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2002 Fiscal Year Final Research Report Summary

Study on the Variation of Environmental Neutron Dose During a Solar Maximum Period and its Effect

Research Project

Project/Area Number 12480133
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Nuclear engineering
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

NAKAMURA Takashi  Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (70026029)

Co-Investigator(Kenkyū-buntansha) TAKAGI Shunji  Mitsubishi Research Institute Co.Ltd., Researcher, 総合安全研究センター・原子力システム研究部, 研究員(研究職)
IWASAKI Tomohiko  Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (70184869)
BABA Mamoru  Tohoku University, Cyclotron and Radioisotope Center, Professor, サイクロトロン・ラジオアイソトープセンター, 教授 (20005466)
NUNOMIYA Tomoya  Tohoku University, Graduate School of Engineering, Japan Society for promotion of Science Researcher, 大学院・工学研究科, 日本学術振興会特別研究員
TAKADA Masashi  National Institute of Radiological Sciences, Researcher, 国際宇宙医学研究センター, 研究員(研究職) (50291109)
Project Period (FY) 2000 – 2002
KeywordsCosmic-Ray Neutrons / Solar Flare / Solar Activity / Dose / Energy Spectrum / Rem Counter / Liquid Organic Scintillator / Multi-Moderator Spectrometer
Research Abstract

The Cosmic-ray neutron spectrum and dose rate have been measured with three neutron detectors. Bonner sphere(Multi-moderator), high-sensitivity rem counter and NE213 organic liquid scintillator sequentially from October 2000 to March 2003, where the solar activity reaches a maximum. The neutron spectra have three distinct peaks, thermal energy peak, evaporation peak around a few MeV and cascade peak around 100 MeV. There can be seen a tendency that a cascade peak relatively increases on the day of higher neutron flux compared with other two peaks. The neutron flux and dose rate show a clear negative correlation with the atmospheric pressure according to the exponential attenuation during the observation period, and also a Forbush decrease in some cases just after big solar flares. The neutron fluxes above 20 MeV Measured with the Bonner sphere and the NE213 gave almost the same values during the observation period to be about 2 x 10^<-3> n cm^<-2>s^<-1>.

  • Research Products

    (4 results)

All Other

All Publications (4 results)

  • [Publications] D.A.H.Rasolonjatovo: "Measurement for the Dose-rates of the Cosmic-Ray Components on the Ground"Journal of Radiation Research. (in press). (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Nakamura: "Sequential Measurements of Energy Spectrum and Intensity for Cosmic-Ray Neutrons"Seventh International Symposium on Natural Radiation Environment. 20-24 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] D.A.H.Rasolonjatovo, H.Suzuki, N.Hirabayashi, T.Nunomiya, T.Nakamura, N.Nakano: "Measurement for the Dose-rates of the Cosmic-Ray Components on the Ground"Journal of Radiation Research. February in press. (2003)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Nakamura, T.Nunomiya, N.Hirabayashi, H.Suzuki, Y.Sato, D.A.H.Rasolonjatovo: "Sequential Measurements of Energy Spectrum and intensity for Cosmic-Ray Neutrons"Seventh International Symposium on Natural Radiation Environment. May, Rhodes, Greece. 20-24 (2002)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2004-04-14  

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