| A formula that gives buildup factors for two-layered shields has been developed. Gamma-ray absorption buildup factors for infinite medium single materials and two-layer shields have been computed using the Monte Carlo Neutral-Particle Transport Code System (MCNP). The source used in the calculations for single and two-layer shields was point isotropic with the energies from 0.1 MeV to 10 MeV. The shielding materials used in MCNP were water, aluminum, lead, steel, concrete and some of their combinations for two layered shields with thickness' between 1 mfp to 10 mfp. All secondary particles produced inside the shields, e.g. annihilation gammas from pair production and bremsstrahlung from the electrons, were taken into account in the calculations. The values of buildup factors for two-layered materials, obtained with the equations developed agree with the results obtained using MCNP. |
