Transmission-based muography (TM) is an innovative imaging technique based on the measurement and analysis of the cosmic ray muons flux attenuation within the target under investigation. This technique allows imaging inner-body density differences and has successfully been applied in a wide range of research fields: geology, archaeology, engineering geology and civil engineering. The aim of this study is to show the reliability of TM as an innovative, noninvasive geophysical method for ore body prospecting and other mining related studies. The measurements were carried out at the Temperino mine in the San Silvestro Archaeological and Mining Park (Campiglia Marittima, Italy), where several magmatic and metasomatic geological units are embodied. Among them, a Cu–Fe–Zn–Pb(–Ag) sulfide skarn complex primarily composed by hedenbergite and ilvaite minerals. Using the acquired muon imaging data obtained with the MIMA (Muon Imaging for Mining and Archaeology) detector prototype (cubic detector of 0.5 × 0.5 × 0.5 m³), the presence of a high-density vein inside the skarn body within the rock volume above the muon detector was identified, localized and interpreted. Applying a back-projection algorithm to the obtained 2D transmission map made it possible to estimate and visualize as point cloud data, in a 2D or 3D environment, the identified high-density body and its relative distance from the detector. The results of this study highlight the potential of muography as a support tool to other geophysical methods in the field of mining exploration.

Muon absorption radiography is an imaging technique based on the measurement of the absorption of cosmic ray muons. This technique has recently been used successfully to investigate the presence of unknown cavities in the Bourbon Gallery in Naples and in the Chephren Pyramid at Cairo. The MIMA detector (Muon Imaging for Mining and Archaeology) is a prototype muon tracker for muon radiography for application in the fields of archaelogy and mining. It is made of three pairs of X-Y planes each consisting of 21 scintillator bars with a silicon photomultiplier readout. The detector is compact, robust, easily transportable, and has a low power consumption: all of which makes the detector ideal for measurements in confined and isolated environments. With this detector, a measurement from inside the Temperino mine in the San Silvestro archaeo-mining park in Tuscany was performed. The park includes about 25 km of mining tunnels arranged on several levels that have been exploited from the Etruscan time. The measured muon absorption was compared to the simulated one, obtained from the information provided by 3D laser scanner measurements and cartographic maps of the mountain above the mine, in order to obtain information about the average density of the rock. This allowed one to confirm the presence of a partially accessible exploitation opening and provided some hints regarding the presence of a high-density body within the rock.

Muon radiography, also known as muography, is an imaging technique that provides information on the mass density distribution inside large objects. Muons are naturally produced in the interactions of cosmic rays in the Earth's atmosphere. The physical process exploited by muography is the attenuation of the muon flux, that depends on the thickness and density of matter that muons cross in the course of their trajectory. A particle detector with tracking capability allows the measurement of the muons flux as a function of the muon direction. The comparison of the measured muon flux with the expected one gives information on the distribution of the density of matter, in particular, on the presence of cavities. In this article, the measurement performed at Mt. Echia in Naples (Saracino 2017 Sci. Rep. 7 , 1181. ( doi:10.1038/s41598-017-01277-3 )), will be discussed as a practical example of the possible application of muography in archaeology and civil engineering. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.