Test Experiment and Simulation of Water Cherenkov Detectors for Search for Gamma-ray Bursts

塩見 昌司


   The test experiment of a prototype water Cherenkov detector consisting of six 8φ photomultiplier tubes sunk in the reservoir pool of 21 m2 (7 m × 3 m) and the depth 3 m was carried out at Mt. Norikura (2780 m a.s.l.) from 5 September to 3 October in 1994. The prototype detector detected showers with frequency of about 40 Hz at the water depth 1.8 m. For frequency data at several water depth, we understand that the water depth 1.5 m , 2.0 m is suitable for the water Cherenkov detector for observation of proton initiated or gamma-ray initiated showers. The performance of the prototype detector was simulated by a shower simulation code GEANT. Results gotten by the simulation suggest that the prototype detector detects mainly proton initiated air showers with wide energy range from 10 GeV to 10 TeV.