SAIP2026

3D Parameterised Reconstruction of the PAUL Underground Overburden from Cosmic Muons

8 Jul 2026, 10:10

20m

Lecture Hall GH3 (University of the Western Cape)

Oral Presentation Track B - Nuclear, Particle and Radiation Physics Nuclear, Particle and Radiation Physics -2

Speaker

Nkosiphendule Njara

Description

The Paarl Africa Underground Laboratory (PAUL), which will be located in the Huguenot Tunnel under the Du Toitskloof Mountains near Cape Town, South Africa, is Africa's first underground facility specifically for rare-event physics. The site has about 800 m of rock overburden, which protects it from cosmic rays and makes it possible to look for dark matter. Previous GEANT4 studies and open-sky muon telescope measurements have characterized the forward muon flux; however,
the inverse problem of reconstructing overburden geometry from muon observables is still underexplored. This work presents a reconstruction framework built on a parameterised three dimensional model of the tunnel and surrounding mountain, implemented in OpenSCAD and coupled to GEANT4 atmospheric-muon transport simulations. Angular distributions, spatial track-density maps, and path-length spectra are used as indirect probes of the overburden structure. Sensitivity matrices quantify how these observables respond to variations in geometric and density parameters, and a Python-based inversion framework is developed to estimate overburden properties from simulated muon data. The results contribute directly to background characterisation for PAUL and complement ongoing experimental muography efforts inside the Huguenot Tunnel.