PHITS computational investigation of the neutron shielding ability of low-density polyethylene-mixed clay matrix in medical linear accelerator facilities
This study aimed to investigate the neutron shielding ability of clay matrix mixed with low-density polyethylene (LDPE) for neutron energies found in medical linear accelerator facilities. Particle and Heavy-Ion Transport System (PHITS) v3.29 was used to simulate neutron transport across clay-LDPE, concrete, and LDPE for neutron energies of 0 to 15 MeV. The results showed that the clay-LDPE had 51.25%, 50.58%, and 36.67% lower fluence reduction than LDPE for thermal, epithermal, and fast neutron regions, respectively. On the other hand, clay-LDPE had 60.15% and 50.57% higher fluence reduction than concrete for thermal and epithermal neutrons. For fast neutrons, clay-LDPE had 17.25% lower fluence reduction than concrete. The higher concentration of heavy elements which exhibit neutron inelastic scattering, particularly oxygen and silicon, in concrete compared to clay-LDPE is presumed to be the reason behind concrete’s better performance in the fast neutron region.