The radial distribution of reflection and transmission of scattered gamma rays

The lattice model concept of stochastic gamma ray transport is used to calculate the radial distributions of reflected and transmitted gamma rays on the faces of slabs of different thicknesses from a point collimated incident source. The radial distribution of scattered, reflected and transmitted spectra is calculated and the effect of incident angle, slab thickness, and annihilation radiation on iron and aluminum is investigated. Each collision in the medium is considered to be either a Compton scattering, a photoelectric absorption, or a pair production. To reduce variance; the absorption, point of first collision, and reflection and transmission after each collision are calculated analytically. These calculations are very easily done by associating a weight factor with the gamma rays at each lattice point. When pair production occurs, the history of one photon is followed with the statistical weight doubled. Using the model, a computer code is developed which is called PUGRT1 (Pahlavi University Gamma Ray Transport 1). The results of this code are found to be in good agreement with other calculations and experimental results on iron and aluminum.