@article{oai:nagoya.repo.nii.ac.jp:00011861, author = {北澤, 恭平 and Kitazawa, Kyohei and 永冶, 健太朗 and Nagaya, Kentaro and 増田, 公明 and Masuda, Kimiaki and 中村, 俊夫 and Nakamura, Toshio and 宮原, ひろ子 and Miyahara, Hiroko and 村木, 綏 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 = {The sunspot number, which is a typical index of solar activity, shows a clear 11-year periodicity called the Schwabe cycle. However, in the period around 1645 to 1715 AD the sunspots were almost absent on the solar surface. This is considered to be due to extraordinary weakening of solar activity and this period is called the Maunder minimum. We cannot know from the sunspot record if the Schwabe cycle continued or not in the Maunder minimum. Also we cannot know the periodicity of solar activity without sunspot observation as in pre-telescope era. So we use carbon 14, which is one of cosmogenic nuclides as an indirect index of solar activity with inverse correlation, in order to study 11-year periodicity during grand solar minima like the Maunder minimum. Stuiver classified grand solar minima into two types by duration of minima. The Maunder-type minima have a duration of 〜80yr whereas the Spoerer-type minima last 〜120yr. We previously measured carbon 14 content in Japanese tree for the Maunder minimum (the Maunder type), the Spoerer minimum (the Spoerer type) and the 4^-century-BC minimum (the Maunder type) and a periodicity of 14 yr was obtained for the Maunder-type minima. But we have not finished measuring the carbon 14 content around a leading edge of the Spoerer minimum. This year we measured carbon 14 content in tree rings of 80 years for the pre-Spoerer minimum (1346 to 1425 AD). As a result of frequency analysis we obtained a periodicity signal of 13yr, but only with small significance. A limit of measurement error to get significant signal of 11-year periodicity is discussed., 第20回名古屋大学年代測定総合研究センターシンポジウム平成19(2007)年度報告<第2部> Proceedings of the 20th symposiumon on Chronological Studies at the Nagoya University Center for Chronological Research in 2007 日時:平成20 (2008)年1月10日(木)~11日(金) 会場:名古屋大学野依記念学術交流館 Date:January10th-11th, 2008 Venue:Nagoya Uhiversity Noyori Conference Hall}, pages = {103--109}, title = {プレ・シュペーラー極小期における樹木年輪中 ^<14>C濃度測定(第20回名古屋大学年代測定総合研究センターシンポジウム平成19(2007)年度報告)}, volume = {19}, year = {2008} }