RSIC CODE PACKAGE CCC-331

1. NAME AND TITLE
EGS4: Monte Carlo Simulation of the Coupled Transport of Electrons and Photons.
AUXILIARY ROUTINES
MORTRAN 3: Macroprocessor to Convert MORTRAN to ANSI Fortran.
PEGS 4: Data Processor for EGS.
EGS_Windows: Graphical tool for displaying acceleration and geometry data files.

2. CONTRIBUTORS
Radiation Physics Group, Stanford Linear Accelerator Center, Stanford University, 
Stanford, California. 
National Laboratory for High Energy Physics (KEK), Oho-machi, Tsu-kuba-gun, Ibaraki-ken,
Japan.
National Research Council of Canada, Ottawa, Canada. 
Institute for Applied Physiology and Medicine, Seattle, Washington.

3. CODING LANGUAGE AND COMPUTER
Fortran 77, Mortran; Unix workstations and PC's (C00331MNYCP00).
MORTRAN is a structured (extended Fortran) programming language. The capability for 
MORTRAN to Fortran conversion is included in the package.

4. NATURE OF PROBLEM SOLVED
This 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 from a few keV up to several TeV. EGS4 Version 3.0 is available for and Unix 
workstations, while the PC version is still at Version 2.0. The EGS code system is one 
of a chain of three codes designed to solve the electromagnetic shower problem by Monte 
Carlo simulation. This chain makes possible simulation of almost any electron-photon 
transport problem conceivable. The structure of the system, with its global features, 
modular form, and structured programming, is readily adaptable to virtually any 
interfacing scheme that is desired on the part of the user.
EGS4 is a package of subroutines plus block data with a flexible user interface. This 
allows for greater flexibility without requiring the user to be overly familiar with the
internal details of the code. Combining this with the macro facility capabilities of the
Mortran3 language, this reduces the likelihood that user edits will introduce bugs into 
the code. EGS4 uses material cross section and branching ratio data created and fit by 
the companion code, PEGS4.
EGS4 allows for the implementation of importance sampling and other variance reduction 
techniques such as leading particle biasing, splitting, path length biasing, Russian 
roulette, etc. A variety of automated data sets is provided. EGS (Electron-Gamma Shower)
is based on code development in the early 1960s by H. H. Nagel and represents several 
years of additional development.
See the EGS homepage http://www.slac.stanford.edu/egs/ for additional information.

5. METHOD OF SOLUTION
EGS employs the Monte Carlo method of solution. It allows all of the fundamental 
processes to be included and arbitrary geometries can be treated, also. Other minor 
processes, such as photoneutron production, can be added as a further generalization. 
Since showers develop randomly according to the quantum laws of probability, each 
shower is different. We again are led to the Monte Carlo method.

6. RESTRICTIONS OR LIMITATIONS
The EGS_Windows user interface currently is implemented only for SGI and Sun 
workstations.

7. TYPICAL RUNNING TIME
The running time is dependent upon the problem being solved.

8. COMPUTER HARDWARE REQUIREMENTS
EGS4 is available for Unix workstations and PC's. The EGS_Windows executable included 
will run only on Sun workstations.

9. COMPUTER SOFTWARE REQUIREMENTS
A Fortran compiler is required. MORTRAN is a structured programming language that is 
implemented as a set of macros which are used by a macro-processor to translate the 
language into ANSI-standard Fortran (a preliminary step in the job). The resulting 
program is then run like any other Fortran program.
EGS4 v2.0 for Win95/NT/DOS was tested at RSICC on a Micron Pentium II/266 running MS 
Windows 95 (DOS window with no GUI interface) using Lahey Fortran v5.2. Version 3.0 for 
Unix was tested on a SGI IndyStation running Irix 5.3 using SGI Fortan 77 v.3.0.2. 
Because of the dependence on the MORTRAN preprocessor, no executable is included in 
either version with the exception of an Irix executable included in the EGS_Windows 
utility (Unix version only). Additionally, in the SGI platform, the non-shared 
libraries must be installed.

10. REFERENCES
a. Included in documentation:
Registration form.
W. R. Nelson, H. Hirayama and D. W. O. Rogers, "The EGS4 Code System," SLAC-265 
(December 1985). 
W. R. Nelson and T. M. Jenkins, "Writing SUBROUTINE HOWFAR for EGS4," SLAC TN-87-4, 
SLAC, Stanford, California, (August 31, 1988).
A. F. Bielajew and D. W. O. Rogers, "PRESTA - The Parameter Reduced Electron - Step 
Transport Algorithm for Electron Monte Carlo Transport," PIRS No. 042 (July 1986). 
A. F. Bielajew, "README.general.3.0" (December 24, 1996).
A. F. Bielajew, "Directions for EGS4 Installation" (October 19, 1995).
A. F. Bielajew, H. Hirayama, W. R. Nelson, and D. W. O. Rogers, "History, Overview and 
Recent Improvements of EGS4," SLAC-PUB-6499 (NRC-PIRS-0436, KEK Internal 94-4) 
(Revised June 1, 1994).
b. Background information:
A. J. Cook, "Mortran 3 User Guide," Computation Research Group Technical Memo 209 
(December 16, 1982).
R. L. Ford and W. R. Nelson, "The EGS Code System: Computer Programs for the Monte 
Carlo Simulation of Electromagnetic Cascade Showers," (Version 3) SLAC-210 (June 1978).

11. CONTENTS OF CODE PACKAGE
Included are the referenced documents in 10.a. Both PC and Unix distributions are 
included in this package which is transmitted on CD-ROM in self-extracting compressed 
DOS files and a Unix tar file.

12. DATE OF ABSTRACT
August 1979; revised March 1982, June 1986, August 1986, March 1991, April 1991, 
June 1991, September 1994, February 1998.

KEYWORDS: ELECTRON; GAMMA-RAY; MONTE CARLO; ELECTROMAGNETIC CASCADE; HIGH ENERGY; 
BREMSSTRAHLUNG; COMPLEX GEOMETRY; CHARGED PARTICLES; WORKSTATION; MICROCOMPUTER