2–6 Dec 2025
Biblioteca Salaborsa
Europe/Rome timezone
Proceedings submission deadline is ___ 24 March 2026 ___

Preparation status of the Hyper-Kamiokande 50 cm photomultiplier tubes

4 Dec 2025, 15:16
15m
Auditorium Enzo Biagi (Biblioteca Salaborsa)

Auditorium Enzo Biagi

Biblioteca Salaborsa

Biblioteca Salaborsa, Piazza del Nettuno, 3, 40121 Bologna BO
Talk Vacuum Photodetectors (eg. PMTs, MCPs, hybrids) Plenary Session

Speaker

Kota Nakagiri (Kamioka Observatory, ICRR, The University of Tokyo)

Description

The Hyper-Kamiokande (HK) is a next-generation water Cherenkov detector aiming to study a wide range of physics targets such as neutrino oscillations, neutrino astronomy, and nucleon decays. HK is under construction and is scheduled to start operation in 2028.

Approximately 20,000 newly designed 50 cm diameter PMTs manufactured by Hamamatsu Photonics K.K., R12860, will cover the inner surface of the HK inner detector with 20% photo-coverage to detect the Cherenkov photons emitted in the inner detector.
The PMT has excellent characteristics in photon detection efficiency, charge and time resolutions, hydrostatic pressure tolerance, etc.
It is important for HK that the PMTs installed in the detector exhibit high and uniform performance, as well as maintain long-term stability.

The mass production of the HK PMTs started in 2020, and more than three-quarters of the total 20,000 units have been delivered as of September 2025.
A series of measurements has been conducted to ensure the quality of the delivered PMTs by evaluating their performance, including the response against the injected photons and the dark count rates, and their stabilities.

In this talk, our overall strategy of PMT quality assurance and the results of the measurements will be reported.

Speaker Confirmation Yes

Authors

Kota Nakagiri (Kamioka Observatory, ICRR, The University of Tokyo) Shogo Horiuchi (Keio University) Yasuhiro NISHIMURA (Keio University)

Co-author

Presentation materials