Variation of ¹⁴C concentration of single-yr tree rings at the small peak in 2600-yrBP for Choukai Jindai cedar

Abstract

We have measured C-14 concentrations of old tree rings with a measuring accuracy of 0.2% to search variation in an ancient cosmic ray intensity fluctuation. From C-14 dating, the calendar ages of the Choukai Jindai cedar in Japan (39°N) were ranged in from 2757 to 2437 calBP with 320 tree rings, and this wood sample is located at a very interesting era because the C-14 concentrations form a peak area as well as Maunder Minimum at which the sunspot numbers were absent. The C-14 concentrations of single-yr tree rings using the Choukai Jindai cedar in 2650 to 2600 yr BP showed a rapid change. We report the structure of the C-14 variation in the 50 years relating an 11-yr solar cycle.