136 lines
5.4 KiB
C++
136 lines
5.4 KiB
C++
/***************************************************************************
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* musrSim - the program for the simulation of (mainly) muSR instruments. *
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* More info on http://lmu.web.psi.ch/simulation/index.html . *
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* musrSim is based od Geant4 (http://geant4.web.cern.ch/geant4/) *
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* *
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* Copyright (C) 2009 by Paul Scherrer Institut, 5232 Villigen PSI, *
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* Switzerland *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the Free Software *
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. *
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***************************************************************************/
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//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
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// Muon energy loss in thin C-foil adding a Landau distribution to the energy
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// loss
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// Id : musrMuEnergyLossLandau, v 1.0
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// Author: Thomas Prokscha
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// Date : 2016-08
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//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
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#include "musrMuEnergyLossLandau.hh"
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using namespace std;
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musrMuEnergyLossLandau::musrMuEnergyLossLandau(const G4String& name, G4ProcessType aType)
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: G4VDiscreteProcess(name, aType)
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{
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random = new TRandom();
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}
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musrMuEnergyLossLandau::~musrMuEnergyLossLandau(){}
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double musrMuEnergyLossLandau::landauMPV = 0.1;
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double musrMuEnergyLossLandau::landauSigma = 0.1;
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G4VParticleChange* musrMuEnergyLossLandau::PostStepDoIt(const G4Track& trackData,
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const G4Step& aStep)
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{ // Initialize ParticleChange (by setting all its members equal to
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// the corresponding members in G4Track)
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fParticleChange.Initialize(trackData);
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G4Track theNewTrack;
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if(CheckCondition(aStep))
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{
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GetFinalEnergy(&aStep);
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G4Step theStep;
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PrepareSecondary( trackData);
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fParticleChange.AddSecondary(aSecondary);
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fParticleChange.ProposeTrackStatus(fStopAndKill) ;
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}
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else
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{
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fParticleChange.ProposeTrackStatus(trackData.GetTrackStatus()) ;
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}
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return &fParticleChange;
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}
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G4bool musrMuEnergyLossLandau::CheckCondition(const G4Step& aStep)
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{ // Decide when to call the MuEnergyLossLandau - i.e. for muons going through the C foil.
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condition=false;
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p_name = aStep.GetTrack()->GetDefinition()->GetParticleName(); // particle name
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std::string logVolName = aStep.GetTrack()->GetVolume()->GetLogicalVolume()->GetName();
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if(p_name == "mu+" && ((logVolName=="log_coulombCFoil")||(logVolName=="log_CFoil")))
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{
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condition=true;
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}
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return condition;
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}
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G4double musrMuEnergyLossLandau::GetMeanFreePath(const G4Track&,
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G4double,
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G4ForceCondition* condition1)
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{
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*condition1 = Forced;
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return DBL_MAX;
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}
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void musrMuEnergyLossLandau::GetFinalEnergy(const G4Step* aStep)
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{ // Particle generation
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particleTable=G4ParticleTable::GetParticleTable();
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G4double Eloss, Efinal;
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G4double E = aStep->GetTrack()->GetDynamicParticle()->GetKineticEnergy()/CLHEP::keV;
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// Positive muon
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if(p_name=="mu+"){
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do{
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Eloss = random->Landau(landauMPV,landauSigma);
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if (Eloss > 0.) break;
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} while (1);
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Efinal = E - Eloss;
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if (Efinal < 0. ) Efinal = 0.;
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// cout << "E, Eloss, Efinal = " << E << ", " << Eloss << ", " << Efinal << endl;
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particle = particleTable->FindParticle(p_name) ;
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// Set the new dynamic particle DP
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DP = new G4DynamicParticle(particle,
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aStep->GetTrack()->GetDynamicParticle()->GetMomentumDirection(),
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Efinal/1000.);
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/* IMPORTANT : COPY THOSE DATA TO GET THE SAME PARTICLE PROPERTIES!!!
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SHOULD BE KEPT WHEN BUILDING A PARTICLE CHANGE */
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DP->SetProperTime( aStep->GetTrack()->GetDynamicParticle()->GetProperTime());
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DP->SetPolarization(aStep->GetTrack()->GetDynamicParticle()->GetPolarization().x(),
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aStep->GetTrack()->GetDynamicParticle()->GetPolarization().y(),
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aStep->GetTrack()->GetDynamicParticle()->GetPolarization().z());
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DP->SetPreAssignedDecayProperTime(
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aStep->GetTrack()->GetDynamicParticle()->GetPreAssignedDecayProperTime());
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}
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}
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void musrMuEnergyLossLandau::PrepareSecondary(const G4Track& track)
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{
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if(p_name=="mu+")
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{
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aSecondary = new G4Track(DP,track.GetGlobalTime(),track.GetPosition());
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}
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}
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