title: Plutonium-244: confirmation as an extinct radioactivity.
abstract: The mass spectrum of xenon from spontaneous fission in a laboratory sample of plutonium-244 is precisely what meteoriticists predicted it would be; this discovery completes a web of proof that this nuclide is a bona fide extinct radioactivity of galactic origin, that r-process nucleosynthesis was ongoing in the galaxy at the time of the birth of the sun, and that the early meteoritic abundances of plutonium-244, heretofore tentative, can be utilized with confidence in models for the chronology of galactic nucleosynthesis. The search for an explanation for anomalous fission-like xenon in carbonaceous chondrites can now be narrowed.
authors.forename: E C
authors.initials: EC
authors.lastname: Alexander
authors.forename: R S
authors.initials: RS
authors.lastname: Lewis
authors.forename: J H
authors.initials: JH
authors.lastname: Reynolds
authors.forename: M C
authors.initials: MC
authors.lastname: Michel