Surveillance of nuclear threats using multiple, autonomous detection units

A detection systems is presented that involves multiple autonomous detectors, which are merged to a net like structure. Each unit is equipped with a stabilized and linearized multichannel analyzer for the measurement of gamma spectra and optionally a He³ neutron detector. The flexible hard- and software architecture allows the simple integration of a variable number of detectors, even with different volumes. With this technique, spectroscopical screening of large areas, e.g. airports or comparably sensitive objects, can be established by an individual combination of these detectors. The general outline of the nuclide identification algorithm is presented. In the context of medical isotopes, the importance of correct reference data that incorporates the scattering effects of human bodies is clarified. A special focus is drawn to the localization of nuclear sources. The model, corresponding simulations and its applications are depicted. Different tests and verification measures are described that refer to the nuclide identification and the source localization as well as to the spectral quality of the detectors. A finished real application is presented that combines the tested algorithms and has proven its reliability on different occasions.