title: Samarium-146 in the early solar system: evidence from neodymium in the allende meteorite.
abstract: A carbon-chromite fraction from the Allende C3V chondrite shows strikingly large isotopic enrichments of neodymium-142 (0.47 percent) and neodymium- 143 (36 percent). Both apparently formed by alpha decay of samarium-146 and samarium-147 (half-lives 1.03 x 10(8) and 1.06 x 10(11) years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surrounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system [(146)Sm/(144)Sm = (4.5 +/- 0.5) x 10(-3)], higher than predicted by some models of pprocess nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system.
authors.forename: G W
authors.initials: GW
authors.lastname: Lugmair
authors.forename: T
authors.initials: T
authors.lastname: Shimamura
authors.forename: R S
authors.initials: RS
authors.lastname: Lewis
authors.forename: E
authors.initials: E
authors.lastname: Anders