User Documentation

Version: Geant4 11.1 (Documentation Update: 9th December 2022)


Welcome to the Geant4 User's Documents page. This page gives you an overview of all available documents which are created and maintained by the Geant4 international collaboration.

GEANT4 is a toolkit for both full and fast Monte Carlo simulation of detectors in High Energy Physics. It is also designed to take into account the requirements of space and cosmic ray applications, nuclear, heavy ion and radiation computations, and medical applications.

The following document gives you a more complete introduction to Geant4.

For information of changes in User's Documents since the last release, please see the following note.

User's Guides

All guides combined into one web-hierarchy in order to allow searching in all documents: Combined Web Guides

The following five documents comprise a complete set of user's manuals for the Geant4 toolkit. They contain the information necessary to build a simulation at the novice or advanced level, and to make improvements in the toolkit itself.

Installation Guide: For setting up Geant4 in your computing environment [ pdf version ] [ epub version ] [ kindle version ]
We strongly recommend installing the Geant4 toolkit under your computing environment before starting to read the following user's guides. You will gain much more from the user guides if you can check things out with a working version while you are reading them. This installation guide instructs you in the setting up of the Geant4 toolkit on your computer.
[Old Versions]
User's Guide: For Application Developers [ pdf version ] [ epub version ] [ kindle version ]
If you are new to Geant4, we recommend that you read this document first. The first part of the document provides a step-by-step tutorial in the use of Geant4; this is for a novice user. The second part describes the usage of the toolkit for practical applications, with a lot of example codes. After reading this part, you will be able to start to write a detector simulation program for most applications/experiments. The third part is for those who want to make more advanced use of the toolkit.
[Old Versions]
User's Guide: For Toolkit Developers [ pdf version ] [ epub version ] [ kindle version ]
This document is for those who want to contribute to the extension of the functionality to the Geant4 toolkit - for example, to add a new physics process, to add a new particle, etc. It starts with the explanation of the object-oriented analysis and design performed by the original toolkit developers. Understanding this design is mandatory for a new toolkit developer. Then guidance on how to extend the functionality of each class category is given.
[Old Versions]
Physics Reference Manual   [ pdf version ] [ epub version ] [ kindle version ]
This is a detailed description of the physics interactions provided in the Geant4 toolkit. The theory, model or parameterization of each interaction is discussed.
The Physics Reference Manual contains gaps in documentation which correspond to un-implemented interactions. There are also a few sections in which documentation is slight. Improvements in these sections are expected by the next release.
[Old Versions]
Physics List Guide   [ pdf version ] [ epub version ] [ kindle version ]
A brief guide to physics lists in particular the reference ones and the electromagnetic options.
[Old Versions]
Browsing Geant4 source codes
For those who want to know details of the Geant4 codes, the following pages can be helpful.

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Contributions from Users

To make Geant4 a more powerful and reliable detector simulation toolkit, all levels of contributions from you are essential.

Bug Reports and Fixes
Bugs reported and problem tracking system.
Frequently Asked Questions [ pdf version ] [ epub version ] [ kindle version ]
Frequently asked questions from users and answers to them.