Speaker
Description
This study presents a numerical modeling framework for planning future muography experiments aimed at imaging the internal structures of large-scale geological objects through simulations of atmospheric muon flux propagation. Muography utilizes attenuation of high-energy cosmic-ray muons in dense geological media, enabling non-invasive imaging of volcanic conduits and crater regions.
Previous muography experiments in volcanoes, pyramids, and underground facilities have demonstrated the potential of this technique for 3D density imaging. However, such experiments typically require long observation periods to achieve sufficient spatial resolution, which is often impractical under demanding field conditions. In our study, we demonstrate how numerical modelling of atmospheric muon propagation through 3D objects can be used to optimize detector setup and exposure time in muography experiments.
Simulations were conducted using the Geant4 toolkit (Agostinelli, 2003), providing detailed physics models of particle–matter interactions. The approach is demonstrated with the example of the Iwodake volcano, located on Satsuma-Iojima Island, Japan, which has been the subject of prior muographic surveys (Tanaka, 2009). A three-dimensional digital elevation model of Iwodake volcano was constructed from Shuttle Radar Topography Mission (Farr, 2007). To investigate dynamic volcanic processes, multiple density configurations were considered, representing different stages of magma convection and degassing. Muon propagation was modeled using a modified parameterization of the Gaisser formula for sea-level muon spectra (Guan, 2015), with muons generated from a virtual hemisphere surrounding the volcano. Computational efficiency was enhanced through energy thresholds and a backtracing algorithm to focus on trajectories intersecting detector planes. The detection system was represented by virtual observation planes at realistic field locations. We demonstate how the optimal position of detectors and exposure time can be evaluated using analysis of synthetic muographic images.
References
Agostinelli, S., et al., 2003. GEANT4—A simulation toolkit. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 506, 250–303.
Farr, T. G., Rosen, P. A., Caro, E., Crippen, R., Duren, R., Hensley, S., Kobrick, M., Paller, M., Rodriguez, E., Roth, L., Seal, D., Shaffer, S., Shimada, J., Umland, J., Werner, M., Oskin, M., Burbank, D., & Alsdorf, D., 2007. The Shuttle Radar Topography Mission. Reviews of Geophysics, 45, RG2004.
Guan, M., Chu, M.-C., Cao, J., Luk, K.-B., & Yang, C., 2015. A parametrization of the cosmic-ray muon flux at sea-level. arXiv:1509.06176.
Tanaka, H. K. M., Uchida, T., Tanaka, M., Shinohara, H., & Taira, H., 2009. Cosmic-ray muon imaging of magma in a conduit: Degassing process of Satsuma-Iwojima Volcano, Japan. Geophysical Research Letters 36, L01304.