| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥300,000)
Fiscal Year 2007: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2006: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
We have developed techniques of new anti-neutrino detectors for a front detector of a reador neutrino oscillation expertnent “KarnLAND". In everinents with liquid scintillator, including KamLAND, the delayed coincidence technique works strongly to reduce background. However, the front detector, which should measure the reador anti-neutrino spectrum near the reactors to know the neutrino spectrum without oscillation, should work near the ground level, not deep underground, then even delayed coincidence cannot reject all background events faked by large flux of cosmic rays at ground level. Then we started development of a new detector with an ability of particle identification and directional measurement. We produced the following two prototype detectors. The frst one is a segmented detector. Using this detector we confimned that the position resolution of vertexes is improved to several centimeters. With this high resolution, cosmogenic fast neutron events, which fake delayed coincidence events, can be distinguished from real antineutrino events using the difference of topology of vertexes between real and fake events. We plan to place this prototype detector in front of any of reactors. The second prototype detector is an “imaging camera detector", which employs a CCD camera and an image intensifier to take a photograph of scintillation spots of each event. With this technique, we aim at detecting the prompt and delayed vertexes with~1cm or better resolution to measure relative postion of those vertexes, by which incoming direction of anti-neutrinos can be measured. Using the prototype detector we succeeded in taking photographs of cosmic-ray muon tracks. We plan to improve this detector to detect neutron events and also to detect anti-neutrino events with directional sensitivity.
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