Which material is used for shielding against alpha radiation?

Shielding against alpha radiation is effectively achieved using materials such as skin and paper due to the nature of alpha particles. Alpha radiation consists of positively charged particles (helium nuclei) that have a relatively low penetration ability. They can be stopped by very thin barriers, including the outer layer of human skin or even a sheet of paper.

This is significant when considering the fundamental properties of alpha particles. They have a high mass and are positively charged, leading to a high interaction rate with matter; thus, their ability to penetrate materials is limited. In practical scenarios, alpha particles cannot penetrate the skin barrier and will not reach living tissues unless there is a break in the skin.

While materials like lead and concrete are effective shields against higher energy radiation (such as gamma rays and X-rays), they are not necessary for alpha radiation due to its low penetration capability. Plastic and aluminum can also provide some degree of shielding, but they are not as effective or simple as such minimal barriers as skin and paper. Therefore, using skin and paper to stop alpha particles demonstrates a clear understanding of both the radiation's characteristics and the principles of radiation protection.