PU-244 DATING .9. FISSION XENON IN CARBONACEOUS CHONDRITES

Re-examination of a vast amount of xenon isotope data which have been accumulated since the 1960s reveals that the so-called CCF (carbonaceo us chondrite fission) xenon is a mixture of Pu-244 fission xenon and a severely mass-fractionated primordial xenon, whose isotopic compositi on has been further altered by neutron-capture and spallation reaction s, which occurred in the vicinity of a supernova that most likely expl oded sometime more than 4.8 billion years ago. T integrated flux of 10 KeV (stellar temperature) neutrons to which the xenon was exposed app ears to have been in excess of 10(23) n/cm2.