3D Cosmic Ray Muon Tomography from an Underground Tunnel

TL;DR

This study demonstrates the use of cosmic ray muon tomography in an underground tunnel to image 3D geological structures, showing good agreement with gravity data and LIDAR, highlighting its potential for passive geophysical imaging.

Contribution

First application of underground cosmic ray muon tomography for 3D geological imaging, demonstrating its effectiveness and potential for borehole geophysical surveys.

Findings

Densities agree with gravity modeling and literature values.

Rock-air interface matches LIDAR data within 4 meters.

Proves muon tomography as a viable tool for shallow geological imaging.

Abstract

We present an underground cosmic ray muon tomographic experiment imaging 3D density of overburden, part of a joint study with differential gravity. Muon data were acquired at four locations within a tunnel beneath Los Alamos, New Mexico, and used in a 3D tomographic inversion to recover the spatial variation in the overlying rock-air interface, and compared with a priori knowledge of the topography. Densities obtained exhibit good agreement with preliminary results of the gravity modeling, which will be presented elsewhere, and are compatible with values reported in the literature. The modeled rock-air interface matches that obtained from LIDAR within 4 m, our resolution, over much of the model volume. This experiment demonstrates the power of cosmic ray muons to image shallow geological targets using underground detectors, whose development as borehole devices will be an important new direction of passive geophysical imaging.