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# Accession Number:

## AD0672021

# Title:

## GREAT, A MONTE CARLO PROCEDURE FOR CALCULATING GAMMA-RADIATION ENVIRONMENTS ABOVE TERRAIN,

# Descriptive Note:

# Corporate Author:

## RADIATION RESEARCH ASSOCIATES INC FORT WORTH TEX

# Report Date:

## 1967-12-01

# Pagination or Media Count:

##
58.0

# Abstract:

## The GREAT Monte Carlo Procedure was written for the IBM 1130 computer to calculate the energy and angle distribution of the scattered gamma-ray flux at a point detector in an air-ground geometry resulting from a plane-isotropic monoenergetic gamma-ray source parallel to the air-ground interface. The source, which is finite and annular in shape, may be positioned below the smooth ground surface to simulate the effects of a source located on rough ground. The point detector is located on the vertical axis of the annular source. Initial photon parameters, path lengths, interactions and scattering angles are obtained by random sampling of appropriate probability distributions. Each photon is traced as it scatters within the defined geometry and estimates are made of the flux contribution at the detector from each collision. Portions of the procedure were taken from COHORT, a general purpose Monte Carlo procedure. However, much of the versatility of COHORT was sacrificed for speed and compactness, allowing GREAT to be compatible with the storage available in the IBM 1130 computer and to efficiently perform gamma-ray scattering calculations in an air-ground geometry. Author

# Distribution Statement:

## APPROVED FOR PUBLIC RELEASE

#