Number: 2006-016-1-200
Title: Recommendations for isotope
data in geosciences
Task Group
Chairman: Paul Renne
Members: Mauro
Bonardi, Paul
De Bièvre, Ales
Fajgelj, Norman
E. Holden, Dunyi
Liu, and Igor
M. Villa
Objective:
Update and harmonize recommendations on half-lives and isotopic
compositions.
Description:
The inter-Union project with the International Union of Geological
Sciences (IUGS)
strives to provide an authoritative recommendation based on a critical
reevaluation of data on half-lives and decay schemes of long-lived
radioactive nuclides used by the geological and planetary science
communities. A specific goal of the project is to reconcile current
inconsistencies between values used in geological and planetary
sciences on the one hand, and those used in the nuclear physics
and chemistry communities on the other.
The project will draw on complementary
expertise present in IUGS and IUPAC. Previous work by IUGS (Working
Group "Decay constants in geochronology") and IUPAC (Commissions
II.1 "Isotopic abundance" and V.7 "Radiochemistry
and Nuclear Techniques") will be included, harmonized, and
updated. IUGS-IUPAC interaction will be tightened.
Initial work (2006-2008) focuses on 9
nuclides used in geochronology (40K, 87Rb, 138La, 147Sm, 176Lu,
187Re, 232Th, 235U, 238U). Half-lives, decay schemes, and measurement
techniques will be critically evaluated, as well as isotopic compositions
of parent and daughter elements. Uncertainty analyses need to be
adequately reassessed following ISO/GUM procedures. Successive phases
will both expand the number of nuclides and refine the isotopic
abundances in view of an additional recommendation.
