1987 Fiscal Year Final Research Report Summary
Observation of Solar Neutrunos
| Project/Area Number |
61420007
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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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 | University of Tokyo |
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Principal Investigator |
TOTSUKA YOJI Faculty of Science, University of Tokyo, 理学部, 教授 (40011712)
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| Co-Investigator(Kenkyū-buntansha) |
ATSUTO Suzuki Faculty of Science, University of Tokyo, 理学部, 助手 (00100818)
TADASHI Kifune Insfifute for Cosmic Rays, University of Tokyo, 宇宙線研究所, 助教授 (40011621)
TERUHIRO Suda Insfifute for Cosmic Rays, University of Tokyo, 宇宙線研究所, 助教授 (30011555)
KASUKE Takahashi Physics Department, Nat, Lab, for High Energy Phys, KEK, 物理系, 教授 (90004283)
MASATOSHI Koshiba Faculty of Science, Tokai University, 理学部, 教授 (00011461)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Sun / Solar neutrino / Neutrino / SN1987A |
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| Research Abstract |
Solar neutrinos are produced naturally by nuclear fusion reactions at the solar center. Their flux is predictable once the heat output of operational since 1970, however, revealed that the observed solar neutrino flux was about a quarter of what the standard solar model predicts. This observation indicates either that something is wrong in the solar model or that properties of the neutrino has something to do with it. Therefore the second experiment has been awaited.
We started to improve the KAMIOKANDE detector with the present Grant-in-Aid foundation. We installed two sets of the magnetic tape drives to greatly improve the efficiency of data taking. At the same time an ion exchanger column was newly installed so as to remove ions in water, especially U and Ra ions. After months of operation U and Ra contamination was reduced to 1/1000 and the water transparency became better.
Data analysis was being made constantly. The result so far obtained from the analysis upto September 1987 gave still no sign of solar neutrino signals, whose upper limit is already less than a half of the standard solar model predictions. This result is important because it confirmed the solar neutrino problem independently of Davis' experiment and at the different energy range.
On 23 February 1987 we observed a neutrino burst from the supernova SN1987A in the Large Magellanic Cloud. This is the first neutrino observtion from outside of the solar system and a beginning of the neutrino astronomy. This important observation was indeed possible by the detector improvement made by the presentGrant-in-Aid foundation.
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