MoMIS - Mobile Muon Imaging System

We have grown used to the idea that technology can make the world transparent. The first time we see our children is on an ultrasound picture. CT and MRI scans allow us to diagnose illnesses and optimize treatment. Our vision is to extend this transparency to bridges and other civil structures and to do so without any additional, artificial radiation source. We also see important applications in nuclear security, in particular in verification for safeguards.

High-energy cosmic rays that enter the atmosphere create large showers of particles and some of these particles reach all the way down to the Earth's surface. These particles are muons - elementary particles similar to electrons but 200 times as heavy. Their typical energy is about 10,000 times higher than that of X-rays, which makes them highly penetrating - in fact they can pass through meters of rock, concrete or steel.

With the right kind of detection system, that tracks the incoming and the outgoing muons, they can be used to create 3D images (aka muon tomograms) of the contents of shielded containers or of steel reinforcements in concrete. Because muons are highly penetrating, muon imaging can 'see' through larger thicknesses of material than other non-destructive testing techniques like ultrasound or ground-penetrating radar that are typically limited to about 30 cm.

Muons occur naturally and the technique does not use any artificial radiation and is entirely passive. Muon imaging therefore is health-and-safety neutral and therefore also does not require special permits.

There are a lot less cosmic-ray muons per given area and time than there are e.g. X-ray photons in a CAT scan. This means that measurements take hours or days, not seconds. Especially good candidates for practical applications of muon imaging therefore a those that are not time critical, that involve a lot of shielding or that take place in public spaces, where permits for active methods (e.g. involving gamma sources) would be difficult to obtain.

Muon imaging, or muography, has already been used for many different applications, ranging from volcanology over nuclear waste containers to the discovery of a 'big void' within the Khufu pyramid in Egypt. Lynkeos Technology Ltd., a University of Glasgow spin-off company, has successfully CE-certified and installed a muon imaging system at Sellafield in October 2018. The Lynkeos MIS at Sellalfield is a static muon tomography system at TRL 8.

Market research carried out with support from Scottish Enterprise in 2019/20 has shown that there is a larger market for a mobile muon imaging system, especially for non-destructive testing in a civil engineering context. Test measurements at the University of Glasgow in collaboration with the German Federal Institute for Material Science and Testing (BAM) have demonstrated the feasibility on a civil engineering test object. Monte Carlo simulations of the verification of the contents of a dry storage cask have been shown at the IAEA Safeguards Symposium.

The crucial step for muon imaging to become a practical method in civil engineering and nuclear security is the creation of a practical mobile muon imaging system. This system should be simple and robust, have detectors with sufficient resolution and efficiency, and at the same time be portable and outdoor-proof. Up to now no mobile muon tomography system exists that fulfils these requirements.

The objective of this proposal is the design and construction of just such a system, more specifically a small-scale prototype for such a system - albeit of a size that is already useful for some applications and that can be tested in a realistic environment.

The research will be carried out at the University of Glasgow, in collaboration with Lynkeos Technology, BAM, Babcock, and Swansea University.