Fig. 1. Gamma dose attenuation ratio of Al sphere

Fig. 2. Neutron dose attenuation ratio of Al sphere

Fig. 3. Equivalent model of planar source to point source

Fig. 4. Structural modeling in MC program

Fig. 5. 1/F_NPvs side length (Al slab with thickness 15 cm )

Fig. 6. Radiation attenuation ratio of different slab materials for 1 MeV neutrons

Fig. 7. Radiation attenuation ratio vs steel slab thicknesses for different neutron incident energies

Fig. 8. Radiation attenuation ratio vs steel slab thicknesses for neutron spectra

Fig. 9. Radiation attenuation ratio of different slab materials for 1 MeV γ

Fig. 10. Radiation attenuation ratio vs steel slab thicknesses for Little Boy γ spectra

Fig. 11. Total radiation attenuation ratio vs steel slab thicknesses for neutron and γ

Fig. 12. Neutron energy spectrum at detector for different slab thickness

Fig. 13. γ energy spectrum at detector for different slab thickness

Fig. 14. Secondary γ energy spectrum at detector for different slab thickness

Fig. 15. Vertical irradiation downward to chamber

Fig. 16. Total protection coefficient