**1. NAME AND TITLE**

SANDYL: A Monte Carlo Three-Dimensional Code System for Calculating Combined Photon-Electron Transport in Complex Systems.

SANDYL incorporates material from the SORS photon and ETRAN photon-electron codes. Major
additions and modifications occur in the atomic ionization and relaxation routines and in the general-geometry multiple-material aspects of the electron transport.

**2. CONTRIBUTOR**

Sandia Laboratories, Livermore, California.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; CDC.

**4. NATURE OF PROBLEM SOLVED**

SANDYL performs time- and space-dependent transport calculations of the photon-electron cascade
in complex systems. All generations of particles in the 1 keV to 1000 MeV energy range are followed.

**5. METHOD OF SOLUTION**

SANDYL uses the Monte Carlo method. In its computations, a large number of possible particle trajectories are generated one at a time and, as the particle proceeds through the material of the system, contributions to the quantities making up the desired information are tallied. After a number of trajectories, the averages of these quantities are statistical approximations to the solution.

The problem geometry is divided into zones of homogeneous atomic composition bounded by sections of planes and quadrics. Thus, the material of each zone is a specified element or combination of elements.

For a photon history, the trajectory is generated by following the photon from scattering to
scattering using the various probability distributions to find distances between collisions, types of
collisions, types of secondaries, and their energies and scattering angles. The condensed-history Monte
Carlo method is used for the electron transport.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

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

In order to obtain generality, sacrifices are made in efficiency. A user may be able to achieve
significant economies in computer run time either by programming modifications or by the judicial use
of the zoning and variance reduction techniques available in the code.

**8. COMPUTER HARDWARE REQUIREMENTS**

SANDYL is operable on the CDC computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCES**

H. M. Colbert, "SANDYL A Computer Program for Calculating Combined Photon-Electron Transport in Complex Systems," SLL-74-0012 (May 1974).

L. G. Haggmark, C. J. MacCallum, and M. E. Riley, "New Scattering Cross Sections for Electron
Transport," *Trans. Am. Nucl. Soc.* 19, 471 (1974).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source
codes and sample problem input and output.

**12. DATE OF ABSTRACT**

January 1982.

**KEYWORDS:** TIME-DEPENDENT; ELECTRON; GAMMA-RAY; BREMSSTRAHLUNG;
POSITRON; COMPLEX GEOMETRY; MONTE CARLO