Portable ??/?? Scintillation Detector with Improved RadioxeNon MDC's

Radioxenon detection is an important component in both the nation & apos;s and the CTBTO & apos;s programs for nuclear explosion monitoring. Existing detectors (SAUNA, PhosWatch, SPALAX & amp; ARIX) can achieve minimum detection levels (MDLs) below 1 mBq/m3 using a 12-24 hour measurement and depending upon the isotope, but are expensive, heavy systems that are not well suited to transportable, airborne or on-site applications. For the next generation there is a need for detectors that are light and stable enough for mobile operation while achieving MDLs of order 0.1 mBq/m3 or below so that radioxenon background levels can be characterized, preferably with little or no shielding or current MDLs attained with much shorter collection and measurement times. Since the major limitations to achieving lower MDLs are background counts arising from Compton scattering, the memory effect (residual counts from previous samples), and interferences between the radioxenon isotopes, we are proposing a novel / scintillation counter that eliminates the memory effect, reduces Compton scattering by reducing detector mass, and eliminates interferences by geometric partitioning decay products between multiple detectors. In Phase I we will demonstrate feasibility by producing a GEANT model of the new design, which will be verified by comparison to experiments with the detector & apos;s components.. We will first design and build high efficiency scintillator-photomultiplier modules, test them with laboratory sources and confirm GEANT descriptions of their behavior. We will then assemble a few of these modules into a detector mock-up and test it with radioxenon. These results will be used to calibrate the GEANT model that we will then use to design the full detector to be developed in Phase II. Commercial Applications and Other Benefits: If successful, this detector & apos;s major benefit will be its contribution to enhancing national and international nuclear security through improved nuclear test detection and monitoring. Maximum sales are estimated to be 50-100 units (2.5 5.0 M$), which would be significant for a small company.