Gabriele Cosmo
441 lines
15 KiB
C++
441 lines
15 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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// $Id: G4BetheBlochModel.cc,v 1.41 2010/11/12 18:37:47 vnivanch Exp $
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// GEANT4 tag $Name: geant4-09-04 $
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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: G4BetheBlochModel
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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: 03.01.2002
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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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// 24-03-05 Add G4EmCorrections (V.Ivanchenko)
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// 11-04-05 Major optimisation of internal interfaces (V.Ivanchenko)
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// 11-02-06 ComputeCrossSectionPerElectron, ComputeCrossSectionPerAtom (mma)
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// 12-02-06 move G4LossTableManager::Instance()->EmCorrections()
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// in constructor (mma)
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// 12-08-08 Added methods GetParticleCharge, GetChargeSquareRatio,
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// CorrectionsAlongStep needed for ions(V.Ivanchenko)
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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 "G4BetheBlochModel.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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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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using namespace std;
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G4BetheBlochModel::G4BetheBlochModel(const G4ParticleDefinition* p,
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const G4String& nam)
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: G4VEmModel(nam),
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particle(0),
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tlimit(DBL_MAX),
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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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isIon(false),
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isInitialised(false)
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{
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fParticleChange = 0;
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theElectron = G4Electron::Electron();
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if(p) {
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SetGenericIon(p);
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SetParticle(p);
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} else {
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SetParticle(theElectron);
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}
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corr = G4LossTableManager::Instance()->EmCorrections();
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nist = G4NistManager::Instance();
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SetLowEnergyLimit(2.0*MeV);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4BetheBlochModel::~G4BetheBlochModel()
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{}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4BetheBlochModel::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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void G4BetheBlochModel::Initialise(const G4ParticleDefinition* p,
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const G4DataVector&)
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{
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SetGenericIon(p);
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SetParticle(p);
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//G4cout << "G4BetheBlochModel::Initialise for " << p->GetParticleName()
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// << " isIon= " << isIon
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// << G4endl;
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// always false before the run
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SetDeexcitationFlag(false);
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if(!isInitialised) {
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isInitialised = true;
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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 G4BetheBlochModel::GetChargeSquareRatio(const G4ParticleDefinition* p,
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const G4Material* mat,
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G4double kineticEnergy)
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{
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// this method is called only for ions
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G4double q2 = corr->EffectiveChargeSquareRatio(p,mat,kineticEnergy);
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corrFactor = q2*corr->EffectiveChargeCorrection(p,mat,kineticEnergy);
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return corrFactor;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4BetheBlochModel::GetParticleCharge(const G4ParticleDefinition* p,
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const G4Material* mat,
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G4double kineticEnergy)
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{
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// this method is called only for ions, so no check if it is an ion
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return corr->GetParticleCharge(p,mat,kineticEnergy);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4BetheBlochModel::SetupParameters()
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{
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mass = particle->GetPDGMass();
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spin = particle->GetPDGSpin();
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G4double q = particle->GetPDGCharge()/eplus;
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chargeSquare = q*q;
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corrFactor = chargeSquare;
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ratio = electron_mass_c2/mass;
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G4double magmom =
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particle->GetPDGMagneticMoment()*mass/(0.5*eplus*hbar_Planck*c_squared);
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magMoment2 = magmom*magmom - 1.0;
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formfact = 0.0;
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if(particle->GetLeptonNumber() == 0) {
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G4double x = 0.8426*GeV;
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if(spin == 0.0 && mass < GeV) {x = 0.736*GeV;}
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else if(mass > GeV) {
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x /= nist->GetZ13(mass/proton_mass_c2);
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// tlimit = 51.2*GeV*A13[iz]*A13[iz];
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}
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formfact = 2.0*electron_mass_c2/(x*x);
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tlimit = 2.0/formfact;
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double
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G4BetheBlochModel::ComputeCrossSectionPerElectron(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 = 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*log(maxEnergy/cutEnergy)/tmax;
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// +term for spin=1/2 particle
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if( 0.5 == spin ) { cross += 0.5*(maxEnergy - cutEnergy)/energy2; }
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// High order correction different for hadrons and ions
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// nevetheless they are applied to reduce high energy transfers
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// if(!isIon)
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//cross += corr->FiniteSizeCorrectionXS(p,currentMaterial,
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// kineticEnergy,cutEnergy);
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cross *= twopi_mc2_rcl2*chargeSquare/beta2;
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}
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// G4cout << "BB: e= " << kineticEnergy << " tmin= " << cutEnergy
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// << " tmax= " << tmax << " 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 G4BetheBlochModel::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 G4BetheBlochModel::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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currentMaterial = material;
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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 G4BetheBlochModel::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 cutEnergy = std::min(cut,tmax);
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G4double tau = kineticEnergy/mass;
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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 = log(2.0*electron_mass_c2*bg2*cutEnergy/eexc2)
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- (1.0 + cutEnergy/tmax)*beta2;
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if(0.5 == spin) {
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G4double del = 0.5*cutEnergy/(kineticEnergy + mass);
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dedx += del*del;
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}
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// density correction
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G4double x = log(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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// now compute the total ionization loss
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dedx *= twopi_mc2_rcl2*chargeSquare*eDensity/beta2;
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//High order correction different for hadrons and ions
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if(isIon) {
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dedx += corr->IonBarkasCorrection(p,material,kineticEnergy);
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} else {
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dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy);
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}
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if (dedx < 0.0) { dedx = 0.0; }
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return dedx;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4BetheBlochModel::CorrectionsAlongStep(const G4MaterialCutsCouple* couple,
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const G4DynamicParticle* dp,
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G4double& eloss,
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G4double&,
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G4double length)
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{
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if(isIon) {
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const G4ParticleDefinition* p = dp->GetDefinition();
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const G4Material* mat = couple->GetMaterial();
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G4double preKinEnergy = dp->GetKineticEnergy();
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G4double e = preKinEnergy - eloss*0.5;
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if(e < 0.0) e = preKinEnergy*0.5;
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G4double q2 = corr->EffectiveChargeSquareRatio(p,mat,e);
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GetModelOfFluctuations()->SetParticleAndCharge(p, q2);
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G4double qfactor = q2*corr->EffectiveChargeCorrection(p,mat,e)/corrFactor;
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G4double highOrder = length*corr->IonHighOrderCorrections(p,couple,e);
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eloss *= qfactor;
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eloss += highOrder;
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//G4cout << "G4BetheBlochModel::CorrectionsAlongStep: e= " << preKinEnergy
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// << " qfactor= " << qfactor
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// << " highOrder= " << highOrder << " (" << highOrder/eloss << ")" << G4endl;
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4BetheBlochModel::SampleSecondaries(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 deltaKinEnergy, f;
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G4double f1 = 0.0;
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G4double fmax = 1.0;
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if( 0.5 == spin ) fmax += 0.5*maxKinEnergy*maxKinEnergy/etot2;
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// sampling without nuclear size effect
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do {
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G4double q = G4UniformRand();
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deltaKinEnergy = minKinEnergy*maxKinEnergy
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/(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
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f = 1.0 - beta2*deltaKinEnergy/tmax;
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if( 0.5 == spin ) {
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f1 = 0.5*deltaKinEnergy*deltaKinEnergy/etot2;
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f += f1;
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}
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} while( fmax*G4UniformRand() > f);
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// projectile formfactor - suppresion of high energy
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// delta-electron production at high energy
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G4double x = formfact*deltaKinEnergy;
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if(x > 1.e-6) {
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G4double x1 = 1.0 + x;
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G4double g = 1.0/(x1*x1);
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if( 0.5 == spin ) {
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G4double x2 = 0.5*electron_mass_c2*deltaKinEnergy/(mass*mass);
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g *= (1.0 + magMoment2*(x2 - f1/f)/(1.0 + x2));
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}
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if(g > 1.0) {
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G4cout << "### G4BetheBlochModel WARNING: g= " << g
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<< dp->GetDefinition()->GetParticleName()
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<< " Ekin(MeV)= " << kineticEnergy
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<< " delEkin(MeV)= " << deltaKinEnergy
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<< G4endl;
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}
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if(G4UniformRand() > g) return;
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}
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// delta-electron is produced
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G4double totMomentum = totEnergy*sqrt(beta2);
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G4double deltaMomentum =
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sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
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G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
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(deltaMomentum * totMomentum);
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/*
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if(cost > 1.0) {
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G4cout << "### G4BetheBlochModel WARNING: cost= "
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<< cost << " > 1 for "
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<< dp->GetDefinition()->GetParticleName()
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<< " Ekin(MeV)= " << kineticEnergy
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<< " p(MeV/c)= " << totMomentum
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<< " delEkin(MeV)= " << deltaKinEnergy
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<< " delMom(MeV/c)= " << deltaMomentum
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<< " tmin(MeV)= " << minKinEnergy
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<< " tmax(MeV)= " << maxKinEnergy
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<< " dir= " << dp->GetMomentumDirection()
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<< G4endl;
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cost = 1.0;
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}
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*/
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G4double sint = sqrt((1.0 - cost)*(1.0 + 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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G4ThreeVector direction = dp->GetMomentumDirection();
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deltaDirection.rotateUz(direction);
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// create G4DynamicParticle object for delta ray
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G4DynamicParticle* delta = new G4DynamicParticle(theElectron,
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deltaDirection,deltaKinEnergy);
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vdp->push_back(delta);
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// Change kinematics of primary particle
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kineticEnergy -= deltaKinEnergy;
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G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum;
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finalP = finalP.unit();
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fParticleChange->SetProposedKineticEnergy(kineticEnergy);
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fParticleChange->SetProposedMomentumDirection(finalP);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4BetheBlochModel::MaxSecondaryEnergy(const G4ParticleDefinition* pd,
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G4double kinEnergy)
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{
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// here particle type is checked for any method
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SetParticle(pd);
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G4double tau = kinEnergy/mass;
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G4double tmax = 2.0*electron_mass_c2*tau*(tau + 2.) /
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(1. + 2.0*(tau + 1.)*ratio + ratio*ratio);
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return std::min(tmax,tlimit);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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