What type of radiation can be stopped by paper?

Alpha particles are a type of radiation that can be effectively stopped by a sheet of paper. This is due to their relatively large mass and positive charge, which causes them to interact with matter in a way that leads to significant energy loss, even with just a few centimeters of air or a thin barrier like paper.

In practical terms, when alpha particles travel through air or attempt to penetrate materials, they quickly lose energy because they have a strong interaction with electrons in nearby atoms. This results in alpha particles having a very short range and low penetrating ability. Therefore, a simple barrier such as paper is sufficient to stop them completely.

Other forms of radiation, such as beta particles, gamma rays, and X-rays, have different properties. Beta particles are more penetrating than alpha particles and can pass through paper, while gamma rays and X-rays are highly penetrating forms of electromagnetic radiation that require much denser materials, like lead, to shield effectively. This distinction highlights the unique nature of alpha particles regarding their interaction with materials.