Improvement of build up factors for multi-energy -rays penetration through Al, Fe and Pb shield combinations

The calculated transmission dose build up factors for various double-layer shields and for three energies (1.6, 6.13 and 7.10 MeV) photon penetration are improved by applying the Kitazume formula. The same approach was reported recently for two energies (1.43 and 2.75 MeV) photon penetration and for similar shield combinations consisting of AI, Fe and Pb layers (Bakos and Tsagas, 1994).