| Budget Amount *help |
¥16,900,000 (Direct Cost: ¥13,000,000、Indirect Cost: ¥3,900,000)
Fiscal Year 2016: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2015: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2014: ¥9,100,000 (Direct Cost: ¥7,000,000、Indirect Cost: ¥2,100,000)
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| Outline of Final Research Achievements |
Galactic cosmic rays come to the earth under the solar effect and produce 14C nuclei in the atmosphere, being archived in tree rings. Measurement of past 14C content with 1-2 year resolution tells us a detailed history of cosmic ray intensity. Here we obtained characteristics of the sun during AD500-1350. Also we surveyed cosmic ray intensity in a part of past 7000 years and found a rapid increase, being considered to be due to abnormal solar activities.
We confirmed by accelerator experiments using heavy-ions that ion-induced cloud condensation nuclei can be produced from ionization by cosmic-ray particles in atmosphere. Produced ion density and size distributions of produced aerosol particles were measured and no clear change in characteristics of particle production was observed for kind of heavy ion.
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