NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHOR, MATERIAL, CATEGORIES

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available here.

Program name | Package id | Status | Status date |
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BETA-2B | CCC-0117/01 | Tested | 01-SEP-1977 |

Machines used:

Package ID | Orig. computer | Test computer |
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CCC-0117/01 | IBM 370 series | IBM 370 series |

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3. DESCRIPTION OF PROBLEM OR FUNCTION

BETA-2B is a time-dependent Monte Carlo bremsstrahlung and electron transport analysis code for complex geometries. It is designed primarily for electron energy deposition calculations.

The electron transport includes the effects of fixed electric and magnetic fields and self-produced electric fields. In following both primary and knock-on electrons, energy loss straggling effects are included.

The code solves photon transport not only from bremsstrahlung sources, but also from a fixed source. The effects of incoherent and coherent (Compton) scattering, pair production and photoelectric processes are included.

BETA-2B accepts generalized source distributions that are functions of space, angle, energy and time, including sources for which both energy and intensity vary with time.

The code can treat both simple 1,2 and 3-dimensional multiple material geometries, or complex 3-dimensional quadric surface geometries.

BETA-2B is a time-dependent Monte Carlo bremsstrahlung and electron transport analysis code for complex geometries. It is designed primarily for electron energy deposition calculations.

The electron transport includes the effects of fixed electric and magnetic fields and self-produced electric fields. In following both primary and knock-on electrons, energy loss straggling effects are included.

The code solves photon transport not only from bremsstrahlung sources, but also from a fixed source. The effects of incoherent and coherent (Compton) scattering, pair production and photoelectric processes are included.

BETA-2B accepts generalized source distributions that are functions of space, angle, energy and time, including sources for which both energy and intensity vary with time.

The code can treat both simple 1,2 and 3-dimensional multiple material geometries, or complex 3-dimensional quadric surface geometries.

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4. METHOD OF SOLUTION

BETA-2B uses a condensed history Monte Carlo technique.

The electron transport proceeds by calculating the length of each electron segment from a preset fractional energy loss. The electron is allowed to traverse this path and its direction and energy are altered by random sampling a multiple scattering distribution and an energy loss straggling distribution.

BETA-2B uses a condensed history Monte Carlo technique.

The electron transport proceeds by calculating the length of each electron segment from a preset fractional energy loss. The electron is allowed to traverse this path and its direction and energy are altered by random sampling a multiple scattering distribution and an energy loss straggling distribution.

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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Calculational

accuracy within 5 per cent of experimental results can be obtained for both low and high atomic number targets in the energy range from 0.05 to 15.0 MeV. The program can be applied outside this energy range, although the physical models are less accurate at lower energies.

Data arrays are packed into the blank COMMON block using variable dimensioning techniques. The length of blank COMMON is sufficient for fairly complex problems; unusually large problems, particularly those requesting many of the optional output edits,may require the storage allocation to be increased.

Calculational

accuracy within 5 per cent of experimental results can be obtained for both low and high atomic number targets in the energy range from 0.05 to 15.0 MeV. The program can be applied outside this energy range, although the physical models are less accurate at lower energies.

Data arrays are packed into the blank COMMON block using variable dimensioning techniques. The length of blank COMMON is sufficient for fairly complex problems; unusually large problems, particularly those requesting many of the optional output edits,may require the storage allocation to be increased.

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6. TYPICAL RUNNING TIME

The following sample problems were run on a CDC 6600.

i) A calculation of the angle-energy distribution of an 8 MeV electron beam as it penetrates a slab of aluminium, using a P24 Goudsmit-Sanderson distribution, 2 per cent energy loss per path length segment, and following 3000 histories required 15 minutes.

ii) About 5 minutes were required to calculate the energy deposition profile for a beam of 2 MeV electrons normally incident on a semi-infinite slab of aluminium or lead. A Gaussian angular straggling model was used, with 2 per cent energy loss steps, and 500 histories were followed.

iii) A source of 10 MeV electrons, normally incident at one end of a system of concentric cylinders of aluminium, iron and tungsten with a central void was set up. Each cylinder was divided into 25 regions. The energy deposition distribution was calculated using 5 per cent energy loss steps, and following 256 histories Less than 2 minutes were required for a no-field case, 10 minutes were required with a 100,000 gauss uniform axial magnetic field.

iv) A time-dependent energy deposition calculation on a lucite cylinder require 7 minutes for 10 time steps. The electron source was normally incident and uniformly distributed on the end of the cylinder which was divided into 5 radial and 20 axial segments. 64 electron histories were followed per time step.

The following sample problems were run on a CDC 6600.

i) A calculation of the angle-energy distribution of an 8 MeV electron beam as it penetrates a slab of aluminium, using a P24 Goudsmit-Sanderson distribution, 2 per cent energy loss per path length segment, and following 3000 histories required 15 minutes.

ii) About 5 minutes were required to calculate the energy deposition profile for a beam of 2 MeV electrons normally incident on a semi-infinite slab of aluminium or lead. A Gaussian angular straggling model was used, with 2 per cent energy loss steps, and 500 histories were followed.

iii) A source of 10 MeV electrons, normally incident at one end of a system of concentric cylinders of aluminium, iron and tungsten with a central void was set up. Each cylinder was divided into 25 regions. The energy deposition distribution was calculated using 5 per cent energy loss steps, and following 256 histories Less than 2 minutes were required for a no-field case, 10 minutes were required with a 100,000 gauss uniform axial magnetic field.

iv) A time-dependent energy deposition calculation on a lucite cylinder require 7 minutes for 10 time steps. The electron source was normally incident and uniformly distributed on the end of the cylinder which was divided into 5 radial and 20 axial segments. 64 electron histories were followed per time step.

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10. REFERENCES

- Thomas J. Jordan:

BETA, A Monte-Carlo Program for Bremsstrahlung and Electron

Transport Analysis

AFWL-TR-68-III (October 1968).

- Thomas J. Jordan:

BETA, A Monte-Carlo Program for Bremsstrahlung and Electron

Transport Analysis

AFWL-TR-68-III (October 1968).

CCC-0117/01, included references:

- Thomas M. Jordan:BETA-2, A Time-Dependent, Generalized Geometry Monte Carlo Program

for Bremsstrahlung and Electron Transport Analysis

Volume I: Summary Report, Volume II: Users Manual

A.R.T. Research Corporation Report ART-60 (October 29, 1971).

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11. MACHINE REQUIREMENTS

The amount of core storage depends on the size of the blank COMMON block, and the degree of overlay. The maxi- mum degree of program segmentation for efficient operation is given in volume 2 of reference 1. Five external storage units are required.

The program interfaces with the Calcomp plotting package through four entry points: PLOT, PLOTS, SYMBOL and NUMBER. If plotting is required the dummy subprograms with these names should be removed.

The amount of core storage depends on the size of the blank COMMON block, and the degree of overlay. The maxi- mum degree of program segmentation for efficient operation is given in volume 2 of reference 1. Five external storage units are required.

The program interfaces with the Calcomp plotting package through four entry points: PLOT, PLOTS, SYMBOL and NUMBER. If plotting is required the dummy subprograms with these names should be removed.

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CCC-0117/01

File name | File description | Records |
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CCC0117_01.001 | BETA-2B SOURCE - FORTRAN IV | 13765 |

CCC0117_01.002 | BETA-2B OVERLAY CARDS | 79 |

CCC0117_01.003 | BETA-2B JOB CONTROL | 5 |

CCC0117_01.004 | BETA-2B SAMPLE PROBLEM INPUT | 68 |

CCC0117_01.005 | BETA-2B SAMPLE PROBLEM OUTPUT | 317 |

Keywords: Monte Carlo method, bremsstrahlung, electrons, transport theory.