title: Isotopic abundances of actinide elements in lunar material.
abstract: The abunldanzces of uranium and thorium were measured mass spectrometrically as 0.59 +/- 0.02 and 2.24 +/- 0.06 parts per million, respectively, in the fines of Apollo 11 builk sample. The ratio (235)U/(238)U was 0.007258 +/- 0.000016, in agreement with terrestrial uranium. The following upper limits were set: (236)U/(238)U</=3 x 10(-9); parts per million of sample, (239)Pu.</=1 x 10(-9); (244)Pu</=9 x 10(-1l), and (247)Cm </= 1.25 x 10(-10). More alpha activity from (227)Th and its decay products appears to be presenit than would be in equtilibrilum with the (235)U in the sample. The search for other actinide and transactinide nuclides is continuing.
authors.forename: P R
authors.initials: PR
authors.lastname: Fields
authors.forename: H
authors.initials: H
authors.lastname: Diamond
authors.forename: D N
authors.initials: DN
authors.lastname: Metta
authors.forename: C M
authors.initials: CM
authors.lastname: Stevens
authors.forename: D J
authors.initials: DJ
authors.lastname: Rokop
authors.forename: P E
authors.initials: PE
authors.lastname: Moreland