Fission xenon from extinct Pu in 14301

Xenon extracted in step-wise heating of lunar breccia 14 301 contains a fission-like component in excess of that attributable to uranium decay during the age of the solar system. There seems to be no adequate source for this component other than ²⁴⁴Pu. Verification that this component is in fact due to the spontaneous fission of extinct ²⁴⁴Pu comes from the derived spectrum which is similar to that observed from artificially produced ²⁴⁴Pu. It thus appears that ²⁴⁴Pu was extant at the time lunar crustal material cooled sufficiently to arrest the thermal diffusion of xenon. Subsequent history has apparently maintained the isotopic integrity of plutonium fission xenon.