Exposure Buildup Factors in Concrete, Lead for Point Isotropic and Unidirectional Photon Sources in the Energy Range from 10 to 50 MeV

The exposure buildup factors in concrete and lead for a point isotropic and flat unidirectional photon source in the energy range from 10 to 50 MeV were determined using Monte Carlo simulation “FLUKA” software. The exposure buildup factors were also obtained for different material thickness up to 40 mpf. The calculations were done in a barrier geometry where the contributions of all photon-matter interactions were taken into account in the performed calculations. Amendments for the barrier-geometry effect for both materials under study were deduced. The results showed that barrier-effect amendments were independent of the material thickness, material type, and energy of the photon source