RSIC COMPUTER CODE PSR-004

1. NAME AND TITLE

HEITLER: Cross Section Generator.

2. CONTRIBUTOR

UKAEA Atomic Energy Research Establishment, Harwell, England, through the NEA Computer Programme Library, Ispra (Varese), Italy.

3. CODING LANGUAGE AND COMPUTER

Fortran; IBM 7090 and 7030.

4. NATURE OF PROBLEM SOLVED

HEITLER computes the Compton, photoelectric, pair-production, and total microscopic cross sections for any element in the range of atomic numbers from 1 to 94 inclusive, for any photon energy in the range of 10 keV to 20 MeV inclusive. It also computes either the Compton absorption cross section or the Klein-Nishina differential scattering cross section as desired.

5. METHOD OF SOLUTION

The Compton cross sections are computed analytically. The photoelectric and pair-production cross sections are obtained by suitable interpolation in atomic number and energy using a compilation of 25 sets of measured cross sections.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

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

8. COMPUTER HARDWARE REQUIREMENTS

HEITLER was designed for the IBM 7030 computer and is also operable on the IBM 7090 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

HEITLER was written in basic Fortran in order to minimize conversion problems. It has been compiled on the IBM 7030 S2 System and on the IBM 7090 IBSYS Operating System.

10. REFERENCE

A. Foderaro, "Subroutine HEITLER," AERE-M 1956 (September 1967).

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.

12. DATE OF ABSTRACT

November 1972.