Study of Neutrino Oscillation
Grant-in-Aid for Scientific Research (B).
|Allocation Type||Single-year Grants|
|Research Institution||University of Tokyo|
SUZUKI Yoichiro University of Tokyo, ICRR, Professor, 宇宙線研究所, 教授 (70144425)
FUKUDA Yoshiyuki University of Tokyo, ICRR, Research Associate, 宇宙線研究所, 助手 (40272520)
NAKAHATA Masayuki University of Tokyo, ICRR, Associate Professor, 宇宙線研究所, 助教授 (70192672)
KAJITA Takaaki University of Tokyo, ICRR, Professor, 宇宙線研究所, 教授 (40185773)
MIURA Mokoto University of Tokyo, ICRR, Research Associate, 宇宙線研究所, 助手 (10272519)
ITOW Yoshitaka University of Tokyo, ICRR, Research Associate, 宇宙線研究所, 助手 (50272521)
竹内 康雄 東京大学, 宇宙線研究所, 助手 (60272522)
|Project Period (FY)
1998 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥5,100,000 (Direct Cost : ¥5,100,000)
Fiscal Year 2000 : ¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1999 : ¥2,800,000 (Direct Cost : ¥2,800,000)
|Keywords||Water Cherenkov / Superkamiokande / Long Baseline Neutrino Oscillation Experiment / Atmospheric neutrino oscillation / Neutrino Oscillation / ニュートリノ / 大気ニュートリノ / 長基線ニュートリノ振動 / ニュートリノ質量|
This purpose of this research will confirm the neutrino oscillation observed in the atmospheric neutrino study by Super-Kamiokande in 1998. This experiment uses the neutrino beam produced at KEK and two detectors, one in KEK and the other at Kamioka, Super-Kamiokande and study neutrino oscillations.
By using the 10^<20> protons delivered on the target, we are able to obtain about 200 neutrino interactions in Super-Kamiokande for the no oscillation case. If the oscillation parameters of the atmospheric neutrino oscillations are 3〜5xl0^<-3>eV^2, then the number of events to be observed at SuperK will be reduced to 80%.
We have started the experiment in April 1999 and we have collected the data based on the 2.3x1019 protons on target by June 2000.
We have observed 28 neutrino events in the 22.5kton effective volume of SuperK.The neutrino beam traverses the SuperK every 2 seconds with the duration of 1 micro seconds, therefore the backgrounds, for example, from atmospheric neutrinos, are negligible.
The expected event number calculated based on the number of events observed at the detectors placed at KEK is 38 with systematic errors of about 10%. This observed deficits of 75% is 1.5s effect from the assumption of no oscillations. This measurement is consistent with the atmospheric neutrino oscillations.
We have accumulated more than million's of neutrino interactions in the detectors at KEK.We, therefore, are able to study neutrino interactions, for example, the ration of neutral current over charged current, in details. This information will also be useful for the atmospheric neutrino study in SuperK.
Research Output (2results)