
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| 166 | |
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| 167 | dedx += 0.5 * k - B[nmpl]; |
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| 168 | |
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| 169 | // density effect correction |
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| 170 | G4double x = log(bg2)/twoln10; |
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| 171 | dedx -= material->GetIonisation()->DensityCorrection(x); |
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| 172 | |
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| 173 | // now compute the total ionization loss |
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| 174 | dedx *= pi_hbarc2_over_mc2 * eDensity * nmpl * nmpl; |
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| 175 | |
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| 176 | if (dedx < 0.0) { dedx = 0; } |
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| 177 | return dedx; |
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| 178 | } |
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| 179 | |
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| 180 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 181 | |
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| 182 | G4double |
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| 183 | G4mplIonisationWithDeltaModel::ComputeCrossSectionPerElectron( |
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| 184 | const G4ParticleDefinition* p, |
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| 185 | G4double kineticEnergy, |
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| 186 | G4double cutEnergy, |
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| 187 | G4double maxKinEnergy) |
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| 188 | { |
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| 189 | G4double cross = 0.0; |
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| 190 | G4double tmax = MaxSecondaryEnergy(p, kineticEnergy); |
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| 191 | G4double maxEnergy = min(tmax,maxKinEnergy); |
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| 192 | if(cutEnergy < maxEnergy) { |
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| 193 | cross = (1.0/cutEnergy - 1.0/maxEnergy)*twopi_mc2_rcl2*chargeSquare; |
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| 194 | } |
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| 195 | return cross; |
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| 196 | } |
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| 197 | |
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| 198 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 199 | |
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| 200 | G4double |
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| 201 | G4mplIonisationWithDeltaModel::ComputeCrossSectionPerAtom( |
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| 202 | const G4ParticleDefinition* p, |
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| 203 | G4double kineticEnergy, |
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| 204 | G4double Z, G4double, |
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| 205 | G4double cutEnergy, |
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| 206 | G4double maxEnergy) |
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| 207 | { |
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| 208 | G4double cross = |
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| 209 | Z*ComputeCrossSectionPerElectron(p,kineticEnergy,cutEnergy,maxEnergy); |
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| 210 | return cross; |
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| 211 | } |
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| 212 | |
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| 213 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 214 | |
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| 215 | void |
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| 216 | G4mplIonisationWithDeltaModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp, |
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| 217 | const G4MaterialCutsCouple*, |
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| 218 | const G4DynamicParticle* dp, |
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| 219 | G4double minKinEnergy, |
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| 220 | G4double maxEnergy) |
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| 221 | { |
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| 222 | G4double kineticEnergy = dp->GetKineticEnergy(); |
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| 223 | G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(),kineticEnergy); |
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| 224 | |
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| 225 | G4double maxKinEnergy = std::min(maxEnergy,tmax); |
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| 226 | if(minKinEnergy >= maxKinEnergy) { return; } |
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| 227 | |
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| 228 | //G4cout << "G4mplIonisationWithDeltaModel::SampleSecondaries: E(GeV)= " |
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| 229 | // << kineticEnergy/GeV << " M(GeV)= " << mass/GeV |
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| 230 | // << " tmin(MeV)= " << minKinEnergy/MeV << G4endl; |
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| 231 | |
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| 232 | G4double totEnergy = kineticEnergy + mass; |
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| 233 | G4double etot2 = totEnergy*totEnergy; |
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| 234 | G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2; |
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| 235 | |
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| 236 | // sampling without nuclear size effect |
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| 237 | G4double q = G4UniformRand(); |
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| 238 | G4double deltaKinEnergy = minKinEnergy*maxKinEnergy |
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| 239 | /(minKinEnergy*(1.0 - q) + maxKinEnergy*q); |
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| 240 | |
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| 241 | // delta-electron is produced |
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| 242 | G4double totMomentum = totEnergy*sqrt(beta2); |
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| 243 | G4double deltaMomentum = |
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| 244 | sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2)); |
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| 245 | G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) / |
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| 246 | (deltaMomentum * totMomentum); |
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| 247 | if(cost > 1.0) { cost = 1.0; } |
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| 248 | |
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| 249 | G4double sint = sqrt((1.0 - cost)*(1.0 + cost)); |
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| 250 | |
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| 251 | G4double phi = twopi * G4UniformRand() ; |
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| 252 | |
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| 253 | G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost); |
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| 254 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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| 255 | deltaDirection.rotateUz(direction); |
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| 256 | |
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| 257 | // create G4DynamicParticle object for delta ray |
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| 258 | G4DynamicParticle* delta = |
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| 259 | new G4DynamicParticle(theElectron,deltaDirection,deltaKinEnergy); |
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| 260 | |
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| 261 | vdp->push_back(delta); |
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| 262 | |
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| 263 | // Change kinematics of primary particle |
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| 264 | kineticEnergy -= deltaKinEnergy; |
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| 265 | G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum; |
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| 266 | finalP = finalP.unit(); |
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| 267 | |
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| 268 | fParticleChange->SetProposedKineticEnergy(kineticEnergy); |
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| 269 | fParticleChange->SetProposedMomentumDirection(finalP); |
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| 270 | } |
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| 271 | |
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| 272 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 273 | |
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| 274 | G4double G4mplIonisationWithDeltaModel::SampleFluctuations( |
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| 275 | const G4Material* material, |
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| 276 | const G4DynamicParticle* dp, |
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| 277 | G4double& tmax, |
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| 278 | G4double& length, |
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| 279 | G4double& meanLoss) |
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| 280 | { |
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| 281 | G4double siga = Dispersion(material,dp,tmax,length); |
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| 282 | G4double loss = meanLoss; |
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| 283 | siga = sqrt(siga); |
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| 284 | G4double twomeanLoss = meanLoss + meanLoss; |
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| 285 | |
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| 286 | if(twomeanLoss < siga) { |
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| 287 | G4double x; |
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| 288 | do { |
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| 289 | loss = twomeanLoss*G4UniformRand(); |
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| 290 | x = (loss - meanLoss)/siga; |
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| 291 | } while (1.0 - 0.5*x*x < G4UniformRand()); |
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| 292 | } else { |
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| 293 | do { |
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| 294 | loss = G4RandGauss::shoot(meanLoss,siga); |
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| 295 | } while (0.0 > loss || loss > twomeanLoss); |
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| 296 | } |
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| 297 | return loss; |
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| 298 | } |
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| 299 | |
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| 300 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 301 | |
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| 302 | G4double |
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| 303 | G4mplIonisationWithDeltaModel::Dispersion(const G4Material* material, |
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| 304 | const G4DynamicParticle* dp, |
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| 305 | G4double& tmax, |
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| 306 | G4double& length) |
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| 307 | { |
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| 308 | G4double siga = 0.0; |
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| 309 | G4double tau = dp->GetKineticEnergy()/mass; |
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| 310 | if(tau > 0.0) { |
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| 311 | G4double electronDensity = material->GetElectronDensity(); |
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| 312 | G4double gam = tau + 1.0; |
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| 313 | G4double invbeta2 = (gam*gam)/(tau * (tau+2.0)); |
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| 314 | siga = (invbeta2 - 0.5) * twopi_mc2_rcl2 * tmax * length |
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| 315 | * electronDensity * chargeSquare; |
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| 316 | } |
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| 317 | return siga; |
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| 318 | } |
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| 319 | |
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| 320 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 321 | |
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| 322 | G4double |
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| 323 | G4mplIonisationWithDeltaModel::MaxSecondaryEnergy(const G4ParticleDefinition*, |
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| 324 | G4double kinEnergy) |
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| 325 | { |
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| 326 | G4double tau = kinEnergy/mass; |
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| 327 | return 2.0*electron_mass_c2*tau*(tau + 2.); |
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| 328 | } |
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| 329 | |
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| 330 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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