Search

The employment of remote sensing (RS) survey methods, in particular of close-range methods, as part of the muon imaging process is becoming a topic of growing interest. Use of light detection and ranging (LiDAR) methodologies, like terrestrial laser scanner (TLS), together with the unmanned aerial vehicles digital photogrammetry (UAV-DP) and satellite data are proving to be fundamental tools to carry out a reliable muographic measurements campaign. The main purpose of this presentation is to show the importance of correctly plan TLS and UAV-DP field surveys for muon radiography applications. To this aim, a real case study is presented: the research of hidden tombs at the Volumni Hypogeum archeo-geosite (Umbria, Italy). A high-resolution digital terrain model (DTM) and three-dimensional models of the surface/sub-surface were created merging different RS survey methods. The muon flux transmission was measured using the MIMA detector prototype (Muon Imaging for Mining and Archaeology). The latter is a small tracker (0.5 x 0.5. x 0.5 m3) developed by the physicists of the National Institute of Nuclear Physics (INFN), unit of Florence, and the Department of Physics and Astronomy of Florence. The measured muon flux was compared to the simulated one, obtained using the three-dimensional created environment, to infer information about the average density of the studied target along the various LoS (line of sight). The study highlights the importance of correctly carrying out the TLS and UAV-DP survey to make reliable hypotheses and decisions throughout the muographic measurement campaign. Furthermore, we pointed out how the precision of the tridimensional data can bias the muon imaging results.

Muon radiography, or muography, is a non-invasive technique allowing imaging of the interior of large structures (target) thanks to the study of the absorption of atmospheric muons in materials. The muons absorption effect depends not only on the thickness, but also on the density of the target. Careful comparisons of the muographic results with simulations taking into account a precise description of the target's geometry, allow estimating the two dimensional distribution of the average density of the structure under study as seen from the measurement point of view. In this presentation an application in the geological field for the research and localization of low density anomalies attributable to cavities inside an abandoned mine will be shown. The aim of the study is to identify and locate areas that might be responsible for the production of anomalous concentrations of radon gas inside underground mining sites used for touristic itineraries. Radon is a natural radioactive gas that exposes tourists to ionizing radiation. Radon decay products are the second cause of lung cancer after smoking. It is important therefore to understand where the radon gas comes from before moving through the different galleries. The case study is the Temperino mine near Campiglia Marittima (LI-Italy). Here, the mining activity ended in 1980 and it was primarily focused on the extraction of copper, silver lead and zinc minerals. The area to be explored with muon radiography is part of an area dating back to the Etruscan period that has not yet been completely mapped and that is located above the tourist path of the Temperino mine at a depth of about 40 m from the surface of the hill above. Any nearby cavity could represent a prime conduit that brings radon gas into the tourist trail. The identification and localization in space of these ancient excavations is also interesting from a geological and archaeological point of view. The detector employed for the muographic measurements reported in this presentation, designed in Florence by the National Institute of Nuclear Physics (INFN) and the Department of Physics and Astronomy, is called MIMA (Muon Imaging for Mining and Archaeology) and has cubic shape and approximate dimensions of (50x50x50) cm3. MIMA is equipped with a special protective aluminum mechanism that allows its altazimuth orientation.

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.

In the last twenty years several applications of muography (or muon radiography) technique have been carried out for geological purposes. Among them, particular attention was given to underground ore bodies prospections. For thousands of years humans have been searching new methods to understand where to find underground ore bodies and how to localize it in the three-dimensional space. Often, economically useful minerals are bounded to other minerals, forming rocks of high density values that are hosted, usually, in rocks with lower density values. In literature gravimetry and magnetometry represent the most employed geophysical methods for imaging and detection of mineral-rich ore bodies. To verify the feasibility of muography as a non-invasive geophysical prospecting technique, our research group, composed by subnuclear physicists and geologists, carried out some underground measurement campaigns at the Temperino Mine (Campiglia Marittima, Italy). Here it is located a pliocenic metasomatic ore deposit, a Cu-Pb-Zn-Fe skarn complex composed by johannsenite, quartz, hedenbergite, ilvaite and accessory primary sulphides (chalcopyrite, galena, sphalerite, pyrite). These metalliferous bodies of skarn have tabular geometries with sub-vertical orientations. Currently, the first level of Temperino Mine has been equipped as a touristic path and belong to the Archeological Mining Park of San Silvestro. Along this gallery, carved both into the metamorphic and non-metamorphic rocks, it’s been installed the MIMA muon tracker (Muon Imaging for Mining and Archaeology), a small and rugged prototype (0.5 x 0.5. x 0.5 m3) developed by the physicists of the National Institute of Nuclear Physics (INFN), unit of Florence, and the Department of Physics and Astronomy of Florence. MIMA detector is able to measure the underground muon flux inside the mine gallery. Matching the simulated muon transmission rate with the experimentally measured one it’s possible to obtain a two dimensional average density angular map of the observed target. Also, using algorithms based on triangulation and back-projection techniques is possible to obtain a reconstruction of the 3D volume of high-density areas (and also low-density areas) inside the studied volume. The latter is the volume that falls within the detector’s acceptance. The aim of this research is to obtain a georeferenced 3D model of the Cu-Pb-Zn ore bodies hosted in the rocks between the top of the mine gallery and the surface of the Temperino Mine area. We want to confirm that muography technique could become a suitable and reliable tool for the mining prospections field.

Muon radiography is a non-invasive imaging technique that allows, through cosmic muon absorption measurements, to obtain two-dimensional and three-dimensional images of the internal structure and average density of very large material volumes. Its applications currently range from many fields: geological, archaeological, industrial, civil and nuclear safety. The technique of muon radiography being non-invasive represents a valid alternative to the common survey techniques in these fields of applications. In this presentation I will show some results obtained with this technique in the geological field for the three-dimensional imaging of cavities and tunnels within the Temperino mine located in the San Silvestro Archaeological Mining Park near Campiglia Marittima in the province of Livorno in Tuscany (Italy). The Temperino mine has ancient etruscan origins and still has areas which are not mapped in the available documentation. The mining activities of the area have always been focused on the search for a hard and dense rock called skarn in which there are metallic sulphides of Cu, Ag, Pb, Zn, Fe. Currently only one of the most superficial levels of the mine is accessible to the public through a tourist route. The muographic measurements on this site therefore have a dual objective, on the one hand to test the imaging technique on known cavities, on the other hand to discover new cavities whose knowledge could be useful, for example, for important assessments concerning historical and safety aspect of the site. All measurements were carried out with the muon detector MIMA (Muon Imaging for Mining and Archaeology) designed and built at the National Institute of Nuclear Physics (INFN) in Florence. MIMA is a cubic tracker of approximate dimensions (50x50x50) cm3and is equipped with a special protective aluminum mechanism that allows its altazimuth orientation. Various measurements were made within the tourist gallery located about 50 m below ground level for the observation of areas above. By comparing muon transmission measurements with simulations, it was possible to generate two-dimensional angular maps of average density of material observed in every direction within the detector's acceptance. The presence of some low-density anomalies associated with the presence of cavities was thus identified. Through algorithms based on the triangulation technique and on a track backprojection technique, the cavities were located in three-dimensions. For the known cavities it was also possible to compare the reconstructed development with their real profile that was acquired with the laser scanner technique, finding a good compatibility (average deviation below 1 m for a 7 m high cavity located 20 m above the detector’s installation location). These measurements therefore validate the muon radiography technique in the geological field for the search for cavities inside mines. The technique can be applied to identify not only low-density anomalies or voids, but also high-density areas: the application of the muon imaging technique for the identification of dense ore bodies is being studied at Temperino mine.

A multidisciplinary geomechanical method to evaluate and quantify rockfall hazards in rock slopes equipped for sport climbing is presented. This method exploits close-range survey data obtained from terrestrial laser scanner (TLS) and unmanned aerial vehicle-based digital photogrammetry (UAV-DP) and integrates them with traditional scanline survey data collected in the field. Based on the acquired information, a kinematic analysis is performed to predict the location of structurally controlled rock failure mechanisms. An index denoted as route stability index (RSI) is then proposed to quantify the associated hazard along sport climbing routes in the study area. In addition, hazard is also assessed at the overall slope scale. The method was successfully applied at an abandoned climbing site historically affected by rockfalls, 5 km north of Florence (Italy). RSI can be adopted as part of the planning and monitoring strategies for the management of risk related to outdoor climbing activities, which are becoming an important part of Italian and European geo-tourism.