| 研究分担者 |
久世 正弘 東京工業大学, 理学院, 教授 (00225153)
石塚 正基 東京理科大学, 理工学部物理学科, 教授 (40533196)
西村 康宏 慶應義塾大学, 理工学部(矢上), 准教授 (40648119)
石田 卓 大学共同利用機関法人高エネルギー加速器研究機構, 素粒子原子核研究所, 講師 (70290856)
角野 秀一 首都大学東京, 理学研究科, 教授 (70376698)
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| 研究実績の概要 |
Research with FY2019 funding focused on completion of the testing of photomultiplier tubes (PMTs) to be used in the photodetector modules for the Hyper-K intermediate and main detectors. Measurements as Kavli IPMU, Tokyo University of Science and Keio University where done to characterize the linearity, noise, timing resolution, charge resolution, gain and after-pulsing rate of the PMTs. Results of these measurements have been applied to the simulation of the proposed Hyper-K Intermediate Water Cherenkov Detector (IWCD) to evaluate the PMT impact on event reconstruction in the detector. Based on these studies, the PMT characteristics are all found to allow for optimal performance of the IWCD, except for the after-pulsing rate, which was found to be higher than expected. Based on this conclusion, two courses of action were taken. First, the prospective supplier of the PMTs, Hamamatsu Photonics, has initiated work to modify the design of the PMT to reduce the after-pulse rate. Second, we have developed advanced analysis techniques needed to minimize the impact of after-pulsing on the event reconstruction.
During this period, we made tests of a Cockroft-Walton low power high voltage source that may be used with the PMTs at Tokyo Metropolitan University. Researchers at Kavli IPMU completed materials compatibility testing for the photodetector modules components, including pressure tolerance testing, compatibility with ultra-pure water, and radon emission measurements. The initial design of the IWCD facility at the candidate site was completed by KEK.
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