Import Geant4 5.0.0 source tree
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Gabriele Cosmo
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//
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// ********************************************************************
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// * DISCLAIMER *
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// * *
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// * The following disclaimer summarizes all the specific disclaimers *
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// * of contributors to this software. The specific disclaimers,which *
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// * govern, are listed with their locations in: *
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// * http://cern.ch/geant4/license *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. *
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// * *
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// * This code implementation is the intellectual property of the *
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// * GEANT4 collaboration. *
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// * By copying, distributing or modifying the Program (or any work *
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// * based on the Program) you indicate your acceptance of this *
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// * statement, and all its terms. *
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// ********************************************************************
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//
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//
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// -------------------------------------------------------------------
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//
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// GEANT4 Class header file
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//
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//
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// File name: G4MuBetheBlochModel
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//
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// Author: Vladimir Ivanchenko on base of Laszlo Urban code
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//
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// Creation date: 09.08.2002
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//
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// Modifications: 04.12.2002 VI Fix problem of G4DynamicParticle constructor
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//
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// -------------------------------------------------------------------
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//
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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#include "G4MuBetheBlochModel.hh"
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#include "Randomize.hh"
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#include "G4Electron.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4MuBetheBlochModel::G4MuBetheBlochModel(const G4ParticleDefinition* p)
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: G4VEmModel(),
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particle(0),
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highKinEnergy(100.*TeV),
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lowKinEnergy(2.0*MeV),
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twoln10(2.0*log(10.0)),
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bg2lim(0.0169),
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taulim(8.4146e-3)
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{
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if(p) SetParticle(p);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4MuBetheBlochModel::~G4MuBetheBlochModel()
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{}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4MuBetheBlochModel::SetParticle(const G4ParticleDefinition* p)
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{
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particle = p;
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mass = particle->GetPDGMass();
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G4double q = particle->GetPDGCharge()/eplus;
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chargeSquare = q*q;
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lowKinEnergy *= mass/proton_mass_c2;
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ratio = electron_mass_c2/mass;
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qc = mass/ratio;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4MuBetheBlochModel::HighEnergyLimit(const G4ParticleDefinition* p,
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const G4Material*)
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{
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if(!particle) SetParticle(p);
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return highKinEnergy;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4MuBetheBlochModel::LowEnergyLimit(const G4ParticleDefinition* p,
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const G4Material*)
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{
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if(!particle) SetParticle(p);
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return lowKinEnergy;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4MuBetheBlochModel::MinEnergyCut(const G4ParticleDefinition* p,
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const G4Material* material)
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{
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return material->GetIonisation()->GetMeanExcitationEnergy();
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4bool G4MuBetheBlochModel::IsInCharge(const G4ParticleDefinition* p,
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const G4Material*)
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{
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return (p->GetPDGCharge() != 0.0 && p->GetPDGMass() > 10.*MeV
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&& p->GetPDGSpin() == 0.5);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4MuBetheBlochModel::ComputeDEDX(const G4Material* material,
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const G4ParticleDefinition* p,
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G4double kineticEnergy,
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G4double cutEnergy)
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{
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if(!particle) SetParticle(p);
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G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
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G4double tau = kineticEnergy/mass;
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G4double x = 1.0;
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if(cutEnergy < tmax) x = cutEnergy/tmax;
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G4double gam = tau + 1.0;
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G4double beta2 = 1. - 1./(gam*gam);
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G4double bg2 = tau * (tau+2.0);
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G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
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G4double eexc2 = eexc*eexc;
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G4double taul = material->GetIonisation()->GetTaul();
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G4double cden = material->GetIonisation()->GetCdensity();
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G4double mden = material->GetIonisation()->GetMdensity();
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G4double aden = material->GetIonisation()->GetAdensity();
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G4double x0den = material->GetIonisation()->GetX0density();
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G4double x1den = material->GetIonisation()->GetX1density();
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G4double* shellCorrectionVector =
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material->GetIonisation()->GetShellCorrectionVector();
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G4double eDensity = material->GetElectronDensity();
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G4double dedx = log(2.0*electron_mass_c2*bg2*tmax*x/eexc2)-(1.0 + x)*beta2;
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G4double totEnergy = kineticEnergy + mass;
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G4double del = 0.5*x*tmax/totEnergy;
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dedx += del*del;
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// density correction
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x = log(bg2)/twoln10;
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if ( x >= x0den ) {
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dedx -= twoln10*x - cden ;
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if ( x < x1den ) dedx -= aden*pow((x1den-x),mden) ;
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}
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// shell correction
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G4double sh = 0.0;
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x = 1.0;
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if ( bg2 > bg2lim ) {
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for (G4int k=0; k<3; k++) {
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x *= bg2 ;
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sh += shellCorrectionVector[k]/x;
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}
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} else {
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for (G4int k=0; k<3; k++) {
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x *= bg2lim ;
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sh += shellCorrectionVector[k]/x;
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}
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sh *= log(tau/taul)/log(taulim/taul);
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}
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dedx -= sh;
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// now compute the total ionization loss
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if (dedx < 0.0) dedx = 0.0 ;
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// correction of R. Kokoulin // has been taken out ***************
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// G4double apar = log(2.*(tmax/electron_mass_c2 + 1.0));
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// dedx += fine_structure_const*(log(2.*totEnergy/mass)-apar/3.)*apar*apar/twopi;
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dedx *= twopi_mc2_rcl2*chargeSquare*eDensity/beta2;
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return dedx;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4MuBetheBlochModel::CrossSection(const G4Material* material,
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const G4ParticleDefinition* p,
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G4double kineticEnergy,
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G4double cutEnergy,
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G4double maxEnergy)
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{
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if(!particle) SetParticle(p);
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G4double cross = 0.0;
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G4double tmaxSecondary = MaxSecondaryEnergy(p, kineticEnergy);
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G4double tmax = G4std::min(tmaxSecondary, maxEnergy);
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if(cutEnergy < tmax) {
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const G4ElementVector* theElementVector = material->GetElementVector();
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const G4double* NbOfAtomsPerVolume = material->GetVecNbOfAtomsPerVolume();
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G4int NumberOfElements = material->GetNumberOfElements();
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for (G4int iel=0; iel<NumberOfElements; iel++ ) {
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cross += NbOfAtomsPerVolume[iel]* CrossSectionPerAtom(
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(*theElementVector)[iel]->GetZ(),
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kineticEnergy, cutEnergy, tmax, tmaxSecondary);
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}
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}
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// G4cout << "tmin= " << cutEnergy << " tmax= " << tmax
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// << " cross= " << cross << G4endl;
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBetheBlochModel::CrossSectionPerAtom(
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G4double Z,
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G4double kineticEnergy,
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G4double tmin,
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G4double tmax,
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G4double tmaxSecondary)
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{
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G4double cross = 0.;
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const G4double xgi[] = {0.06943,0.33001,0.66999,0.93057};
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const G4double wgi[] = {0.17393,0.32607,0.32607,0.17393};
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const G4double ak1 = 4.6;
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const G4int k2 = 2;
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G4double aaa = log(tmin);
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G4double bbb = log(tmax);
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G4int kkk = int((bbb-aaa)/ak1)+k2;
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G4double hhh = (bbb-aaa)/(float)kkk;
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G4double step = exp(hhh);
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G4double ymax = 1./tmax;
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for (G4int k=0; k<kkk; k++) {
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G4double ymin = ymax;
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ymax = ymin*step;
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G4double hhy = ymax-ymin;
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for (G4int i=0; i<4; i++) {
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G4double y = ymin+hhy*xgi[i];
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G4double ep = 1./y ;
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cross += ep*ep*wgi[i]*hhy*DifCrossSectionPerAtom(kineticEnergy, ep, tmaxSecondary);
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}
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}
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cross *= twopi_mc2_rcl2*Z*chargeSquare;
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBetheBlochModel::DifCrossSectionPerAtom(G4double kineticEnergy,
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G4double knockonEnergy,
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G4double tmaxSecondary)
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// Calculates the differential cross section per atom
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// using the cross section formula of R.P. Kokoulin (10/98)
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{
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const G4double alphaprime = fine_structure_const/twopi;
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G4double totalEnergy = kineticEnergy + mass;
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G4double gam = totalEnergy/mass;
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G4double beta2 = 1. - 1./(gam*gam);
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G4double v = knockonEnergy/totalEnergy;
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G4double cross = (1.-beta2*knockonEnergy/tmaxSecondary + 0.5*v*v)/
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(beta2*knockonEnergy*knockonEnergy);
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G4double a1 = log(1.+2.*knockonEnergy/electron_mass_c2);
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G4double a3 = log(4.*totalEnergy*(totalEnergy-knockonEnergy)/(mass*mass));
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cross *= (1.+alphaprime*a1*(a3-a1));
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4std::vector<G4DynamicParticle*>* G4MuBetheBlochModel::SampleSecondary(
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const G4Material* material,
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const G4DynamicParticle* dp,
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G4double tmin,
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G4double maxEnergy)
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{
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G4double tmax = MaxSecondaryEnergy(dp);
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G4double xmin = tmin/tmax;
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G4double xmax = G4std::min(tmax, maxEnergy)/tmax;
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if(xmin >= xmax) return 0;
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G4ThreeVector momentum = dp->GetMomentumDirection();
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G4double kineticEnergy = dp->GetKineticEnergy();
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G4double totEnergy = kineticEnergy + mass;
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G4double beta2 = 1. - mass*mass/(totEnergy*totEnergy);
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G4double x = 0.5*tmax*tmax/(totEnergy*totEnergy);
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const G4double alphaprime = fine_structure_const/twopi;
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G4double a0=log(2.*totEnergy/mass);
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G4double grej = (1.0 - beta2*xmin + xmax*xmax*x)*(1. + alphaprime*a0*a0);
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G4double z, f, a1, twoep;
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// sampling follows ...
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do {
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G4double q = G4UniformRand();
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z = xmin*xmax/(xmin*(1.0 - q) + xmax*q);
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twoep = 2.0*z*tmax;
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a1= log(1.0 + twoep/electron_mass_c2);
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f = (1.0 - beta2 * z + z*z*x)
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* (1. + alphaprime*a1*(a0 + log((2.0*totEnergy-twoep)/mass) - a1));
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if(f > grej) {
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G4cout << "G4MuBetheBlochModel::SampleSecondary Warning! "
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<< "Majorant " << grej << " < "
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<< f << " for x= " << z
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<< G4endl;
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}
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} while( grej*G4UniformRand() >= f );
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G4double deltaKinEnergy = z * tmax;
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G4double deltaMomentum =
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sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
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G4double totMomentum = sqrt(totEnergy*totEnergy - mass*mass);
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G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
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(deltaMomentum * totMomentum);
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G4double sint = sqrt(1.0 - cost*cost);
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G4double phi = twopi * G4UniformRand() ;
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G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost) ;
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deltaDirection.rotateUz(momentum);
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// create G4DynamicParticle object for delta ray
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G4DynamicParticle* delta = new G4DynamicParticle();
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delta->SetDefinition(G4Electron::Electron());
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delta->SetKineticEnergy(deltaKinEnergy);
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delta->SetMomentumDirection(deltaDirection);
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G4std::vector<G4DynamicParticle*>* vdp = new G4std::vector<G4DynamicParticle*>;
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vdp->push_back(delta);
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return vdp;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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