Hadronic Interactions in GEANT4

Paper: 214
Session: A (talk)
Speaker: Wellisch, Johannes-Peter, CERN, Geneva
Keywords: C++, object-oriented methods, simulation, simulation tools

Hadronic Interactions in GEANT4

Johannes Peter Wellisch
TRIUMF, 4004 Wessbrook Mall, Vancouver, BC, Canada, V6T2A3
Scientific Associate at CERN.


Simulation of hadronic showers has been a field of strong activity for
many year. Today we face the challenge to maintain through a change
in software technology the knowledge and experience collected over
time, and to use the advantages of the new technology to improve on the
existing Monte Carlo codes, in order to match the stringent requirements
of the LHC experiments.

The effort described is generic part of the GEANT4 project.
It involves three phases, each equally important to the quality of
the final Object Oriented hadronic shower Monte Carlo.
Phase one is the rewriting of an existing, and widely used package
in a language, that allows for OO structures, thus reusing the experience
in both algorithmic problem solving as well as the physics insight encapsulated
in the code. Phase two is the redesign of the program, to match the
Object Oriented paradigm, and to maximize the possibility for future
extension and improvement of the underlying physics as well as the ease in
maintainence. Phase three is the stepwise improvement of the underlying

TRIUMF carries main responsibilities in all three phases of the project.
The re-engeneering of GHEISHA in C++ is already well advanced for both coherent
elastic, and inelastic interactions of hadrons with matter. An Analysis and
Design iteration has been completed successfully, allowing for full flexibility
in process type, particle type, and energy range. Efforts to enlarge the
underlying physics in the low and intermediate energy ranges have been
launched, and show first successes in an increasingly large collection of
experimental cross-section data, and improved empirical models for these data.
Here, the initial efforts focus on the interactions of protons and neutrons
with matter.