Introduction to Geant4
is a complete redesign and rewrite of the Geant3 simulation package
using C++ and object oriented technology. The project (CERN RD44) was
initiated in 1994 by the CERN
Geant team led by Simone Giani and is being undertaken by an
international collaboration of
over 70 physicists
representing most major current and upcoming
HEP experiments. Geant4 is being continuously compared through its development with the frozen
with the objective of producing by the end of 1998 a validated public release that betters Geant 3.21
in terms of physics, performance and capabilities. The complementary
RD45 Project is developing a persistent object manager for HEP and will provide Geant4's object
persistency (I/O). Geant4 is allied with the LHC++/CLHEP project to develop a standard suite of C++ classes and development/analysis tools for HEP.
Geant4 Background and Related Information
Geant3 to Geant4 Migration via g3tog4
STAR Activity and Plans
- Three G4 collaborators in STAR: Peter Jacobs, Thomas Ullrich, Torre Wenaus
- Thomas Ullrich is actively working with G4 for STAR
- Import and build G4 alpha release 2, done
- g3tog4 conversion of detailed GSTAR geometry, in progress
- Use Geant4 with converted geometry as testbed to study capabilities and
- Timescale for migration is long; post-startup
- Possible areas for future Geant4 development in STAR are being explored.
Peter Jacobs has enumerated some good candidates...
- Event size: Our heavy ion events are simply too large to be held in
memory at once and it is necessary to break them into pieces (whose size
needs to be optimised for performance but is otherwise irrelevant) and
reassembled on output in a way that is transparent to the user, as is done
now with gstar/g2t. This is handled by G4.
- Event pileup: especially for pp running, we will have pileup in the
TPC and SVT from events prior to and following the trigger event, due to
the long drift time of the devices (the amount fo this obviosuly goes as
the luminosity). An explicit mechanism for this is in G4.
- Parameterisation and fast simulation: trading off simulation
detail for speed for coarse high-statistics studies. G4 is developing
powerful facilities for parameterised simulation.
See this page for parameterisation information.