NEW COSMIC RAY MUON TOMOGRAPHY FOR VISUALIZING INTERNAL OF RIVER EMBANKMENT

Abstract

 We have succeeded in visualizing density distribution internal of river embankment, which is necessary for maintenance and quantitative evaluation of embankment failure risk, by using cosmic ray muon. However, conventional method can only evaluate density qualitatively because solution depends on initial value. In this study, we propose the new exploration method that introduces the Moore-Penrose inverse matrix, which uniquely determines the solution of underdetermined system of simultaneous equations, Tikhonov's regularization method, which suppresses effect of observation errors, and Morozov's contradiction principle, which determines regularization parameter. The results show good agreement between the analytical and actual ground densities. It is also found that when space of wave rays is less than 1/4 scale of analytical grid scale, it is possible to estimate location of structures and cavities in ground.