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db49709b532cdbe4a21775b0b28ce7fdf435e735
geant4/source/processes/electromagnetic/polarisation/src/G4PolarizedAnnihilationModel.cc
T
Gabriele Cosmo db49709b53 Import Geant4 10.5.0 source tree
2018-12-07 15:15:39 +01:00

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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: G4PolarizedAnnihilationModel
//
// Author: Andreas Schaelicke
//
// Creation date: 01.05.2005
//
// Modifications:
// 18-07-06 use newly calculated cross sections (P. Starovoitov)
// 21-08-06 update interface (A. Schaelicke)
// 17-11-06 add protection agaist e+ zero energy PostStep (V.Ivanchenko)
// 10-07-07 copied Initialise() method from G4eeToTwoGammaModel to provide a
// local ParticleChangeForGamma object and reduce overhead
// in SampleSecondaries() (A. Schaelicke)
//
//
// Class Description:
//
// Implementation of polarized gamma Annihilation scattering on free electron
//
// -------------------------------------------------------------------
#include "G4PolarizedAnnihilationModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4PolarizationManager.hh"
#include "G4PolarizationHelper.hh"
#include "G4StokesVector.hh"
#include "G4PolarizedAnnihilationCrossSection.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4TrackStatus.hh"
#include "G4Gamma.hh"
G4PolarizedAnnihilationModel::G4PolarizedAnnihilationModel(const G4ParticleDefinition* p,
const G4String& nam)
: G4eeToTwoGammaModel(p,nam),
crossSectionCalculator(nullptr),
verboseLevel(0),
gParticleChange(nullptr)
{
crossSectionCalculator = new G4PolarizedAnnihilationCrossSection();
}
G4PolarizedAnnihilationModel::~G4PolarizedAnnihilationModel()
{
delete crossSectionCalculator;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4PolarizedAnnihilationModel::Initialise(const G4ParticleDefinition* part,
const G4DataVector& dv)
{
G4eeToTwoGammaModel::Initialise(part, dv);
if(gParticleChange) { return; }
gParticleChange = GetParticleChangeForGamma();
}
G4double
G4PolarizedAnnihilationModel::ComputeCrossSectionPerElectron(G4double kinEnergy)
{
// cross section from base model
G4double xs = G4eeToTwoGammaModel::ComputeCrossSectionPerElectron(kinEnergy);
G4double polzz = theBeamPolarization.z()*theTargetPolarization.z();
G4double poltt = theBeamPolarization.x()*theTargetPolarization.x()
+ theBeamPolarization.y()*theTargetPolarization.y();
if (polzz!=0 || poltt!=0) {
G4double xval,lasym,tasym;
ComputeAsymmetriesPerElectron(kinEnergy,xval,lasym,tasym);
xs*=(1.+polzz*lasym+poltt*tasym);
}
return xs;
}
void G4PolarizedAnnihilationModel::ComputeAsymmetriesPerElectron(G4double ene,
G4double & valueX,
G4double & valueA,
G4double & valueT)
{
// *** calculate asymmetries
G4double gam = 1. + ene/electron_mass_c2;
G4double xs0=crossSectionCalculator->TotalXSection(0.,1.,gam,
G4StokesVector::ZERO,
G4StokesVector::ZERO);
G4double xsA=crossSectionCalculator->TotalXSection(0.,1.,gam,
G4StokesVector::P3,
G4StokesVector::P3);
G4double xsT1=crossSectionCalculator->TotalXSection(0.,1.,gam,
G4StokesVector::P1,
G4StokesVector::P1);
G4double xsT2=crossSectionCalculator->TotalXSection(0.,1.,gam,
G4StokesVector::P2,
G4StokesVector::P2);
G4double xsT=0.5*(xsT1+xsT2);
valueX=xs0;
valueA=xsA/xs0-1.;
valueT=xsT/xs0-1.;
// G4cout<<valueX<<"\t"<<valueA<<"\t"<<valueT<<" energy = "<<gam<<G4endl;
if ( (valueA < -1) || (1 < valueA)) {
G4cout<< " ERROR PolarizedAnnihilationPS::ComputeAsymmetries \n";
G4cout<< " something wrong in total cross section calculation (valueA)\n";
G4cout<< " LONG: "<<valueX<<"\t"<<valueA<<"\t"<<valueT<<" energy = "<<gam<<G4endl;
}
if ( (valueT < -1) || (1 < valueT)) {
G4cout<< " ERROR PolarizedAnnihilationPS::ComputeAsymmetries \n";
G4cout<< " something wrong in total cross section calculation (valueT)\n";
G4cout<< " TRAN: "<<valueX<<"\t"<<valueA<<"\t"<<valueT<<" energy = "<<gam<<G4endl;
}
}
void G4PolarizedAnnihilationModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
const G4MaterialCutsCouple*,
const G4DynamicParticle* dp,
G4double, G4double)
{
const G4Track * aTrack = gParticleChange->GetCurrentTrack();
// kill primary
gParticleChange->SetProposedKineticEnergy(0.);
gParticleChange->ProposeTrackStatus(fStopAndKill);
// V.Ivanchenko add protection against zero kin energy
G4double PositKinEnergy = dp->GetKineticEnergy();
if(PositKinEnergy == 0.0) {
G4double cosTeta = 2.*G4UniformRand()-1.;
G4double sinTeta = std::sqrt((1.0 - cosTeta)*(1.0 + cosTeta));
G4double phi = twopi * G4UniformRand();
G4ThreeVector dir(sinTeta*std::cos(phi), sinTeta*std::sin(phi), cosTeta);
fvect->push_back( new G4DynamicParticle(G4Gamma::Gamma(), dir, electron_mass_c2));
fvect->push_back( new G4DynamicParticle(G4Gamma::Gamma(),-dir, electron_mass_c2));
return;
}
// *** obtain and save target and beam polarization ***
G4PolarizationManager * polarizationManager = G4PolarizationManager::GetInstance();
// obtain polarization of the beam
theBeamPolarization = aTrack->GetPolarization();
// obtain polarization of the media
G4VPhysicalVolume* aPVolume = aTrack->GetVolume();
G4LogicalVolume* aLVolume = aPVolume->GetLogicalVolume();
const G4bool targetIsPolarized = polarizationManager->IsPolarized(aLVolume);
theTargetPolarization = polarizationManager->GetVolumePolarization(aLVolume);
if (verboseLevel >= 1) {
G4cout << "G4PolarizedComptonModel::SampleSecondaries in "
<< aLVolume->GetName() << G4endl;
}
// transfer target electron polarization in frame of positron
if (targetIsPolarized)
theTargetPolarization.rotateUz(dp->GetMomentumDirection());
G4ParticleMomentum PositDirection = dp->GetMomentumDirection();
// polar asymmetry:
G4double polarization = theBeamPolarization.p3()*theTargetPolarization.p3();
G4double gamam1 = PositKinEnergy/electron_mass_c2;
G4double gama = gamam1+1. , gamap1 = gamam1+2.;
G4double sqgrate = std::sqrt(gamam1/gamap1)/2. , sqg2m1 = std::sqrt(gamam1*gamap1);
// limits of the energy sampling
G4double epsilmin = 0.5 - sqgrate , epsilmax = 0.5 + sqgrate;
G4double epsilqot = epsilmax/epsilmin;
//
// sample the energy rate of the created gammas
// note: for polarized partices, the actual dicing strategy
// will depend on the energy, and the degree of polarization !!
//
G4double epsil;
G4double gmax=1. + std::fabs(polarization); // crude estimate
//G4bool check_range=true;
crossSectionCalculator->Initialize(epsilmin, gama, 0., theBeamPolarization, theTargetPolarization);
if (crossSectionCalculator->DiceEpsilon()<0) {
G4cout<<"ERROR in PolarizedAnnihilationPS::PostStepDoIt\n"
<<"epsilmin DiceRoutine not appropriate ! "<<crossSectionCalculator->DiceEpsilon()<<G4endl;
//check_range=false;
}
crossSectionCalculator->Initialize(epsilmax, gama, 0., theBeamPolarization, theTargetPolarization);
if (crossSectionCalculator->DiceEpsilon()<0) {
G4cout<<"ERROR in PolarizedAnnihilationPS::PostStepDoIt\n"
<<"epsilmax DiceRoutine not appropriate ! "<<crossSectionCalculator->DiceEpsilon()<<G4endl;
//check_range=false;
}
G4int ncount=0;
G4double trejectmax=0.;
G4double treject;
do {
//
epsil = epsilmin*std::pow(epsilqot,G4UniformRand());
crossSectionCalculator->Initialize(epsil, gama, 0., theBeamPolarization, theTargetPolarization,1);
treject = crossSectionCalculator->DiceEpsilon();
treject*=epsil;
if (treject>gmax || treject<0.)
G4cout<<"ERROR in PolarizedAnnihilationPS::PostStepDoIt\n"
<<" eps ("<<epsil<<") rejection does not work properly: "<<treject<<G4endl;
++ncount;
if (treject>trejectmax) trejectmax=treject;
if (ncount>1000) {
G4cout<<"WARNING in PolarizedAnnihilationPS::PostStepDoIt\n"
<<"eps dicing very inefficient ="<<trejectmax/gmax
<<", "<<treject/gmax<<". For secondary energy = "<<epsil<<" "<<ncount<<G4endl;
break;
}
// Loop checking, 03-Aug-2015, Vladimir Ivanchenko
} while( treject < gmax*G4UniformRand() );
//
// scattered Gamma angles. ( Z - axis along the parent positron)
//
G4double cost = (epsil*gamap1-1.)/(epsil*sqg2m1);
G4double sint = std::sqrt((1.+cost)*(1.-cost));
G4double phi = 0.;
G4double beamTrans = std::sqrt(sqr(theBeamPolarization.p1()) + sqr(theBeamPolarization.p2()));
G4double targetTrans = std::sqrt(sqr(theTargetPolarization.p1()) + sqr(theTargetPolarization.p2()));
// G4cout<<"phi dicing START"<<G4endl;
do{
phi = twopi * G4UniformRand();
crossSectionCalculator->Initialize(epsil, gama, 0., theBeamPolarization, theTargetPolarization,2);
G4double gdiced =crossSectionCalculator->getVar(0);
gdiced += crossSectionCalculator->getVar(3)*theBeamPolarization.p3()*theTargetPolarization.p3();
gdiced += 1.*(std::fabs(crossSectionCalculator->getVar(1))
+ std::fabs(crossSectionCalculator->getVar(2)))*beamTrans*targetTrans;
gdiced += 1.*std::fabs(crossSectionCalculator->getVar(4))
*(std::fabs(theBeamPolarization.p3())*targetTrans + std::fabs(theTargetPolarization.p3())*beamTrans);
G4double gdist = crossSectionCalculator->getVar(0);
gdist += crossSectionCalculator->getVar(3)*theBeamPolarization.p3()*theTargetPolarization.p3();
gdist += crossSectionCalculator->getVar(1)*(std::cos(phi)*theBeamPolarization.p1()
+ std::sin(phi)*theBeamPolarization.p2())
*(std::cos(phi)*theTargetPolarization.p1()
+ std::sin(phi)*theTargetPolarization.p2());
gdist += crossSectionCalculator->getVar(2)*(std::cos(phi)*theBeamPolarization.p2()
- std::sin(phi)*theBeamPolarization.p1())
*(std::cos(phi)*theTargetPolarization.p2()
- std::sin(phi)*theTargetPolarization.p1());
gdist += crossSectionCalculator->getVar(4)
*(std::cos(phi)*theBeamPolarization.p3()*theTargetPolarization.p1()
+ std::cos(phi)*theBeamPolarization.p1()*theTargetPolarization.p3()
+ std::sin(phi)*theBeamPolarization.p3()*theTargetPolarization.p2()
+ std::sin(phi)*theBeamPolarization.p2()*theTargetPolarization.p3());
treject = gdist/gdiced;
//G4cout<<" treject = "<<treject<<" at phi = "<<phi<<G4endl;
if (treject>1.+1.e-10 || treject<0){
G4cout<<"!!!ERROR in PolarizedAnnihilationPS::PostStepDoIt\n"
<<" phi rejection does not work properly: "<<treject<<G4endl;
G4cout<<" gdiced = "<<gdiced<<G4endl;
G4cout<<" gdist = "<<gdist<<G4endl;
G4cout<<" epsil = "<<epsil<<G4endl;
}
if (treject<1.e-3) {
G4cout<<"!!!ERROR in PolarizedAnnihilationPS::PostStepDoIt\n"
<<" phi rejection does not work properly: "<<treject<<"\n";
G4cout<<" gdiced="<<gdiced<<" gdist="<<gdist<<"\n";
G4cout<<" epsil = "<<epsil<<G4endl;
}
// Loop checking, 03-Aug-2015, Vladimir Ivanchenko
} while( treject < G4UniformRand() );
// G4cout<<"phi dicing END"<<G4endl;
G4double dirx = sint*std::cos(phi) , diry = sint*std::sin(phi) , dirz = cost;
//
// kinematic of the created pair
//
G4double TotalAvailableEnergy = PositKinEnergy + 2*electron_mass_c2;
G4double Phot1Energy = epsil*TotalAvailableEnergy;
G4double Phot2Energy =(1.-epsil)*TotalAvailableEnergy;
// *** prepare calculation of polarization transfer ***
G4ThreeVector Phot1Direction (dirx, diry, dirz);
// get interaction frame
G4ThreeVector nInteractionFrame =
G4PolarizationHelper::GetFrame(PositDirection,Phot1Direction);
// define proper in-plane and out-of-plane component of initial spins
theBeamPolarization.InvRotateAz(nInteractionFrame,PositDirection);
theTargetPolarization.InvRotateAz(nInteractionFrame,PositDirection);
// calculate spin transfere matrix
crossSectionCalculator->Initialize(epsil,gama,phi,theBeamPolarization,theTargetPolarization,2);
// **********************************************************************
Phot1Direction.rotateUz(PositDirection);
// create G4DynamicParticle object for the particle1
G4DynamicParticle* aParticle1= new G4DynamicParticle (G4Gamma::Gamma(),
Phot1Direction, Phot1Energy);
finalGamma1Polarization=crossSectionCalculator->GetPol2();
G4double n1=finalGamma1Polarization.mag2();
if (n1>1) {
G4cout<<"ERROR: PolarizedAnnihilation Polarization Vector at epsil = "
<<epsil<<" is too large!!! \n"
<<"annihi pol1= "<<finalGamma1Polarization<<", ("<<n1<<")\n";
finalGamma1Polarization*=1./std::sqrt(n1);
}
// define polarization of first final state photon
finalGamma1Polarization.SetPhoton();
finalGamma1Polarization.RotateAz(nInteractionFrame,Phot1Direction);
aParticle1->SetPolarization(finalGamma1Polarization.p1(),
finalGamma1Polarization.p2(),
finalGamma1Polarization.p3());
fvect->push_back(aParticle1);
// **********************************************************************
G4double Eratio= Phot1Energy/Phot2Energy;
G4double PositP= std::sqrt(PositKinEnergy*(PositKinEnergy+2.*electron_mass_c2));
G4ThreeVector Phot2Direction (-dirx*Eratio, -diry*Eratio,
(PositP-dirz*Phot1Energy)/Phot2Energy);
Phot2Direction.rotateUz(PositDirection);
// create G4DynamicParticle object for the particle2
G4DynamicParticle* aParticle2= new G4DynamicParticle (G4Gamma::Gamma(),
Phot2Direction, Phot2Energy);
// define polarization of second final state photon
finalGamma2Polarization=crossSectionCalculator->GetPol3();
G4double n2=finalGamma2Polarization.mag2();
if (n2>1) {
G4cout<<"ERROR: PolarizedAnnihilation Polarization Vector at epsil = "<<epsil<<" is too large!!! \n";
G4cout<<"annihi pol2= "<<finalGamma2Polarization<<", ("<<n2<<")\n";
finalGamma2Polarization*=1./std::sqrt(n2);
}
finalGamma2Polarization.SetPhoton();
finalGamma2Polarization.RotateAz(nInteractionFrame,Phot2Direction);
aParticle2->SetPolarization(finalGamma2Polarization.p1(),
finalGamma2Polarization.p2(),
finalGamma2Polarization.p3());
fvect->push_back(aParticle2);
}
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