Single-year measurements of radiocarbon (14C) in tree rings have led to the discovery of rapid cosmic-ray events as well as longer lasting anomalies, which have given new insights into the Sun’s behavior in the past. Here, we present two new single-year 14C records based on Danish oak that span the periods AD 692–790 and 966–1057, respectively, and consequently include the two rapid cosmic-ray events in AD 775 and 994. The new data are presented along with relevant information on the dendrochronological dating of the wood pieces, implying that these new measurements may contribute towards generating the next international calibration curve. The new data covering the AD 966–1057 period suggest that the increase in atmospheric 14C associated with the cosmic-ray event in AD 994 actually occurred in AD 993, i.e. one year earlier than the year reported in Fogtmann-Schulz et al. (2017) based on oak from southern Denmark. Careful reanalysis of the dendrochronology that underpins the new 14C records based on oak material from southern Denmark reveals that the cosmic-ray event reported in Fogtmann-Schulz et al. (2017) actually took place in AD 993.

中文翻译：

---

基于丹麦橡木的新单年放射性碳测量，涵盖公元 692-790 年和 966-1057 年

放射性碳的单年测量值（14C) 在年轮中的发现导致了快速宇宙射线事件以及更持久的异常现象的发现，这些异常现象使人们对过去的太阳行为有了新的认识。在这里，我们介绍两个新的单年14基于丹麦橡木的 C 记录分别跨越公元 692-790 年和 966-1057 年，因此包括公元 775 年和 994 年的两次快速宇宙射线事件。新数据与有关树木年代学年代学的相关信息一起呈现木片，这意味着这些新的测量可能有助于生成下一个国际校准曲线。涵盖公元 966-1057 年期间的新数据表明，大气14与公元 994 年的宇宙射线事件相关的 C 实际上发生在公元 993 年，即比 Fogtmann-Schulz 等人报道的年份早一年。(2017) 基于丹麦南部的橡木。对支撑新的树木年代学的仔细重新分析14基于丹麦南部橡木材料的 C 记录揭示了 Fogtmann-Schulz 等人报道的宇宙射线事件。（2017）实际上发生在公元 993 年。