Assessment of proton shielding properties of rare earth metal-concrete using PHITS Monte Carlo code

This study evaluates the proton shielding performance of concrete modified with rare earth metals (REMs) using the Particle and Heavy Ion Transport code System (PHITS) Monte Carlo simulations. Standard concrete was doped with cerium, lanthanum, neodymium, and yttrium at 2 %, 5 %, and 10 % weight percentages. Proton energies of 50 and 100 MeV/u and shielding thicknesses of 5, 15, and 30 cm were analyzed to assess particle flux, including primary protons and secondary particles (neutrons, photons, electrons). Results show that REM-doped concrete effectively attenuates protons, with 10 % neodymium-doped concrete exhibiting the lowest flux of both primary and secondary particles. Increased REM concentration and thickness enhance shielding, though secondary particle production requires additional consideration. Neodymium-enriched concrete, particularly at 10 % concentration, is a promising material for compact shielding in proton therapy facilities, supporting the use of locally sourced REMs.