The muon portal project: A dedicated muon detector for the inspection of shipping containers

Traditional techniques, such as those based on X-rays absorption, to inspect shipping container in search of potential fissile threats cannot be employed on occupied vehicles and are of limited use in presence of a large amount of shielding materials. To overcome such limitations, prototypes of detection systems employing the muon tomography technique, based on cosmic muon scattering from high-Z materials, are being tested worldwide. The Muon Portal project aims to build a large area muon detector (18 m²) for the inspection of TEU containers with good spatial and angular resolution. The detector is made by four XY tracking planes of plastic scintillator bars with embedded WLS fibers and SiPM readout, placed above and below the volume to be inspected. Different imaging and visualization algorithms are being designed and tested over tomographic scenarios simulated with a detailed software replica of the entire detector. Experimental tests of the individual detection modules are already in progress. The design and operational parameters of the portal under construction are reported, together with the preliminary detector tests and imaging results.