THE EGS5 CODE SYSTEM

Chapter 1
INTRODUCTION
1.1 Intent of This Report
The EGS (Electron-Gamma Shower) code system is a general purpose package for the Monte Carlo
simulation of the coupled transport of electrons and photons in an arbitrary geometry for particles
with energies above a few keV up to several hundred GeV (depending on the atomic numbers of
the target materials). This report introduces a new, enhanced version called EGS5. In addition
to explaining and documenting the various enhancements and changes to the previous version
(EGS4[126]), this document includes several introductory and advanced tutorials on the use of
EGS5, and also contains the EGS5 User Manual. Our intention has been to make this document
wholly self-contained so that the user need not refer to the original EGS4 manual (SLAC-265[126])
in order to use the code. To this end, we have taken the liberty of incorporating into Chapter 2
of this report those portions of Chapter 2 of SLAC-265 which describe physics models of EGS4
retained by EGS5, thereby documenting all the physics contained in EGS5.
On the practical side this report can be used in order to create EGS5 user codes and to run EGS5.
Formerly a stand-alone data preparation code, PEGS (Preprocessor for EGS), is now integrated in
this version of EGS.
1.2 History of EGS
A great deal of the content of the following historical sections of this report has been plagiarized
unashamedly from the original EGS3 document (SLAC-210) authored by Richard Ford and Ralph
Nelson[61]. There are several reasons for this aside from laziness. This history predates one of the
author’s (AFB) involvement with EGS and he found it very difficult to improve upon the words
penned by Ford and Nelson in that original document. Moreover, the EGS3 manual is now out-
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