A study of heliosphere before 25000 years measuring a variation of 22-year for cosmic rays

我们<14>用加速质谱法（AMS）测量了一个25000年前的古老木材样品的单年年轮中^ C浓度。测量<14>了连续26个一年树木年轮的^ C浓度，为AMS生产了60个石墨样品。由于每个树木年轮测量两个石墨样品，计数精度约为0.7%。26个树木年轮的放射性碳年龄平均为22271±118 yr BP，用Faibanks0107年龄校正程序计算的日历年龄为26778±178 yr BP。26个单年年轮的放射性碳年龄的时间剖面暗示了一个变化与两个驼峰表示约12年的间隔。尖峰和钝峰距移动平均值曲线的高度分别为157和109年。它们分别对应于<14>2.0%和1.4%的^ C浓度。由于<14>25000年前的年代比现在高40%，这种变化暗示了11年或22年的太阳周期活动。

We have measured the ^<14>C concentrations in single-year tree rings of an old wood sample before approximately 25000years, using accelerated mass spectrometry (AMS). The ^<14>C concentrations of consecutive 26 single-year tree rings were measured producing the 60 graphite samples for the AMS. The counting accuracy was approximately 0.7% because of the measurement of two graphite samples for each tree ring. The radiocarbon age was 22271±118 yrBP on average for the 26 tree rings, indicating the calendar age of 26778±178 yrBP by the age calibration program of Faibanks0107. Time profile of the radiocarbon ages for 26 single-yr tree rings implied a variability with two humps indicating an interval of approximately 12-year. The heights of sharp and dull humps were 157 yrBP and 109 yrBP from the moving average curve, respectively. They are corresponding to the ^<14>C concentrations of 2.0% and 1.4%, respectively. As the ^<14>C concentrations of this era before 25000 years was 40% higher than that at present time, the variation is suggestive solar periodic activities such as 11-year and/or 22-year.