Ryan P. Fitzgerald, Lizbeth Laureano-Perez, Michelle M. Hammond, Leticia S. Pibida, Svetlana Nour, Brian E. Zimmerman
The National Institute of Standards and Technology (NIST) has certified a high-purity Th-229 Standard Reference Material as SRM 4328C, based on live-timed 4-pi alpha,beta-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.
Applied Radiation and Isotopes
mass spectrometry standard, primary standard, radioactivity, tracer, Th-229