MUON TOMOGRAPHY
Part of our Data Acquisition, Data Delivery & Analytics Solutions
Central Alliance has collaborated with Geoptic to pioneer the use of muon tomography in infrastructure investigations in the UK.
What is Muon Tomography Used For?
This innovative technique has successfully been used by Central Alliance and Geoptic to detect voids above railway tunnels and abutments with a high degree of confidence. By taking readings over several night shifts, this was achieved with no disturbance to the operation of the railway.
Work is currently underway to detect ore deposits around existing mining sites. The use of muon tomography as an exploratory tool was used in Wales to identify new resources and assist with the delineation of existing zones of mineralisation at the mine.
More famous uses of the technique include mapping the inside of volcanoes such as Mount Vesuvius and locating previously undiscovered chambers in the Great Pyramid.
By comparing the muon rate inside or below a structure to an open sky measurement, it is possible to detect changes in density. This method is called ‘Muon Radiography’.
What Are The Applications?
Muon tomography can be used to map density variations in the subsurface, providing a non-invasive method for investigating geological structures at depth.
In the exploration of heavy and critical elements such as nickel sulphides, uranium, and rare earth element deposits, Muon Tomography can identify and delineate high-density mineralisation with greater spatial coverage than conventional drilling, improving resource targeting and reducing exploration costs.
It is also highly effective for void detection, allowing the identification of underground cavities, rubble zones, and areas of historical extraction that may present geotechnical hazards.
In down borehole Tomography applications, detectors deployed within boreholes can image large rock volumes surrounding the hole, generating three-dimensional density models that enhance geological interpretation and support mine planning.
For mine workings, the technique enables the mapping of abandoned tunnels, stopes, and other subsurface features with meter-scale resolution, improving safety, reducing uncertainty, and supporting the efficient management of active and legacy mining operations.
Key Benefits
Non-intrusive & safer methods of investigation
Remote assessment including structures & sites
‘Seeing’ into structures or the Earth by detecting muons, the Earth’s natural ‘X-rays’
A passive system easily deployable to any site or environment
Mitigating risk by identifying previously unknown hazards
A variety of applications including locating voids or density changes & structure assessments
What Are Muons?
Cosmic ray muons are subatomic particles that are generated by high-energy radiation hitting the Earth’s atmosphere. By detecting cosmic ray muons, we can map density changes, providing valuable insights that traditional technologies cannot match. Cosmic rays that were created millions of years ago in deep space and have since been on a collision course with the Earth are utilised for this technique. When cosmic rays hit the Earth’s outer atmosphere, they disperse into sub-atomic particles known as muons. Muons continue at high velocity toward the Earth. Highly penetrating, they travel deep into the Earth’s surface and through any structures built on, or in the Earth. These muons hit the earth at an average rate of 10,000 per m² every minute.
We can detect muons at depth using specially developed muon detectors. Using the simple concept of monitoring muon flux and by considering the direction and angle of detected muons, we can make assessments of density anomalies within the substrate above the detector. Similar to X-rays, the muons are scattered as they travel through dense material, making them ideal for mapping large or dense structures.