1. NAME AND TITLE

LEBC: Electron Bremsstrahlung Code.

AUXILIARY ROUTINE

LMFC: Mission Flux Generator (Trapped Radiation).

LEBC is one of a series of space codes maintained by RSIC to preserve the technology. It has been distributed by RSIC six times in 1966-1971 and once in 1980.

2. CONTRIBUTOR

Lockheed-Georgia Company, Nuclear Analysis Department, Marietta, Georgia.

3. CODING LANGUAGE AND COMPUTER

FORTRAN II and FAP; IBM 7090 and 7094.

4. NATURE OF PROBLEM SOLVED

LEBC estimates dose from electron bremsstrahlung generated in and transmitted through a slab shield.

The mission flux generator, LMFC, calculates proton and electron flux spectra integrated over trajectories through the trapped radiation belts of earth. Arbitrary trajectories or orbital parameters may be specified.

5. METHOD OF SOLUTION

In LEBC, the incident electron flux may be monoenergetic, exponential (integral in energy), or tabular (integral in energy). Electrons incident normally upon a slab shield are stopped in the first layer. Bremsstrahlung are started straight ahead at the second layer which may consist of a different material. Bremsstrahlung cross sections are based on the Born approximation without screening. Point isotropic dose buildup factors are used.

LMFC converts geographic coordinates to B-L coordinates and performs logarithmic interpolations in flux maps.

6. RESTRICTIONS OR LIMITATIONS

LEBC: Number of tabular electron spectra < 4

Number of values per spectrum < 200

Number of stopping power tables < 6

Number of values per stopping power table < 60

Number of gamma-ray attenuation coefficient tables < 6

Number of values per attenuation coefficient table < 60

Number of gamma-ray buildup tables < 6

Number of energy values per buildup table < 20

Number of mean free path values per buildup table < 20

Number of entries in flux-to-dose conversion table < 60

LMFC: Number of trajectory points < 150

7. TYPICAL RUNNING TIME

LEBC: Variable, approximately 20 seconds per case (IBM 7094) for an input spectrum tabulated at 51 energies.

LMFC: Variable, usually 2 minutes per 100 point orbit.

Estimated time for running the sample problem through both codes on the IBM 7090 computer: 8 minutes.

8. COMPUTER HARDWARE REQUIREMENTS

The codes were designed for the IBM 7090 and 7094 computers. A 32,768 core memory and three tape units are required.

9. COMPUTER SOFTWARE REQUIREMENTS

The codes were designed for and are operable in the IBM FORTRAN II Monitor System, using standard system, input and output tapes. Included in the code package is at least one nonstandard arithmetic routine.

10. REFERENCES

C. W. Hill, C. C. Douglass, Jr., W. B. Ritchie, K. M. Simpson, Jr., "Computer Programs for Shielding Problems in Manned Space Vehicles," ER-6643 (January 1964).

C. W. Hill, W. B. Ritchie, K. M. Simpson, "Data Compilation and Evaluation of Space Shielding Problems, Volume II, Dose Calculations in Space Vehicles," ER-7777 (August 1965).

11. CONTENTS OF CODE PACKAGE

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

12. DATE OF ABSTRACT

July 1967; updated July 1981; revised January 1983.