Abstract
We have constructed a unique instrument for
use in the search for orphan sources. The system uses
gamma-ray imaging to "see through" the natural background
variations that effectively limit the search range of
normal devices to ~10 m. The imager is mounted in a 4.9-
m-long trailer and can be towed by a large personal vehicle.
Source locations are determined both in range and
along the direction of travel as the vehicle moves. A fully
inertial platform coupled to a Global Positioning System
receiver is used to map the gamma-ray images onto overhead
geospatial imagery. The resulting images provide
precise source locations, allowing rapid follow-up work.
The instrument simultaneously searches both sides of the
street to a distance of 50 m (100-m swath) for milliCurieclass
sources with near-perfect performance.
