Year
2012
Abstract
A practical gamma ray detector approach is considered, which is suitable for detecting and measuring radionuclides over a range of distances and distributions. The uniqueness of this detection system lies in the integration and use of well-known properties and behaviors of radiation interactions to provide a uniquely performing radiation detection system with separable neutron and gamma responses. The approach utilizes existing and known technologies configured to provide neutron sensitivity. The potential therefore exists, for some radionuclides, to extend the system net detection capability, overcoming situations where significant source shielding may be present to make their detection unlikely by gamma ray emissions alone. The approach utilizes high atomic number (Z) materials surrounding the gamma ray detector that result in annihilation gamma ray creation which is separately observable in the detector energy spectrum. In addition, shield components may be cadmium coated to enhance system neutron sensitivity. The system functions with HPGe, NaI(Tl) scintillation, or other detection elements, and consequently provides gamma ray spectral information. Measurement of the created 511 keV full energy peak interferes little with the gamma ray analysis and indicates presence of the neutron flux. Where cadmium is utilized, a lower energy contribution is added to the gamma ray spectrum when neutron interactions occur. The detector element has a controllable field of view. When oriented and combined with additional detectors in proximity, then the coordinates for sensed materials may be determined. Where compressive imaging techniques are utilized, image reconstruction is possible even with sparse pixel population. Because of system simplicity, detection efficiency is optimized with a minimum of complexity and cost. Therefore it is possible to build additional detector systems to enable rapid assessment of the scene of interest. Where detector outputs are wireless linked then each is capable of displaying the net radiation scene to the operator at that location. Experimental data are presented and results shown for portable and transportable detector systems.