Radiation transport in one-dimensional finite systems. II. Gamma-ray transport studies with ASFIT

Here we present the results of extensive calculations on the gamma-ray transport in finite heterogeneous systems using the technique developed in Part I of this paper. Systems studied are water, concrete, aluminum, iron, and lead, and the data presented are: evolution of spectra with collisions, reflected and transmitted spectra, spectra at different depths, and buildup factors for different source energies and different thicknesses of each medium. Similar data are also presented for two-region systems of water-iron, iron-lead, and water-lead. Several interesting results have been observed, among which are: (a) a step structure and a second peak in the low energy part of the back-scattered spectra from light media, (b) progressive buildup of a peak in the low energy region of transmitted flux, and (c) significant dip in the build-up factors near the outer boundary of the systems. The results are discussed on the basis of the physical processes involved. A comparison of the present results with those published in literature is made.