A chemical element, symbol Am, atomic number 95. The isotope ²⁴¹Am is an alpha emitter with a half-life of 433 years. Other isotopes of americium range in mass from 232 to 247, but only the isotopes of mass 241 and 243 are important. The isotope ²⁴¹Am is routinely separated from “old” plutonium and sold for a variety of industrial uses, such as 59-keV gamma sources and as a component in neutron sources. The longer-lived ²⁴³Am (half-life 7400 years) is a precursor in ²⁴⁴Cm production.