How to stop these three different types of radioactivity is determined by their penetrating power. Therefore, alpha, beta, and gamma radiations have different requirements to be stopped.
o Alpha particles have a low penetrating power and are relatively slow and heavy, and can be stopped with merely a piece of paper
· Beta Radiation
o Beta particles have a medium penetrating power and are relatively fast and light, and require a sheet of aluminum or certain plastics such as Perspex to be stopped.
· Gamma Radiation
o Gamma rays have a high penetrating power although have no mass, as they are waves and not particles. Since they have a high penetrating power, it is very difficult to completely stop gamma rays, although concrete or a thick sheet of metal can significantly reduce them.