Gabriele Cosmo
337 lines
13 KiB
C++
337 lines
13 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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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. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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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:
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//
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// 04-12-02 Fix problem of G4DynamicParticle constructor (V.Ivanchenko)
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// 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko)
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// 27-01-03 Make models region aware (V.Ivanchenko)
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// 13-02-03 Add name (V.Ivanchenko)
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// 10-02-04 Calculation of radiative corrections using R.Kokoulin model (V.I)
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// 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko)
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// 12-04-05 Add usage of G4EmCorrections (V.Ivanchenko)
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// 13-02-06 ComputeCrossSectionPerElectron, ComputeCrossSectionPerAtom (mma)
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//
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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 "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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#include "Randomize.hh"
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#include "G4Electron.hh"
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#include "G4LossTableManager.hh"
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#include "G4EmCorrections.hh"
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#include "G4ParticleChangeForLoss.hh"
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#include "G4Log.hh"
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#include "G4Exp.hh"
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G4double G4MuBetheBlochModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083, 0.5917,
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0.7628, 0.8983, 0.9801 };
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G4double G4MuBetheBlochModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813, 0.1813,
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0.1569, 0.1112, 0.0506 };
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4MuBetheBlochModel::G4MuBetheBlochModel(const G4ParticleDefinition* p,
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const G4String& nam)
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: G4VEmModel(nam),
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limitKinEnergy(100.*CLHEP::keV),
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logLimitKinEnergy(G4Log(limitKinEnergy)),
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twoln10(2.0*G4Log(10.0)),
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alphaprime(CLHEP::fine_structure_const/CLHEP::twopi)
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{
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theElectron = G4Electron::Electron();
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corr = G4LossTableManager::Instance()->EmCorrections();
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if(nullptr != p) { SetParticle(p); }
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBetheBlochModel::MinEnergyCut(const G4ParticleDefinition*,
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const G4MaterialCutsCouple* couple)
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{
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return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy();
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
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G4double G4MuBetheBlochModel::MaxSecondaryEnergy(const G4ParticleDefinition*,
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G4double kinEnergy)
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{
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G4double tau = kinEnergy/mass;
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G4double tmax = 2.0*CLHEP::electron_mass_c2*tau*(tau + 2.) /
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(1. + 2.0*(tau + 1.)*ratio + ratio*ratio);
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return tmax;
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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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if(nullptr == particle) {
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particle = p;
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mass = particle->GetPDGMass();
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massSquare = mass*mass;
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ratio = CLHEP::electron_mass_c2/mass;
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4MuBetheBlochModel::Initialise(const G4ParticleDefinition* p,
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const G4DataVector&)
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{
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SetParticle(p);
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if(nullptr == fParticleChange) {
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fParticleChange = GetParticleChangeForLoss();
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBetheBlochModel::ComputeCrossSectionPerElectron(
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const G4ParticleDefinition* p,
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G4double kineticEnergy,
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G4double cutEnergy,
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G4double maxKinEnergy)
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{
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G4double cross = 0.0;
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G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
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G4double maxEnergy = std::min(tmax, maxKinEnergy);
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if(cutEnergy < maxEnergy) {
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G4double totEnergy = kineticEnergy + mass;
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G4double energy2 = totEnergy*totEnergy;
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G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2;
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cross = 1.0/cutEnergy - 1.0/maxEnergy -
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beta2*G4Log(maxEnergy/cutEnergy)/tmax +
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0.5*(maxEnergy - cutEnergy)/energy2;
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// radiative corrections of R. Kokoulin
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if (maxEnergy > limitKinEnergy) {
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G4double logtmax = G4Log(maxEnergy);
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G4double logtmin = G4Log(std::max(cutEnergy,limitKinEnergy));
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G4double logstep = logtmax - logtmin;
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G4double dcross = 0.0;
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for (G4int ll=0; ll<8; ++ll) {
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G4double ep = G4Exp(logtmin + xgi[ll]*logstep);
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G4double a1 = G4Log(1.0 + 2.0*ep/CLHEP::electron_mass_c2);
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G4double a3 = G4Log(4.0*totEnergy*(totEnergy - ep)/massSquare);
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dcross += wgi[ll]*(1.0/ep - beta2/tmax + 0.5*ep/energy2)*a1*(a3 - a1);
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}
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cross += dcross*logstep*alphaprime;
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}
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cross *= CLHEP::twopi_mc2_rcl2/beta2;
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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::ComputeCrossSectionPerAtom(
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const G4ParticleDefinition* p,
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G4double kineticEnergy,
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G4double Z, G4double,
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G4double cutEnergy,
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G4double maxEnergy)
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{
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G4double cross = Z*ComputeCrossSectionPerElectron
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(p,kineticEnergy,cutEnergy,maxEnergy);
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBetheBlochModel::CrossSectionPerVolume(
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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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G4double eDensity = material->GetElectronDensity();
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G4double cross = eDensity*ComputeCrossSectionPerElectron
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(p,kineticEnergy,cutEnergy,maxEnergy);
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBetheBlochModel::ComputeDEDXPerVolume(const G4Material* material,
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const G4ParticleDefinition* p,
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G4double kineticEnergy,
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G4double cut)
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{
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G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
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G4double tau = kineticEnergy/mass;
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G4double cutEnergy = std::min(cut, tmax);
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G4double gam = tau + 1.0;
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G4double bg2 = tau * (tau+2.0);
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G4double beta2 = bg2/(gam*gam);
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G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
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G4double eexc2 = eexc*eexc;
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G4double eDensity = material->GetElectronDensity();
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G4double dedx = G4Log(2.0*CLHEP::electron_mass_c2*bg2*cutEnergy/eexc2)
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-(1.0 + cutEnergy/tmax)*beta2;
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G4double totEnergy = kineticEnergy + mass;
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G4double del = 0.5*cutEnergy/totEnergy;
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dedx += del*del;
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// density correction
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G4double x = G4Log(bg2)/twoln10;
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dedx -= material->GetIonisation()->DensityCorrection(x);
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// shell correction
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dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy);
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dedx = std::max(dedx, 0.0);
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// radiative corrections of R. Kokoulin
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if (cutEnergy > limitKinEnergy) {
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G4double logtmax = G4Log(cutEnergy);
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G4double logstep = logtmax - logLimitKinEnergy;
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G4double dloss = 0.0;
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G4double ftot2= 0.5/(totEnergy*totEnergy);
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for (G4int ll=0; ll<8; ++ll) {
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G4double ep = G4Exp(logLimitKinEnergy + xgi[ll]*logstep);
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G4double a1 = G4Log(1.0 + 2.0*ep/CLHEP::electron_mass_c2);
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G4double a3 = G4Log(4.0*totEnergy*(totEnergy - ep)/massSquare);
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dloss += wgi[ll]*(1.0 - beta2*ep/tmax + ep*ep*ftot2)*a1*(a3 - a1);
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}
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dedx += dloss*logstep*alphaprime;
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}
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dedx *= CLHEP::twopi_mc2_rcl2*eDensity/beta2;
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//High order corrections
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dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy);
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dedx = std::max(dedx, 0.);
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return dedx;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4MuBetheBlochModel::SampleSecondaries(
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std::vector<G4DynamicParticle*>* vdp,
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const G4MaterialCutsCouple*,
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const G4DynamicParticle* dp,
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G4double minKinEnergy,
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G4double maxEnergy)
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{
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G4double kineticEnergy = dp->GetKineticEnergy();
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G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(), kineticEnergy);
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G4double maxKinEnergy = std::min(maxEnergy, tmax);
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if(minKinEnergy >= maxKinEnergy) { return; }
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G4double totEnergy = kineticEnergy + mass;
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G4double etot2 = totEnergy*totEnergy;
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G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
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G4double grej = 1.;
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if(tmax > limitKinEnergy) {
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G4double a0 = G4Log(2.*totEnergy/mass);
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grej += alphaprime*a0*a0;
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}
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G4double tkin, f;
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// sampling follows ...
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do {
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G4double q = G4UniformRand();
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tkin = minKinEnergy*maxKinEnergy/(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
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f = 1.0 - beta2*tkin/tmax + 0.5*tkin*tkin/etot2;
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if(tkin > limitKinEnergy) {
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G4double a1 = G4Log(1.0 + 2.0*tkin/CLHEP::electron_mass_c2);
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G4double a3 = G4Log(4.0*totEnergy*(totEnergy - tkin)/massSquare);
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f *= (1. + alphaprime*a1*(a3 - a1));
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}
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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 edelta= " << tkin
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<< " tmin= " << minKinEnergy << " max= " << maxKinEnergy
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<< G4endl;
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}
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// Loop checking, 03-Aug-2015, Vladimir Ivanchenko
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} while( grej*G4UniformRand() > f );
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G4double deltaMomentum =
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std::sqrt(tkin * (tkin + 2.0*CLHEP::electron_mass_c2));
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G4double totalMomentum = totEnergy*std::sqrt(beta2);
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G4double cost = tkin * (totEnergy + CLHEP::electron_mass_c2) /
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(deltaMomentum * totalMomentum);
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G4double sint = std::sqrt(1.0 - cost*cost);
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G4double phi = CLHEP::twopi * G4UniformRand();
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G4ThreeVector deltaDirection(sint*std::cos(phi), sint*std::sin(phi), cost);
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G4ThreeVector direction = dp->GetMomentumDirection();
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deltaDirection.rotateUz(direction);
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// primary change
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kineticEnergy -= tkin;
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G4ThreeVector dir = totalMomentum*direction - deltaMomentum*deltaDirection;
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direction = dir.unit();
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fParticleChange->SetProposedKineticEnergy(kineticEnergy);
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fParticleChange->SetProposedMomentumDirection(direction);
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// create G4DynamicParticle object for delta ray
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G4DynamicParticle* delta =
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new G4DynamicParticle(theElectron, deltaDirection, tkin);
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vdp->push_back(delta);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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