A Rotating Modulation Imager for the Orphan Source Search Problem.

Abstract

This dissertation explores the application of a mechanically collimated imaging device known as a rotating modulation collimator (RMC) to the orphan source search problem. Orphan sources are lost radioactive sources (accidentally or through material diversion) that can pose a threat to both human health and national security when they fall into the wrong hands. The RMC is a simple imaging system that can see through complex background scenes that can often mask these lost sources. Key developments for this research include the development of a new system model for predicting the system response when the source is located at any distance from the detector, the design, construction, and characterization of a prototype RMC, new methods for locating sources in three dimensions with a RMC, a new operating mode for imaging extended sources, an initial study on adaptive imaging with the RMC, and a method for predicting the time required to detect a hidden source of a known activity to a given level of confidence. Results from simulations and measurements are used to asses the performance of the RMC for the orphan source search problem.