Simulation study on shallow and deep geological structures based on muon imaging technology

BackgroundThe exploration of mineral resources and geological structures is crucial for the sustainable development of the economy, society, and environment. Cosmic ray muons, a type of natural background radiation, can be utilized in muon transmission imaging which is based on density differences of transmitted target.PurposeThis study aims to enable non-contact, long-range, and non-destructive imaging of target objects, making it a powerful complement to traditional exploration methods for mineral resources.MethodsThe Geant4 software was utilized to simulate the physical processes of cosmic ray muons with materials of varying densities, and the shallow and deep geological structures were explored using a "telescope" configuration for muon transmission imaging. Firstly, the discriminability of muon imaging technology for substances with varying percentage density differences in rocks. For the simulation of, a volcanic model was constructed and four muon detectors was employed for simulating the imaging of the shallow geological structures from different angles, ensuring coverage of the entire mountain. Then, muon detectors located 600 m underground were utilized to extend exploration above unexplored areas with varying scales of undiscovered gold ore to obtain deep geological structures. Muons with energy lower than the minimum penetrating energy along their paths were absorbed by objects whilst muons that reached the detectors carried information about the materials along their paths. Meanwhile, the collected ray information was utilized to establish a density inversion model to obtain the minimum penetrating energy for each path, enabling the deduction of opacity distribution. Finally, the density distribution of volcanic model was determined by combining the geometric structure of the detected object, and individual detection points enabled two-dimensional monitoring whilst multiple detection points allowed for three-dimensional monitoring.ResultsThe imaging results of simulation show that the muon transmission imaging method can differentiate between different geological structures when the density difference exceeds 5%. In deep geological exploration, due to the low muon flux, imaging requires more time to accumulate sufficient muon events. Muon transmission imaging technology can effectively identify mineral deposits within deep rock formations when the difference in opacity between the path of muon penetration through the gold ore and the surrounding rock is greater than 4%.ConclusionsResults of his study demonstrate that the cosmic ray muon transmission imaging technology can be applied to geological exploration to achieve non-destructive exploration and obtain higher imaging accuracy when there is a reasonable density difference in the mineral resources and geological structures of the exploration area.