THE USE OF OPTICALLY STIMULATED LUMINESCENCE FOR FORENSICS AND NUCLEAR COMPLIANCE

A high degree of concern currently exists surrounding the illicit acquisition of radioactive or nuclear material by terrorist organizations. The ability to detect and attribute this material before its use is desirable to the policing community due to the present-day threat of radiological terrorism. Effectively all available radiation detection equipment requires close proximity to the physical location of the source in order to measure the emitted radiation. Thus the simple act of periodically moving a source will confound existing detection techniques. However, radiation inherently deposits energy into surrounding material, trapping electrons in excited meta-stable states. In certain materials, these trapped electrons may be stored subsequent to the removal of the radiation source and can be released via optical stimulation and detected at a later date. This radiation-induced charge storage and subsequent release with light is the basis of Optically Stimulated Luminescence (OSL). This paper will describe the application of the OSL approach to forensics, providing investigators with a capability to identify suspected former R/N storage sites with a portable detector. This technique is also applicable to nuclear compliance testing. The expected use of such a technology would be to identify suspected former R/N storage sites with a portable detector on site followed by analysis of a core sample in an OSL laboratory for a more detailed characterization. Stored radiation-induced charge in a variety of common building materials and house-hold items has been characterized and results are presented. Furthermore, laboratory and field testing results of a newly constructed sensitive field prototype OSL reader are also presented.