118 lines
5.1 KiB
C++
118 lines
5.1 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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/// \file GB05BOptnSplitAndKillByCrossSection.cc
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/// \brief Implementation of the GB05BOptnSplitAndKillByCrossSection class
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#include "GB05BOptnSplitAndKillByCrossSection.hh"
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#include "Randomize.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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GB05BOptnSplitAndKillByCrossSection::GB05BOptnSplitAndKillByCrossSection(G4String name)
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: G4VBiasingOperation(name), fParticleChange(), fInteractionLength(-1.0)
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{}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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GB05BOptnSplitAndKillByCrossSection::~GB05BOptnSplitAndKillByCrossSection() = default;
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double GB05BOptnSplitAndKillByCrossSection::DistanceToApplyOperation(const G4Track*, G4double,
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G4ForceCondition* condition)
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{
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*condition = NotForced;
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// -- Sample the exponential law using the total interaction length of processes
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// -- to couterbalance for:
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G4double proposedStepLength = -std::log(G4UniformRand()) * fInteractionLength;
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return proposedStepLength;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4VParticleChange*
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GB05BOptnSplitAndKillByCrossSection::GenerateBiasingFinalState(const G4Track* track, const G4Step*)
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{
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// -- This method is called if we have limited the step.
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// -- We hence make the splitting or killing.
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// Get track weight:
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G4double initialWeight = track->GetWeight();
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// The "particle change" is the object to be used to communicate to
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// the tracking the update of the primary state and/or creation
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// secondary tracks.
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fParticleChange.Initialize(*track);
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// -- Splitting and killing factors.
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// -- They are taken the same, but the killing factor can be make bigger.
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G4double splittingFactor = 2.0;
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G4double killingFactor = 2.0;
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if (track->GetMomentumDirection().z() > 0) {
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// -- We split if the track is moving forward:
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// Define the tracks weight:
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G4double weightOfTrack = initialWeight / splittingFactor;
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// Ask currect track weight to be changed to new value:
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fParticleChange.ProposeParentWeight(weightOfTrack);
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// Now make clones of this track (this is the actual splitting):
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// we will then have the primary and clone of it, hence the
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// splitting by a factor 2:
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auto clone = new G4Track(*track);
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clone->SetWeight(weightOfTrack);
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fParticleChange.AddSecondary(clone);
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// -- Below's call added for safety & illustration : inform particle change to not
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// -- modify the clone (ie : daughter) weight to male it that of the
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// -- primary. Here call not mandatory and both tracks have same weights.
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fParticleChange.SetSecondaryWeightByProcess(true);
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}
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else {
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// -- We apply Russian roulette if the track is moving backward:
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// Shoot a random number (in ]0,1[ segment):
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G4double random = G4UniformRand();
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G4double killingProbability = 1.0 - 1.0 / killingFactor;
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if (random < killingProbability) {
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// We ask for the the track to be killed:
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fParticleChange.ProposeTrackStatus(fStopAndKill);
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}
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else {
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// In this case, the track survives. We change its weight
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// to conserve weight among killed and survival tracks:
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fParticleChange.ProposeParentWeight(initialWeight * killingFactor);
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}
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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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