Absorbers of α, β, and γ radiation.
Ionizing radiation may consist of streams of high-energy particles or high-frequency (short-wavelength) electromagnetic radiation, including:
· alpha particles (high-speed helium nuclei)
· beta particles (high-speed electrons)
· other fast-moving particles, such as neutrons and protons
· X-rays and gamma rays (high frequency electromagnetic waves)
Neutrons are not themselves ionizing but their collisions with nuclei lead to the ejection of other charged particles that do cause ionization.
Ionizing radiation can have a particularly serious effect on biological tissues, although this depends much on the type of radiation and the extent of exposure.
Absorbers of ionizing radiation
An absorber is any material that is efficient at stopping ionizing radiation from passing through. Alpha particles are totally absorbed by a sheet of paper. Beta particles are absorbed by a few cm of plastic material or 1 cm of aluminum. Materials with a high atomic number and high density (e.g., lead, steel, and concrete) are used as absorbers of gamma rays. Neutron absorbers such as boron, hafnium, and cadmium are used in control rods for reactors.