**1. NAME AND TITLE**

BETA-II: Monte Carlo Bremsstrahlung and Electron Transport Analysis in Geometry.

DATA LIBRARY

Stopping Powers Data.

BETA was originally packaged in 1969; upgraded in 1973. The code package has been
distributed by RSIC 38 times (19691981).

**2. CONTRIBUTORS**

A.R.T. Research Corporation, Los Angeles, California.

Air Force Weapons Laboratory, Albuquerque, New Mexico.

Thomas M. Jordan, Santa Monica, California.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; UNIVAC 1108 (A), IBM 360/370 (B), and CDC 6600 (C).

**4. NATURE OF PROBLEM SOLVED**

BETA-II is a computer procedure for bremsstrahlung and electron transport analysis developed to augment experimental efforts. Generalized three-dimensional geometry is included. Electron transport and bremsstrahlung production and transport are treated explicitly for the energy range from 0.05 to 15 MeV. Arbitrary sources are handled as functions of energy, time, space, and angle. Point, surface, and/or volume detectors are considered. The effects of electric field due to charge buildup are treated.

Photon transport problems as either a primary source or as a secondary bremsstrahlung source
may also be solved.

**5. METHOD OF SOLUTION**

BETA-II uses random sampling techniques to perform the integrations of the order-of-scatter
equations to give the unscattered and scattered components of the flux. Electron transport
considers electron-nucleus, electron-electron, and electron-bremsstrahlung scattering. Wide angle
scatterings are considered explicitly, while narrow angle scatterings are grouped and the net effect
lumped together. Klein-Nishina scattering is considered for photon transport. BETA-II will
recognize simple surfaces such as planes, cones, elliptic cylinders and ellipsoids in specifying the
geometry. Multiple energy and angular dependent sources in rectangular, cylindrical, and
spherical geometry may be considered with the geometry of each source being superimposed over
the various geometric regions. Flux estimation at points, surfaces, and in volumes is accomplished
by summing contributions from all order-of-scatter components. Legendre moments of the angular
flux are used to construct azimuthally-averaged differential angular fluxes. The time dependence is
obtained by computing temporal moments and then analytically regenerating the temporal
dependence from these moments.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No effort has been made by RSIC to establish typical running time.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code is operable on IBM 360/370, CDC 6600, and UNIVAC 1108 computers.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The code should be compatible with most FORTRAN IV compilers.

**10. REFERENCES**

**a. Included in package:**

T. M. Jordan, "BETA-II, A Time Dependent, Generalized-Geometry Monte Carlo Program for Bremsstrahlung and Electron Transport Analysis. Vol. I: Summary Report," ART-60 (October 1971).

T. M. Jordan, "BETA-II, A Time Dependent, Generalized-Geometry Monte Carlo Program for
Bremsstrahlung and Electron Transport Analysis. Vol II: User's Manual," ART-60 (October
1971).

**b. Background information:**

T. M. Jordan, "BETA, A Monte Carlo Computer Program for Bremsstrahlng and Electron
Transport Analysis," AFWL-TR-68-111 (October 1968).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the
source code, the data library and input and output for a sample problem.

**12. DATE OF ABSTRACT**

August 1971; updated July 1981.

**KEYWORDS:** MONTE CARLO; BREMSSTRAHLUNG; ELECTRON; GAMMA-RAY; COMPLEX GEOMETRY