1997 Fiscal Year Final Research Report Summary
Study of neutrino oscillations using solar neutrinos
| Project/Area Number |
08640351
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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 | University of Tokyo |
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Principal Investigator |
NAKAHATA Masayuki ICRR Univ.of Tokyo, Assistant professor, 宇宙線研究所, 助教授 (70192672)
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| Co-Investigator(Kenkyū-buntansha) |
MIURA Makoto ICRR Univ.of Tokyo, Research Associate, 宇宙線研究所, 助手 (10272519)
FUKUDA Yoshiyuki ICRR Univ.of Tokyo, Research Assciate, 宇宙線研究所, 助手 (40272520)
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| Project Period (FY) |
1996 – 1997
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| Keywords | neutrino / solar neutrino / neutrino oscillations / Super-Kamiokande / LINAC |
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| Research Abstract |
In this research, the neutrino oscillations were studied using the Super-Kamiokande which was start from April 1996. The Super-Kamiokande detector observes solar neutrinos using neutrino-electron scatterings. The Super-Kamiokande detector has a fiducial volume of 22,000 tons and it is able to detect world largest number of solar neutrino events (10-20 events per day). Hence, it is able to study day/night difference of the solar neutrino flux and distortion of energy spectrum. They are purely due to the property of neutrinos and they are free from any ambiguities of solar models. The most crucial thing in this research was the energy calibration of the detector. We have calibrated the detector using an electron linear accelerator (LINAC). We have achieved an accuracy of better than 1 % in the absolute energy scale. Using the date taken in 1996 and 1997, we have processed 374 days' date. The flux obtained from the data sample is 35.8 % of the expectation from the standard solar model. The results reconfirmed the "solar neutrino problem" with an unprecedented statistics. At the moment, however, no significant difference between fluxes between dattime and nighttime is observed. And the shape of the energy spectrum is statistically consistent with the expectation at the moment. If we have few more years of data, we can discuss neutrino oscillations using day/night difference and the energy spectrum.
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Research Products
(8 results)
