Improvement in radiation shielding property by the multi-layered structurewith narrow gaps due to reflection and absorption before and behind the gaps

A new type of radiation shield structure with narrow gaps is proposed and i ts shielding property is shown to be improved by taking the effects of refl ection and absorption before and behind the gaps into consideration. The present shield structure consists of the multi-layered structure of shi eld materials. The thickness of one unit shield layer is about one mean fre e path of the incident X-ray in the shielding material. Three basic element s are applied to the present shield structure as follows. The first element is to equip narrow gaps between the shield layers. The second element is t o use scattering/absorbing composite materials. The third element is to enc lose the outside of multi-layered shield structure with absorbing materials . In the present paper the basic concept for the present shield structure is proposed as the X-ray shielding design and simplified equations are derived by considering X-ray energy flow. Using the derived equations shielding ca lculations are made as to a simple multi-layered structure model. Furthermo re, the fundamental X-ray penetration experiments and calculations by the M onte Carlo code EGS4 are performed in order to prove the improvement in shi elding property due to the present multi-layered structure with gaps. From these investigations, we obtained the result that the present multi-layered structure with narrow gaps can improve effectively shielding property.