The first object of radiation protection equipment is: α - ray alpha particle is the nucleus of helium-4 with high energy. Due to the Coulomb field effect and elastic collision, the energy of alpha particles is often consumed to absorb other substances. Therefore, the protection against radiation is relatively simple, and a piece of paper can basically prevent it. However, it does great harm to people in close range. Alpha particle internal irradiation will consume all the energy in a short distance, so it damages the cells and tissues exposed to short distance irradiation seriously.
Protection object 2: beta ray beta particle is essentially a high-speed moving electron beam with a negative charge (a positive charge to a positron), with a mass of 1 / 1837 of a proton or neutron. The penetration ability of β - ray is between α - ray and γ - ray.
Since bremsstrahlung is easy to be produced when β - ray interacts with substances with large atomic weight, for beta radiation sources with large activity, light materials such as plexiglass are generally selected for protection first, and then materials with larger atomic weight are selected for shielding. Both internal and external irradiation should be considered in the protection of β - ray.
Protection object 3: gamma ray gamma ray is essentially a high-energy photon beam. Because the photon is not charged and its static mass is 0, it is not easy to lose energy. Only when the interaction between gamma ray and matter occurs photoelectric effect, Compton scattering and electron pair annihilation, will the energy be lost.
Because of the strong penetration ability of gamma ray, materials with higher atomic number (such as lead, depleted uranium, tungsten) or concrete and water with large thickness are generally selected for shielding. In addition, the higher the energy, the more difficult it is to protect. The protection of gamma ray mainly considers the external radiation factor, but because it is usually accompanied by α, β decay, so the internal radiation protection can not be ignored.