Speaker
Description
We developed high-performance 50-cm-aperture photomultiplier tubes (PMTs) for Hyper-Kamiokande, the next-generation water Cherenkov detector. Its operation is scheduled to begin in 2028 to address various neutrino physics and nucleon decay searches.
The improved PMT with a box-and-line dynode structure (R12860, manufactured by Hamamatsu Photonics) enhances physics sensitivity through a factor-of-two improvement in timing resolution and twice the detection efficiency compared to the 50-cm PMTs (R3600) used in Super-Kamiokande. In addition, the background rate was reduced, and the mechanical strength against high hydrostatic pressure was doubled.
During the mass production for Hyper-Kamiokande started in 2020, the long-term performance of the PMTs has been ensured through a continuous quality monitoring system. This system utilizes two 8-PMT measurement rooms for detection performance evaluation, two 100-PMT measurement rooms for dark noise stability monitoring, and a 16-PMT measurement setup for year-long stability tests. Detailed characterization was performed to investigate response uniformity and dependence of performance on environmental conditions, such as temperature and the geomagnetic field, to suppress systematic uncertainties.
With the procurement of over twenty thousand PMTs completed in 2026, we report the overall achievements in PMT development, performance validation with quality assurance, and the current status of preparation for detector installation in 2027.
| I read the instructions above | Yes |
|---|