Comparison of gamma-ray point isotropic buildup factors including fluorescence and bremsstrahlung in lead using discrete ordinates and point Monte Carlo methods.

Abstract

Exposure buildup factors and energy spectra of γ-rays, including fluorescence or bremsstrahlung radiations, in Pb for a point isotropic source have been calculated in the vicinity of the K edge and at 10 MeV using a discrete ordinate code, PALLAS. Comparisons of PALLAS results with those by the point Monte Carlo code, EGS4 showed good agreement for exposure buildup factors and energy spectra in two energy regions. Exposure buildup factors calculated with another discrete ordinate code, ASFIT, are also compared with those calculated by the PALLAS and EGS4 codes. The values obtained by all three codes showed good agreement. The effects of the cross section data on the buildup factors were investigated by using the PALLAS code.