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geant4/source/processes/electromagnetic/polarisation/src/G4PolarizedComptonModel.cc
T
Gabriele Cosmo b79225fb37 Import Geant4 9.2.0 source tree
2016-06-09 15:58:43 +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. *
// ********************************************************************
//
//
// $Id: G4PolarizedComptonModel.cc,v 1.4 2007/05/23 08:52:20 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-02 $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name: G4PolarizedComptonModel
//
// Author: Andreas Schaelicke
//
// Creation date: 01.05.2005
//
// Modifications:
// 18-07-06 use newly calculated cross sections (P. Starovoitov)
// 21-08-05 update interface (A. Schaelicke)
//
// Class Description:
//
// -------------------------------------------------------------------
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
#include "G4PolarizedComptonModel.hh"
#include "G4Electron.hh"
#include "G4Gamma.hh"
#include "Randomize.hh"
#include "G4DataVector.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4StokesVector.hh"
#include "G4PolarizationManager.hh"
#include "G4PolarizationHelper.hh"
#include "G4PolarizedComptonCrossSection.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4PolarizedComptonModel::G4PolarizedComptonModel(const G4ParticleDefinition*,
const G4String& nam)
: G4KleinNishinaCompton(0,nam),
verboseLevel(0)
{
crossSectionCalculator=new G4PolarizedComptonCrossSection();
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4PolarizedComptonModel::~G4PolarizedComptonModel()
{
if (crossSectionCalculator) delete crossSectionCalculator;
}
G4double G4PolarizedComptonModel::ComputeAsymmetryPerAtom
(G4double gammaEnergy, G4double /*Z*/)
{
G4double asymmetry = 0.0 ;
G4double k0 = gammaEnergy / electron_mass_c2 ;
G4double k1 = 1 + 2*k0 ;
asymmetry = -k0;
asymmetry *= (k0 + 1.)*sqr(k1)*std::log(k1) - 2.*k0*(5.*sqr(k0) + 4.*k0 + 1.);
asymmetry /= ((k0 - 2.)*k0 -2.)*sqr(k1)*std::log(k1) + 2.*k0*(k0*(k0 + 1.)*(k0 + 8.) + 2.);
// G4cout<<"energy = "<<GammaEnergy<<" asymmetry = "<<asymmetry<<"\t\t GAM = "<<k0<<G4endl;
if (asymmetry>1.) G4cout<<"ERROR in G4PolarizedComptonModel::ComputeAsymmetryPerAtom"<<G4endl;
return asymmetry;
}
G4double G4PolarizedComptonModel::ComputeCrossSectionPerAtom(
const G4ParticleDefinition* pd,
G4double kinEnergy,
G4double Z,
G4double A,
G4double cut,
G4double emax)
{
double xs =
G4KleinNishinaCompton::ComputeCrossSectionPerAtom(pd,kinEnergy,
Z,A,cut,emax);
G4double polzz = theBeamPolarization.p3()*theTargetPolarization.z();
if (polzz!=0) {
G4double asym=ComputeAsymmetryPerAtom(kinEnergy, Z);
xs*=(1.+polzz*asym);
}
return xs;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4PolarizedComptonModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
const G4MaterialCutsCouple*,
const G4DynamicParticle* aDynamicGamma,
G4double,
G4double)
{
const G4Track * aTrack = fParticleChange->GetCurrentTrack();
G4VPhysicalVolume* aPVolume = aTrack->GetVolume();
G4LogicalVolume* aLVolume = aPVolume->GetLogicalVolume();
if (verboseLevel>=1)
G4cout<<"G4PolarizedComptonModel::SampleSecondaries in "
<< aLVolume->GetName() <<G4endl;
G4PolarizationManager * polarizationManager = G4PolarizationManager::GetInstance();
// obtain polarization of the beam
theBeamPolarization = aDynamicGamma->GetPolarization();
theBeamPolarization.SetPhoton();
// obtain polarization of the media
const G4bool targetIsPolarized = polarizationManager->IsPolarized(aLVolume);
theTargetPolarization = polarizationManager->GetVolumePolarization(aLVolume);
// if beam is linear polarized or target is transversely polarized
// determine the angle to x-axis
// (assumes same PRF as in the polarization definition)
G4ThreeVector gamDirection0 = aDynamicGamma->GetMomentumDirection();
// transfere theTargetPolarization
// into the gamma frame (problem electron is at rest)
if (targetIsPolarized)
theTargetPolarization.rotateUz(gamDirection0);
// The scattered gamma energy is sampled according to Klein - Nishina formula.
// The random number techniques of Butcher & Messel are used
// (Nuc Phys 20(1960),15).
// Note : Effects due to binding of atomic electrons are negliged.
G4double gamEnergy0 = aDynamicGamma->GetKineticEnergy();
G4double E0_m = gamEnergy0 / electron_mass_c2 ;
//
// sample the energy rate of the scattered gamma
//
G4double epsilon, epsilonsq, onecost, sint2, greject ;
G4double epsilon0 = 1./(1. + 2.*E0_m);
G4double epsilon0sq = epsilon0*epsilon0;
G4double alpha1 = - std::log(epsilon0);
G4double alpha2 = 0.5*(1.- epsilon0sq);
G4double polarization = theBeamPolarization.p3()*theTargetPolarization.p3();
do {
if ( alpha1/(alpha1+alpha2) > G4UniformRand() ) {
epsilon = std::exp(-alpha1*G4UniformRand()); // epsilon0**r
epsilonsq = epsilon*epsilon;
} else {
epsilonsq = epsilon0sq + (1.- epsilon0sq)*G4UniformRand();
epsilon = std::sqrt(epsilonsq);
};
onecost = (1.- epsilon)/(epsilon*E0_m);
sint2 = onecost*(2.-onecost);
G4double gdiced = 2.*(1./epsilon+epsilon);
G4double gdist = 1./epsilon + epsilon - sint2
- polarization*(1./epsilon-epsilon)*(1.-onecost);
greject = gdist/gdiced;
if (greject>1) G4cout<<"ERROR in PolarizedComptonScattering::PostStepDoIt\n"
<<" costh rejection does not work properly: "<<greject<<G4endl;
} while (greject < G4UniformRand());
//
// scattered gamma angles. ( Z - axis along the parent gamma)
//
G4double cosTeta = 1. - onecost;
G4double sinTeta = std::sqrt (sint2);
G4double Phi;
do {
Phi = twopi * G4UniformRand();
G4double gdiced = 1./epsilon + epsilon - sint2
+ std::abs(theBeamPolarization.p3())*
( std::abs((1./epsilon-epsilon)*cosTeta*theTargetPolarization.p3())
+(1.-epsilon)*sinTeta*(std::sqrt(sqr(theTargetPolarization.p1())
+ sqr(theTargetPolarization.p2()))))
+sint2*(std::sqrt(sqr(theBeamPolarization.p1()) + sqr(theBeamPolarization.p2())));
G4double gdist = 1./epsilon + epsilon - sint2
+ theBeamPolarization.p3()*
((1./epsilon-epsilon)*cosTeta*theTargetPolarization.p3()
+(1.-epsilon)*sinTeta*(std::cos(Phi)*theTargetPolarization.p1()+
std::sin(Phi)*theTargetPolarization.p2()))
-sint2*(std::cos(2.*Phi)*theBeamPolarization.p1()
+std::sin(2.*Phi)*theBeamPolarization.p2());
greject = gdist/gdiced;
if (greject>1.+1.e-10 || greject<0) G4cout<<"ERROR in PolarizedComptonScattering::PostStepDoIt\n"
<<" phi rejection does not work properly: "<<greject<<G4endl;
if (greject<1.e-3) {
G4cout<<"ERROR in PolarizedComptonScattering::PostStepDoIt\n"
<<" phi rejection does not work properly: "<<greject<<"\n";
G4cout<<" greject="<<greject<<" phi="<<Phi<<" cost="<<cosTeta<<"\n";
G4cout<<" gdiced="<<gdiced<<" gdist="<<gdist<<"\n";
G4cout<<" eps="<<epsilon<<" 1/eps="<<1./epsilon<<"\n";
}
} while (greject < G4UniformRand());
G4double dirx = sinTeta*std::cos(Phi), diry = sinTeta*std::sin(Phi), dirz = cosTeta;
//
// update G4VParticleChange for the scattered gamma
//
G4ThreeVector gamDirection1 ( dirx,diry,dirz );
gamDirection1.rotateUz(gamDirection0);
G4double gamEnergy1 = epsilon*gamEnergy0;
fParticleChange->SetProposedKineticEnergy(gamEnergy1);
if(gamEnergy1 > lowestGammaEnergy) {
fParticleChange->ProposeMomentumDirection(gamDirection1);
} else {
fParticleChange->ProposeTrackStatus(fStopAndKill);
gamEnergy1 += fParticleChange->GetLocalEnergyDeposit();
fParticleChange->ProposeLocalEnergyDeposit(gamEnergy1);
}
//
// kinematic of the scattered electron
//
G4double eKinEnergy = gamEnergy0 - gamEnergy1;
G4ThreeVector eDirection = gamEnergy0*gamDirection0 - gamEnergy1*gamDirection1;
eDirection = eDirection.unit();
//
// calculate Stokesvector of final state photon and electron
//
G4ThreeVector nInteractionFrame;
if((gamEnergy1 > lowestGammaEnergy) ||
(eKinEnergy > DBL_MIN)) {
// determine interaction plane
// nInteractionFrame =
// G4PolarizationHelper::GetFrame(gamDirection1,eDirection);
if (gamEnergy1 > lowestGammaEnergy)
nInteractionFrame = G4PolarizationHelper::GetFrame(gamDirection1,gamDirection0);
else
nInteractionFrame = G4PolarizationHelper::GetFrame(gamDirection0, eDirection);
// transfere theBeamPolarization and theTargetPolarization
// into the interaction frame (note electron is in gamma frame)
if (verboseLevel>=1) {
G4cout << "========================================\n";
G4cout << " nInteractionFrame = " <<nInteractionFrame<<"\n";
G4cout << " GammaDirection0 = " <<gamDirection0<<"\n";
G4cout << " gammaPolarization = " <<theBeamPolarization<<"\n";
G4cout << " electronPolarization = " <<theTargetPolarization<<"\n";
}
theBeamPolarization.InvRotateAz(nInteractionFrame,gamDirection0);
theTargetPolarization.InvRotateAz(nInteractionFrame,gamDirection0);
if (verboseLevel>=1) {
G4cout << "----------------------------------------\n";
G4cout << " gammaPolarization = " <<theBeamPolarization<<"\n";
G4cout << " electronPolarization = " <<theTargetPolarization<<"\n";
G4cout << "----------------------------------------\n";
}
// initialize the polarization transfer matrix
crossSectionCalculator->Initialize(epsilon,E0_m,0.,
theBeamPolarization,
theTargetPolarization,2);
}
// if(eKinEnergy > DBL_MIN)
{
// in interaction frame
// calculate polarization transfer to the photon (in interaction plane)
finalGammaPolarization = crossSectionCalculator->GetPol2();
if (verboseLevel>=1) G4cout << " gammaPolarization1 = " <<finalGammaPolarization<<"\n";
finalGammaPolarization.SetPhoton();
// translate polarization into particle reference frame
finalGammaPolarization.RotateAz(nInteractionFrame,gamDirection1);
//store polarization vector
fParticleChange->ProposePolarization(finalGammaPolarization);
if (finalGammaPolarization.mag() > 1.+1.e-8){
G4cout<<"ERROR in Polarizaed Compton Scattering !"<<G4endl;
G4cout<<"Polarization of final photon more than 100%"<<G4endl;
G4cout<<finalGammaPolarization<<" mag = "<<finalGammaPolarization.mag()<<G4endl;
}
if (verboseLevel>=1) {
G4cout << " gammaPolarization1 = " <<finalGammaPolarization<<"\n";
G4cout << " GammaDirection1 = " <<gamDirection1<<"\n";
}
}
// if (ElecKineEnergy > fminimalEnergy) {
{
finalElectronPolarization = crossSectionCalculator->GetPol3();
if (verboseLevel>=1)
G4cout << " electronPolarization1 = " <<finalElectronPolarization<<"\n";
// transfer into particle reference frame
finalElectronPolarization.RotateAz(nInteractionFrame,eDirection);
if (verboseLevel>=1) {
G4cout << " electronPolarization1 = " <<finalElectronPolarization<<"\n";
G4cout << " ElecDirection = " <<eDirection<<"\n";
}
}
if (verboseLevel>=1)
G4cout << "========================================\n";
if(eKinEnergy > DBL_MIN) {
// create G4DynamicParticle object for the electron.
G4DynamicParticle* aElectron = new G4DynamicParticle(theElectron,eDirection,eKinEnergy);
//store polarization vector
if (finalElectronPolarization.mag() > 1.+1.e-8){
G4cout<<"ERROR in Polarizaed Compton Scattering !"<<G4endl;
G4cout<<"Polarization of final electron more than 100%"<<G4endl;
G4cout<<finalElectronPolarization<<" mag = "<<finalElectronPolarization.mag()<<G4endl;
}
aElectron->SetPolarization(finalElectronPolarization.p1(),
finalElectronPolarization.p2(),
finalElectronPolarization.p3());
fvect->push_back(aElectron);
}
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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