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

我们用加速质谱仪(AMS)测量了大约25000年前的一个老木材样品的一年生树木年轮中的~(14)C浓度。测量了连续26个一年生年轮的14&C浓度，产生了60个用于AMS的石墨样品。由于每个树轮测量了两个石墨样品，因此计数精度约为0.7%。26个年轮的平均放射性碳年龄为22271±118yrBP，根据Faibans0107的年龄校正程序得到的日历年龄为26778±178yrBP。26个一年生年轮的放射性碳年龄的时间分布暗示了一个变异性，两个驼峰表明间隔约为12年。尖峰和钝峰的高度分别比移动平均曲线高157yrBP和109yrBP。它们分别对应于2.0%和1.4%的^&lt；14；C浓度。由于25000年前这个时代的~(14)&C浓度比现在高40%，这种变化暗示了太阳周期活动，如11年和/或22年。

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.