Table of Contents ECSS Model Page
Background Information Background Information
Geant4 tools

Table of contents

  1. Background on Geant4
  2. Geant4 tools in the SPENVIS environment
  3. References

Background on Geant4

Geant4 is a toolkit for the Monte Carlo simulation of the passage of particles through matter. Its application areas include high-energy physics and nuclear experiments, medical, accelerator and space physics studies.

Geant4 provides a complete set of tools for all the domains of detector simulation: Geometry, Tracking, Detector Response, Run, Event and Track management, Visualisation and User Interface. An abundant set of physics processes handles the diverse interactions of particles with matter across a wide energy range, as required by Geant4's multi-disciplinary nature; for many physics processes a choice of different models is available.

In addition a large set of utilities, including a powerful set of random number generators, physics units and constants, Particle Data Group compliant Particle management, as well as interfaces to event generators and to object persistency solutions, complete the toolkit.

Geant4 exploits advanced Software Engineering techniques and Object Oriented technology to achieve the transparency of the physics implementation and hence provide the possibility of validating the physics results. The Geant4 Object Oriented design allows the user to understand, customise or extend the toolkit in all the domains. At the same time, the modular architecture of Geant4 allows the user to load and use only the components needed.

The Geant4 software was developed by RD44, a world-wide collaboration of about 100 scientists participating in more than 10 experiments in Europe, Russia, Japan, Canada and the United States. Since 1999 the Production Service, User Support and development of Geant4 have been managed by the international Geant4 Collaboration, which is based on a Memorandum of Understanding among the participating Laboratories, Experiments and National Institutes. Many specialised working groups are responsible for the various domains of the toolkit.

The Geant4 source code is freely available, accompanied by an Installation Guide and an extensive set of documentation.[2] In general, one needs to install the Geant4 source code in order to recompile code for a particular Geant4 application. However, this is not necessary when a static version of this program is available ( e.g. the SPENVIS version of MULASSIS).

Geant4 tools in the SPENVIS environment

The following table gives an overview of the various Geant4 tools available in SPENVIS.

Tool name Tool version
(Geant4 version)
Home page
MULASSIS V1.26 (4.10.1p3) ESA European Space Software Repository
V1.23 (4.9.5p02)
GEMAT V2.8 (4.9.5p02)
SSAT V2.1 (4.9.0) ESA TEC-EPS SVN Repository
GRAS V4.0 (4.10.3p3) ESA European Space Software Repository
V3.1 (4.9.5p02)

The SPENVIS interface of all these tools simplifies the process of defining run parameters using a number of input pages (see the detailed tool help pages for more information).

Advanced users have the option to input a number of fine-tuning parameters.

The Geant4 tools use a Monte-Carlo simulation-based code and execution times can be very long. In order to guarantee the consistency between the different models available in the SPENVIS system (e.g. particle spectrum vs. total ionising dose), the user project is 'blocked' while running any simulation. However, navigation remains possible. The excution is limited to ten minutes of CPU-time on the simulation machine. If the application run exceeds this limit, the simulation will be terminated and intermediate results returned to the user.


  1. ESA TEC-EPS SVN Repository
  2. Geant4 website
  3. Geant4 Space Users Page
  4. Geant4 Physics Reference Manual

Last update: Thu, 16 Jun 2022