1. NAME AND TITLE

BEBC: Electron Bremsstrahlung Penetration Code for Space Vehicles.

This code package is retained by RSIC to preserve space technology developed in the 1960's.

2. CONTRIBUTORS

NASA Langley Research Center, Hampton, Virginia.

Air Force Weapons Laboratory, Kirtland Air Force Base, New Mexico.

The Boeing Company, Seattle, Washington.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; IBM 7090 and 7094.

4. NATURE OF PROBLEM SOLVED

BEBC calculates the Bremsstrahlung dose received through multilayered slabs of shield material. Bremsstrahlung is an x-ray created when high energy electrons are slowed down by a material. Required inputs to this program are: the incident electron spectrum, photon attenuation coefficients, build-up coefficients, shield materials and thicknesses, and solid angles, and flux to dose conversion factors.

5. METHOD OF SOLUTION

The Bremsstrahlung is assumed to be generated on the surface of the outermost shield layer and thus is treated as a parallel beam source of infinite area with semi-infinite slab shielding. It is assumed that the electrons do not penetrate the surface. To account for the additional dose from scattered radiation, empirical buildup factors are used. Angular distribution of the source is accomplished with a weighting factor. For successive shielding layers, the dose buildup is assumed to be multiplicative.

6. RESTRICTIONS OR LIMITATIONS

The incident electron spectrum must be analytically defined as a function of electron energy. Only 12 or fewer shield materials may be considered at one time. A polyhedron of no more than 350 sides may be used to represent a vehicle.

7. TYPICAL RUNNING TIME

No study has been made by RSIC as to typical running time. Estimated running time for the sample problem: 0.03 hour.

8. COMPUTER HARDWARE REQUIREMENTS

The code is operable on a 32 K IBM 7090 computer with standard I-O equipment.

9. COMPUTER SOFTWARE REQUIREMENTS

The code may be compiled and executed on the IBM FORTRAN IV IBJOB Monitor within the IBM IBSYS Operating System.

10. REFERENCES

Included in document:

J. A. Barton, B. W. Mar, G. L. Keister, W. R. Doherty, J. R. Benbrook, W. R. Sheldon, J. R. Thomas, K. Moriyasu and M. C. Wilkinson, "Computer Codes for Space Radiation Environment and Shielding," WL-TDR-64-71, Volume I and II (August 1964).

Background information:

J. A. Barton and G. L. Keister, "Symposium on Space Radiation Environment," D2-90684-1 (April 1965).

11. CONTENTS OF CODE PACKAGE

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

12. DATE OF ABSTRACT

January 1968; updated July 1981, February 1985.

KEYWORDS: SPACE RADIATION; BREMSSTRAHLUNG; ELECTRON; SLAB