Sources of alpha radiation are common in nature and include thorium, uranium, and radium. These heavy elements are not commonly used in campus research. Alpha radiation is also produced by sources other than the decay of an unstable nucleus such as accelerators. Alpha emitters such as 239 Pu and 241 Am are mixed with beryllium to create sealed neutron sources. These are used to study neutron effects on materials.
Alpha particles are highly energetic.
These energies are up to an order of magnitude greater than other types of radiation emitted by radioisotopes commonly used in research laboratories. From a radiation safety standpoint, alpha particles are easily stopped by a thin absorber such as a sheet of paper or the dead layer of the skin. External to the body such sources do not present a great hazard. Inside the body, however, alpha emitters are highly significant. Because the alpha particle is doubly charged and relatiely massive, it undergoes many interactions with surrounding atoms, depositing all its energy in a very small volume, on the order of 3 x 10 -9 cm 3 in muscle.