Study of imaging unknown objects by cosmic-ray muons

Introduction Cosmic-ray muon imaging is a kind of nondestructive detection technology which can be used to detect unknown objects in geological exploration, civil engineering and nuclear safety. Transmission imaging and scattering tomography schemes are studied.
Method The transmission scheme uses a multilayer detector to measure the direction of a cosmic-ray muon passing through an object. The scattering scheme involves placing two detectors upstream and downstream of the object to record the incident and exit directions of the muon passing through the object. The effect of the detector resolution on the imaging clarity of transmission imaging was studied. The applicable scenarios of the two schemes were analyzed.
Results The results by calculating show that in the transmission imaging of a hundred-meter object, a spatial resolution of 2.5 m can be achieved, and Cu and Fe can be discriminated with a density difference of 1.1 g/cm³. Scattering tomography is mainly suitable for meter-level objects, which can detect 0.2 m chamber and distinguish 0.05 m heavy metal blocks in rock.