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This commit is contained in:
Gabriele Cosmo
2016-06-09 15:58:43 +02:00
parent 96c8bcd0af
commit b79225fb37
7544 changed files with 245407 additions and 91099 deletions
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source/processes/electromagnetic/lowenergy/src/G4LivermoreGammaConversionModel.cc
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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. *
// ********************************************************************
//
// $Id: G4LivermoreGammaConversionModel.cc,v 1.1 2008/10/30 14:16:35 sincerti Exp $
// GEANT4 tag $Name: geant4-09-02 $
//
#include "G4LivermoreGammaConversionModel.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
using namespace std;
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4LivermoreGammaConversionModel::G4LivermoreGammaConversionModel(const G4ParticleDefinition*,
const G4String& nam)
:G4VEmModel(nam),smallEnergy(2.*MeV),isInitialised(false)
{
lowEnergyLimit = 1.022000 * MeV;
highEnergyLimit = 100 * GeV;
G4cout << "Livermore Gamma conversion is constructed " << G4endl
<< "Energy range: "
<< lowEnergyLimit / keV << " keV - "
<< highEnergyLimit / GeV << " GeV"
<< G4endl;
verboseLevel= 0;
// Verbosity scale:
// 0 = nothing
// 1 = warning for energy non-conservation
// 2 = details of energy budget
// 3 = calculation of cross sections, file openings, sampling of atoms
// 4 = entering in methods
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4LivermoreGammaConversionModel::~G4LivermoreGammaConversionModel()
{
delete meanFreePathTable;
delete crossSectionHandler;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4LivermoreGammaConversionModel::Initialise(const G4ParticleDefinition* particle,
const G4DataVector& cuts)
{
if (verboseLevel > 3)
G4cout << "Calling G4LivermoreGammaConversionModel::Initialise()" << G4endl;
InitialiseElementSelectors(particle,cuts);
// Energy limits
if (LowEnergyLimit() < lowEnergyLimit)
{
G4cout << "G4LivermoreGammaConversionModel: low energy limit increased from " <<
LowEnergyLimit()/eV << " eV to " << lowEnergyLimit << " eV" << G4endl;
SetLowEnergyLimit(lowEnergyLimit);
}
if (HighEnergyLimit() > highEnergyLimit)
{
G4cout << "G4LivermoreGammaConversionModel: high energy limit decreased from " <<
HighEnergyLimit()/GeV << " GeV to " << highEnergyLimit << " GeV" << G4endl;
SetHighEnergyLimit(highEnergyLimit);
}
// Read data tables for all materials
crossSectionHandler = new G4CrossSectionHandler();
crossSectionHandler->Initialise(0,1.0220*MeV,100.*GeV,400);
G4String crossSectionFile = "pair/pp-cs-";
crossSectionHandler->LoadData(crossSectionFile);
meanFreePathTable = 0;
meanFreePathTable = crossSectionHandler->BuildMeanFreePathForMaterials();
//
if (verboseLevel > 2)
G4cout << "Loaded cross section files for PenelopeGammaConversion" << G4endl;
G4cout << "Livermore Gamma Conversion model is initialized " << G4endl
<< "Energy range: "
<< LowEnergyLimit() / MeV << " MeV - "
<< HighEnergyLimit() / GeV << " GeV"
<< G4endl;
if(isInitialised) return;
if(pParticleChange)
fParticleChange = reinterpret_cast<G4ParticleChangeForGamma*>(pParticleChange);
else
fParticleChange = new G4ParticleChangeForGamma();
isInitialised = true;}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4LivermoreGammaConversionModel::ComputeCrossSectionPerAtom(
const G4ParticleDefinition*,
G4double GammaEnergy,
G4double Z, G4double,
G4double, G4double)
{
if (verboseLevel > 3)
G4cout << "Calling ComputeCrossSectionPerAtom() of G4LivermoreGammaConversionModel" << G4endl;
G4double cs = crossSectionHandler->FindValue(G4int(Z), GammaEnergy);
return cs;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4LivermoreGammaConversionModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
const G4MaterialCutsCouple* couple,
const G4DynamicParticle* aDynamicGamma,
G4double,
G4double)
{
// The energies of the e+ e- secondaries are sampled using the Bethe - Heitler
// cross sections with Coulomb correction. A modified version of the random
// number techniques of Butcher & Messel is used (Nuc Phys 20(1960),15).
// Note 1 : Effects due to the breakdown of the Born approximation at low
// energy are ignored.
// Note 2 : The differential cross section implicitly takes account of
// pair creation in both nuclear and atomic electron fields. However triplet
// prodution is not generated.
if (verboseLevel > 3)
G4cout << "Calling SampleSecondaries() of G4LivermoreGammaConversionModel" << G4endl;
G4double photonEnergy = aDynamicGamma->GetKineticEnergy();
G4ParticleMomentum photonDirection = aDynamicGamma->GetMomentumDirection();
G4double epsilon ;
G4double epsilon0 = electron_mass_c2 / photonEnergy ;
// Do it fast if photon energy < 2. MeV
if (photonEnergy < smallEnergy )
{
epsilon = epsilon0 + (0.5 - epsilon0) * G4UniformRand();
}
else
{
// Select randomly one element in the current material
const G4Element* element = crossSectionHandler->SelectRandomElement(couple,photonEnergy);
if (element == 0)
{
G4cout << "G4LivermoreGammaConversionModel::SampleSecondaries - element = 0" << G4endl;
}
G4IonisParamElm* ionisation = element->GetIonisation();
if (ionisation == 0)
{
G4cout << "G4LivermoreGammaConversionModel::SampleSecondaries - ionisation = 0" << G4endl;
}
// Extract Coulomb factor for this Element
G4double fZ = 8. * (ionisation->GetlogZ3());
if (photonEnergy > 50. * MeV) fZ += 8. * (element->GetfCoulomb());
// Limits of the screening variable
G4double screenFactor = 136. * epsilon0 / (element->GetIonisation()->GetZ3()) ;
G4double screenMax = std::exp ((42.24 - fZ)/8.368) - 0.952 ;
G4double screenMin = std::min(4.*screenFactor,screenMax) ;
// Limits of the energy sampling
G4double epsilon1 = 0.5 - 0.5 * std::sqrt(1. - screenMin / screenMax) ;
G4double epsilonMin = std::max(epsilon0,epsilon1);
G4double epsilonRange = 0.5 - epsilonMin ;
// Sample the energy rate of the created electron (or positron)
G4double screen;
G4double gReject ;
G4double f10 = ScreenFunction1(screenMin) - fZ;
G4double f20 = ScreenFunction2(screenMin) - fZ;
G4double normF1 = std::max(f10 * epsilonRange * epsilonRange,0.);
G4double normF2 = std::max(1.5 * f20,0.);
do {
if (normF1 / (normF1 + normF2) > G4UniformRand() )
{
epsilon = 0.5 - epsilonRange * std::pow(G4UniformRand(), 0.3333) ;
screen = screenFactor / (epsilon * (1. - epsilon));
gReject = (ScreenFunction1(screen) - fZ) / f10 ;
}
else
{
epsilon = epsilonMin + epsilonRange * G4UniformRand();
screen = screenFactor / (epsilon * (1 - epsilon));
gReject = (ScreenFunction2(screen) - fZ) / f20 ;
}
} while ( gReject < G4UniformRand() );
} // End of epsilon sampling
// Fix charges randomly
G4double electronTotEnergy;
G4double positronTotEnergy;
if (CLHEP::RandBit::shootBit())
{
electronTotEnergy = (1. - epsilon) * photonEnergy;
positronTotEnergy = epsilon * photonEnergy;
}
else
{
positronTotEnergy = (1. - epsilon) * photonEnergy;
electronTotEnergy = epsilon * photonEnergy;
}
// Scattered electron (positron) angles. ( Z - axis along the parent photon)
// Universal distribution suggested by L. Urban (Geant3 manual (1993) Phys211),
// derived from Tsai distribution (Rev. Mod. Phys. 49, 421 (1977)
G4double u;
const G4double a1 = 0.625;
G4double a2 = 3. * a1;
// G4double d = 27. ;
// if (9. / (9. + d) > G4UniformRand())
if (0.25 > G4UniformRand())
{
u = - std::log(G4UniformRand() * G4UniformRand()) / a1 ;
}
else
{
u = - std::log(G4UniformRand() * G4UniformRand()) / a2 ;
}
G4double thetaEle = u*electron_mass_c2/electronTotEnergy;
G4double thetaPos = u*electron_mass_c2/positronTotEnergy;
G4double phi = twopi * G4UniformRand();
G4double dxEle= std::sin(thetaEle)*std::cos(phi),dyEle= std::sin(thetaEle)*std::sin(phi),dzEle=std::cos(thetaEle);
G4double dxPos=-std::sin(thetaPos)*std::cos(phi),dyPos=-std::sin(thetaPos)*std::sin(phi),dzPos=std::cos(thetaPos);
// Kinematics of the created pair:
// the electron and positron are assumed to have a symetric angular
// distribution with respect to the Z axis along the parent photon
// aParticleChange.SetNumberOfSecondaries(2) ;
G4double electronKineEnergy = std::max(0.,electronTotEnergy - electron_mass_c2) ;
// SI - The range test has been removed wrt original G4LowEnergyGammaconversion class
G4ThreeVector electronDirection (dxEle, dyEle, dzEle);
electronDirection.rotateUz(photonDirection);
G4DynamicParticle* particle1 = new G4DynamicParticle (G4Electron::Electron(),
electronDirection,
electronKineEnergy);
// The e+ is always created (even with kinetic energy = 0) for further annihilation
G4double positronKineEnergy = std::max(0.,positronTotEnergy - electron_mass_c2) ;
// SI - The range test has been removed wrt original G4LowEnergyGammaconversion class
G4ThreeVector positronDirection (dxPos, dyPos, dzPos);
positronDirection.rotateUz(photonDirection);
// Create G4DynamicParticle object for the particle2
G4DynamicParticle* particle2 = new G4DynamicParticle(G4Positron::Positron(),
positronDirection, positronKineEnergy);
// Fill output vector
fvect->push_back(particle1);
fvect->push_back(particle2);
// kill incident photon
fParticleChange->SetProposedKineticEnergy(0.);
fParticleChange->ProposeTrackStatus(fStopAndKill);
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4LivermoreGammaConversionModel::ScreenFunction1(G4double screenVariable)
{
// Compute the value of the screening function 3*phi1 - phi2
G4double value;
if (screenVariable > 1.)
value = 42.24 - 8.368 * std::log(screenVariable + 0.952);
else
value = 42.392 - screenVariable * (7.796 - 1.961 * screenVariable);
return value;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4LivermoreGammaConversionModel::ScreenFunction2(G4double screenVariable)
{
// Compute the value of the screening function 1.5*phi1 - 0.5*phi2
G4double value;
if (screenVariable > 1.)
value = 42.24 - 8.368 * std::log(screenVariable + 0.952);
else
value = 41.405 - screenVariable * (5.828 - 0.8945 * screenVariable);
return value;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4LivermoreGammaConversionModel::GetMeanFreePath(const G4Track& track,
G4double, // previousStepSize
G4ForceCondition*)
{
const G4DynamicParticle* photon = track.GetDynamicParticle();
G4double energy = photon->GetKineticEnergy();
const G4MaterialCutsCouple* couple = track.GetMaterialCutsCouple();
size_t materialIndex = couple->GetIndex();
G4double meanFreePath;
if (energy > highEnergyLimit) meanFreePath = meanFreePathTable->FindValue(highEnergyLimit,materialIndex);
else if (energy < lowEnergyLimit) meanFreePath = DBL_MAX;
else meanFreePath = meanFreePathTable->FindValue(energy,materialIndex);
return meanFreePath;
}