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geant4/source/processes/electromagnetic/highenergy/src/G4mplIonisationWithDeltaModel.cc
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Gabriele Cosmo 28a70706e0 Import Geant4 10.5.1 source tree
2019-04-17 10:39:02 +02:00

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//
// ********************************************************************
// * License and Disclaimer *
// * *
// * The Geant4 software is copyright of the Copyright Holders of *
// * the Geant4 Collaboration. It is provided under the terms and *
// * conditions of the Geant4 Software License, included in the file *
// * LICENSE and available at http://cern.ch/geant4/license . These *
// * include a list of copyright holders. *
// * *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work make any representation or warranty, express or implied, *
// * regarding this software system or assume any liability for its *
// * use. Please see the license in the file LICENSE and URL above *
// * for the full disclaimer and the limitation of liability. *
// * *
// * This code implementation is the result of the scientific and *
// * technical work of the GEANT4 collaboration. *
// * By using, copying, modifying or distributing the software (or *
// * any work based on the software) you agree to acknowledge its *
// * use in resulting scientific publications, and indicate your *
// * acceptance of all terms of the Geant4 Software license. *
// ********************************************************************
//
//
// -------------------------------------------------------------------
//
// GEANT4 Class header file
//
//
// File name: G4mplIonisationWithDeltaModel
//
// Author: Vladimir Ivanchenko
//
// Creation date: 06.09.2005
//
// Modifications:
// 12.08.2007 Changing low energy approximation and extrapolation.
// Small bug fixing and refactoring (M. Vladymyrov)
// 13.11.2007 Use low-energy asymptotic from [3] (V.Ivanchenko)
//
//
// -------------------------------------------------------------------
// References
// [1] Steven P. Ahlen: Energy loss of relativistic heavy ionizing particles,
// S.P. Ahlen, Rev. Mod. Phys 52(1980), p121
// [2] K.A. Milton arXiv:hep-ex/0602040
// [3] S.P. Ahlen and K. Kinoshita, Phys. Rev. D26 (1982) 2347
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#include "G4mplIonisationWithDeltaModel.hh"
#include "Randomize.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4ParticleChangeForLoss.hh"
#include "G4Electron.hh"
#include "G4DynamicParticle.hh"
#include "G4ProductionCutsTable.hh"
#include "G4MaterialCutsCouple.hh"
#include "G4Log.hh"
#include "G4Pow.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
using namespace std;
std::vector<G4double>* G4mplIonisationWithDeltaModel::dedx0 = nullptr;
G4mplIonisationWithDeltaModel::G4mplIonisationWithDeltaModel(G4double mCharge,
const G4String& nam)
: G4VEmModel(nam),G4VEmFluctuationModel(nam),
magCharge(mCharge),
twoln10(std::log(100.0)),
betalow(0.01),
betalim(0.1),
beta2lim(betalim*betalim),
bg2lim(beta2lim*(1.0 + beta2lim))
{
nmpl = G4lrint(std::abs(magCharge) * 2 * fine_structure_const);
if(nmpl > 6) { nmpl = 6; }
else if(nmpl < 1) { nmpl = 1; }
pi_hbarc2_over_mc2 = pi * hbarc * hbarc / electron_mass_c2;
chargeSquare = magCharge * magCharge;
dedxlim = 45.*nmpl*nmpl*GeV*cm2/g;
fParticleChange = nullptr;
theElectron = G4Electron::Electron();
G4cout << "### Monopole ionisation model with d-electron production, Gmag= "
<< magCharge/eplus << G4endl;
monopole = nullptr;
mass = 0.0;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4mplIonisationWithDeltaModel::~G4mplIonisationWithDeltaModel()
{
if(IsMaster()) { delete dedx0; }
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4mplIonisationWithDeltaModel::SetParticle(const G4ParticleDefinition* p)
{
monopole = p;
mass = monopole->GetPDGMass();
G4double emin =
std::min(LowEnergyLimit(),0.1*mass*(1./sqrt(1. - betalow*betalow) - 1.));
G4double emax =
std::max(HighEnergyLimit(),10*mass*(1./sqrt(1. - beta2lim) - 1.));
SetLowEnergyLimit(emin);
SetHighEnergyLimit(emax);
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void
G4mplIonisationWithDeltaModel::Initialise(const G4ParticleDefinition* p,
const G4DataVector&)
{
if(!monopole) { SetParticle(p); }
if(!fParticleChange) { fParticleChange = GetParticleChangeForLoss(); }
if(IsMaster()) {
if(!dedx0) { dedx0 = new std::vector<G4double>; }
G4ProductionCutsTable* theCoupleTable=
G4ProductionCutsTable::GetProductionCutsTable();
G4int numOfCouples = theCoupleTable->GetTableSize();
G4int n = dedx0->size();
if(n < numOfCouples) { dedx0->resize(numOfCouples); }
G4Pow* g4calc = G4Pow::GetInstance();
// initialise vector
for(G4int i=0; i<numOfCouples; ++i) {
const G4Material* material =
theCoupleTable->GetMaterialCutsCouple(i)->GetMaterial();
G4double eDensity = material->GetElectronDensity();
G4double vF = electron_Compton_length*g4calc->A13(3.*pi*pi*eDensity);
(*dedx0)[i] = pi_hbarc2_over_mc2*eDensity*nmpl*nmpl*
(G4Log(2*vF/fine_structure_const) - 0.5)/vF;
}
}
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double
G4mplIonisationWithDeltaModel::MinEnergyCut(const G4ParticleDefinition*,
const G4MaterialCutsCouple* couple)
{
return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy();
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double
G4mplIonisationWithDeltaModel::ComputeDEDXPerVolume(const G4Material* material,
const G4ParticleDefinition* p,
G4double kineticEnergy,
G4double maxEnergy)
{
if(!monopole) { SetParticle(p); }
G4double tmax = MaxSecondaryEnergy(p,kineticEnergy);
G4double cutEnergy = std::min(tmax, maxEnergy);
cutEnergy = std::max(LowEnergyLimit(), cutEnergy);
G4double tau = kineticEnergy / mass;
G4double gam = tau + 1.0;
G4double bg2 = tau * (tau + 2.0);
G4double beta2 = bg2 / (gam * gam);
G4double beta = sqrt(beta2);
// low-energy asymptotic formula
G4double dedx = (*dedx0)[CurrentCouple()->GetIndex()]*beta;
// above asymptotic
if(beta > betalow) {
// high energy
if(beta >= betalim) {
dedx = ComputeDEDXAhlen(material, bg2, cutEnergy);
} else {
G4double dedx1 = (*dedx0)[CurrentCouple()->GetIndex()]*betalow;
G4double dedx2 = ComputeDEDXAhlen(material, bg2lim, cutEnergy);
// extrapolation between two formula
G4double kapa2 = beta - betalow;
G4double kapa1 = betalim - beta;
dedx = (kapa1*dedx1 + kapa2*dedx2)/(kapa1 + kapa2);
}
}
return dedx;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double
G4mplIonisationWithDeltaModel::ComputeDEDXAhlen(const G4Material* material,
G4double bg2,
G4double cutEnergy)
{
G4double eDensity = material->GetElectronDensity();
G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
// Ahlen's formula for nonconductors, [1]p157, f(5.7)
G4double dedx =
0.5*(G4Log(2.0*electron_mass_c2*bg2*cutEnergy/(eexc*eexc)) -1.0);
// Kazama et al. cross-section correction
G4double k = 0.406;
if(nmpl > 1) { k = 0.346; }
// Bloch correction
const G4double B[7] = { 0.0, 0.248, 0.672, 1.022, 1.243, 1.464, 1.685};
dedx += 0.5 * k - B[nmpl];
// density effect correction
G4double x = G4Log(bg2)/twoln10;
dedx -= material->GetIonisation()->DensityCorrection(x);
// now compute the total ionization loss
dedx *= pi_hbarc2_over_mc2 * eDensity * nmpl * nmpl;
dedx = std::max(dedx, 0.0);
return dedx;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double
G4mplIonisationWithDeltaModel::ComputeCrossSectionPerElectron(
const G4ParticleDefinition* p,
G4double kineticEnergy,
G4double cut,
G4double maxKinEnergy)
{
if(!monopole) { SetParticle(p); }
G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
G4double maxEnergy = std::min(tmax, maxKinEnergy);
G4double cutEnergy = std::max(LowEnergyLimit(), cut);
G4double cross = (cutEnergy < maxEnergy)
? (0.5/cutEnergy - 0.5/maxEnergy)*pi_hbarc2_over_mc2 * nmpl * nmpl : 0.0;
return cross;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double
G4mplIonisationWithDeltaModel::ComputeCrossSectionPerAtom(
const G4ParticleDefinition* p,
G4double kineticEnergy,
G4double Z, G4double,
G4double cutEnergy,
G4double maxEnergy)
{
G4double cross =
Z*ComputeCrossSectionPerElectron(p,kineticEnergy,cutEnergy,maxEnergy);
return cross;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void
G4mplIonisationWithDeltaModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp,
const G4MaterialCutsCouple*,
const G4DynamicParticle* dp,
G4double minKinEnergy,
G4double maxEnergy)
{
G4double kineticEnergy = dp->GetKineticEnergy();
G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(),kineticEnergy);
G4double maxKinEnergy = std::min(maxEnergy,tmax);
if(minKinEnergy >= maxKinEnergy) { return; }
//G4cout << "G4mplIonisationWithDeltaModel::SampleSecondaries: E(GeV)= "
// << kineticEnergy/GeV << " M(GeV)= " << mass/GeV
// << " tmin(MeV)= " << minKinEnergy/MeV << G4endl;
G4double totEnergy = kineticEnergy + mass;
G4double etot2 = totEnergy*totEnergy;
G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2;
// sampling without nuclear size effect
G4double q = G4UniformRand();
G4double deltaKinEnergy = minKinEnergy*maxKinEnergy
/(minKinEnergy*(1.0 - q) + maxKinEnergy*q);
// delta-electron is produced
G4double totMomentum = totEnergy*sqrt(beta2);
G4double deltaMomentum =
sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) /
(deltaMomentum * totMomentum);
cost = std::min(cost, 1.0);
G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
G4double phi = twopi * G4UniformRand() ;
G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost);
G4ThreeVector direction = dp->GetMomentumDirection();
deltaDirection.rotateUz(direction);
// create G4DynamicParticle object for delta ray
G4DynamicParticle* delta =
new G4DynamicParticle(theElectron,deltaDirection,deltaKinEnergy);
vdp->push_back(delta);
// Change kinematics of primary particle
kineticEnergy -= deltaKinEnergy;
G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum;
finalP = finalP.unit();
fParticleChange->SetProposedKineticEnergy(kineticEnergy);
fParticleChange->SetProposedMomentumDirection(finalP);
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4mplIonisationWithDeltaModel::SampleFluctuations(
const G4MaterialCutsCouple* couple,
const G4DynamicParticle* dp,
G4double tmax,
G4double length,
G4double meanLoss)
{
G4double siga = Dispersion(couple->GetMaterial(),dp,tmax,length);
G4double loss = meanLoss;
siga = sqrt(siga);
G4double twomeanLoss = meanLoss + meanLoss;
if(twomeanLoss < siga) {
G4double x;
do {
loss = twomeanLoss*G4UniformRand();
x = (loss - meanLoss)/siga;
// Loop checking, 07-Aug-2015, Vladimir Ivanchenko
} while (1.0 - 0.5*x*x < G4UniformRand());
} else {
do {
loss = G4RandGauss::shoot(meanLoss,siga);
// Loop checking, 07-Aug-2015, Vladimir Ivanchenko
} while (0.0 > loss || loss > twomeanLoss);
}
return loss;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double
G4mplIonisationWithDeltaModel::Dispersion(const G4Material* material,
const G4DynamicParticle* dp,
G4double tmax,
G4double length)
{
G4double siga = 0.0;
G4double tau = dp->GetKineticEnergy()/mass;
if(tau > 0.0) {
G4double electronDensity = material->GetElectronDensity();
G4double gam = tau + 1.0;
G4double invbeta2 = (gam*gam)/(tau * (tau+2.0));
siga = (invbeta2 - 0.5) * twopi_mc2_rcl2 * tmax * length
* electronDensity * chargeSquare;
}
return siga;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double
G4mplIonisationWithDeltaModel::MaxSecondaryEnergy(const G4ParticleDefinition*,
G4double kinEnergy)
{
G4double tau = kinEnergy/mass;
return 2.0*electron_mass_c2*tau*(tau + 2.);
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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