[819] | 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 | // |
---|
[961] | 26 | // $Id: G4mplIonisationModel.cc,v 1.6 2009/02/20 16:38:33 vnivanch Exp $ |
---|
| 27 | // GEANT4 tag $Name: geant4-09-02-ref-02 $ |
---|
[819] | 28 | // |
---|
| 29 | // ------------------------------------------------------------------- |
---|
| 30 | // |
---|
| 31 | // GEANT4 Class header file |
---|
| 32 | // |
---|
| 33 | // |
---|
| 34 | // File name: G4mplIonisationModel |
---|
| 35 | // |
---|
| 36 | // Author: Vladimir Ivanchenko |
---|
| 37 | // |
---|
| 38 | // Creation date: 06.09.2005 |
---|
| 39 | // |
---|
| 40 | // Modifications: |
---|
| 41 | // 12.08.2007 Changing low energy approximation and extrapolation. |
---|
| 42 | // Small bug fixing and refactoring (M. Vladymyrov) |
---|
| 43 | // 13.11.2007 Use low-energy asymptotic from [3] (V.Ivanchenko) |
---|
| 44 | // |
---|
| 45 | // |
---|
| 46 | // ------------------------------------------------------------------- |
---|
| 47 | // References |
---|
| 48 | // [1] Steven P. Ahlen: Energy loss of relativistic heavy ionizing particles, |
---|
| 49 | // S.P. Ahlen, Rev. Mod. Phys 52(1980), p121 |
---|
| 50 | // [2] K.A. Milton arXiv:hep-ex/0602040 |
---|
| 51 | // [3] S.P. Ahlen and K. Kinoshita, Phys. Rev. D26 (1982) 2347 |
---|
| 52 | |
---|
| 53 | |
---|
| 54 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 55 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 56 | |
---|
| 57 | #include "G4mplIonisationModel.hh" |
---|
| 58 | #include "Randomize.hh" |
---|
| 59 | #include "G4LossTableManager.hh" |
---|
| 60 | #include "G4ParticleChangeForLoss.hh" |
---|
| 61 | |
---|
| 62 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 63 | |
---|
| 64 | using namespace std; |
---|
| 65 | |
---|
| 66 | G4mplIonisationModel::G4mplIonisationModel(G4double mCharge, const G4String& nam) |
---|
| 67 | : G4VEmModel(nam),G4VEmFluctuationModel(nam), |
---|
| 68 | magCharge(mCharge), |
---|
| 69 | twoln10(log(100.0)), |
---|
| 70 | betalow(0.01), |
---|
| 71 | betalim(0.1), |
---|
| 72 | beta2lim(betalim*betalim), |
---|
| 73 | bg2lim(beta2lim*(1.0 + beta2lim)) |
---|
| 74 | { |
---|
| 75 | nmpl = G4int(abs(magCharge) * 2 * fine_structure_const + 0.5); |
---|
| 76 | if(nmpl > 6) nmpl = 6; |
---|
| 77 | else if(nmpl < 1) nmpl = 1; |
---|
| 78 | pi_hbarc2_over_mc2 = pi * hbarc * hbarc / electron_mass_c2; |
---|
| 79 | chargeSquare = magCharge * magCharge; |
---|
| 80 | dedxlim = 45.*nmpl*nmpl*GeV*cm2/g; |
---|
| 81 | } |
---|
| 82 | |
---|
| 83 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 84 | |
---|
| 85 | G4mplIonisationModel::~G4mplIonisationModel() |
---|
| 86 | {} |
---|
| 87 | |
---|
| 88 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 89 | |
---|
| 90 | void G4mplIonisationModel::Initialise(const G4ParticleDefinition* p, |
---|
| 91 | const G4DataVector&) |
---|
| 92 | { |
---|
| 93 | monopole = p; |
---|
| 94 | mass = monopole->GetPDGMass(); |
---|
| 95 | |
---|
| 96 | if(pParticleChange) |
---|
| 97 | fParticleChange = reinterpret_cast<G4ParticleChangeForLoss*>(pParticleChange); |
---|
| 98 | else |
---|
| 99 | fParticleChange = new G4ParticleChangeForLoss(); |
---|
| 100 | } |
---|
| 101 | |
---|
| 102 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 103 | |
---|
| 104 | G4double G4mplIonisationModel::ComputeDEDXPerVolume(const G4Material* material, |
---|
| 105 | const G4ParticleDefinition*, |
---|
| 106 | G4double kineticEnergy, |
---|
| 107 | G4double) |
---|
| 108 | { |
---|
| 109 | G4double tau = kineticEnergy / mass; |
---|
| 110 | G4double gam = tau + 1.0; |
---|
| 111 | G4double bg2 = tau * (tau + 2.0); |
---|
| 112 | G4double beta2 = bg2 / (gam * gam); |
---|
| 113 | G4double beta = sqrt(beta2); |
---|
| 114 | |
---|
| 115 | // low-energy asymptotic formula |
---|
| 116 | G4double dedx = dedxlim*beta*material->GetDensity(); |
---|
| 117 | |
---|
| 118 | // above asymptotic |
---|
| 119 | if(beta > betalow) { |
---|
| 120 | |
---|
| 121 | // high energy |
---|
| 122 | if(beta >= betalim) { |
---|
| 123 | dedx = ComputeDEDXAhlen(material, bg2); |
---|
| 124 | |
---|
| 125 | } else { |
---|
| 126 | |
---|
| 127 | G4double dedx1 = dedxlim*betalow*material->GetDensity(); |
---|
| 128 | G4double dedx2 = ComputeDEDXAhlen(material, bg2lim); |
---|
| 129 | |
---|
| 130 | // extrapolation between two formula |
---|
| 131 | G4double kapa2 = beta - betalow; |
---|
| 132 | G4double kapa1 = betalim - beta; |
---|
| 133 | dedx = (kapa1*dedx1 + kapa2*dedx2)/(kapa1 + kapa2); |
---|
| 134 | } |
---|
| 135 | } |
---|
| 136 | return dedx; |
---|
| 137 | } |
---|
| 138 | |
---|
| 139 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 140 | |
---|
[961] | 141 | G4double G4mplIonisationModel::ComputeDEDXAhlen(const G4Material* material, |
---|
| 142 | G4double bg2) |
---|
[819] | 143 | { |
---|
| 144 | G4double eDensity = material->GetElectronDensity(); |
---|
| 145 | G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy(); |
---|
| 146 | G4double cden = material->GetIonisation()->GetCdensity(); |
---|
| 147 | G4double mden = material->GetIonisation()->GetMdensity(); |
---|
| 148 | G4double aden = material->GetIonisation()->GetAdensity(); |
---|
| 149 | G4double x0den = material->GetIonisation()->GetX0density(); |
---|
| 150 | G4double x1den = material->GetIonisation()->GetX1density(); |
---|
| 151 | |
---|
| 152 | // Ahlen's formula for nonconductors, [1]p157, f(5.7) |
---|
| 153 | G4double dedx = log(2.0 * electron_mass_c2 * bg2 / eexc) - 0.5; |
---|
| 154 | |
---|
| 155 | // Kazama et al. cross-section correction |
---|
| 156 | G4double k = 0.406; |
---|
| 157 | if(nmpl > 1) k = 0.346; |
---|
| 158 | |
---|
| 159 | // Bloch correction |
---|
| 160 | const G4double B[7] = { 0.0, 0.248, 0.672, 1.022, 1.243, 1.464, 1.685}; |
---|
| 161 | |
---|
| 162 | dedx += 0.5 * k - B[nmpl]; |
---|
| 163 | |
---|
| 164 | // density effect correction |
---|
| 165 | G4double deltam; |
---|
| 166 | G4double x = log(bg2) / twoln10; |
---|
| 167 | if ( x >= x0den ) { |
---|
| 168 | deltam = twoln10 * x - cden; |
---|
| 169 | if ( x < x1den ) deltam += aden * pow((x1den-x), mden); |
---|
| 170 | dedx -= 0.5 * deltam; |
---|
| 171 | } |
---|
| 172 | |
---|
| 173 | // now compute the total ionization loss |
---|
| 174 | dedx *= pi_hbarc2_over_mc2 * eDensity * nmpl * nmpl; |
---|
| 175 | |
---|
| 176 | if (dedx < 0.0) dedx = 0; |
---|
| 177 | return dedx; |
---|
| 178 | } |
---|
| 179 | |
---|
| 180 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 181 | |
---|
[961] | 182 | void G4mplIonisationModel::SampleSecondaries(std::vector<G4DynamicParticle*>*, |
---|
| 183 | const G4MaterialCutsCouple*, |
---|
| 184 | const G4DynamicParticle*, |
---|
| 185 | G4double, |
---|
| 186 | G4double) |
---|
| 187 | {} |
---|
| 188 | |
---|
| 189 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 190 | |
---|
[819] | 191 | G4double G4mplIonisationModel::SampleFluctuations( |
---|
| 192 | const G4Material* material, |
---|
| 193 | const G4DynamicParticle* dp, |
---|
| 194 | G4double& tmax, |
---|
| 195 | G4double& length, |
---|
| 196 | G4double& meanLoss) |
---|
| 197 | { |
---|
| 198 | G4double siga = Dispersion(material,dp,tmax,length); |
---|
| 199 | G4double loss = meanLoss; |
---|
| 200 | siga = sqrt(siga); |
---|
| 201 | G4double twomeanLoss = meanLoss + meanLoss; |
---|
| 202 | |
---|
| 203 | if(twomeanLoss < siga) { |
---|
| 204 | G4double x; |
---|
| 205 | do { |
---|
| 206 | loss = twomeanLoss*G4UniformRand(); |
---|
| 207 | x = (loss - meanLoss)/siga; |
---|
| 208 | } while (1.0 - 0.5*x*x < G4UniformRand()); |
---|
| 209 | } else { |
---|
| 210 | do { |
---|
| 211 | loss = G4RandGauss::shoot(meanLoss,siga); |
---|
| 212 | } while (0.0 > loss || loss > twomeanLoss); |
---|
| 213 | } |
---|
| 214 | return loss; |
---|
| 215 | } |
---|
[961] | 216 | |
---|
| 217 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 218 | |
---|
| 219 | G4double G4mplIonisationModel::Dispersion(const G4Material* material, |
---|
| 220 | const G4DynamicParticle* dp, |
---|
| 221 | G4double& tmax, |
---|
| 222 | G4double& length) |
---|
| 223 | { |
---|
| 224 | G4double siga = 0.0; |
---|
| 225 | G4double tau = dp->GetKineticEnergy()/mass; |
---|
| 226 | if(tau > 0.0) { |
---|
| 227 | G4double electronDensity = material->GetElectronDensity(); |
---|
| 228 | G4double gam = tau + 1.0; |
---|
| 229 | G4double invbeta2 = (gam*gam)/(tau * (tau+2.0)); |
---|
| 230 | siga = (invbeta2 - 0.5) * twopi_mc2_rcl2 * tmax * length |
---|
| 231 | * electronDensity * chargeSquare; |
---|
| 232 | } |
---|
| 233 | return siga; |
---|
| 234 | } |
---|
| 235 | |
---|
| 236 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|