title: A new primary standardization of 229Th.
abstract: The National Institute of Standards and Technology (NIST) has certified a high-purity (229)Th Standard Reference Material as SRM 4328C, based on live-timed 4pialphabeta-gamma anticoincidence counting (LTAC) of the equilibrium solution. The LTAC system was optimized to minimize the uncertainty in the result due to the two short-lived ground-states present in the decay chain. Confirmatory measurements were carried out by four other methods. Furthermore, the present absolute activity and measured gamma-ray emission rates were combined to obtain gamma-ray emission probabilities.
authors.affiliation: Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. ryan.fitzgerald@nist.gov
authors.forename: R
authors.initials: R
authors.lastname: Fitzgerald
authors.forename: R
authors.initials: R
authors.lastname: Collé
authors.forename: L
authors.initials: L
authors.lastname: Laureano-Pérez
authors.forename: L
authors.initials: L
authors.lastname: Pibida
authors.forename: M M
authors.initials: MM
authors.lastname: Hammond
authors.forename: S
authors.initials: S
authors.lastname: Nour
authors.forename: B E
authors.initials: BE
authors.lastname: Zimmerman
mesh_terms: D004784:Environmental Monitoring / Q000592:standards; D005720:Gamma Rays; D012015:Reference Standards; D013910:Thorium / Q000032:analysis / Q000592:standards*
chemical_list: D013910:Thorium