Recent developments in Geant4

Abstract During the last two to three years extensive development of the G eant 4 simulation toolkit has occurred, which will culminate in a major release at the end of 2013. This development includes the adoption of multi-threading, the extension and improvement of physics models, improvements to the geometry modeler with a revised implementation of most geometrical primitives, advances in visualization and graphical user interfaces (GUI), the move from GNU make to CMake and the extension and automation of the G eant 4 testing suite. The reasons for and implementation of multi-threading will be discussed. Certain electromagnetic and hadronic model extensions will also be discussed along with their effects on calorimeter results. Finally, visualization and GUI improvements will be highlighted along with the new configuration, build and testing systems.