A new cylindrical detector for borehole muon radiography

Muons of cosmic origin have a great capability to penetrate through matter. This property is exploited in muon radiography, also known as muography, a technique which allows to highlight the presence of discontinuities of the mass density in the subsoil such as cavities, tunnels or rock masses. A detector of cylindrical geometry, optimized for borehole studies and with a diameter of 24 cm, was developed and tested. The scintillation light is read out by 384 Silicon Photomultipliers, directly coupled to the bars. The front-end and acquisition electronics, entirely housed inside the detector, are based on the EASIROC chip and are characterized by limited energy consumption (about 30 W for the entire detector). The detector has been designed in such a way as to simplify its construction as much as possible for its eventual mass production. In this article some details concerning the construction and preliminary results of measurements conducted in the Mt Echia (Naples, Italy) underground are presented.