What type of ionizing radiation can be stopped by a sheet of paper?

Alpha particles are relatively large and positively charged compared to other types of ionizing radiation. Due to their size and charge, they have a very limited ability to penetrate materials. A sheet of paper is sufficient to stop alpha particles because they can only travel a few centimeters in air and are unable to penetrate even the outer dead layer of human skin. This property makes alpha radiation the least penetrating among common types of ionizing radiation. In contrast, gamma rays, beta particles, and X-rays can penetrate materials to varying degrees, requiring denser substances or thicker barriers to effectively shield against them.