| Project/Area Number |
14540274
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
CHIBA Masami Tokyo Metropolitan University, Physics, Research associate, 大学院・理学研究科, 助手 (60128577)
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| Co-Investigator(Kenkyū-buntansha) |
YASUDA Osamu Tokyo Metropolitan University, Physics, Research associate, 大学院・理学研究科, 助手 (50183116)
KAMIJO Toshio Tokyo Metropolitan University, Engineering, Research associate, 大学院・理学研究科, 助手 (70117703)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Ultra high energy neutrino / Rock salt / GZK effect / Askaryan effect / Ultra high energy cosmic / Perturbation cavity resonator method / Cherenkov effect / Radio Wave / 超高エネルギー / ニュートリノ / 干渉性チェレンコフ効果 / 電波検出 / 電波減衰長 |
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| Research Abstract |
Ultra high energy (UHE) neutrino should be generated by GZK effect by a reaction between UHE cosmic ray and cosmic microwave background. UHE cosmic ray loses the energy by the effect UHE neutrino should be generated at the big bang or a sort of active galactic nuclei etc. Neutrino is the highest energy particle possible to travel very long cosmic distance. Therefore only UHE neutrino gives us directly information of high energy state at the big bang or so. The flux of UHE neutrino is very low, so we need very massive detection media to detect. We pay attention to natural rock salt mine which has a huge mass and long attenuation length for radio wave. Radio wave could be generated through Askaryan effect by electromagnetic shower occurred at the interaction between UHE neutrino and rock salt. Askaryan effect is essentially a coherent Cherenkov effect between excess electrons in the electromagnetic shower. We measured the attenuation length at 1GHz and 0.3GHz by a perturbation cavity resonator method. The summary of the measurement is as follows.
1)The largest attenuation length (200m-500m) will be between 0.5GHz and 2GHz at the synthetic and Hockley sample (Texas).
2)Economical antenna array with the spacing around 350m could detect GZK neutrino.
3)The attenuation length has frequency dependence in rock salts.
4)The attenuation length of Hockley increases with respect the frequency from 0.3GHz to 1GHz. Water in rock salt crystal or brine closed inside at the rock salt may shortens the attenuation length in the frequency range.
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