A new primary standardization of 229Th.
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.
Fitzgerald
R
R
Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. ryan.fitzgerald@nist.gov
Collé
R
R
Laureano-Pérez
L
L
Pibida
L
L
Hammond
M M
MM
Nour
S
S
Zimmerman
B E
BE
D004784:Environmental Monitoring / Q000592:standards; D005720:Gamma Rays; D012015:Reference Standards; D013910:Thorium / Q000032:analysis / Q000592:standards*
D013910:Thorium