Muography Applied in Underground Geological Surveys: Ongoing Work at the Lousal Mine (Iberian Pyrite Belt, Portugal)

Abstract

The LouMu Project is an ongoing collaboration between the Laboratory of Instrumentation and Experimental Particle Physics (LIP), the Institute of Earth Sciences—University of Évora and the Lousal Ciência Viva Center which is evaluating the muography potential in the Lousal Mine, with the general aim to create the conditions to use muography as a novel method for geophysical surveys in Portugal. The National Laboratory of Energy and Geology is also supporting the project. The aim is to do a first geological survey of the area, map** already known structures and ore lenses and measuring their densities. In the end, newfound data will be added to the existing information to improve it, but the whole process is also serving to test the performance of the muon telescope and the muographic analysis tools. The muon telescope, developed by LIP, uses RPC detectors to observe the crossing muons in real time. Available geological and geophysical information and new measurements done with seismic refraction and ground penetrating radar are being used to create a 3D model, which provides a reference against which to compare the muography results. From the muography data, an equivalent 3D map of densities will be reconstructed, and the geological model will be used to cross-check and improve the muography results. This paper provides an overview of this ongoing project, focused on the muography work done so far. Its implementation is described, and the first image obtained with the telescope is presented, showing the local geology and in particular the Corona N–S direction strike-slip fault visible in the mine gallery. The planned work progression is shared as a final consideration.