Yusuke Suda

A Test of New Large Aperture Photodetectors in a Water Cherenkov Detector

Yuji OKAJIMAa, Miao JIANGb, Daisuke FUKUDAc, Ryosuke AKUTSU, Yusuke SUDAd, Seiko HIROTAb, Shoei NAKAYAMAe, Masato SHIOZAWAe, Masashi YOKOYAMAd, Yoshinari HAYATOe, Hidekazu TANAKAe, Masayuki NAKAHATAe, Tsuyoshi NAKAYAb, Masahiro KUZEa, Yusuke KOSHIOc, Akimichi TAKETA f aDepartment of Physics, Tokyo Institute of Technology bDepartment of Physics, Kyoto University cDepartment of Physics, Okayama University dDepartment of Physics, The University of Tokyo eKamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo f Earthquake Research Institute, The University of Tokyo

Detailed performance evaluation of a new 20-inch photomultiplier tube with a Box and Line dynode

Yasuhiro Nishimuraa, Ryosuke Akutsua, Yusuke Sudab, Miao Jiangc, Seiko Hirotac, Daisuke Fukudad , Masahiro Kuzee, Masaki Ishitsukae, Masayuki Nakahataa, Masato Shiozawaa, Yoshinari Hayatoa, Shoei Nakayamaa, Hidekazu Tanakaa, Masashi Yokoyamab, Tsuyoshi Nakayac, Akihiro Minaminoc, Akimichi Taketa f , Yoshihiko Kawaig, Takayuki Ohmurag, Masatoshi Suzukig a Institute for Cosmic Ray Research, University of Tokyo b Department of Physics, University of Tokyo c Department of Physics, Kyoto University d Department of Physics, Okayama University e Department of Physics, Tokyo Institute of Technology f Earthquake Research Institute, University of Tokyo g Hamamatsu Photonics K.K.

Temperature Dependence Measurement of a Hybrid Photo-Detector for Hyper-Kamiokande

1 Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan 2 Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan 3 Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan 4 Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan 5 Earthquake Research Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan 6 Hamamatsu Photonics K.K., Hamamatsu, Shizuoka, 430-8587, Japan

Development and measurement of new large-aperture photodetectors for Hyper-Kamiokande

Two types of new photodetectors are currently being developed with a large aperture, for use in the large water Cherenkov detector, Hyper-Kamiokande planned in Japan [1]: Hybrid Photo-Detector (HPD) of a 20-inch diameter size with an avalanche diode and a 20-inch Photomultiplier Tube (PMT) with a dynode upgrade to a box-and-line type. These are expected to have an excellent performance about timing and collection efficiency compared to a 20-inch PMT with a venetian blind dynode used in Super-Kamiokande. Also there is a possibility to improve quantum efficiency (QE) of these photodetectors from 22% to around 30% using the super-bialkali technique. A proof test in a smaller water Cherenkov detector is planned in advance for these photodetectors to determine the best candidate for Hyper-Kamiokande. Two prototypes of new photodetectors have already been manufactured for testing: the 8-inch HPD, and a 20-inch PMT with a higher QE of 30% compared with 22% of the 20-inch PMT used in Super-Kamiokande. These photodetectors were installed in a 200-ton water tank in summer 2013 for a proof of using test in a water Cherenkov detector. We report the specification of these photodetectors, a status and plan of the development and proof test.