**1. NAME AND TITLE**

DEMON: Demonstration Monte Carlo Code System in Slab Geometry.

**AUXILIARY ROUTINE**

MIRAN: FORTRAN machine-independent random number generator.

**2. CONTRIBUTORS**

Radiation Research Associates, Fort Worth, Texas.

Nuclear Science Center, Louisiana State University, Baton Rouge, Louisiana.

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

DEMON is a neutron transport code system for slab geometry and was designed to be a simple demonstration for the novice in Monte Carlo. The neutron source is a monoenergetic, or fission spectrum, cosine current on the face of the homogeneous slab. Only capture and isotropic (center of mass) scattering are allowed. The cross section data are input. The sample problems provide cross sections for water, boric acid solution, sodium, and other materials. Leakage energy-angular distributions and absorption information are tabulated.

**5. METHOD OF SOLUTION**

The Monte Carlo method is used to trace case histories. No variance reduction scheme is employed. The FORTRAN random number generator is essentially machine-independent; only a constant must be changed to use on a machine other than the IBM 360.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

Most of the sample problems (10,000 histories) can be run in 30 seconds on the IBM 360/91.

**8. COMPUTER HARDWARE REQUIREMENTS**

DEMON was designed for an IBM 360 computer but is essentially machine independent.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler is required.

**10. REFERENCES**

**a. Included in the documentation:**

W. E. Selph, J. D. Marshall, and N. M. Schaeffer, "Demonstration Monte Carlo Program," RRA-N7122A (June 15, 1972).

J. C. Courtney and D. S. Ambuehl, "Fission Spectrum Calculations in Slab Geometries," Informal Notes (1975).

E. J. McGrath and D. C. Irving, "MIRANA Machine-Independent Package for Generating
Uniform Random Numbers," from *Techniques for Efficient Monte Carlo Simulation Vol. III,
Appendix B, Random Number Generation for Selected Probability Distributions*, ORNL-RSIC-38
Vol II (SAI-72-590-LJ) (1975).

**b. Background information:**

N. M. Schaeffer, Ed., "Reactor Shielding for Nuclear Engineers," Appendix J and pp. 251-254, TID-25951 (1973).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents (10.a) and one (1.2MB) DOS diskette which contains the source codes, control cards for a test case, plus input and output for sample problems.

**12. DATE OF ABSTRACT**

May 1975.

**KEYWORDS:** NEUTRON; MONTE CARLO; SLAB