Development and operation of a muon detection system under extremely high humidity environment for monitoring underground water table

Abstract

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 CWPMTs 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.

Muography

“…There are several potential applications of muographic imagery (Figure 7A). These include (A) geological investigation of volcanoes 1 , landslides 69 , mines 70 , glaciers 71 , etc., (B) non-destructive testing, evaluation and monitoring of industrial plants and civil engineering structures such as electric furnace 72 , blast furnace 73 , nuclear reactors 74,75 , railway tunnels 76 , underground pillars 77 , check valve 78 , etc., and (C) non-destructive surveys of cultural heritage, such as pyramids 44,79 . Although it is impossible to introduce all of these applications here, several successful examples will be briefly explained in this section.…”

“…In 2011, groundwater dynamics (as a response to heavy rainfall events) were first captured within a mechanically fractured zone inside a seismic fault 114 . Since then, muographic survey and monitoring activities have been conducted to search for water resources 115 , for prevention of landslides (most respond slowly to rainfall and move at low speeds, but have substantial impacts on landscapes after several years) 69 , and monitoring of debris flows that are gravity-driven, rapid movements of material composed of a mixture of rock debris and water 97,98 . The main goal of the Tomographic Research of Underground and large STructures with Muographic Expertise (TRUST-ME) project, carried out by the Low Background Noise Underground Research Laboratory of Rustrel (LSBB), is to characterize the dynamics of the water transfer processes in the critical zone, and the cycles of these processes within the region of the Fontaine-de-Vaucluse in particular.…”

Particle Geophysics

“…In muography, most scintillation counters are designed as thin strips (e.g., Tanaka et al 2001Tanaka et al , 2003Tanaka et al , 2005Basset et al 2006;Menichelli et al 2007;Beauducel et al 2010;Gibert et al 2010;Taira & Tanaka 2010;Tanaka & Sannomiya 2013). Particle trajectories can be tracked by connecting two or more vertex points (muon passing points) determined by the geometrical address of the strips that are hit by the particle and their corresponding timings.…”

“…Currently, muography observations are becoming more active than before. In addition to the presently running experiments [fault zones in Japan (Tanaka et al 2011, Tanaka & Sannomiya 2013 and Spain (Cumbre Vieja; Hernández et al 2013); volcanoes in Japan (Unzen; Miyamoto et al 2012), Italy (Stromboli and Etna;Aleksandrov et al 2012, Anastasio et al 2013, Carbone et al 2013Hernández et al 2013)], new projects to explore small Solar System bodies (Prettyman 2013) and to monitor a carbon storage (Kudryavtsev et al 2012) have begun.…”

Interpreting muon radiographic data in a fault zone: possible application to geothermal reservoir detection and monitoring

“…1). However, this problem could be solved with borehole/tunnel observations from underground muon detectors (Tanaka and Sannomiya, 2013). Secondly, this technique only resolves the average density distribution along individual muon paths.…”