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Half-life of /sup 138/La

Technical Report ·
OSTI ID:6291334
Tanaka and Masuda recently have observed /sup 138/Ce//sup 142/Ce isotopic abundance ratios which vary linearly with the /sup 138/La//sup 142/Ce abundance ratios in samples of ancient rocks. These variations have been interpreted to be the result of in situ decay of /sup 138/La and thus suggest the potential usefulness of the /sup 138/La//sup 138/Ce geochronometer. However, in order to reconcile the age of the samples inferred from the /sup 138/La//sup 138/Ce clock with that obtained from the well-established /sup 147/Sm//sup 143/Nd chronometer, these authors had to use a value of the /sup 138/La half-life approximately 16% less than the mean of the published values for this quantity. to justify the use of this shorter half-life, Tanaka and Masuda argued that the absorption of atmospheric H/sub 2/O and CO/sub 2/ by La/sub 2/O/sub 3/ probably led to overestimates of the amounts of La contained in samples used in /sup 138/La half-life determinations. Recently, however, we have reinvestigated the half-life and decay scheme of /sup 138/La using 99.999% pure La/sub 2/O/sub 3/ samples. Results are reported. (WHK)
Research Organization:
Washington Univ., Seattle (USA). Nuclear Physics Lab.
DOE Contract Number:
AC06-81ER40048
OSTI ID:
6291334
Report Number(s):
DOE/ER/40048-33-L2; ON: DE83011483
Country of Publication:
United States
Language:
English