Introduction to Geant4 Part I – General Introduction Makoto Asai (SLAC) Takashi Sasaki (KEK) March 22 nd, 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 Physics IHEP Protvino MEPHI Moscow Pittsburg University

Geant4 Collaboration More than 100 developers belonging to many laboratories, institutes & HEP experiments World-wide collaboration Adoption of the most recent software engineering methodologies Choice 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 categories Testing and QA teams Technical steering board Management board

Geant4 – Its history and future Dec ’ 94 - Project start Sept ’ 95 – Proof of concepts Apr ’ 97 - First alpha release Jul ’ 98 - First beta release Dec ’ 98 - Geant4 0.0 release Jul ’ 99 - Geant4 0.1 release … Dec ’ 02 - Geant4 4.0 release Two public releases per year and monthly reference tag releases for collaboration users Expect to continue to maintain and upgrade Geant4 for decades, e.g. LHC lifetime. CERN RD44 MoU-based collaboration

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 muon Optical photon Parton string models Low energy EM processes At rest processes Shower parameterization Event biasing technique new areas are coming...

Flexibility? Geant4 has many types of geometrical descriptions CSG, BREP, Boolean STEP compliant Event and Track are class objects Natural treatment of overlap events, pile up Suspension of slow looping tracks and postponement to next event Priority control of tracks without performance overhead Everything is open to the user Choice of physics processes/models Choice 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

User support Example codes of three levels Novice, advanced and extended examples Five sets of users guides Installation guide Users guide for application developers Users guide for toolkit developers Physics reference manual Software reference manual Self-training kits and exercises Problem reporting system HyperNews Requirements committees represent user communities Users workshops and tutorial courses Geant4 home - Japanese G4 users association -

User Documents (1) All documents available in html, pdf, ps and ps.gz Introduction to Geant4 overview of Geant4 link to FAQ Installation Guide How to set up the toolkit on your computer Application Developers Guide How to set up and run a simulation application Describe the most useful tools Introduce new users to toolkit

User Documents (2) Physics Reference Manual Reference describing physics behind the tools Theories, models, parameterizations Toolkit Developers Guide Description of OO design of toolkit For advanced users wanting to extend Geant4 functionality Software Reference Manual Detailed description of all toolkit classes and their public methods Currently only html version available

Online User Forum 20 forums roughly based on categories New forums may be requested by members To join, click membership on Forum main page Once joined, go to “ Central HyperNews Subscription Page ” and select forums You can expect replies both from experienced users and developers.

Problem Reporting Known problems Before reporting a problem, check here first and search Existing problems organized by release, category, status, platform, etc. Problem Report Need registration to file report Fill out form

Training Materials One-day course Introduction and overview of Geant4 Tutorial or school course More detailed course with exercises Academic course Designed as university style lecture

Users workshop Also, Japanese domestic users workshops