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

Tracking and Physicsand cannot be described here (see again hep-ex/0001020). For brave users the Gflash framework already forseesthe possibility of passing a class with the (users) parameters,GVFlashHomoShowerTuning, to the GFlashHomoShowerParamterisationconstructor. The default parameters are the original Gflash parameters:GFlashHomoShowerParameterisation(G4Material * aMat, GVFlashHomoShowerTuning * aPar = 0);Now there is also a preliminary implemenation of a parameterization for sampling calorimeters.The user must specify the active and passive material, as well as the thickness of the active and passive layer.The sampling structure of the calorimeter is taken into account by using an "effective medium" to compute theshower shape.All material properties needed are calculated automatically. If tuning is required, the user can pass his own parameterset in the class GFlashSamplingShowerTuning. Here the user can also set his calorimeter resolution.All in all the constructor looks the following:GFlashSamplingShowerParamterisation(G4Material * Mat1, G4Material * Mat2,G4double d1,G4double d2,GVFlashSamplingShowerTuning * aPar = 0);An implementation of some tools that should help the user to tune the parameterization is forseen.5.2.7. Transportation ProcessTo be delivered by J. Apostolakis ().5.3. Particles5.3.1. Basic conceptsThere are three levels of classes to describe particles in Geant4.G4ParticleDefinitiondefines a particleG4DynamicParticledescribes a particle interacting with materialsG4Trackdescribes a particle traveling in space and timeG4ParticleDefinition aggregates information to characterize a particle's properties, such as name, mass, spin, lifetime, and decay modes. G4DynamicParticle aggregates information to describe the dynamics of particles, such asenergy, momentum, polarization, and proper time, as well as ``particle definition'' information. G4Track includesall information necessary for tracking in a detector simulation, such as time, position, and step, as well as ``dynamicparticle'' information.G4Track has all the information necessary for tracking in Geant4. It includes position, time, and step, as well askinematics. Details of G4Track will be described in Section 5.1.5.3.2. Definition of a particleThere are a large number of elementary particles and nuclei. Geant4 provides the G4ParticleDefinition class torepresent particles, and various particles, such as the electron, proton, and gamma have their own classes derivedfrom G4ParticleDefinition.179