We are developing a rugged and person-transportable Compton gamma imager for
use in security investigations of radioactive materials, and for radiological
incident remediation. The imager is composed of layers of scintillator with
light collection for the forward layers provided by silicon photomultipliers
and for the rear layer by photomultiplier tubes. As a first step, we have
developed a 1/5th-scale demonstration unit of the final imager. We present the
imaging performance of this demonstration unit for Cs-137 at angles of up to 30
degrees off-axis. Results are also presented for Sn-113 and Na-22. This
represents the first demonstration of the use of silicon photomultipliers as an
embedded component for light collection in a Compton gamma imager.Comment: 19 pages, 6 figure
