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

摘要

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 to that of Maunder or Sporer era when sunspots were absent.The least squares fit of a sine function for the DELTA~(14)C of 22 single-year tree rings indicated the amplitude of 0.39% and the period of 11.5-year.It indicate that the tree rings of ca.2500 years ago record 11-year solar variations for the ~(14)C concentrations.