Development and optimization of a bakelite RPC-based muon tomography system

Abstract

Cosmic-ray muon scattering tomography has emerged as a powerful non-invasive imaging technique for the detection of concealed high atomic number (high-Z) materials inside large and densely shielded objects, where conventional X-ray and gamma-ray imaging methods often face limitations. The technique exploits the multiple Coulomb scattering of naturally occurring cosmic muons to identify and localize materials with high atomic number, making it particularly attractive for cargo inspection applications. A Bakelite Resistive Plate Chamber (RPC) based muon tomography prototype is developed to explore the feasibility of scaling the detector architecture to a large-area system capable of non-destructively detecting high-Z contraband materials concealed inside cargo containers. Accordingly, the primary objective is to develop both the experimental prototype and the envisioned large-area detector system in a cost-effective manner without compromising structural robustness and detection efficiency. To address this, an appropriate trade-off between detector performance and system cost is established through extensive Geant4 simulations using two different high-Z materials with varying volumes and readout strip widths. Simulation results are validated using a Bakelite RPC-based prototype. The optimized detector configuration is subsequently implemented in a corresponding experimental prototype. The results obtained from both the Geant4 simulations and the investigations using the developed experimental prototype are presented and discussed in the paper.