Muon scattering tomography for cargo screening

J. Burnsa, S. Quillina, M. Stapletona, C. Steera , P. Baessob, D. Cussansb, C. Thomayb, J. Velthuisb

aAWE, Aldermaston, Reading, Berkshire, RG7 4PR, United Kingdom

bUniversity of Bristol, H. H. Wills Physics Laboratory, BS8 1TL, United Kingdom

Abstract

Muon tomography allows the identification of high atomic number (Z) materials by measuring the scattering angle of atmospheric cosmic ray muons passing through an inspection region. The multiple coulomb scattering process causes the magnitude of the deflection of a muon incident upon a target material to increase in proportion to the atomic number. Several reconstructed muon trajectories are combined to produce an image of the inspection area. A number of techniques used to produce such an image are based on the Point of Closest Approach (POCA) of the incoming and outgoing muon trajectories and extensions to this approach using Maximum Likelihood Fitting (ML). We report on two possible detector systems capable of providing the required detector resolution to precisely measure the muon scattering angle: the first comprises a series of drift chamber detectors and the second a series of resistive plate chambers.

Keywords: cosmic; muon; scattering; tomography; screening.