Final answer:
Gamma particles, also known as gamma rays, require several centimeters of lead or concrete to stop them as they are the most penetrating type of radiation.
Step-by-step explanation:
The type of particle that requires several centimeters of lead or concrete to stop it is the gamma particle (y ray). Gamma rays are the most penetrating type of radiation compared to alpha and beta particles. Alpha particles are the least penetrating and can be stopped by a sheet of paper or skin, while beta particles have greater penetration power but can still be stopped by a thin piece of metal, such as aluminum. However, gamma rays, with no charge and essentially no mass, penetrate deeply into most materials, requiring several inches of lead or more than 12 inches of special concrete to absorb them effectively. Neutrons, which are neutral particles, also have high penetrating power and can be best shielded by water or moisture-containing materials like concrete.