Types of Radiation

There are three primary types of radiation: Alpha, Beta and Gamma rays. Alpha particles are fast-moving helium nuclei with a positive charge. Due to their relatively large size, they are not highly penetrating and can be stopped by a sheet of paper or a few centimeters of air. Beta particles consist of high-speed electrons (beta minus) or positrons (beta plus, the antimatter counterpart of electrons with a positive charge). Beta particles can penetrate deeper than alpha particles and can be blocked by several feet of air, a few millimeters of plastic, or thin layers of light metals. Because beta particles carry a charge opposite to alpha particles, they are deflected in opposite directions when exposed to a magnetic field. Gamma rays are high-energy photons, similar to X-rays but produced differently, typically from nuclear reactions. Gamma radiation is highly penetrating and requires several centimeters of lead or thick concrete to be effectively blocked.