Hyper-Kamiokande is a next generation huge water Cherenkov detector proposed for a discovery of proton decay and neutrino observations. It is planed to have 20 times larger volume than Super-Kamiokande, with 100,000 next generation photo sensors. One candidate of the sensor is a 50 cm Box-and-Line dynode photomultiplier tube (BL PMT), which have excellent time resolution and energy resolution. However, the performance of the BL PMT is to be confirmed under a condition expected in Hyper-Kamikoande. For example, a response of the BL PMT is affected by a geomagnetic field especially in a certain direction. Since Hyper-Kamiokande is a large detector, the geomagnetic field cannot be completely canceled and the effect cannot be ignored. And the temperature in Hyper-Kamiokande is presumably different with usual environment, therefore, the temperature dependency has to be also checked. Such kind of a precise investigation in BL PMT has never been performed, though the design concept and the basic performance are established.

In this presentation, several results of these specific characteristics will be reported, i.e., the effect of the magnetic field, the temperature, the incident point of photons, and the high-voltage value. The comparison of their effects to the original designed value will be also discussed.

Okayama University

Tokyo University ,Kyoto University, Tokyo Tech University, Hamamatsu Photonics