GEANT - Detector Description and Simulation Tool

The GEANT program describes the passage of elementary particles through the matter. Originally designed for the High Energy Physics experiments, it has today found applications also outside this domain in the areas of medical and biological sciencies, radioprotection and astronautics. The principal applications of GEANT in High Energy Physics are:
  1. the tracking of particles through an experimental setup for simulation of detector response
  2. the graphical representation of the setup and of the particle trajectories.

Documentation in Postscript, PDF and in HTML3
This is the latest version of the GEANT manual. You will need a browser capable of viewing the HTML3 to view the online version of the document.
Latest information about GEANT4, the new production simulation toolkit.
Latest version
Obtain the latest version of GEANT and other Cern libraries for different architectures and operating systems.
CADD - Computer Aided Detector Design
Would you like to have the detector structure transferred to another design program?
If you are not familiar with GEANT and want to learn to use it, this is probably where you want to go.
Frequently asked questions are listed here as well as answers to them.
Bug reports
If you believe you have found a bug, please report this problem to Please provide sufficient detail allowing us to reproduce and understand the problem, e.g. version of geant, hardware and OS, etc.

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Last Mod. 7 May 2003 (John Apostolakis).