Earth Planets Space, Vol. 62 (No. 2), pp. 173-177, 2010
Yasushi Yamashina1, Tsuneo Yamashina1, Hideaki Taira2, and Hiroyuki K. M. Tanaka2,3
1CI Industry, 2-674-2, Mikkajima, Tokorozawa, Saitama 359-1164, Japan
2Earthquake Research Institute, the University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113-0032, Japan
3Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
(Received November 28, 2008; Revised March 25, 2009; Accepted March 30, 2009; Online published February 22, 2010)
Muon radiography has recently made it possible to perform imaging of the internal structure of a volcano. Muon-detecting experiments were carried out at Asama and Usu volcanoes using a newly developed scintillator. The goal was to build a large detector that would improve the quality of the data collected by the muon radiography experimental set-up that is currently being used to study volcanic activities. To this end, a cost-effective plastic scintillator was developed by a simple "heating-melting method". The detector consists of planes of scintillator strips and is currently in the prototyping phase. Using a cosmic-ray muon source, we found that the signal from our scintillator was consistent with the zenith-angle dependence of the cosmic-ray muon spectrum with no significant attenuation effects in the scintillator. We confirmed that our scintillators can be incorporated into a portable assembly-type cosmic-ray muon telescope system.
Key words: Cosmic-ray muon radiography, volcano, plastic scintillator, detection system.