src/MyGlobalField.cc

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#include <time.h>

#include "Randomize.hh"
#include "G4TransportationManager.hh"

#include "G4ExplicitEuler.hh"
#include "G4ImplicitEuler.hh"
#include "G4SimpleRunge.hh"
#include "G4SimpleHeum.hh"
#include "G4ClassicalRK4.hh"
#include "G4CashKarpRKF45.hh"

#include "MyGlobalField.hh"

MyGlobalField* MyGlobalField::object = 0;

MyGlobalField::MyGlobalField() : G4ElectroMagneticField(),
minStep(0.01*mm), deltaChord(3.0*mm),
deltaOneStep(0.01*mm), deltaIntersection(0.1*mm),
epsMin(2.5e-7*mm), epsMax(0.05*mm),
fEquation(0), fFieldManager(0),
fFieldPropagator(0), fStepper(0), fChordFinder(0) {
    //MyGlobalField::MyGlobalField() : G4MagneticField(),
    //                             minStep(0.01*mm), deltaChord(3.0*mm),
    //                             deltaOneStep(0.01*mm), deltaIntersection(0.1*mm),
    //                             epsMin(2.5e-7*mm), epsMax(0.05*mm),
    //                             fEquation(0), fFieldManager(0),
    //                             fFieldPropagator(0), fStepper(0), fChordFinder(0)
    fGlobalFieldMessenger = new MyGlobalFieldMessenger(this);

    fields = new FieldList();

    fStepperType = 4 ;                                // ClassicalRK4 is default stepper

    //  set object

    object = this;

    updateField();
}


MyGlobalField::~MyGlobalField() {
    clear();

    delete fGlobalFieldMessenger;

    if (fEquation)        delete fEquation;
    if (fFieldManager)    delete fFieldManager;
    if (fFieldPropagator) delete fFieldPropagator;
    if (fStepper)         delete fStepper;
    if (fChordFinder)     delete fChordFinder;
}


void MyGlobalField::updateField() {
    first = true;

    nfp = 0;
    fp = 0;

    clear();

    //  Construct equ. of motion of particles through B fields
    //  fEquation = new G4Mag_EqRhs(this);
    //  Construct equ. of motion of particles through e.m. fields
    //  fEquation = new G4EqMagElectricField(this);
    //  Construct equ. of motion of particles including spin through B fields
    //  fEquation = new G4Mag_SpinEqRhs(this);
    //  Construct equ. of motion of particles including spin through e.m. fields
    fEquation = new G4EqEMFieldWithSpin(this);

    //  Get transportation, field, and propagator managers
    G4TransportationManager* fTransportManager =
        G4TransportationManager::GetTransportationManager();

    fFieldManager = GetGlobalFieldManager();

    fFieldPropagator = fTransportManager->GetPropagatorInField();

    //  Need to SetFieldChangesEnergy to account for a time varying electric
    //  field (r.f. fields)
    fFieldManager->SetFieldChangesEnergy(true);

    //  Set the field
    fFieldManager->SetDetectorField(this);

    //  Choose a stepper for integration of the equation of motion
    SetStepper();

    //  Create a cord finder providing the (global field, min step length,
    //  a pointer to the stepper)
    fChordFinder = new G4ChordFinder((G4MagneticField*)this,minStep,fStepper);

    // Set accuracy parameters
    fChordFinder->SetDeltaChord( deltaChord );

    fFieldManager->SetAccuraciesWithDeltaOneStep(deltaOneStep);

    fFieldManager->SetDeltaIntersection(deltaIntersection);

    fFieldPropagator->SetMinimumEpsilonStep(epsMin);
    fFieldPropagator->SetMaximumEpsilonStep(epsMax);

    G4cout << "Accuracy Parameters:" <<
        " MinStep=" << minStep <<
        " DeltaChord=" << deltaChord <<
        " DeltaOneStep=" << deltaOneStep << G4endl;
    G4cout << "                    " <<
        " DeltaIntersection=" << deltaIntersection <<
        " EpsMin=" << epsMin <<
        " EpsMax=" << epsMax <<  G4endl;

    fFieldManager->SetChordFinder(fChordFinder);

}


MyGlobalField* MyGlobalField::getObject() {
    if (!object) new MyGlobalField();
    return object;
}


void MyGlobalField::SetStepper() {
    if(fStepper) delete fStepper;

    switch ( fStepperType ) {
        case 0:
            //      fStepper = new G4ExplicitEuler( fEquation, 8 ); // no spin tracking
                                                      // with spin tracking
            fStepper = new G4ExplicitEuler( fEquation, 12 );
            G4cout << "G4ExplicitEuler is called" << G4endl;
            break;
        case 1:
            //      fStepper = new G4ImplicitEuler( fEquation, 8 ); // no spin tracking
                                                      // with spin tracking
            fStepper = new G4ImplicitEuler( fEquation, 12 );
            G4cout << "G4ImplicitEuler is called" << G4endl;
            break;
        case 2:
            //      fStepper = new G4SimpleRunge( fEquation, 8 ); // no spin tracking
                                                      // with spin tracking
            fStepper = new G4SimpleRunge( fEquation, 12 );
            G4cout << "G4SimpleRunge is called" << G4endl;
            break;
        case 3:
            //      fStepper = new G4SimpleHeum( fEquation, 8 ); // no spin tracking
                                                      // with spin tracking
            fStepper = new G4SimpleHeum( fEquation, 12 );
            G4cout << "G4SimpleHeum is called" << G4endl;
            break;
        case 4:
            //      fStepper = new G4ClassicalRK4( fEquation, 8 ); // no spin tracking
                                                      // with spin tracking
            fStepper = new G4ClassicalRK4( fEquation, 12 );
            G4cout << "G4ClassicalRK4 (default) is called" << G4endl;
            break;
        case 5:
            //      fStepper = new G4CashKarpRKF45( fEquation, 8 ); // no spin tracking
                                                      // with spin tracking
            fStepper = new G4CashKarpRKF45( fEquation, 12 );
            G4cout << "G4CashKarpRKF45 is called" << G4endl;
            break;
        default: fStepper = 0;
    }
}


G4FieldManager* MyGlobalField::GetGlobalFieldManager() {
    return G4TransportationManager::GetTransportationManager()
        ->GetFieldManager();
}


void MyGlobalField::GetFieldValue(const G4double* point, G4double* field) const {
    // NOTE: this routine dominates the CPU time for tracking.
    // Using the simple array fp[] instead of fields[]
    // directly sped it up

    field[0] = field[1] = field[2] = field[3] = field[4] = field[5] = 0.0;

    // protect against Geant4 bug that calls us with point[] NaN.
    if(point[0] != point[0]) return;

    // (can't use nfp or fp, as they may change)
    if (first) ((MyGlobalField*)this)->setupArray();  // (cast away const)

    for (int i=0; i<nfp; ++i) {
        const MyElementField* p = fp[i];
        if (p->isInBoundingBox(point)) {
            p->addFieldValue(point,field);
        }
    }

    if(0) {
        G4cout << "Point = [" << point[0]/cm << ", "
            << point[1]/cm << ", " << point[2]/cm << "] cm" << G4endl;
        G4cout << " Field = [" << field[0]/tesla << ", " << field[1]/tesla << ", "
            << field[2]/tesla << "]" << G4endl
            << "         [" << field[3] << ", " << field[4]
            << ", " << field[5]<< "] " << G4endl;
    }
}


void MyGlobalField::clear() {
    if (fields) {
        if (fields->size()>0) {
            FieldList::iterator i;
            for (i=fields->begin(); i!=fields->end(); ++i) delete *i;
            fields->clear();
        }
    }

    if (fp) delete[] fp;

    first = true;

    nfp = 0;
    fp = NULL;
}


void MyGlobalField::setupArray() {
    first = false;
    nfp = fields->size();
    fp = new const MyElementField* [nfp+1];           // add 1 so it's never 0
    for (int i=0; i<nfp; ++i) fp[i] = (*fields)[i];

    //G4cout << " In MyGlobalField::setupArray nfp is " << nfp << G4endl;
}

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