Gabriele Cosmo
122 lines
4.8 KiB
Plaintext
122 lines
4.8 KiB
Plaintext
//
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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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// class G4BFieldIntegrationDriver
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//
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// Class description:
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//
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// Specialized integration driver for pure magnetic field
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// Author: D.Sorokin, CERN
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// --------------------------------------------------------------------
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#include "globals.hh"
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#include "G4GeometryTolerance.hh"
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#include "G4FieldTrack.hh"
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#include "G4FieldUtils.hh"
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namespace internal
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{
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G4Mag_EqRhs* toMagneticEquation(G4EquationOfMotion* equation)
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{
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auto e = dynamic_cast<G4Mag_EqRhs*>(equation);
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if (!e)
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{
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G4Exception("G4BFieldIntegrationDriver::G4BFieldIntegrationDriver",
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"GeomField0003", FatalErrorInArgument,
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"Works only with G4Mag_EqRhs");
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}
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return e;
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}
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} // internal
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template <class T>
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G4BFieldIntegrationDriver<T>::G4BFieldIntegrationDriver(G4double hminimum,
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T* pStepper,
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G4int numComponents,
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G4int statisticsVerbose)
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: G4IntegrationDriver<T>(hminimum, pStepper, numComponents, statisticsVerbose),
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fallbackThreshold(pi / 3.),
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fequation(internal::toMagneticEquation(pStepper->GetEquationOfMotion())),
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fallbackStepper(fequation)
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{
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}
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template <class T>
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bool G4BFieldIntegrationDriver<T>::QuickAdvance(G4FieldTrack& fieldTrack,
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const G4double dydx[],
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G4double hstep,
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G4double inverseCurvatureRadius,
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G4double& dchord_step,
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G4double& dyerr)
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{
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if (hstep * inverseCurvatureRadius < fallbackThreshold)
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{
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return G4IntegrationDriver<T>::QuickAdvance(
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fieldTrack, dydx, hstep, inverseCurvatureRadius, dchord_step, dyerr);
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}
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G4IntegrationDriver<T>::IncrementQuickAdvanceCalls();
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G4double yError[G4FieldTrack::ncompSVEC],
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yIn[G4FieldTrack::ncompSVEC],
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yOut[G4FieldTrack::ncompSVEC];
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fieldTrack.DumpToArray(yIn);
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fallbackStepper.Stepper(yIn, dydx, hstep, yOut, yError);
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dchord_step = fallbackStepper.DistChord();
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dyerr = field_utils::absoluteError(yOut, yError, hstep);
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fieldTrack.LoadFromArray(yOut, fallbackStepper.GetNumberOfVariables());
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fieldTrack.SetCurveLength(fieldTrack.GetCurveLength() + hstep);
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return true;
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}
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template <class T>
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void G4BFieldIntegrationDriver<T>::
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SetEquationOfMotion(G4EquationOfMotion* equation)
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{
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G4IntegrationDriver<T>::SetEquationOfMotion(equation);
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fequation = internal::toMagneticEquation(equation);
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}
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template <class T>
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G4double G4BFieldIntegrationDriver<T>::
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GetInverseCurvatureRadius(const G4FieldTrack& track,
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G4double field[]) const
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{
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const G4double Bmag = std::sqrt(field[0] * field[0]
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+ field[1] * field[1] + field[2] * field[2]);
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const G4double momentum = track.GetMomentum().mag();
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const G4double particleCharge = fequation->FCof()
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/ (CLHEP::eplus * CLHEP::c_light);
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return std::abs(field_utils::inverseCurvatureRadius(particleCharge,
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momentum, Bmag));
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}
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