A modular muon telescope for tomography and radiography applications

Abstract

Cosmic-ray muons undergo multiple Coulomb scattering when passing through a material. Muon tomography is a non-invasive technique that exploits this feature of cosmic-ray muons and produces projectional image of the target volume. A tracking detector is simulated with four layers of Resistive Plate Chambers (RPC) of active area 160 × 160 mm${}^2$, two for each upper and lower tracker. A Lead block of size 100 × 100 × 100 mm${}^3$ is placed between the upper and lower trackers and its image is reconstructed using the Point of Closest Approach (PoCA) algorithm. The image reconstruction is further improved by implementing the Binned Clustering Algorithm (BCA). The simulation studies demonstrated that the designed muon telescope can distinguish high and medium atomic number (Z) materials and BCA can be used to image a miniature spent nuclear fuel dry cask. For building the tracker, four RPCs and four acrylic casings, to house the RPCs and signal readouts, are constructed. The measured cosmic-ray muon detection efficiency of RPC is $\sim$95%. For the airtightness test, the relative humidity is monitored inside the acrylic casing for about 30 days. The design of the muon telescope, simulation studies and detector development activities are discussed.