Geant4 User's Guide for Application Developers - Geant4 - CERN

Tracking and PhysicsInformation in G4Step includes:• Pointers to PreStep and PostStepPoint• Geometrical step length (step length before the correction of multiple scattering)• True step length (step length after the correction of multiple scattering)• Increment of position and time between PreStepPoint and PostStepPoint• Increment of momentum and energy between PreStepPoint and PostStepPoint. (Note: to get the energydeposited in the step, you cannot use this 'Delta energy'. You have to use 'Total energy deposit' as below.)• Pointer to G4Track• Total energy deposited during the step - this is the sum of• the energy deposited by the energy loss process, and• the energy lost by secondaries which have NOT been generated because each of their energies was belowthe cut threshold• Energy deposited not by ionization during the stepInformation in G4StepPoint (PreStepPoint and PostStepPoint) includes:• (x, y, z, t)• (px, py, pz, Ek)• Momentum direction (unit vector)• Pointers to physical volumes• Safety• Beta, gamma• Polarization• Step status• Pointer to the physics process which defined the current step and its DoIt type• Pointer to the physics process which defined the previous step and its DoIt type• Total track length• Global time (time since the current event began)• Local time (time since the current track began)• Proper timeHow to Get "particle change"Particle change information can be accessed by invoking various Get methods provided in the G4ParticleChangeclass. Typical information available includes (for details, see the Software Reference Manual):• final momentum direction of the parent particle• final kinetic energy of the parent particle• final position of the parent particle• final global time of the parent particle• final proper time of the parent particle• final polarization of the parent particle• status of the parent particle (G4TrackStatus)• true step length (this is used by multiple scattering to store the result of the transformation from the geometricalstep length to the true step length)• local energy deposited - this consists of either• energy deposited by the energy loss process, or• the energy lost by secondaries which have NOT been generated because each of their energies was belowthe cut threshold.• number of secondaries particles• list of secondary particles (list of G4Track)5.1.3. Handling of Secondary ParticlesSecondary particles are passed as G4Tracks from a physics process to tracking. G4ParticleChange provides thefollowing four methods for a physics process:145