Development and operation of a muon detection system under extremely high humidity environment for monitoring underground water table
- 1Earthquake Research Institute (ERI), University of Tokyo, Tokyo, Japan
- 2Chigasaki Research Institute, J-POWER, Chigasaki, Kanagawa, Japan
Abstract. In order to investigate the complex nature of landslides triggered by rainfall, dynamic muon radiography of the motion of the underground water table is planned in a drainage tunnel drilled underneath an estimated fault plane. However, the humidity inside the tunnel is almost 100%. In order to suppress moisture effects, a scintillation counter with Cockcroft–Walton photomultipler tubes (CW-MPT) was developed and tested at the observation site located in Shizuoka Prefecture, Japan. The counter was stably operated for 38 days without gain degrading. Based on the result, we constructed a muon detection system with CW-PMTs at the same site and started operation runs. In this work, the data from borehole-based water gauge measurements of the underground water levels were analyzed and discussed. It was confirmed that the comparison between muon and borehole data would be useful.