1. NAME AND TITLE

MCRTOF: Monte Carlo Code System for Calculation of Multiple Scattering of Neutrons in the Resonance Region.

2. CONTRIBUTOR

Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken, Japan.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; FACOM-M200 (A) or IBM 3033 (B).

4. NATURE OF PROBLEM SOLVED

MCRTOF systematically calculates capture and scattering probabilities for neutrons incident on a material disk, with neutron cross sections calculated from the resonance parameters. Capture, front and rear face scattering, transmission, etc., probabilities are obtained from the average destinations of the incident neutrons.

5. METHOD OF SOLUTION

Paths of a neutron which impinges onto a disk inclined with an arbitrary angle to the incident direction are simulated by the Monte Carlo method, using capture and scattering cross sections which are produced from a given set of resonance parameters. For each incident energy, the probabilities of capture, front and rear face scattering, and transmission are obtained by averaging over many incident neutrons. The incident neutron energy is changed step by step in order to reproduce these probabilities over resonances. All these probabilities are listed in a format convenient for comparison with the experimental ones, and these probabilities are illustrated with sheet plots as functions of incident energies. At some energy points, the spatial distributions of neutron capture reactions are also illustrated in a projection on the plane normal to the disk surface.

6. RESTRICTIONS OR LIMITATIONS

The maximum number of resonances is five. Reactions other than capture and scattering are neglected.

7. TYPICAL RUNNING TIME

Running time depends on resonance parameters and disk thickness. The sample problem ran in 22 seconds on the IBM 3033 computer.

8. COMPUTER HARDWARE REQUIREMENTS

MCRTOF was designed for the FACOM-M200 computer. It was converted by RSIC to run on the IBM 3033 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCES

M. Ohkubo, "MCRTOF A Monte Carlo Program for Multiple Scattering of Neutrons in Resonance Energy Region," JAERI-M 7988 (November 1978).

M. Ohkubo, "Neutron Capture Probabilities for Think Samples at Resonance Energies," Nucl. Sci. Eng. 66 (1978) 217-228.

M. Ohkubo, "A Normalization Standard for Neutron Capture Probability in the Resonance Region," Nucl. Instrum. Methods 184, 465-467 (1981).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one DOS diskette which contains the source code and sample problem input plus output from the sample problem written in list format (B).

12. DATE OF ABSTRACT

February 1983; revised September 1983.