G4MonopoleTransportation.cxx

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//
// $Id: G4MonopoleTransportation.cc 111448 2018-08-10 07:54:47Z gcosmo $
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//
// This class is a process responsible for the transportation of
// magnetic monopoles, ie the geometrical propagation that encounters the
// geometrical sub-volumes of the detectors.
//
// For monopoles, uses a different equation of motion and ignores energy
// conservation.
//
 
// =======================================================================
// Created:  3 May 2010, J. Apostolakis, B. Bozsogi
// =======================================================================
 
#include "G4MonopoleTransportation.hh"
#include "G4ChordFinder.hh"
#include "G4FieldManagerStore.hh"
#include "G4Monopole.hh"
#include "G4ParticleTable.hh"
#include "G4ProductionCutsTable.hh"
#include "G4SafetyHelper.hh"
#include "G4SystemOfUnits.hh"
#include "G4TransportationProcessType.hh"
 
class G4VSensitiveDetector;
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4MonopoleTransportation::G4MonopoleTransportation(
  const G4Monopole* mpl, G4int verb)
  : G4VProcess(G4String("MonopoleTransportation"), fTransportation),
    fParticleDef(mpl),
    fMagSetup(0),
    fLinearNavigator(0),
    fFieldPropagator(0),
    fParticleIsLooping(false),
    fPreviousSftOrigin(0., 0., 0.),
    fPreviousSafety(0.0),
    fThreshold_Warning_Energy(100 * MeV),
    fThreshold_Important_Energy(250 * MeV),
    fThresholdTrials(10),
    // fUnimportant_Energy( 1 * MeV ),
    fNoLooperTrials(0),
    fSumEnergyKilled(0.0),
    fMaxEnergyKilled(0.0),
    fShortStepOptimisation(false), // Old default: true (=fast short steps)
    fpSafetyHelper(0),
    noCalls(0)
{
  verboseLevel = verb;
 
  // set Process Sub Type
  SetProcessSubType(TRANSPORTATION);
 
  // Do not finalize the G4MonopoleTransportation class
  if (G4Threading::IsMasterThread() &&
      G4Threading::IsMultithreadedApplication()) {
    return;
  }
 
  fMagSetup = G4MonopoleFieldSetup::GetMonopoleFieldSetup();
 
  G4TransportationManager* transportMgr =
    G4TransportationManager::GetTransportationManager();
 
  fLinearNavigator = transportMgr->GetNavigatorForTracking();
 
  fFieldPropagator = transportMgr->GetPropagatorInField();
  fpSafetyHelper = transportMgr->GetSafetyHelper();
 
  // New
 
  // Cannot determine whether a field exists here,
  //  because it would only work if the field manager has informed
  //  about the detector's field before this transportation process
  //  is constructed.
  // Instead later the method DoesGlobalFieldExist() is called
  fCurrentTouchableHandle = nullptr;
 
  fEndGlobalTimeComputed = false;
  fCandidateEndGlobalTime = 0;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4MonopoleTransportation::~G4MonopoleTransportation()
{
  if ((verboseLevel > 0) && (fSumEnergyKilled > 0.0)) {
    G4cout << " G4MonopoleTransportation: Statistics for looping particles "
           << G4endl;
    G4cout << "   Sum of energy of loopers killed: " << fSumEnergyKilled
           << G4endl;
    G4cout << "   Max energy of loopers killed: " << fMaxEnergyKilled << G4endl;
  }
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//
// Responsibilities:
//    Find whether the geometry limits the Step, and to what length
//    Calculate the new value of the safety and return it.
//    Store the final time, position and momentum.
 
G4double G4MonopoleTransportation::AlongStepGetPhysicalInteractionLength(
  const G4Track& track,
  G4double, //  previousStepSize
  G4double currentMinimumStep, G4double& currentSafety,
  G4GPILSelection* selection)
{
  fMagSetup->SetStepperAndChordFinder(1);
  // change to monopole equation
 
  G4double geometryStepLength, newSafety;
  fParticleIsLooping = false;
 
  // Initial actions moved to  StartTrack()
  // --------------------------------------
  // Note: in case another process changes touchable handle
  //    it will be necessary to add here (for all steps)
  // fCurrentTouchableHandle = aTrack->GetTouchableHandle();
 
  // GPILSelection is set to defaule value of CandidateForSelection
  // It is a return value
  //
  *selection = CandidateForSelection;
 
  // Get initial Energy/Momentum of the track
  //
  const G4DynamicParticle* pParticle = track.GetDynamicParticle();
  G4ThreeVector startMomentumDir = pParticle->GetMomentumDirection();
  G4ThreeVector startPosition = track.GetPosition();
 
  // G4double   theTime        = track.GetGlobalTime() ;
 
  // The Step Point safety can be limited by other geometries and/or the
  // assumptions of any process - it's not always the geometrical safety.
  // We calculate the starting point's isotropic safety here.
  //
  G4ThreeVector OriginShift = startPosition - fPreviousSftOrigin;
  G4double MagSqShift = OriginShift.mag2();
  if (MagSqShift >= sqr(fPreviousSafety)) {
    currentSafety = 0.0;
  }
  else {
    currentSafety = fPreviousSafety - std::sqrt(MagSqShift);
  }
 
  // Is the monopole charged ?
  //
  G4double particleMagneticCharge = fParticleDef->MagneticCharge();
  G4double particleElectricCharge = pParticle->GetCharge();
 
  fGeometryLimitedStep = false;
  // fEndGlobalTimeComputed = false ;
 
  // There is no need to locate the current volume. It is Done elsewhere:
  //   On track construction
  //   By the tracking, after all AlongStepDoIts, in "Relocation"
 
  // Check whether the particle have an (EM) field force exerting upon it
  //
  G4FieldManager* fieldMgr = 0;
  G4bool fieldExertsForce = false;
 
  if ((particleMagneticCharge != 0.0)) {
    fieldMgr = fFieldPropagator->FindAndSetFieldManager(track.GetVolume());
    if (fieldMgr != 0) {
      // Message the field Manager, to configure it for this track
      fieldMgr->ConfigureForTrack(&track);
      // Moved here, in order to allow a transition
      //   from a zero-field  status (with fieldMgr->(field)0
      //   to a finite field  status
 
      // If the field manager has no field, there is no field !
      fieldExertsForce = (fieldMgr->GetDetectorField() != 0);
    }
  }
 
  // G4cout << " G4Transport:  field exerts force= " << fieldExertsForce
  //          << "  fieldMgr= " << fieldMgr << G4endl;
 
  // Choose the calculation of the transportation: Field or not
  //
  if (!fieldExertsForce) {
    G4double linearStepLength;
    if (fShortStepOptimisation && (currentMinimumStep <= currentSafety)) {
      // The Step is guaranteed to be taken
      //
      geometryStepLength = currentMinimumStep;
      fGeometryLimitedStep = false;
    }
    else {
      //  Find whether the straight path intersects a volume
      //
      linearStepLength = fLinearNavigator->ComputeStep(
        startPosition, startMomentumDir, currentMinimumStep, newSafety);
      // Remember last safety origin & value.
      //
      fPreviousSftOrigin = startPosition;
      fPreviousSafety = newSafety;
      // fpSafetyHelper->SetCurrentSafety( newSafety, startPosition);
 
      // The safety at the initial point has been re-calculated:
      //
      currentSafety = newSafety;
 
      fGeometryLimitedStep = (linearStepLength <= currentMinimumStep);
      if (fGeometryLimitedStep) {
        // The geometry limits the Step size (an intersection was found.)
        geometryStepLength = linearStepLength;
      }
      else {
        // The full Step is taken.
        geometryStepLength = currentMinimumStep;
      }
    }
    endpointDistance = geometryStepLength;
 
    // Calculate final position
    //
    fTransportEndPosition =
      startPosition + geometryStepLength * startMomentumDir;
 
    // Momentum direction, energy and polarisation are unchanged by transport
    //
    fTransportEndMomentumDir = startMomentumDir;
    fTransportEndKineticEnergy = track.GetKineticEnergy();
    fTransportEndSpin = track.GetPolarization();
    fParticleIsLooping = false;
    fMomentumChanged = false;
    fEndGlobalTimeComputed = false;
  }
  else //  A field exerts force
  {
    G4double momentumMagnitude = pParticle->GetTotalMomentum();
    G4ThreeVector EndUnitMomentum;
    G4double lengthAlongCurve;
    G4double restMass = fParticleDef->GetPDGMass();
 
    G4ChargeState chargeState(particleElectricCharge, // The charge can change
      fParticleDef->GetPDGSpin(),
      0,                       //  Magnetic moment:
      0,                       //  Electric Dipole moment
      particleMagneticCharge); // in Mev/c
 
    G4EquationOfMotion* equationOfMotion = fFieldPropagator->GetChordFinder()
                                             ->GetIntegrationDriver()
                                             ->GetEquationOfMotion();
 
    equationOfMotion->SetChargeMomentumMass(
      chargeState, momentumMagnitude, restMass);
    // SetChargeMomentumMass now passes both the electric and magnetic
    // charge in chargeState
 
    G4ThreeVector spin = track.GetPolarization();
    G4FieldTrack aFieldTrack =
      G4FieldTrack(startPosition, track.GetMomentumDirection(), 0.0,
        track.GetKineticEnergy(), restMass, track.GetVelocity(),
        track.GetGlobalTime(), // Lab.
        track.GetProperTime(), // Part.
        &spin);
    if (currentMinimumStep > 0) {
      // Do the Transport in the field (non recti-linear)
      //
      lengthAlongCurve = fFieldPropagator->ComputeStep(
        aFieldTrack, currentMinimumStep, currentSafety, track.GetVolume());
      fGeometryLimitedStep = lengthAlongCurve < currentMinimumStep;
      if (fGeometryLimitedStep) {
        geometryStepLength = lengthAlongCurve;
      }
      else {
        geometryStepLength = currentMinimumStep;
      }
    }
    else {
      geometryStepLength = lengthAlongCurve = 0.0;
      fGeometryLimitedStep = false;
    }
 
    // Remember last safety origin & value.
    //
    fPreviousSftOrigin = startPosition;
    fPreviousSafety = currentSafety;
    // fpSafetyHelper->SetCurrentSafety( newSafety, startPosition);
 
    // Get the End-Position and End-Momentum (Dir-ection)
    //
    fTransportEndPosition = aFieldTrack.GetPosition();
 
    // Momentum:  Magnitude and direction can be changed too now ...
    //
    fMomentumChanged = true;
    fTransportEndMomentumDir = aFieldTrack.GetMomentumDir();
 
    fTransportEndKineticEnergy = aFieldTrack.GetKineticEnergy();
 
    fCandidateEndGlobalTime = aFieldTrack.GetLabTimeOfFlight();
    fEndGlobalTimeComputed = true;
 
    fTransportEndSpin = aFieldTrack.GetSpin();
    fParticleIsLooping = fFieldPropagator->IsParticleLooping();
    endpointDistance = (fTransportEndPosition - startPosition).mag();
  }
 
  // If we are asked to go a step length of 0, and we are on a boundary
  // then a boundary will also limit the step -> we must flag this.
  //
  if (currentMinimumStep == 0.0) {
    if (currentSafety == 0.0) fGeometryLimitedStep = true;
  }
 
  // Update the safety starting from the end-point,
  // if it will become negative at the end-point.
  //
  if (currentSafety < endpointDistance) {
    // if( particleMagneticCharge == 0.0 )
    // G4cout  << "  Avoiding call to ComputeSafety : charge = 0.0 " << G4endl;
 
    if (particleMagneticCharge != 0.0) {
 
      G4double endSafety =
        fLinearNavigator->ComputeSafety(fTransportEndPosition);
      currentSafety = endSafety;
      fPreviousSftOrigin = fTransportEndPosition;
      fPreviousSafety = currentSafety;
      fpSafetyHelper->SetCurrentSafety(currentSafety, fTransportEndPosition);
 
      // Because the Stepping Manager assumes it is from the start point,
      //  add the StepLength
      //
      currentSafety += endpointDistance;
 
#ifdef G4DEBUG_TRANSPORT
      G4cout.precision(12);
      G4cout << "***G4MonopoleTransportation::AlongStepGPIL ** " << G4endl;
      G4cout << "  Called Navigator->ComputeSafety at " << fTransportEndPosition
             << "    and it returned safety= " << endSafety << G4endl;
      G4cout << "  Adding endpoint distance " << endpointDistance
             << "   to obtain pseudo-safety= " << currentSafety << G4endl;
#endif
    }
  }
 
  fParticleChange.ProposeTrueStepLength(geometryStepLength);
 
  fMagSetup->SetStepperAndChordFinder(0);
  // change back to usual equation
 
  return geometryStepLength;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//
//   Initialize ParticleChange  (by setting all its members equal
//                               to corresponding members in G4Track)
 
G4VParticleChange* G4MonopoleTransportation::AlongStepDoIt(
  const G4Track& track, const G4Step& stepData)
{
  const G4ParticleDefinition* fOpticalPhoton =
    G4ParticleTable::GetParticleTable()->FindParticle("opticalphoton");
 
  ++noCalls;
 
  fParticleChange.Initialize(track);
 
  //  Code for specific process
  //
  fParticleChange.ProposePosition(fTransportEndPosition);
  fParticleChange.ProposeMomentumDirection(fTransportEndMomentumDir);
  fParticleChange.ProposeEnergy(fTransportEndKineticEnergy);
  fParticleChange.SetMomentumChanged(fMomentumChanged);
 
  fParticleChange.ProposePolarization(fTransportEndSpin);
 
  G4double deltaTime = 0.0;
 
  // Calculate  Lab Time of Flight (ONLY if field Equations used it!)
 
  G4double startTime = track.GetGlobalTime();
 
  if (!fEndGlobalTimeComputed) {
    // The time was not integrated .. make the best estimate possible
    //
    G4double finalVelocity = track.GetVelocity();
    G4double initialVelocity = stepData.GetPreStepPoint()->GetVelocity();
    G4double stepLength = track.GetStepLength();
 
    deltaTime = 0.0; // in case initialVelocity = 0
    const G4DynamicParticle* fpDynamicParticle = track.GetDynamicParticle();
    if (fpDynamicParticle->GetDefinition() == fOpticalPhoton) {
      //  A photon is in the medium of the final point
      //  during the step, so it has the final velocity.
      deltaTime = stepLength / finalVelocity;
    }
    else if (finalVelocity > 0.0) {
      G4double meanInverseVelocity;
      // deltaTime = stepLength/finalVelocity ;
      meanInverseVelocity = 0.5 * (1.0 / initialVelocity + 1.0 / finalVelocity);
      deltaTime = stepLength * meanInverseVelocity;
 
      // G4cout << "finalVelocity > 0.0 gives deltaTime " << deltaTime <<
      // G4endl;
    }
    else if (initialVelocity > 0.0) {
      deltaTime = stepLength / initialVelocity;
    }
    fCandidateEndGlobalTime = startTime + deltaTime;
    // G4cout << "not EndGlobalTimeComputed" << G4endl;
    // G4cout << "deltaTime, fCandidateEndGlobalTime "
    //        << deltaTime << ", " << fCandidateEndGlobalTime << G4endl;
  }
  else {
    deltaTime = fCandidateEndGlobalTime - startTime;
    // G4cout << "is EndGlobalTimeComputed" << G4endl;
    // G4cout << "deltaTime, fCandidateEndGlobalTime "
    //        << deltaTime << ", " << fCandidateEndGlobalTime << G4endl;
  }
 
  fParticleChange.ProposeGlobalTime(fCandidateEndGlobalTime);
 
  // Now Correct by Lorentz factor to get "proper" deltaTime
 
  G4double restMass = track.GetDynamicParticle()->GetMass();
  G4double deltaProperTime = deltaTime * (restMass / track.GetTotalEnergy());
 
  fParticleChange.ProposeProperTime(track.GetProperTime() + deltaProperTime);
  // G4cout << "ProposeProperTime: " << track.GetProperTime() + deltaProperTime
  // << G4endl;
 
  // If the particle is caught looping or is stuck (in very difficult
  // boundaries) in a magnetic field (doing many steps)
  //   THEN this kills it ...
  //
  if (fParticleIsLooping) {
    G4double endEnergy = fTransportEndKineticEnergy;
 
    if ((endEnergy < fThreshold_Important_Energy) ||
        (fNoLooperTrials >= fThresholdTrials)) {
      // Kill the looping particle
      //
      fParticleChange.ProposeTrackStatus(fStopAndKill);
 
      // 'Bare' statistics
      fSumEnergyKilled += endEnergy;
      if (endEnergy > fMaxEnergyKilled) {
        fMaxEnergyKilled = endEnergy;
      }
 
#ifdef G4VERBOSE
      if ((verboseLevel > 1) || (endEnergy > fThreshold_Warning_Energy)) {
        G4cout << " G4MonopoleTransportation is killing track "
               << "that is looping or stuck " << G4endl << "   This track has "
               << track.GetKineticEnergy() / MeV << " MeV energy." << G4endl;
        G4cout << "   Number of trials = " << fNoLooperTrials
               << "   No of calls to AlongStepDoIt = " << noCalls << G4endl;
      }
#endif
      fNoLooperTrials = 0;
    }
    else {
      fNoLooperTrials++;
#ifdef G4VERBOSE
      if ((verboseLevel > 2)) {
        G4cout << "   G4MonopoleTransportation::AlongStepDoIt(): "
               << "Particle looping - "
               << "   Number of trials = " << fNoLooperTrials
               << "   No of calls to  = " << noCalls << G4endl;
      }
#endif
    }
  }
  else {
    fNoLooperTrials = 0;
  }
 
  // Another (sometimes better way) is to use a user-limit maximum Step size
  // to alleviate this problem ..
 
  // Introduce smooth curved trajectories to particle-change
  //
  fParticleChange.SetPointerToVectorOfAuxiliaryPoints(
    fFieldPropagator->GimmeTrajectoryVectorAndForgetIt());
 
  return &fParticleChange;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//
//  This ensures that the PostStep action is always called,
//  so that it can do the relocation if it is needed.
//
 
G4double G4MonopoleTransportation::PostStepGetPhysicalInteractionLength(
  const G4Track&,
  G4double, // previousStepSize
  G4ForceCondition* pForceCond)
{
  *pForceCond = Forced;
  return DBL_MAX; // was kInfinity ; but convention now is DBL_MAX
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4VParticleChange* G4MonopoleTransportation::PostStepDoIt(
  const G4Track& track, const G4Step&)
{
  G4TouchableHandle retCurrentTouchable; // The one to return
 
  // Initialize ParticleChange  (by setting all its members equal
  //                             to corresponding members in G4Track)
  // fParticleChange.Initialize(track) ;  // To initialise TouchableChange
 
  fParticleChange.ProposeTrackStatus(track.GetTrackStatus());
 
  // If the Step was determined by the volume boundary,
  // logically relocate the particle
 
  if (fGeometryLimitedStep) {
    // fCurrentTouchable will now become the previous touchable,
    // and what was the previous will be freed.
    // (Needed because the preStepPoint can point to the previous touchable)
 
    fLinearNavigator->SetGeometricallyLimitedStep();
    fLinearNavigator->LocateGlobalPointAndUpdateTouchableHandle(
      track.GetPosition(), track.GetMomentumDirection(),
      fCurrentTouchableHandle, true);
    // Check whether the particle is out of the world volume
    // If so it has exited and must be killed.
    //
    if (fCurrentTouchableHandle->GetVolume() == 0) {
      fParticleChange.ProposeTrackStatus(fStopAndKill);
    }
    retCurrentTouchable = fCurrentTouchableHandle;
    fParticleChange.SetTouchableHandle(fCurrentTouchableHandle);
  }
  else // fGeometryLimitedStep  is false
  {
    // This serves only to move the Navigator's location
    //
    fLinearNavigator->LocateGlobalPointWithinVolume(track.GetPosition());
 
    // The value of the track's current Touchable is retained.
    // (and it must be correct because we must use it below to
    // overwrite the (unset) one in particle change)
    //  It must be fCurrentTouchable too ??
    //
    fParticleChange.SetTouchableHandle(track.GetTouchableHandle());
    retCurrentTouchable = track.GetTouchableHandle();
  } // endif ( fGeometryLimitedStep )
 
  const G4VPhysicalVolume* pNewVol = retCurrentTouchable->GetVolume();
  const G4Material* pNewMaterial = 0;
  const G4VSensitiveDetector* pNewSensitiveDetector = 0;
  if (pNewVol != 0) {
    pNewMaterial = pNewVol->GetLogicalVolume()->GetMaterial();
    pNewSensitiveDetector = pNewVol->GetLogicalVolume()->GetSensitiveDetector();
  }
 
  // ( <const_cast> pNewMaterial ) ;
  // ( <const_cast> pNewSensitiveDetector) ;
 
  fParticleChange.SetMaterialInTouchable((G4Material*)pNewMaterial);
  fParticleChange.SetSensitiveDetectorInTouchable(
    (G4VSensitiveDetector*)pNewSensitiveDetector);
 
  const G4MaterialCutsCouple* pNewMaterialCutsCouple = 0;
  if (pNewVol != 0) {
    pNewMaterialCutsCouple =
      pNewVol->GetLogicalVolume()->GetMaterialCutsCouple();
  }
 
  if (pNewVol != 0 && pNewMaterialCutsCouple != 0 &&
      pNewMaterialCutsCouple->GetMaterial() != pNewMaterial) {
    // for parametrized volume
    //
    pNewMaterialCutsCouple =
      G4ProductionCutsTable::GetProductionCutsTable()->GetMaterialCutsCouple(
        pNewMaterial, pNewMaterialCutsCouple->GetProductionCuts());
  }
  fParticleChange.SetMaterialCutsCoupleInTouchable(pNewMaterialCutsCouple);
 
  // temporarily until Get/Set Material of ParticleChange,
  // and StepPoint can be made const.
  // Set the touchable in ParticleChange
  // this must always be done because the particle change always
  // uses this value to overwrite the current touchable pointer.
  //
  fParticleChange.SetTouchableHandle(retCurrentTouchable);
 
  return &fParticleChange;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
// New method takes over the responsibility to reset the state
// of G4MonopoleTransportation object at the start of a new track
// or the resumption of a suspended track.
 
void G4MonopoleTransportation::StartTracking(G4Track* aTrack)
{
  G4VProcess::StartTracking(aTrack);
 
  // The actions here are those that were taken in AlongStepGPIL
  //   when track.GetCurrentStepNumber()==1
 
  // reset safety value and center
  //
  fPreviousSafety = 0.0;
  fPreviousSftOrigin = G4ThreeVector(0., 0., 0.);
 
  // reset looping counter -- for motion in field
  fNoLooperTrials = 0;
  // Must clear this state .. else it depends on last track's value
  //  --> a better solution would set this from state of suspended track TODO ?
  // Was if( aTrack->GetCurrentStepNumber()==1 ) { .. }
 
  // ChordFinder reset internal state
  //
  if (DoesGlobalFieldExist()) {
    fFieldPropagator->ClearPropagatorState();
    // Resets all state of field propagator class (ONLY)
    // including safety values
    // in case of overlaps and to wipe for first track).
 
    // G4ChordFinder* chordF= fFieldPropagator->GetChordFinder();
    // if( chordF ) chordF->ResetStepEstimate();
  }
 
  // Make sure to clear the chord finders of all fields (ie managers)
  G4FieldManagerStore* fieldMgrStore = G4FieldManagerStore::GetInstance();
  fieldMgrStore->ClearAllChordFindersState();
 
  // Update the current touchable handle  (from the track's)
  //
  fCurrentTouchableHandle = aTrack->GetTouchableHandle();
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......