A test of new large aperture photodetectors in a water Cherenkov detector

Yasuhiro Nishimura, Yuji Okajima, Miao Jiang, Daisuke Fukuda, Ryosuke Akutsu, Yusuke Suda, Seiko Hirota, Shoei Nakayama, Masato Shiozawa, Masashi Yokoyama, Yoshinari Hayato, Hidekazu Tanaka, Masayuki Nakahata, Tsuyoshi Nakaya, Masahiro Kuze, Yusuke Koshio, Akimichi Taketa

Research output: Contribution to journalConference articlepeer-review


Several new photodetectors with high resolution and efficiency have been developed for a one megaton water Cherenkov detector, Hyper-Kamiokande, planned in Japan. A reliable photodetector is essential for such a long-term experiment aiming at the neutrino physics and the nucleon decay search. In 2013, a first proof test started using a 200 ton water Cherenkov detector in order to evaluate the feasibility of new photodetector techniques for Hyper-Kamiokande: high quantum efficiency (QE), a hybrid photodetector (HPD) and a new photomultiplier tube (PMT) with a box-and-line dynode. Eight HPDs with a 20 cm diameter were installed to the 200-ton water tank in advance of a 50 cm HPD. The QE of 50 cm Venetian-blind-dynode PMT used in SuperKamiokande was improved to 30% from 22%. Five of such high-QE PMTs were attached as well in 2013. Three 50 cm high-QE box-and-line PMTs joined in 2014 and showed high detection performance. In the 200-ton tank, in total 240 photodetectors including the 50 cm conventional Super-Kamiokande PMTs have been tested over a year. Sufficient performance to detect the single photoelectron was confirmed in the tank; 40-45% charge resolution in sigma and 5.1 nsec timing resolution at FWHM for box-and-line PMTs. New photodetectors were monitored over a year, and a stability of gain is confirmed in 2% level. The test allows to select the best candidate photodetector for Hyper-Kamiokande, with coming 50 cm high-QE HPDs.

Original languageEnglish
Article number017
JournalProceedings of Science
Publication statusPublished - 2015 Jan 1
Externally publishedYes
Event4th International Conference on New Photo-Detectors, PhotoDet 2015 - Moscow, Troitsk, Russian Federation
Duration: 2015 Jul 62015 Jul 9

ASJC Scopus subject areas

  • General


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