Geant4 is a toolkit to simulate the interaction of particles in matter, created by the Geant4 Collaboration. The SFT group provides a team that undertakes the development, maintenance and support of several modules, including the geometry and a number of physics models, and provides infrastructure for collaborating on, testing and releasing the software in support of the project.
 

Geometry and Field Transport
The Geant4 geometry team in SFT is responsible for and leads the development and maintenance of the geometry modeller in the Geant4 toolkit. The development in the Geant4 geometry modeller spans the following areas: geometrical shapes definition, navigation algorithms, detector modelling techniques (volumes positioning), transportation in field and importance biasing techniques.

E-M and Hadronic Physics
Provides models of hadronic/nuclear interactions with matter, including the high energy String models, the Binary Cascade and the de-excitation models. In addition members contribute to the development and support of a complete set of models for simulating electromagnetic interactions of leptons and hadrons for HEP experiments. We provide and validate several physics lists (configurations of Geant4 physics models) focusing on those used for production or for the investigation of systematics in LHC and other HEP experiments.

Testing and Release Management
Undertakes system testing and release of the Geant4 software. Manages the distribution of the software for public releases for download from the web, and provides internal development releases on CVMFS for CERN experiments and users. Undertakes the execution and monitoring of an extensive suite of integration tests covering all components of the toolkit. Tracks CPU performance for chosen benchmark use cases and undertakes regression testing of development and candidate Geant4 releases. Also involved in porting the code to new platforms and compilers.