| Co-Investigator(Kenkyū-buntansha) |
INOUE Kunio Tohoku University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (10242166)
SUEKANE Fumihiko Tohoku University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (10196678)
SHIRAI Junpei Tohoku University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (90171032)
KOGA Masayuki Tohoku University, Graduate School of Science, Assistant Professor, 大学院・理学研究科, 助手 (90343029)
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| Research Abstract |
The KamLAND experiment which is led by the head investigator, completed the construction of 1000ton liquid scintillator neutrino/anti-neutrino detector in the Kamioka mine in the year 2001. This project is supported by the Center of Excellence program (1997-2003). The experiment has been taking data since January, 2002. In December 2002, the experiment found a large deficit of anti-neutrinos from reactors for the first time. The result strongly supports the existence of neutrino oscillations, which is caused by the finite mass of the neutrinos. The paper (Phys. Rev. Lett. 90, 021802, 2003) has been giving a strong impact on the elementary particle physics and has been cited by 537 papers so far. According to the Thomson ISI Web of Science data, shown in the latest (March/April, 2004) issue of 'Science Watch' magazine, this paper ranks the top score among the physics papers and 2nd score among the scientific papers, regarding the monthly most cited papers. The definite evidence of the oscillation will be published next paper in July. The experiment is now challenging to measure anti-neutrinos coming from the earth by identifying uranium and thorium peaks in the energy spectrum. The performance of the detector has been evaluated to be sufficient to detect such neutrinos and the successful detection is anticipated. If the measurement is performed, the amount of uranium and thorium in the earth and its ratio will be obtained, which is inevitable information to study the origin of heat generation in the earth and evolution of the geological history of the earth. The KamLAND experiment is now planning lo improve the detector sensitivity to detect solar ^7Be neutrinos for the first time.
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