Measurements by test persons operating the INT measurement car DeGeN

A lot of detection systems for measurements of nuclear radiation are developed. Very often the manufacturers propose that the devices could be used without problems by non‐expert users. The Fraunhofer INT has long lasting experience in evaluating measuring results of different detection systems especially in the area of nuclear material. Automated analysis routines partly lead to results which are not correct and could be recognized as such directly by experts but would be taken as correct by non‐experts. Measurements with hand‐held devices operated by different persons have shown the influence of the human factor. In general studies on that topic are rare. Therefore we investigated the influence of the human factor by investigating measurement results obtained by a larger group of test persons operating our measurement car DeGeN. The Fraunhofer‐INT has designed a measurement car equipped with highly efficient gamma and neutron detection systems to track down and analyze nuclear or radioactive material. The car is suitable for search tasks, e.g. the searching of a defined area or the tracking of suspicious vehicles. The test persons had different levels of experience in the field of search for nuclear or radioactive material. Two test persons formed a measurement team. After a briefing they searched a test area in which several radioactive sources were hidden. The teams had to search and identify the sources in a pre‐defined time. After the drive the results were documented in a result sheet. Data were also obtained concerning the experience of the test persons. Correlations between the measurement results and the experiences are drawn. The measurements have been performed on the very suitable test area of the institute of the fire brigade IdF in Münster (Germany). It allows car‐borne search in a realistic environment using radioactive sources. Measurements of this kind are essential to test such measurement systems and to gain information of their performance.