Detailed Investigation of the Buildup Factors and Spectra for Point Isotropic Gamma-Ray Sources in the Vicinity of the K Edge in Lead

Detailed calculations of the buildup factors and spectra of gamma rays including fluorescence radiations in lead are carried out using a discrete ordinates code, PALLAS-PL,SP-Br. The exposure and absorbed dose buildup factors with and without fluorescence are tabulated for 11 source energies from 0.09 to 0.3 MeV for penetration depths up to 40 mfp. Important characteristics of the gamma-ray transport in the vicinity of the K edge of lead are explored using detailed energy spectra in the medium. The contribution of the fluorescence to buildup factors is extremely significant for the sources close to the K edge energy.