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geant4/source/processes/electromagnetic/standard/src/G4eplusTo3GammaOKVIModel.cc
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Gabriele Cosmo e58e650b32 Import Geant4 11.3.0.beta source tree
2024-06-28 13:08:51 +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 file
//
//
// File name: G4eplusTo3GammaOKVIModel
//
// Authors: Andrei Alkin, Vladimir Ivanchenko, Omrame Kadri
//
// Creation date: 29.03.2018
//
// -------------------------------------------------------------------
//
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
#include "G4eplusTo3GammaOKVIModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4EmParameters.hh"
#include "G4TrackStatus.hh"
#include "G4Electron.hh"
#include "G4Positron.hh"
#include "G4Gamma.hh"
#include "Randomize.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4Log.hh"
#include "G4Exp.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
using namespace std;
G4eplusTo3GammaOKVIModel::G4eplusTo3GammaOKVIModel(const G4ParticleDefinition*,
const G4String& nam)
: G4VEmModel(nam), fDelta(0.001)
{
theGamma = G4Gamma::Gamma();
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4eplusTo3GammaOKVIModel::~G4eplusTo3GammaOKVIModel() = default;
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4eplusTo3GammaOKVIModel::Initialise(const G4ParticleDefinition*,
const G4DataVector&)
{}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
// (A.A.) F_{ijk} calculation method
G4double G4eplusTo3GammaOKVIModel::ComputeF(G4double fr1, G4double fr2,
G4double fr3, G4double kinEnergy)
{
G4double ekin = std::max(eV,kinEnergy);
G4double tau = ekin/electron_mass_c2;
G4double gam = tau + 1.0;
G4double gamma2 = gam*gam;
G4double bg2 = tau * (tau+2.0);
G4double bg = sqrt(bg2);
G4double rho = (gamma2+4.*gam+1.)*G4Log(gam+bg)/(gamma2-1.)
- (gam+3.)/(sqrt(gam*gam - 1.)) + 1.;
G4double border;
if(ekin < 500*MeV) {
border = 1. - (electron_mass_c2)/(2*(ekin + electron_mass_c2));
} else {
border = 1. - (100*electron_mass_c2)/(2*(ekin + electron_mass_c2));
}
border = std::min(border, 0.9999);
if (fr1>border) { fr1 = border; }
if (fr2>border) { fr2 = border; }
if (fr3>border) { fr3 = border; }
G4double fr1s = fr1*fr1; // "s" for "squared"
G4double fr2s = fr2*fr2;
G4double fr3s = fr3*fr3;
G4double aa = (1.-fr1)*(1.-fr2);
G4double ab = fr3s + (fr1-fr2)*(fr1-fr2);
G4double add= ((1.-fr1)*(1.-fr1) + (1.-fr2)*(1.-fr2))/(fr3s*aa);
G4double fres = -rho*(1./fr1s + 1./fr2s)
+ (ab/(2.*(fr1*fr2*aa)))*(G4Log(2.*gam*aa/(fr1*fr2)))
+ (ab/(2.*fr1*fr2*(1-fr3)))*G4Log(2.*gam*(1.-fr3)/(fr1*fr2)) - add;
return fres;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
// (A.A.) F_{ijk} calculation method
G4double G4eplusTo3GammaOKVIModel::ComputeF0(G4double fr1, G4double fr2,
G4double fr3)
{
G4double tau = 0.0;
G4double gam = tau + 1.0;
G4double gamma2 = gam*gam;
G4double bg2 = tau * (tau+2.0);
G4double bg = sqrt(bg2);
G4double rho = (gamma2+4.*gam+1.)*G4Log(gam+bg)/(gamma2-1.)
- (gam+3.)/(sqrt(gam*gam - 1.)) + 1.;
G4double border = 0.5;
if (fr1>border) { fr1 = border; }
if (fr2>border) { fr2 = border; }
if (fr3>border) { fr3 = border; }
G4double fr1s = fr1*fr1; // "s" for "squared"
G4double fr2s = fr2*fr2;
G4double fr3s = fr3*fr3;
G4double aa = (1.-fr1)*(1.-fr2);
G4double ab = fr3s + (fr1-fr2)*(fr1-fr2);
G4double add= ((1.-fr1)*(1.-fr1) + (1.-fr2)*(1.-fr2))/(fr3s*aa);
G4double fres = -rho*(1./fr1s + 1./fr2s)
+ (ab/(2.*(fr1*fr2*aa)))*(G4Log(2.*gam*aa/(fr1*fr2)))
+ (ab/(2.*fr1*fr2*(1-fr3)))*G4Log(2.*gam*(1.-fr3)/(fr1*fr2)) - add;
return fres;
}
//(A.A.) diff x-sections for maximum search and rejection
G4double G4eplusTo3GammaOKVIModel::ComputeFS(G4double fr1,
G4double fr2, G4double fr3, G4double kinEnergy)
{
G4double ekin = std::max(eV,kinEnergy);
G4double tau = ekin/electron_mass_c2;
G4double gam = tau + 1.0;
G4double fsum = fr1*fr1*(ComputeF(fr1,fr2,fr3,ekin) +
ComputeF(fr3,fr1,fr2,ekin) +
ComputeF(fr2,fr3,fr1,ekin));
G4double dcross = fsum/((3*fr1*fr1*(gam+1.)));
return dcross;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double
G4eplusTo3GammaOKVIModel::ComputeCrossSectionPerElectron(G4double kinEnergy)
{
// Calculates the cross section per electron of annihilation into 3 photons
// from the Heilter formula.
G4double ekin = std::max(CLHEP::eV, kinEnergy);
G4double tau = ekin/CLHEP::electron_mass_c2;
G4double gam = tau + 1.0;
G4double gamma2 = gam*gam;
G4double bg2 = tau * (tau+2.0);
G4double bg = sqrt(bg2);
G4double rho = (gamma2+4*gam+1.)*G4Log(gam+bg)/(gamma2-1.)
- (gam+3.)/(sqrt(gam*gam - 1.));
G4double cross = alpha_rcl2*(4.2 - (2.*G4Log(fDelta)+1.)*rho*rho)/(gam+1.);
return cross;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double G4eplusTo3GammaOKVIModel::ComputeCrossSectionPerAtom(
const G4ParticleDefinition*,
G4double kineticEnergy, G4double Z,
G4double, G4double, G4double)
{
G4double cross = Z*ComputeCrossSectionPerElectron(kineticEnergy);
return cross;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double G4eplusTo3GammaOKVIModel::CrossSectionPerVolume(
const G4Material* material,
const G4ParticleDefinition*,
G4double kineticEnergy,
G4double, G4double)
{
// Calculates the cross section per volume of annihilation into two photons
G4double eDensity = material->GetElectronDensity();
G4double cross = eDensity*ComputeCrossSectionPerElectron(kineticEnergy);
return cross;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
// Polarisation of gamma according to M.H.L.Pryce and J.C.Ward,
// Nature 4065 (1947) 435.
void
G4eplusTo3GammaOKVIModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp,
const G4MaterialCutsCouple*,
const G4DynamicParticle* dp,
G4double, G4double)
{
// let us perform sampling in C.M.S. reference frame of e- at rest and e+ on fly
G4double posiKinEnergy = dp->GetKineticEnergy();
G4LorentzVector lv(dp->GetMomentum(),
posiKinEnergy + 2*CLHEP::electron_mass_c2);
G4double eGammaCMS = 0.5 * lv.mag();
// the limit value fDelta is defined by a class, which call this method
// thickness of border defined by C.M.S. energy
G4double border =
1.0 - std::min(std::max(CLHEP::electron_mass_c2/eGammaCMS, fDelta), 0.1);
CLHEP::HepRandomEngine* rndmEngine = G4Random::getTheEngine();
G4ThreeVector posiDirection = dp->GetMomentumDirection();
// (A.A.) LIMITS FOR 1st GAMMA
G4double xmin = 0.01;
G4double xmax = 0.667; // CHANGE to 3/2
G4double d1, d0, x1, x2, dmax, x2min;
// (A.A.) sampling of x1 x2 x3 (whole cycle of rejection)
do {
x1 = 1./((1./xmin) - ((1./xmin)-(1./xmax))*rndmEngine->flat());
dmax = ComputeFS(eGammaCMS, x1, 1.-x1, border);
x2min = 1. - x1;
x2 = 1 - rndmEngine->flat()*(1. - x2min);
d1 = dmax*rndmEngine->flat();
d0 = ComputeFS(eGammaCMS, x1, x2, 2.-x1-x2);
}
while(d0 < d1);
G4double x3 = 2 - x1 - x2;
//
// angles between Gammas
//
G4double psi13 = 2*std::asin(std::sqrt(std::abs((x1+x3-1.)/(x1*x3))));
G4double psi12 = 2*std::asin(std::sqrt(std::abs((x1+x2-1.)/(x1*x2))));
//
// kinematic of the created pair
//
G4double phot1Energy = x1*eGammaCMS;
G4double phot2Energy = x2*eGammaCMS;
G4double phot3Energy = x3*eGammaCMS;
// DIRECTIONS
// The azimuthal angles of q1 and q3 with respect to some plane
// through the beam axis are generated at random.
G4ThreeVector phot1Direction(0, 0, 1);
G4ThreeVector phot2Direction(0, std::sin(psi12), std::cos(psi12));
G4ThreeVector phot3Direction(0, std::sin(psi13), std::cos(psi13));
G4LorentzVector lv1(phot1Energy*phot1Direction, phot1Energy);
G4LorentzVector lv2(phot2Energy*phot2Direction, phot2Energy);
G4LorentzVector lv3(phot3Energy*phot3Direction, phot3Energy);
auto boostV = lv.boostVector();
lv1.boost(boostV);
lv2.boost(boostV);
lv3.boost(boostV);
auto aGamma1 = new G4DynamicParticle (theGamma, lv1.vect());
auto aGamma2 = new G4DynamicParticle (theGamma, lv2.vect());
auto aGamma3 = new G4DynamicParticle (theGamma, lv3.vect());
//!!! POLARIZATION - not yet implemented
vdp->push_back(aGamma1);
vdp->push_back(aGamma2);
vdp->push_back(aGamma3);
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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