Speaker
Description
We report developments for the Geant4 electromagnetic (EM) physics sub-packages for Geant4 release 10.4 and beyond. Modifications are introduced to the models of photo-electric effect, bremsstrahlung, gamma conversion, and multiple scattering. Important developments for calorimetry applications were carried out for the modeling of single and multiple scattering of charged particles. Corrections to scattering of positrons and to sampling of displacement have been recently added to the Geant4 default Urban model. The fully theory-based Goudsmit-Saunderson (GS) model for electron/positron multiple scattering has been recently reviewed and a new improved version is available. For testing purposes for novel calorimeters we provide a configuration of electron scattering based on the GS model or on the single scattering model (SS) instead of the Urban model. In addition, the GS model with enabled Mott corrections is included into the EM physics constructor, which recommended for accurate simulations. This EM configuration provides the most accurate results for scattering of electrons and positrons. To improve usability, a new set of User Interface (UI) commands and corresponding C++ interfaces have been added for easier configuration of EM physics. In particular, photo-absorption ionisation model may be enabled per detector region using corresponding UI command. Interfaces to material properties were improved, which includes density effect parameterization for compounds and optical parameters of materials. The last modification allows significantly speed up of the simulation of optical photon transport. These new interfaces and models are already used in LHC applications and may be useful for any type of simulations. We discuss their effective usage for various applications including possible improvements for simulation of LHC and dark matter experiments.
