Title: Enhanced Photon Traps for Hyper-Kamiokande,
Abstract: Hyper-Kamiokande, the next generation large water Cherenkov detector in
Japan, is planning to use approximately 80,000 20-inch photomultiplier tubes
(PMTs). They are one of the major cost factors of the experiment. We propose a
novel enhanced photon trap design based on a smaller and more economical PMT in
combination with wavelength shifters, dichroic mirrors, and broadband mirrors.
GEANT4 is utilized to obtain photon collection efficiencies and timing
resolution of the photon traps. We compare the performance of different trap
configurations and sizes. Our simulations indicate an enhanced photon trap with
a 12-inch PMT can match a 20-inch PMTs collection efficiency, however at a cost
of reduced timing resolution. The photon trap might be suitable as detection
module for the outer detector with large photo coverage area.