Search for annual14C excursions in the past

Fusa Miyake, Kimiaki Masuda, Toshio Nakamura, Katsuhiko Kimura, Masataka Hakozaki, A. J.Timothy Jull, Todd E. Lange, Richard Cruz, Irina P. Panyushkina, Chris Baisan, Matthew W. Salzer

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Two radiocarbon excursions (AD 774-775 and AD 993-994) occurred due to an increase of incoming cosmic rays on a short timescale. The most plausible cause of these events is considered to be extreme solar proton events (SPE). It is possible that there are other annual14C excursions in the past that have yet to be confirmed. In order to detect more of these events, we measured the14C contents in bristlecone pine tree-ring samples during the periods when the rate of14C increase in the IntCal data is large. We analyzed four periods every other year (2479-2455 BC, 4055-4031 BC, 4465-4441 BC, and 4689-4681 BC), and found no anomalous14C excursions during these periods. This study confirms that it is important to do continuous measurements to find annual cosmic-ray events at other locations in the tree-ring record.

Original languageEnglish (US)
Pages (from-to)315-320
Number of pages6
Issue number2
StatePublished - Apr 1 2017


  • Annual cosmic-ray event
  • Cosmogenic nuclides

ASJC Scopus subject areas

  • Archaeology
  • Earth and Planetary Sciences(all)


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