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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.

A novel algorithm developed within muon radiography to localize objects or cavities hidden inside large material volumes was recently proposed by some of the authors (Bonechi et al. 2015 J. Instrum. 10 , P02003 ( doi:10.1088/1748-0221/10/02/P02003 )). The algorithm, based on muon back projection, helps to estimate the three-dimensional position and the transverse extension of detected objects without the need for measurements from different points of view, which would be required to make a triangulation. This algorithm can now be tested owing to the availability of real data collected both in laboratory tests and from real-world measurements. The methodology and some test results are presented in this paper. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.

has been designed to test the application of muon radiography (or muography) to multidisciplinary case studies, to demonstrate its validity as an imaging tool in different fields and to develop dedicated data analysis strategies.The MIMA detector is a scaled-down version of the muon trackers developed for the "Mu-Ray" INFN R&D project and the MURAVES (MUon RAdiography of VESuvius) "Progetto Premiale", financed by the Italian government. Thanks to its compactness, MIMA allowed the use of slightly different technical solutions with respect to the other detectors. Its construction was completed in the first half of 2017 and since then it has been used for several different measurements. In the second half of 2017 the detector was installed in the Bourbon Gallery inside Mount Echia, a hill in the center of Naples containing a complicated system of tunnels and cavities that have been dug over many centuries. The installation of the MIMA tracker was required to validate with an independent detector the results obtained in two previous measurements by the Mu-Ray tracker. After this measurement, the detector has been used in the Tuscany region, mainly for investigating two possible fields of application: geo-hydrological risk assessment and mining activity. The preliminary results of these tests and the future perspectives are shortly presented in this paper. K: Particle tracking detectors; Image filtering; Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators); Search for radioactive and fissile materials 1Corresponding author.