00001 // 00002 // ******************************************************************** 00003 // * License and Disclaimer * 00004 // * * 00005 // * The Geant4 software is copyright of the Copyright Holders of * 00006 // * the Geant4 Collaboration. It is provided under the terms and * 00007 // * conditions of the Geant4 Software License, included in the file * 00008 // * LICENSE and available at http://cern.ch/geant4/license . These * 00009 // * include a list of copyright holders. * 00010 // * * 00011 // * Neither the authors of this software system, nor their employing * 00012 // * institutes,nor the agencies providing financial support for this * 00013 // * work make any representation or warranty, express or implied, * 00014 // * regarding this software system or assume any liability for its * 00015 // * use. Please see the license in the file LICENSE and URL above * 00016 // * for the full disclaimer and the limitation of liability. * 00017 // * * 00018 // * This code implementation is the result of the scientific and * 00019 // * technical work of the GEANT4 collaboration. * 00020 // * By using, copying, modifying or distributing the software (or * 00021 // * any work based on the software) you agree to acknowledge its * 00022 // * use in resulting scientific publications, and indicate your * 00023 // * acceptance of all terms of the Geant4 Software license. * 00024 // ******************************************************************** 00025 // 00026 // 00027 // This is the right-hand side for equation of motion for a 00028 // massive particle in a gravitational field. 00029 // 00030 // History: 00031 // - 14.06.11 P.Gumplinger, Created. 00032 // ------------------------------------------------------------------- 00033 // Adopted from G4EqMagElectricField.hh 00034 // 00035 // Thanks to Peter Fierlinger (PSI) and 00036 // A. Capra and A. Fontana (INFN Pavia) 00037 // ------------------------------------------------------------------- 00038 00039 #include "G4EqGravityField.hh" 00040 #include "globals.hh" 00041 #include "G4PhysicalConstants.hh" 00042 00043 void 00044 G4EqGravityField::SetChargeMomentumMass(G4double, 00045 G4double, 00046 G4double particleMass ) 00047 { 00048 fMass = particleMass; 00049 } 00050 00051 void 00052 G4EqGravityField::EvaluateRhsGivenB(const G4double y[], 00053 const G4double G[], 00054 G4double dydx[] ) const 00055 { 00056 00057 // Components of y: 00058 // 0-2 dr/ds, 00059 // 3-5 dp/ds - momentum derivatives 00060 00061 G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5]; 00062 G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square ); 00063 00064 G4double Energy = std::sqrt(momentum_mag_square + fMass*fMass); 00065 G4double cof2 = Energy/c_light; 00066 G4double cof1 = inv_momentum_magnitude*fMass; 00067 G4double inverse_velocity = Energy*inv_momentum_magnitude/c_light; 00068 00069 dydx[0] = y[3]*inv_momentum_magnitude; // (d/ds)x = Vx/V 00070 dydx[1] = y[4]*inv_momentum_magnitude; // (d/ds)y = Vy/V 00071 dydx[2] = y[5]*inv_momentum_magnitude; // (d/ds)z = Vz/V 00072 00073 dydx[3] = G[0]*cof1*cof2; 00074 dydx[4] = G[1]*cof1*cof2; // m*g 00075 dydx[5] = G[2]*cof1*cof2; 00076 00077 // Lab Time of flight 00078 dydx[7] = inverse_velocity; 00079 00080 return; 00081 }