| 1 | //
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| 2 | // ********************************************************************
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| 3 | // * License and Disclaimer *
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| 4 | // * *
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of *
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and *
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| 7 | // * conditions of the Geant4 Software License, included in the file *
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These *
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| 9 | // * include a list of copyright holders. *
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| 10 | // * *
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| 11 | // * Neither the authors of this software system, nor their employing *
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| 12 | // * institutes,nor the agencies providing financial support for this *
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| 13 | // * work make any representation or warranty, express or implied, *
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| 14 | // * regarding this software system or assume any liability for its *
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| 15 | // * use. Please see the license in the file LICENSE and URL above *
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| 16 | // * for the full disclaimer and the limitation of liability. *
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| 17 | // * *
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| 18 | // * This code implementation is the result of the scientific and *
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| 19 | // * technical work of the GEANT4 collaboration. *
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| 20 | // * By using, copying, modifying or distributing the software (or *
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| 21 | // * any work based on the software) you agree to acknowledge its *
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| 22 | // * use in resulting scientific publications, and indicate your *
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| 23 | // * acceptance of all terms of the Geant4 Software license. *
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| 24 | // ********************************************************************
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| 25 | //
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| 26 | //
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| 27 | // $Id: G4Mag_UsualEqRhs.cc,v 1.12 2006/06/29 18:24:42 gunter Exp $
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| 28 | // GEANT4 tag $Name: geant4-09-02-cand-01 $
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| 29 | //
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| 30 | //
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| 31 | // This is the 'standard' right-hand side for the equation of motion
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| 32 | // of a charged particle in a magnetic field.
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| 33 | //
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| 34 | // Initial version: J. Apostolakis, January 13th, 1997
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| 35 | //
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| 36 | // --------------------------------------------------------------------
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| 37 |
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| 38 | #include "G4Mag_UsualEqRhs.hh"
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| 39 | #include "G4MagneticField.hh"
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| 40 |
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| 41 | G4Mag_UsualEqRhs::G4Mag_UsualEqRhs( G4MagneticField* MagField )
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| 42 | : G4Mag_EqRhs( MagField ) {}
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| 43 |
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| 44 | G4Mag_UsualEqRhs::~G4Mag_UsualEqRhs() {}
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| 45 |
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| 46 | void
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| 47 | G4Mag_UsualEqRhs::EvaluateRhsGivenB( const G4double y[],
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| 48 | const G4double B[3],
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| 49 | G4double dydx[] ) const
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| 50 | {
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| 51 | G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5];
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| 52 | G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
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| 53 |
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| 54 | G4double cof = FCof()*inv_momentum_magnitude;
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| 55 |
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| 56 | dydx[0] = y[3]*inv_momentum_magnitude; // (d/ds)x = Vx/V
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| 57 | dydx[1] = y[4]*inv_momentum_magnitude; // (d/ds)y = Vy/V
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| 58 | dydx[2] = y[5]*inv_momentum_magnitude; // (d/ds)z = Vz/V
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| 59 |
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| 60 | dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; // Ax = a*(Vy*Bz - Vz*By)
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| 61 | dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; // Ay = a*(Vz*Bx - Vx*Bz)
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| 62 | dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; // Az = a*(Vx*By - Vy*Bx)
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| 63 |
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| 64 | return ;
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| 65 | }
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| 66 |
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| 67 | void
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| 68 | G4Mag_UsualEqRhs::
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| 69 | SetChargeMomentumMass( G4double particleCharge, // in e+ units
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| 70 | G4double MomentumXc,
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| 71 | G4double mass)
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| 72 |
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| 73 | {
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| 74 | fInvCurrentMomentumXc= 1.0 / MomentumXc;
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| 75 | G4Mag_EqRhs::SetChargeMomentumMass( particleCharge, MomentumXc, mass);
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| 76 | }
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