ArticlesTrace Elements

Isotopic Abundances of Actinide Elements in Lunar Material

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Science  30 Jan 1970:
Vol. 167, Issue 3918, pp. 499-501
DOI: 10.1126/science.167.3918.499


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 235U/238U was 0.007258 ± 0.000016, in agreement with terrestrial uranium. The following upper limits were set: 236U/238U≤3 x 10-9; parts per million of sample, 239Pu.≤1 x 10-9; 244Pu≤9 x 10-1l, and 247Cm ≤ 1.25 x 10-10. More alpha activity from 227Th and its decay products appears to be presenit than would be in equtilibrilum with the 235U in the sample. The search for other actinide and transactinide nuclides is continuing.

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