Introduction to Geant4Part I – General Introduction

Makoto Asai (SLAC)Takashi Sasaki (KEK)March 22nd, 2002 @ NIRS

What is Geant4?Geant4 is the successor of GEANT3, the world-standard toolkit for HEP detector simulation.

Geant4 is one of the first successful attempt to re-design a major package of HEP software for the next generation of experiments using an Object-Oriented environment.

A variety of requirements also came from heavy ion physics, CP violation physics, cosmic ray physics, medical applications and space science applications.

In order to meet such requirements, a large degree of functionality and flexibility are provided.

Geant4 Collaboration

Budker Inst. of PhysicsIHEP Protvino

MEPHI Moscow Pittsburg University

Geant4 CollaborationMore than 100 developers belonging to

many laboratories, institutes & HEP experiments World-wide collaboration

Adoption of the most recent software engineering methodologiesChoice of Object-orientation and C++

Collaborating institutions provide contributions (MoU) and in return get guarantee of priority support from Geant4 collaboration.Collaboration structure

Working groups for categoriesTesting and QA teamsTechnical steering boardManagement board

Geant4 – Its history and futureDec ’94 - Project startSept ’95 – Proof of conceptsApr ’97 - First alpha release Jul ’98 - First beta release Dec ’98 - Geant4 0.0 releaseJul ’99 - Geant4 0.1 release… Dec ’02 - Geant4 4.0 releaseTwo public releases per year and monthly reference tag releases for collaboration usersExpect to continue to maintain and upgrade Geant4 for decades, e.g. LHC lifetime.

CERNRD44

MoU-basedcollaboration

Flexibility?Much wider coverage of physics comes from mixture of theory-driven, cross-section tables, and empirical formulae. Thanks to polymorphism mechanism, both cross-sections and models can be combined in arbitrary manners into one particular process.

Slow neutron Ultra-high energy muonOptical photonParton string modelsLow energy EM processesAt rest processesShower parameterizationEvent biasing technique new areas are coming...

Flexibility?Geant4 has many types of geometrical descriptions

CSG, BREP, BooleanSTEP compliant

Event and Track are class objectsNatural treatment of overlap events, pile upSuspension of slow looping tracks and postponement to next eventPriority control of tracks without performance overhead

Everything is open to the user Choice of physics processes/modelsChoice of GUI/Visualization/persistency/ histogramming technologies

Usability?User Requirements Document states many different use-cases from various fields.

Thanks to the inheritance mechanism, the user can derive his/her own classes easily. Many abstract layers and default behaviors are provided at the same time.

Many reusable examples and documents are provided and are still continuously evolving with the user’s contribution.

Categories in Geant4

Graphics_reps

Geant4

Readout

Visualization

Persistency

Run

Detector

Event

Tracking

Interfaces

Process

Track

Geometry

Material

Particle

global

Intercoms

User supportExample codes of three levels

Novice, advanced and extended examplesFive sets of users guides

Installation guideUsers guide for application developersUsers guide for toolkit developersPhysics reference manualSoftware reference manual

Self-training kits and exercises Problem reporting systemHyperNewsRequirements committees represent user communitiesUsers workshops and tutorial courses

Geant4 home - http://cern.ch/geant4 Japanese G4 users association - http://geant4.org/

User Documents (1) All documents available in html, pdf, ps and ps.gz

Introduction to Geant4overview of Geant4link to FAQ

Installation GuideHow to set up the toolkit on your computer

Application Developers GuideHow to set up and run a simulation applicationDescribe the most useful toolsIntroduce new users to toolkit

User Documents (2)Physics Reference Manual

Reference describing physics behind the toolsTheories, models, parameterizations

Toolkit Developers GuideDescription of OO design of toolkitFor advanced users wanting to extend Geant4 functionality

Software Reference ManualDetailed description of all toolkit classes and their public methodsCurrently only html version available

Online User Forum20 forums roughly based on categories

New forums may be requested by members

To join, click membership on Forum main pageOnce joined, go to “Central HyperNews Subscription Page” and select forums

You can expect replies both from experienced users and developers.

Problem Reporting

Known problemsBefore reporting a problem, check here first and searchExisting problems organized by release, category, status, platform, etc.

Problem ReportNeed registration to file reportFill out form

Training Materials One-day course

Introduction and overview of Geant4Tutorial or school course

More detailed course with exercisesAcademic course

Designed as university style lecture

Users workshop

Also, Japanese domestic users workshops