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1 // 1 // 2 // ******************************************* 2 // ******************************************************************** 3 // * License and Disclaimer 3 // * License and Disclaimer * 4 // * 4 // * * 5 // * The Geant4 software is copyright of th 5 // * The Geant4 software is copyright of the Copyright Holders of * 6 // * the Geant4 Collaboration. It is provided 6 // * the Geant4 Collaboration. It is provided under the terms and * 7 // * conditions of the Geant4 Software License 7 // * conditions of the Geant4 Software License, included in the file * 8 // * LICENSE and available at http://cern.ch/ 8 // * LICENSE and available at http://cern.ch/geant4/license . These * 9 // * include a list of copyright holders. 9 // * include a list of copyright holders. * 10 // * 10 // * * 11 // * Neither the authors of this software syst 11 // * Neither the authors of this software system, nor their employing * 12 // * institutes,nor the agencies providing fin 12 // * institutes,nor the agencies providing financial support for this * 13 // * work make any representation or warran 13 // * work make any representation or warranty, express or implied, * 14 // * regarding this software system or assum 14 // * regarding this software system or assume any liability for its * 15 // * use. Please see the license in the file 15 // * use. Please see the license in the file LICENSE and URL above * 16 // * for the full disclaimer and the limitatio 16 // * for the full disclaimer and the limitation of liability. * 17 // * 17 // * * 18 // * This code implementation is the result 18 // * This code implementation is the result of the scientific and * 19 // * technical work of the GEANT4 collaboratio 19 // * technical work of the GEANT4 collaboration. * 20 // * By using, copying, modifying or distri 20 // * By using, copying, modifying or distributing the software (or * 21 // * any work based on the software) you ag 21 // * any work based on the software) you agree to acknowledge its * 22 // * use in resulting scientific publicati 22 // * use in resulting scientific publications, and indicate your * 23 // * acceptance of all terms of the Geant4 Sof 23 // * acceptance of all terms of the Geant4 Software license. * 24 // ******************************************* 24 // ******************************************************************** 25 // 25 // 26 // G4Mag_SpinEqRhs implementation << 27 // 26 // 28 // Created: J.Apostolakis, P.Gumplinger - 08.0 << 27 // >> 28 // This is the standard right-hand side for equation of motion. >> 29 // This version of the right-hand side includes the three components >> 30 // of the particle's spin. >> 31 // >> 32 // J. Apostolakis, February 8th, 1999 >> 33 // P. Gumplinger, February 8th, 1999 >> 34 // D. Cote-Ahern, P. Gumplinger, April 11th, 2001 >> 35 // 29 // ------------------------------------------- 36 // -------------------------------------------------------------------- 30 37 31 #include "G4Mag_SpinEqRhs.hh" 38 #include "G4Mag_SpinEqRhs.hh" 32 #include "G4PhysicalConstants.hh" 39 #include "G4PhysicalConstants.hh" 33 #include "G4SystemOfUnits.hh" 40 #include "G4SystemOfUnits.hh" 34 #include "G4MagneticField.hh" 41 #include "G4MagneticField.hh" 35 #include "G4ThreeVector.hh" 42 #include "G4ThreeVector.hh" 36 43 37 G4Mag_SpinEqRhs::G4Mag_SpinEqRhs( G4MagneticFi 44 G4Mag_SpinEqRhs::G4Mag_SpinEqRhs( G4MagneticField* MagField ) 38 : G4Mag_EqRhs( MagField ) << 45 : G4Mag_EqRhs( MagField ), charge(0.), mass(0.), magMoment(0.), >> 46 spin(0.), omegac(0.), anomaly(0.0011659208), beta(0.), gamma(0.) 39 { 47 { 40 } 48 } 41 49 42 G4Mag_SpinEqRhs::~G4Mag_SpinEqRhs() = default; << 50 G4Mag_SpinEqRhs::~G4Mag_SpinEqRhs() >> 51 { >> 52 } 43 53 44 void 54 void 45 G4Mag_SpinEqRhs::SetChargeMomentumMass(G4Charg 55 G4Mag_SpinEqRhs::SetChargeMomentumMass(G4ChargeState particleCharge, 46 G4doubl 56 G4double MomentumXc, 47 G4doubl 57 G4double particleMass) 48 { 58 { 49 G4Mag_EqRhs::SetChargeMomentumMass( particl 59 G4Mag_EqRhs::SetChargeMomentumMass( particleCharge, MomentumXc, mass); 50 60 51 charge = particleCharge.GetCharge(); 61 charge = particleCharge.GetCharge(); 52 mass = particleMass; 62 mass = particleMass; 53 magMoment = particleCharge.GetMagneticDipol 63 magMoment = particleCharge.GetMagneticDipoleMoment(); 54 spin = particleCharge.GetSpin(); 64 spin = particleCharge.GetSpin(); 55 65 56 omegac = (eplus/mass)*c_light; 66 omegac = (eplus/mass)*c_light; 57 67 58 G4double muB = 0.5*eplus*hbar_Planck/(mass/ 68 G4double muB = 0.5*eplus*hbar_Planck/(mass/c_squared); 59 69 60 G4double g_BMT; 70 G4double g_BMT; 61 if ( spin != 0. ) << 71 if ( spin != 0. ) g_BMT = (std::abs(magMoment)/muB)/spin; 62 { << 72 else g_BMT = 2.; 63 g_BMT = (std::abs(magMoment)/muB)/spin; << 64 } << 65 else << 66 { << 67 g_BMT = 2.; << 68 } << 69 73 70 anomaly = (g_BMT - 2.)/2.; 74 anomaly = (g_BMT - 2.)/2.; 71 75 72 G4double E = std::sqrt(sqr(MomentumXc)+sqr( 76 G4double E = std::sqrt(sqr(MomentumXc)+sqr(mass)); 73 beta = MomentumXc/E; 77 beta = MomentumXc/E; 74 gamma = E/mass; 78 gamma = E/mass; 75 } 79 } 76 80 77 void 81 void 78 G4Mag_SpinEqRhs::EvaluateRhsGivenB( const G4do 82 G4Mag_SpinEqRhs::EvaluateRhsGivenB( const G4double y[], 79 const G4do 83 const G4double B[3], 80 G4do 84 G4double dydx[] ) const 81 { 85 { 82 G4double momentum_mag_square = sqr(y[3]) + 86 G4double momentum_mag_square = sqr(y[3]) + sqr(y[4]) + sqr(y[5]); 83 G4double inv_momentum_magnitude = 1.0 / std 87 G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square ); 84 G4double cof = FCof()*inv_momentum_magnitud 88 G4double cof = FCof()*inv_momentum_magnitude; 85 89 86 dydx[0] = y[3] * inv_momentum_magnitude; 90 dydx[0] = y[3] * inv_momentum_magnitude; // (d/ds)x = Vx/V 87 dydx[1] = y[4] * inv_momentum_magnitude; 91 dydx[1] = y[4] * inv_momentum_magnitude; // (d/ds)y = Vy/V 88 dydx[2] = y[5] * inv_momentum_magnitude; 92 dydx[2] = y[5] * inv_momentum_magnitude; // (d/ds)z = Vz/V 89 93 90 if (charge == 0.) << 94 if (charge == 0.) { 91 { << 92 dydx[3] = 0.; 95 dydx[3] = 0.; 93 dydx[4] = 0.; 96 dydx[4] = 0.; 94 dydx[5] = 0.; 97 dydx[5] = 0.; 95 } << 98 } else { 96 else << 97 { << 98 dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; 99 dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; // Ax = a*(Vy*Bz - Vz*By) 99 dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; 100 dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; // Ay = a*(Vz*Bx - Vx*Bz) 100 dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; 101 dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; // Az = a*(Vx*By - Vy*Bx) 101 } 102 } 102 103 103 G4ThreeVector u(y[3], y[4], y[5]); 104 G4ThreeVector u(y[3], y[4], y[5]); 104 u *= inv_momentum_magnitude; 105 u *= inv_momentum_magnitude; 105 106 106 G4ThreeVector BField(B[0],B[1],B[2]); 107 G4ThreeVector BField(B[0],B[1],B[2]); 107 108 108 G4double udb = anomaly*beta*gamma/(1.+gamma 109 G4double udb = anomaly*beta*gamma/(1.+gamma) * (BField * u); 109 G4double ucb = (anomaly+1./gamma)/beta; 110 G4double ucb = (anomaly+1./gamma)/beta; 110 111 111 // Initialise the values of dydx that we do 112 // Initialise the values of dydx that we do not update. 112 dydx[6] = dydx[7] = dydx[8] = 0.0; 113 dydx[6] = dydx[7] = dydx[8] = 0.0; 113 114 114 G4ThreeVector Spin(y[9],y[10],y[11]); 115 G4ThreeVector Spin(y[9],y[10],y[11]); 115 116 116 G4double pcharge; 117 G4double pcharge; 117 if (charge == 0.) << 118 if (charge == 0.) pcharge = 1.; 118 { << 119 else pcharge = charge; 119 pcharge = 1.; << 120 } << 121 else << 122 { << 123 pcharge = charge; << 124 } << 125 120 126 G4ThreeVector dSpin(0.,0.,0.); 121 G4ThreeVector dSpin(0.,0.,0.); 127 if (Spin.mag2() != 0.) << 122 if (Spin.mag2() != 0.) { 128 { << 123 dSpin = pcharge*omegac*(ucb*(Spin.cross(BField))-udb*(Spin.cross(u))); 129 dSpin = pcharge*omegac*(ucb*(Spin.cross(B << 130 } 124 } 131 125 132 dydx[9] = dSpin.x(); << 126 dydx[ 9] = dSpin.x(); 133 dydx[10] = dSpin.y(); 127 dydx[10] = dSpin.y(); 134 dydx[11] = dSpin.z(); 128 dydx[11] = dSpin.z(); 135 129 136 return; << 130 return ; 137 } 131 } 138 132