Plan of large SPE search by the 14C content measurement in Japanese trees for the past 5000 years

Fusa MIYAKE; Kimiaki MASUDA; Masataka HAKOZAKI; Toshio NAKAMURA; Katsuhiko KIMURA

Presentation information

International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM08_1PM2] Space Weather and Space Climate

Thu. May 1, 2014 4:15 PM - 6:00 PM 411 (4F)

Convener:*Ryuho Kataoka(National Institute of Polar Research), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Kanya Kusano(Solar-Terrestrial Environment Laboratory, Nagoya University), Toshifumi Shimizu(Institute of Space and Astronautical Science, JAXA), Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University), Ayumi Asai(Unit for Synergetic Studies of Space, Kyoto University), Tatsuhiko Sato(Japan Atomic Energy Agency), Hidekatsu Jin(National Institude of Information and Communications Technology), Kiminori Itoh(Graduate School of Engineering, Yokohama National University), Hiroko Miyahara(College of Art and Design, Musashino Art University), Chair:Ryuho Kataoka(National Institute of Polar Research), Tatsuhiko Sato(Japan Atomic Energy Agency)

5:30 PM - 5:45 PM

[PEM08-06] Plan of large SPE search by the 14C content measurement in Japanese trees for the past 5000 years

*Fusa MIYAKE¹, Kimiaki MASUDA¹, Masataka HAKOZAKI², Toshio NAKAMURA², Katsuhiko KIMURA³ (1.Solar-Terrestrial Environment Laboratory, Nagoya University, 2.Center for Chronological Research, Nagoya University, 3.Faculty of Symbiotic Systems Science, Fukushima University)

Keywords:radiocarbon, tree-rings, cosmic-ray, SPE

Radiocarbon (¹⁴C) is produced by incoming cosmic rays to the Earth. Produced ¹⁴C becomes ¹⁴CO₂ and is absorbed by trees by photosynthesis. Then,tree-rings record the past cosmic ray intensity. Rapid yearly increases in the ¹⁴C content have been detected for the period from AD 774 to AD 775 and from AD 993 to AD 994. Althogh some candidates for the cause of these cosmic-ray invents have been considered, it has been considered that the solar activity (large SPE) is the most plausible cause.There is the possibility that a lot of ¹⁴C increase events like the AD 775 one are hidden in the periods when the ¹⁴C content has not been measured with a 1-year resolution. If we detect such events, we are able to discuss a detailed occurrence rate of large SPE which is very important factor to prepare for future large SPEs.We are planning to search for ¹⁴C increase events by the measurements of ¹⁴C content in Japanese trees for this 5000 years. In this thesis, we are going to explain the plan and problems.