A signature of cosmic-ray increase in ad 774–775 from tree rings in Japan

  title={A signature of cosmic-ray increase in ad 774–775 from tree rings in Japan},
  author={Fusa Miyake and Kentaro Nagaya and Kimiaki Masuda and Toshio Nakamura},
Increases in 14C concentrations in tree rings could be attributed to cosmic-ray events, as have increases in 10Be and nitrate in ice cores. The record of the past 3,000 years in the IntCal09 data set, which is a time series at 5-year intervals describing the 14C content of trees over a period of approximately 10,000 years, shows three periods during which 14C increased at a rate greater than 3‰ over 10 years. Two of these periods have been measured at high time resolution, but neither showed… 
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