|Polonium-210 emits alpha-rays with energy 5.3 MeV which is dissipated in solid matters penetrating into it to thousandths of millimeter because of radiation braking. Its lifetime allows using it in space ship atomic batteries: 7.5 mg is sufficient for providing power of 1kW. It surpassed other compact "atomic" energy sources. Polonium battery was utilized on "Lunokhod-2" generating heat during moon night. Of course, its power decreased halving each 4.5 months; however, more long-lived isotopes are much more expensive. Polonium may be comfortably used for research of alpha-radiation impact with substance. Polonium and beryllium mixtures are used for neutron compact sources:|
9Be + 4He = 12C + n.