Measurements of C-14 concentration for 22 single-year tree rings of an old cedar ca. 2500 years ago

The 14 C concentrations of 22 tree rings of ca. 2500 years ago have been measured at single-year intervals with a highly accurate liquid scintillation counting system Quantulus (≤0.2%). The calendar age of the wood sample was 477B.C.±20 by 14 C dating and the variation of 14 C during the era is similar