Gabriele Cosmo
267 lines
9.6 KiB
C++
267 lines
9.6 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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//
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// -------------------------------------------------------------------
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//
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// GEANT4 Class file
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//
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//
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// File name: G4eplusAnnihilation
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//
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// Author: Vladimir Ivanchenko on base of Michel Maire code
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//
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// Creation date: 02.08.2004
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//
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// Modified by Michel Maire, Vladimir Ivanchenko and Daren Sawkey
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//
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// Introduced Quantum Entanglement April 2021 John Allison
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// This is activated by /process/em/QuantumEntanglement
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// For e+e- -> gamma gamma, the gammas are "tagged" here
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// and must be "analysed" in a Compton scattering process - see, for
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// example, G4LivermorePolarizedComptonModel. Otherwise entanglement
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// has no effect even if activated.
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//
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// -------------------------------------------------------------------
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//
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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#include "G4eplusAnnihilation.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4MaterialCutsCouple.hh"
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#include "G4Gamma.hh"
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#include "G4Electron.hh"
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#include "G4Positron.hh"
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#include "G4eeToTwoGammaModel.hh"
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#include "G4EmBiasingManager.hh"
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#include "G4EntanglementAuxInfo.hh"
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#include "G4eplusAnnihilationEntanglementClipBoard.hh"
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#include "G4EmParameters.hh"
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#include "G4PhysicsModelCatalog.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4eplusAnnihilation::G4eplusAnnihilation(const G4String& name)
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: G4VEmProcess(name)
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{
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theGamma = G4Gamma::Gamma();
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theElectron = G4Electron::Electron();
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SetCrossSectionType(fEmDecreasing);
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SetBuildTableFlag(false);
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SetStartFromNullFlag(false);
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SetSecondaryParticle(theGamma);
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SetProcessSubType(fAnnihilation);
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enableAtRestDoIt = true;
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mainSecondaries = 2;
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fEntanglementModelID = G4PhysicsModelCatalog::GetModelID("model_GammaGammaEntanglement");
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4eplusAnnihilation::~G4eplusAnnihilation() = default;
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4bool G4eplusAnnihilation::IsApplicable(const G4ParticleDefinition& p)
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{
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return (&p == G4Positron::Positron());
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4eplusAnnihilation::AtRestGetPhysicalInteractionLength(
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const G4Track&, G4ForceCondition* condition)
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{
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*condition = NotForced;
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return 0.0;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4eplusAnnihilation::InitialiseProcess(const G4ParticleDefinition*)
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{
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if(!isInitialised) {
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isInitialised = true;
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if(nullptr == EmModel(0)) { SetEmModel(new G4eeToTwoGammaModel()); }
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EmModel(0)->SetLowEnergyLimit(MinKinEnergy());
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EmModel(0)->SetHighEnergyLimit(MaxKinEnergy());
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AddEmModel(1, EmModel(0));
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4eplusAnnihilation::StreamProcessInfo(std::ostream&) const
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{}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4VParticleChange* G4eplusAnnihilation::AtRestDoIt(const G4Track& track,
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const G4Step& step)
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// Performs the e+ e- annihilation when both particles are assumed at rest.
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{
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fParticleChange.InitializeForPostStep(track);
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DefineMaterial(track.GetMaterialCutsCouple());
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size_t idx = CurrentMaterialCutsCoupleIndex();
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G4double ene(0.0);
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G4VEmModel* model = SelectModel(ene, idx);
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// define new weight for primary and secondaries
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G4double weight = fParticleChange.GetParentWeight();
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// sample secondaries
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secParticles.clear();
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G4double gammaCut = GetGammaEnergyCut();
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model->SampleSecondaries(&secParticles, MaterialCutsCouple(),
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track.GetDynamicParticle(), gammaCut);
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G4int num0 = secParticles.size();
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// splitting or Russian roulette
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if(biasManager) {
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if(biasManager->SecondaryBiasingRegion(idx)) {
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G4double eloss = 0.0;
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weight *= biasManager->ApplySecondaryBiasing(
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secParticles, track, model, &fParticleChange, eloss,
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idx, gammaCut, step.GetPostStepPoint()->GetSafety());
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if(eloss > 0.0) {
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eloss += fParticleChange.GetLocalEnergyDeposit();
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fParticleChange.ProposeLocalEnergyDeposit(eloss);
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}
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}
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}
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// save secondaries
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G4int num = secParticles.size();
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// Check that entanglement is switched on... (the following flag is
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// set by /process/em/QuantumEntanglement).
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G4bool entangled = G4EmParameters::Instance()->QuantumEntanglement();
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// ...and that we have two gammas with both gammas' energies above
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// gammaCut (entanglement is only programmed for e+ e- -> gamma gamma).
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G4bool entangledgammagamma = false;
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if (entangled) {
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if (num == 2) {
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entangledgammagamma = true;
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for (const auto* p: secParticles) {
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if (p->GetDefinition() != theGamma ||
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p->GetKineticEnergy() < gammaCut) {
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entangledgammagamma = false;
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}
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}
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}
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}
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// Prepare a shared pointer for psossible use below. If it is used, the
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// shared pointer is copied into the tracks through G4EntanglementAuxInfo.
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// This ensures the clip board lasts until both tracks are destroyed.
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std::shared_ptr<G4eplusAnnihilationEntanglementClipBoard> clipBoard;
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if (entangledgammagamma) {
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clipBoard = std::make_shared<G4eplusAnnihilationEntanglementClipBoard>();
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clipBoard->SetParentParticleDefinition(track.GetDefinition());
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}
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if(num > 0) {
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fParticleChange.SetNumberOfSecondaries(num);
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G4double edep = fParticleChange.GetLocalEnergyDeposit();
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G4double time = track.GetGlobalTime();
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for (G4int i=0; i<num; ++i) {
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if (secParticles[i]) {
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G4DynamicParticle* dp = secParticles[i];
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const G4ParticleDefinition* p = dp->GetParticleDefinition();
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G4double e = dp->GetKineticEnergy();
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G4bool good = true;
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if(ApplyCuts()) {
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if (p == theGamma) {
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if (e < gammaCut) { good = false; }
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} else if (p == theElectron) {
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if (e < GetElectronEnergyCut()) { good = false; }
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}
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// added secondary if it is good
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}
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if (good) {
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G4Track* t = new G4Track(dp, time, track.GetPosition());
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t->SetTouchableHandle(track.GetTouchableHandle());
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if (entangledgammagamma) {
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// entangledgammagamma is only true when there are only two gammas
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// (See code above where entangledgammagamma is calculated.)
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if (i == 0) { // First gamma
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clipBoard->SetTrackA(t);
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} else if (i == 1) { // Second gamma
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clipBoard->SetTrackB(t);
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}
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t->SetAuxiliaryTrackInformation
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(fEntanglementModelID,new G4EntanglementAuxInfo(clipBoard));
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}
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if (biasManager) {
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t->SetWeight(weight * biasManager->GetWeight(i));
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} else {
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t->SetWeight(weight);
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}
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pParticleChange->AddSecondary(t);
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// define type of secondary
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if(i < mainSecondaries) { t->SetCreatorModelID(secID); }
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else if(i < num0) {
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if(p == theGamma) {
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t->SetCreatorModelID(fluoID);
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} else {
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t->SetCreatorModelID(augerID);
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}
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} else {
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t->SetCreatorModelID(biasID);
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}
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/*
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G4cout << "Secondary(post step) has weight " << t->GetWeight()
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<< ", Ekin= " << t->GetKineticEnergy()/MeV << " MeV "
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<< GetProcessName() << " fluoID= " << fluoID
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<< " augerID= " << augerID <<G4endl;
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*/
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} else {
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delete dp;
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edep += e;
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}
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}
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}
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fParticleChange.ProposeLocalEnergyDeposit(edep);
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}
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return &fParticleChange;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4eplusAnnihilation::ProcessDescription(std::ostream& out) const
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{
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out << " Positron annihilation";
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G4VEmProcess::ProcessDescription(out);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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