Advanced hand-held detection system for on-site localization and identification of nuclear and radioactive material

Scintillation crystals for hand-held detection systems made of Lanthanum Bromide (LaBr) provide better resolution than common NaI crystals. An example of a detection system featuring a LaBr crystal is the InSpector 1000 (manufactured by Canberra). It is a light-weight instrument suitable for mobile search applications to localize and identify both nuclear and radioactive material. It comprises two detectors: a LaBr probe for gamma ray detection and a He-3 tube for neutron detection. Its low weight enables the user to perform thorough on-site inspections of areas where the presence of nuclear or radioactive material is suspected. Its performance clearly surpasses that of common NaI hand-held detectors, showing a resolution better than NaI by a factor 2 at least. Therefore this system shows considerably better results in localization and identification of suspicious material than NaI detectors of a similar size. Two especially important aspects for on-site applications are the time required for the localization of the material and the ability of the device to identify the radioactive nuclides correctly. As for the first aspect, the system's search mode (featuring both acoustic and optical signals) works in a satisfactory manner and is suitable to be applied even in the case of small amounts of (unshielded) radioactive or nuclear material. As for the identification, in the case of energy lines which are too close to one another and can therefore not be properly resolved, the results may become inconclusive possibly because the analysis sequences used for the InSpector 1000 were originally written for semiconductor detectors with considerably better energy resolution. To obtain a more reliable isotope identification one would have to use detectors featuring Germanium crystals which are usually of higher weight and are more expensive. Therefore, the InSpector 1000 system serves as a compromise between lighter NaI hand-held detectors which commonly provide identification of poor quality and heavy-weight Germanium detectors with good or excellent means of identification.