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Total flux of Cosmic Rays around knee region using Tibet Air Shower Array

Research Project

Project/Area Number 06640374
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 素粒子・核・宇宙線
Research InstitutionUtsunomiya University

Principal Investigator

HOTTA Naoki  Utsunomiya Univ., Faculty of Education, Assistant, 教育学部, 助手 (60157039)

Co-Investigator(Kenkyū-buntansha) OHTA Itaru  Utsunomiya Univ., Faculty of Education, Professor, 教育学部, 教授 (30008023)
Project Period (FY) 1994 – 1995
Project Status Completed (Fiscal Year 1995)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
KeywordsCosmic ray / Flux of primary cosmic-rays / Air shower / Knee region / ニ-領域
Research Abstract

We analyzed the experimental data obtained with Tibet array and obtained the energy spectrum of the primary cosmic rays in the energy range between 3*10^<14>and2*10^<16>eV.
The overall primary energy spectrum obtained does not resemble a single power law and shows a gradual steepening of the slope at energies around E_b=10^<15.25>eV.The spectrum can be expressed as
J(E_o)=1.5*10^<-20>(E_o/10^<14.75>eV)^<-2.60<plus-minus>0.04>(m^<-2>sec^<-1>sr^<-1>eV^<-1>)atE_o<10^<14.75>eVand=1.2*10^<-23>(E_o/10^<15.85>eV)^<-3.00<plus-minus>0.05>(m^<-2>sec^<-1>sr^<-1>eV^<-1>)atE_o>10^<15.85>eV,while this changes gradually between 10^<14.75>and 10^<15.85>eV and takes the value J(E_o)=6.7*10^<-22>(m^<-2>sec^<-1>sr^<-1>eV^<-1>)atE_o=10^<15.25>eV
Our spectrum to be smoothly connected to the direct measurements by Grigorov et al.(1971) and JACEE Collaboration (Burnett et al.1993) at the lower energy region. The flux values around 10^<15> eV are higher than the Akeno data (Nagano et al.1984), while those at energies around 10^<16> are about 10 % lower than theirs. The bending of the spectrum is not as abrupt as the Akeno and its energy (E_b) is also lower than theirs. Their lower flux at energies around 10^<15> could be attributed to very low detection effciencies of air showers at the Akeno altitude.
Our spectrum obtained around the knee is almost independent of the primary mass composition and will be rated as most standard.
The gradual steepening of the spectrum at lower energy may be in favor of shock acceleration at SNRs which suggests a considerable change in the relative abundance of the various cosmic ray nuclei as the energy increases, but its confirmation requires more direct information about the primary mass composition at energies around the knee.

Report

(3 results)
  • 1995 Annual Research Report   Final Research Report Summary
  • 1994 Annual Research Report
  • Research Products

    (7 results)

All Other

All Publications (7 results)

  • [Publications] M.Amenomori: "Primary Cosmic Rays at the "knee" Energy Region Observed with the Tibet Air Shower Array" 24th International Cosmic Ray Conference. 2. 736-729 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] M.Amenomori: "The Cosmic Ray Energy Spectrum between 10^<14.5> and 10^<16.3>eV covering the "Knee" Region" Astrophysical Journal. 1996 ((印刷中))

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] M.Amenomori et al.: "Primary Cosmic Rays at the"knee"Energy Region Observed with the Tibet Air Shower Array" International Cosmic Ray Conference (24th). Vol.2. 736 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] M.Amenomori et al.: "The Cosmic Ray Energy Spectrum between 10^<14.5> and 10^<16.3>eV covering the "Knee" Region" Astrophysical Journal. (in press). (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] M. Amenomori: "Primary Cosmic Rays at the "knee"Energy Region Observed with the Tibet Air Shower Array" 24th International Cosmic Ray Conference. 2. 736-729 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] M. Amenomori: "The Cosmic Ray Energy Spectrum between 10^<14.5>and 10^<16.3>eV covering the "Knee"Region" Astrophysical Journal. 4月号. (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] M.Amenomori: "Primary Cosmic Rays at the "Knee" Energy Region Observed with the Tibet Air Shower Array" INTERNATIONAL SYMPOSIUM ON COSMIC RAY PHYSICS IN TIBET. (1995)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2016-04-21  

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