Detection Of High-Z Objects Using Cosmic Ray Muons Based On MWPC

At the ground level, most muons are produced by quite low-energy primary particles whose electromagnetic and nucleonic components die out high in the atmosphere. There is a large ground-level flux of single muons, and thus, they represent a convenient source of particles for laboratory measurements. A muon traversing a medium is deflected by the electromagnetic fields of many nearby nuclei in an effect called multiple Coulomb scattering. Muon detection has numerous potential applications, such as anti-terrorism, large container inspection, nuclear material monitoring, and so on. Measurement of the multiple scattering of cosmic ray muons provides a method for detecting high-Z objects, and measuring the scattering angle enables the identification of the objects. Multi-wire proportional chambers (MWPCs) have many advantages in low-Z surroundings. Thus, MWPCs are suitable for cosmic muon detection.In this work, we describe a detection system to measure the X and Y components of the muon scattering angle in the laboratory frame. We propose the use of MWPCs as the tracking detectors. The delay line readout was taken in the position measurement, and the incident and emergent tracks of muons traversing an object were measured by four MWPCs. The simulation system interfaced with the Geant4 Monte Carlo toolkit simulated the tracking muons and their interactions with the detector and target objects, including multiple scattering. The reference values of the X and Y components of the muon scattering angle were provided by the Geant4 simulation system. By comparing the measured values with the reference values, the high-Z object could be identified.