  Current radiation portal monitors at sea ports and international borders that
employ standard radiation detection techniques are not very sensitive to
nuclear contraband that is well shielded to absorb emanating radiation. Muon
Tomography (MT) based on the measurement of multiple scattering of atmospheric
cosmic ray muons traversing cargo or vehicles that contain high-Z material is a
promising passive interrogation technique for solving this problem. We report
on the design and construction of compact Micro-Pattern Gas Detectors for a
small prototype MT station. This station will employ 10 tracking stations based
on 30cm x 30cm low-mass triple-GEM detectors with 2D readout. Due to the
excellent spatial resolution of GEMs it is sufficient to use a gap of only a
few cm between tracking stations. Together with the compact size of the GEM
detectors this allows the GEM MT station to be an order of magnitude more
compact than MT stations using traditional drift tubes. We present details of
the production and assembly of the GEM-based tracking stations in collaboration
with CERN and the RD51 collaboration as well as the design of the initial
front-end electronics and readout system.
