**1. NAME AND TITLE**

ELTRAN: One-Dimensional Monte Carlo Electron Transport Code System.

ELTRAN was originally developed at the Boeing Company, Seattle, was extended by Avco
Corporation, and evolved into this version.

**2. CONTRIBUTORS**

Sandia Laboratories, Albuquerque, New Mexico.

Ion Physics, Burlington, Massachusetts.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; CDC 3600.

**4. NATURE OF PROBLEM SOLVED**

ELTRAN is designed to compute one-dimensional, electron deposition, in semi-infinite
composite slabs. It has the capability of computing either the energy deposition profile distribution
of stopped electrons or the spectral properties of electrons transmitted by a thin slab, which may be
solid, liquid, or gas. The incident electrons may be monoenergetic or they may form a spectrum;
they may be incident perpendicular or at an angle to the slab.

**5. METHOD OF SOLUTION**

ELTRAN employs a quasi Monte Carlo scheme which involves calculation of the trajectory of an individual electron. This calculation is repeated until a sufficient number of electrons or case histories has been accumulated so that the user obtains the desired degree of statistical precision. Instead of considering each of the tens of thousands of individual collisions, the electron is given an incremental displacement, and the small energy loss and small effective scattering angle are computed. The electron is given additional incremental displacements until the electron is absorbed (stopped), backscattered or transmitted. Again this incrementation is repeated for additional electrons until the desired number of case histories is run.

The energy loss is computed using the continuous slowing-down approximation, with the
effects of density, range straggling, and bremsstrahlung included. The scattering angle is computed
by means of the Moliere multiple scattering angle distribution.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for ELTRAN.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code was designed for the CDC 3600 with standard equipment.

**9. COMPUTER SOFTWARE REQUIREMENTS**

ELTRAN is operable on the CDC 3600 FORTRAN operating system; it can be easily
converted to compile in any CDC FORTRAN IV operating environment.

**10. REFERENCE**

F. H. Brittain, "A Description of ELTRAN: An Electron Deposition Code," SC-TM-68-713
(January 1969).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.2MB) DOS diskette which contains the source
code and sample problem input. Output from the sample problems is listed in the documentation.

**12. DATE OF ABSTRACT**

February 1972; revised December 1984.

**KEYWORDS: ** MONTE CARLO; ELECTRON; ONE-DIMENSION