@article{oai:nagoya.repo.nii.ac.jp:00012835, author = {永冶, 健太朗 and 増田, 公明 and 中村, 俊夫 and 宮原, ひろ子 and 松崎, 浩之 and 村木, 綏 and Nagaya, Kentaro and Masuda, Kimiaki and Nakamura, Toshio and Miyahara, Hiroko and Mtsuzaki, Hiroyuki and Muraki, Yasushi}, journal = {名古屋大学加速器質量分析計業績報告書}, month = {Mar}, note = {Variation of the sunspot number, which reflects solar activity, has shown the periodicity of around 11-year since the early 18th century. However, in the period of 1645 to 1715 AD sunspots were almost absent, and this period is called the Maunder Minimum, one of grand solar minima implying weak solar activity. Variation of solar activity in grand solar minima can be investigated by determining the concentration of cosmogenic isotope ^<14>C in annual tree rings. We previously obtained the ^<14>C records of1413 to 1745 AD including the Spoerer Minimum (1416-1534 AD) and the Maunder Minimum with annual time resolution. As a result of frequency analysis of these ^<14>C records, we found that the cycle length of the "11-year cycle" during the Maunder Minimum was around 14 years while that during the Spoerer Minimum was modulating slightly from 11 years. This result suggests that a pattern of the "11-year" cycle length variation depends on a type of minima classified by their duration of estimated sunspot absence. In order to verify this hypothesis, we have measured ^<14>C contents in Japanese camphor tree rings during a possible grand solar minimum in the 4th century B.C. Preliminary result shows the solar cycle length was several years longer than 11 years, as in the Maunder Minimum.}, pages = {145--151}, title = {年輪中^<14>C 濃度測定による紀元前4 世紀太陽活動極小期における太陽活動周期の研究}, volume = {20}, year = {2009} }