Material Identification with Cosmic Ray Muons using RPCs

Abstract

We plan to build an imaging setup for material identification utilizing the Coulomb scattering of cosmic ray muons due to their interaction with the materials and tracking their trajectories with Resistive Plate Chambers (RPCs). To begin with, we consider a setup of six RPCs stacked in a parallel manner to read the position and timing information of the muons before and after their interaction with a phantom of a given material using a set of three RPCs for each phase. Here we present a simulation work carried out to study the image formation of phantoms of several materials. A detailed modeling of the imaging system consisting of six RPCs was done using GEANT4. Cosmic Ray Library (CRY) was used for generation of particles with the appropriate energy and zenith angle distribution. Three reconstruction algorithms were followed for material identification and image reconstruction, viz. Point of Closest Approach (POCA), Iterative POCA and the Binned Cluster Algorithm. A weighted metric discriminator was calculated for target object identification. Using the algorithms, the imaging of the Region of Interest (ROI) lying between the two layers of RPCs was done. The time required to discriminate target objects and do the image reconstruction has been studied.