G4VPhononProcess.cc

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/// \file processes/phonon/src/G4VPhononProcess.cc
/// \brief Implementation of the G4VPhononProcess base class
//
//
// 20131111  Add verbosity to report creating secondaries
 
#include "G4VPhononProcess.hh"
#include "G4DynamicParticle.hh"
#include "G4ExceptionSeverity.hh"
#include "G4LatticeManager.hh"
#include "G4LatticePhysical.hh"
#include "G4ParticleDefinition.hh"
#include "G4PhononLong.hh"
#include "G4PhononPolarization.hh"
#include "G4PhononTrackMap.hh"
#include "G4PhononTransFast.hh"
#include "G4PhononTransSlow.hh"
#include "G4ProcessType.hh"
#include "G4ThreeVector.hh"
#include "G4Track.hh"
 
namespace {
  const G4ThreeVector nullVec(0.,0.,0.);    // For convenience below
}
 
// Constructor and destructor
 
G4VPhononProcess::G4VPhononProcess(const G4String& processName)
  : G4VDiscreteProcess(processName, fPhonon),
    trackKmap(G4PhononTrackMap::GetInstance()), theLattice(0),
    currentTrack(0) {}
 
G4VPhononProcess::~G4VPhononProcess() {;}
 
 
// Only applies to the known phonon polarization states
 
G4bool G4VPhononProcess::IsApplicable(const G4ParticleDefinition& aPD) {
  return (&aPD==G4PhononLong::Definition() ||
      &aPD==G4PhononTransFast::Definition() ||
      &aPD==G4PhononTransSlow::Definition() );
}
 
 
// Initialize wave vectors for currently active track(s)
 
void G4VPhononProcess::StartTracking(G4Track* track) {
  G4VProcess::StartTracking(track); // Apply base class actions
 
  // FIXME:  THE WAVEVECTOR SHOULD BE COMPUTED BY INVERTING THE K/V MAP
  if (!trackKmap->Find(track)) 
    trackKmap->SetK(track, track->GetMomentumDirection());
 
  currentTrack = track;         // Save for use by EndTracking
 
  // Fetch lattice for current track once, use in subsequent steps
  G4LatticeManager* LM = G4LatticeManager::GetLatticeManager();
  theLattice = LM->GetLattice(track->GetVolume());
}
 
void G4VPhononProcess::EndTracking() {
  G4VProcess::EndTracking();        // Apply base class actions
  trackKmap->RemoveTrack(currentTrack);
  currentTrack = 0;
  theLattice = 0;
}
 
 
// For convenience, map phonon type to polarization code
 
G4int G4VPhononProcess::GetPolarization(const G4Track& track) const {
  return G4PhononPolarization::Get(track.GetParticleDefinition());
}
 
 
// Generate random polarization from density of states
 
G4int G4VPhononProcess::ChoosePolarization(G4double Ldos, G4double STdos,
                       G4double FTdos) const {
  G4double norm = Ldos + STdos + FTdos;
  G4double cProbST = STdos/norm;
  G4double cProbFT = FTdos/norm + cProbST;
 
  // NOTE:  Order of selection done to match previous random sequences
  G4double modeMixer = G4UniformRand();
  if (modeMixer<cProbST) return G4PhononPolarization::TransSlow;
  if (modeMixer<cProbFT) return G4PhononPolarization::TransFast;
  return G4PhononPolarization::Long;
}
 
 
// Create new secondary track from phonon configuration
 
G4Track* G4VPhononProcess::CreateSecondary(G4int polarization,
                       const G4ThreeVector& waveVec,
                       G4double energy) const {
  if (verboseLevel>1) {
    G4cout << GetProcessName() << " CreateSecondary pol " << polarization
       << " K " << waveVec << " E " << energy << G4endl;
  }
 
  G4ThreeVector vgroup = theLattice->MapKtoVDir(polarization, waveVec);
  if (verboseLevel>1) G4cout << " MapKtoVDir returned " << vgroup << G4endl;
 
  vgroup = theLattice->RotateToGlobal(vgroup);
  if (verboseLevel>1) G4cout << " RotateToGlobal returned " << vgroup << G4endl;
 
  if (verboseLevel && std::fabs(vgroup.mag()-1.) > 0.01) {
    G4cout << "WARNING: " << GetProcessName() << " vgroup not a unit vector: "
       << vgroup << G4endl;
  }
 
  G4ParticleDefinition* thePhonon = G4PhononPolarization::Get(polarization);
 
  // Secondaries are created at the current track coordinates
  G4Track* sec = new G4Track(new G4DynamicParticle(thePhonon, vgroup, energy),
                 currentTrack->GetGlobalTime(),
                 currentTrack->GetPosition());
 
  // Store wavevector in lookup table for future tracking
  trackKmap->SetK(sec, theLattice->RotateToGlobal(waveVec));
 
  if (verboseLevel>1) {
    G4cout << GetProcessName() << " secondary K rotated to "
       << trackKmap->GetK(sec) << G4endl;
  }
 
  sec->SetVelocity(theLattice->MapKtoV(polarization, waveVec));    
  sec->UseGivenVelocity(true);
 
  return sec;
}