Development of a coded-aperture backscatter imager using the UC San Diego HEXIS detector

Abstract

Defence R&D Canada-Suffield and the University of California, San Diego, have recently begun a collaborative effort to develop a coded aperture based X-ray backscatter imaging detector that will provide sufficient speed, contrast and spatial resolution to detect antipersonnel landmines and improvised explosive devices. While our final objective is to field a hand-held detector, we have currently constrained ourselves to a design that can be fielded on a small robotic platform. Coded aperture imaging has been used by the observational X-ray and gamma ray astronomy community for a number of years, which has driven advances in detector design that is now being realized in systems that are substantially faster, cheaper and lighter than those only a decade ago. With these advances, a coded aperture hand-held imaging system has only recently become a possibility. One group at the Center for Astrophysics and Space Sciences, University of California, San Diego, has had a longterm programme developing the CZT based HEXIS detector as the detection element of a coded aperture imager. Designed as a satellite payload, this low-power system is ruggedized and light-weight, all necessary qualities for incorporation into the envisioned portable imaging system. This paper will begin with an introduction to the landmine and improvised explosive device detection problem, followed by a discussion of the HEXIS detector. We will then present early results from our proof-of-principle experiments, and conclude with a discussion on future work.