Detection of high-<i>Z</i> objects using multiple scattering of cosmic ray muons

Abstract

We demonstrate that high-Z material can be detected and located in three dimensions using radiographs formed by cosmic-ray muons. Detection of high-Z material hidden inside large volume of ordinary cargo is an important and timely task given the danger associated with illegal transport of uranium and heavier elements. Existing radiography techniques are inefficient for shielded material, often expensive and involve radiation hazards, real and perceived. We recently demonstrated that radiographs can be formed using cosmic-ray muons [K. N. Borozdin et al., Nature (London) 422, 277 (2003)]. Here, we show that compact, high-Z objects can be detected and located in three dimensions with muon radiography. The natural flux of cosmic-ray muons [P. K. F. Grieder, Cosmic Rays at Earth (Elsevier, New York, 2001)], approximately 10 000 m−2 min−1, can form useful images in ∼1 min, using large-area muon detectors like those used in high-energy physics.