1993 Fiscal Year Final Research Report Summary
Observations of radon at the Kamioka Mine and earthquake prediction
| Project/Area Number |
04452026
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | Gifu University |
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Principal Investigator |
TASAKA Shigeki Gifu University, Faculty of Education, Associate Professor, 教育学部, 助教授 (60155059)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Yoshimi Gifu University, Faculty of Education, Professor, 教育学部, 教授 (40021307)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Radon observation / Underwater radon detector / Gass separatin film / PIN photodiode / KAMIOKANDE experiment / Earthquake prediction / Radon emanation rate / Deep underground experiment |
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| Research Abstract |
We newly developed an underwater radon detector for ^<222>Rn concentration determinations in water. A PIN photodiode, an alpha particle detector, installed inside a container attracts radon families when charged electrostatically. Alpha particles emitted from ^<218>Po(RaA), ^<214>Po(RaC'), ^<210>Po(RaF) and ^<212>Po(ThC') are completely isolated from each other. This system cam be applied to a half year period observation for wide variation of radon concentrations from 0.5(Bq/m^3) in pure water to 10,000(Bq/m^3) in underground water. The observed results of pure water radon concentration in the KAMIOKANDE Tank showed that this technique is valid for the monitor of the degasfication system.
Radon emanation rate were measured from various detector materials in KAMIOKANDE.The expected radon concentration from the exhalation in detector materials was estimated to be about 0.03(Bq/m_3). This value is 1/20 of the observed radon concentration 0.5(Bq/m^3) in KAMIOKANDE.
This system can be applied to three years period observation for wide variation of radon concentrations in the fault underground water. The observed results of underground water radon concentration at a depth of 1,000(m) in the Kamioka Mine showed that this technique is valid for earthquake prediction. Significant decrease in the radon concentration were observed about two and a half days before a magnitude 3.9 earthquake occurred on Atotsugawa fault, and about ten days before a magnitude 4.7 earthquake occurred on the center of Gifu Prefecture.
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Research Products
(9 results)
