User’s Guide for Toolkit Developers

Scope of this Manual

The User’s Guide for Toolkit Developers provides detailed information about the design of Geant4 classes as well as the information required to extend the current functionality of the Geant4 toolkit. This manual is designed to:

• provide a repository of information for those who want to understand or refer to the detailed design of the toolkit, and

• provide details and procedures for extending the functionality of the toolkit so that experienced users may contribute code which is consistent with the overall design of Geant4.

This manual is intended for developers and experienced users of Geant4. It is assumed that the reader is already familiar with functionality of the Geant4 toolkit as explained in the “User’s Guide For Application Developers”, and also has a working knowledge of programming using C++. A knowledge of object-oriented analysis and design will also be useful in understanding this manual. It is also useful to consult the “Software Reference Manual” which provides a list of Geant4 classes and their major methods.

Detailed discussions of the physics included in Geant4 are provided in the “Physics Reference Manual”.

Contents

• Introduction
  • How to use this manual
  • User Requirements Document
• Design and Function of Geant4 Categories
  • Introduction
  • Run
    • Design Philosophy
    • Class Design
  • Event
    • Design Philosophy
    • Class Design
  • Tracking
    • Design Philosophy
    • Class Design
    • Tracking Algorithm
    • Interaction with Physics Processes
    • Ordering of Methods of Physics Processes
  • Physics Processes
    • Design Philosophy
    • Class Design
    • Electromagnetic
    • Hadronic
  • Hits and Digitisation
    • Design Philosophy
    • Class Design
  • Geometry
    • Design Philosophy
    • Class Design
    • Additional Geometry Diagrams
  • Electromagnetic Fields
    • Class Design
  • Particles
    • Design Philosophy
    • Class Design
  • Materials
    • Design Philosophy
    • Design
  • Global Usage
    • Design Philosophy
    • Class Design
  • Design of Visualisation Category
    • Design Philosophy
    • The Graphics Interfaces
    • The Geant4 Visualisation System
    • Modelling sub-category
    • View parameters
    • Visualisation Attributes
  • Intercoms
    • Design Philosophy
    • Class Design
  • Parallelism in Geant4: multi-threading capabilities
    • Event level parallelism
    • General Design
    • Memory handling in Geant4 Version 10.0
    • Threading model utilities and functions
    • Random Number Generation Seeding in MT
    • Additional material
• Extending Toolkit Functionality
  • Geometry
    • What can be extended ?
    • Adding a new type of Solid
    • Modifying the Navigator
  • Electromagnetic Fields
    • Creating a New Type of Field
  • Particles
    • Properties of particles
    • Adding New Particles
    • Nuclide properties from the Evaluated Nuclear Structure Data File
  • Electromagnetic Physics
    • Introduction
    • General design
    • Electromagnetic processes
    • Electromagnetic models
  • Hadronic Physics
    • Introduction
    • Principal Considerations
    • Level 1 Framework - processes
    • Level 2 Framework - Cross Sections and Models
    • Level 3 Framework - Theoretical Models
    • Level 4 Frameworks - String Parton Models and Intra-Nuclear Cascade
    • Level 5 Framework - String De-excitation
    • Creating Your Own Hadronic Process
    • Changing Internal Parameters of an Existing Hadronic Model
  • Generic Event Biasing
    • Introduction
    • Design of Generic Biasing
    • Physics Process Occurrence Biasing
  • Visualisation
    • Creating a new graphics driver
    • Adding a new view parameter
    • Enhanced Trajectory Drawing
    • Trajectory Filtering
    • Other Resources
• Bibliography

Status of this Document

Guide for developers of the Geant4 toolkit.

• Rev 1.0: First Sphinx version implemented for Geant4 Release 10.4, 8th Dec 2017

• Rev 2.0: Updates and fixes in documentatio for Geant4 Release 10.4, 15th May 2018

• Rev 3.0: Geant4 Release 10.5, 11th December 2018

• Rev 3.1: Geant4 Updates and fixes - especially to search functionality, 5th March 2019

• Rev 4.0: Geant4 Release 10.6, 6th December 2019

• Rev 5.0: Geant4 Release 10.7, 4th December 2020

• Rev 6.0: Geant4 Release 11.0, 10th December 2021

• Rev 7.0: Geant4 Release 11.1, 9th December 2022

• Rev 7.1: Geant4 Fixes to http links, 15th July 2023

• Rev 8.0: Geant4 Release 11.2, 8th December 2023

• Rev 9.0: Geant4 Release 11.3, 6th December 2024