Imaging from underground with muography

Muography is an imaging technique used to study large structures such as buildings, volcanoes, and pyramids. This thesis was conducted as part of the LouMu collaboration, which seeks to test muography for the first time in Portugal by applying it to the well-known environment of the Lousal mine and evaluating its potential and sensitivity for future applications.

Transmission muography, as the name suggests, analyzes the transmission of the flux of cosmic ray muons through an object to study it. This is a promising technique as it utilizes a natural and non-perturbative flux.

This thesis aims to provide a systematic account of the knowledge gained through muography in the Lousal mine. We collected data using a muon telescope, an apparatus designed to detect muons and determine their trajectories. Our muon telescope recorded data from two different positions within an old Explosive Storehouse in the mine, intersected by a geological fault, which was our target for muography.

We produced 2D muography images, and our ultimate goal is to combine these results from the two positions to create a 3D reconstruction of the mine.

In this work, we present the images obtained so far and explain how we developed a function to describe the muon telescope’s efficiencies.

The function showed promise with simulation, but the results obtained with data still need improvement. We gained valuable insights from this work, and in the future, we intend to explore further the function's applications.