Comparison of airborne radiation detectors carried by rotary-wing unmanned aerial systems

Abstract The Technical University of Catalonia (UPC), the National Metrology Institute of Germany (PTB) and the German Federal Office for Radiation Protection (BfS) have analysed the response of a 50 mm × 50 mm (diameter × height) NaI and a 38 mm × 38 mm CeBr3 scintillator, and a 1500 mm3 CZT semiconductor airborne spectrometric detector mounted on Unmanned Aerial Systems (UAS) in a comparison campaign carried out at the aerial site of Mollerussa (Spain). The decision thresholds that indicate the presence of artificial radioactivity are calculated for the count rates in the low energy region of the spectra, the man-made count rates and the ambient dose equivalent rates from the background flights performed at altitudes ranging between 10 m and 60 m. The capability of the different airborne systems to detect and determine the activity of 345 MBq 137Cs point source at different flight altitudes are compared. Finally, the airborne systems show the ability to localize the 137Cs point source by flying in parallel lines at 10 m, 20 m and 40 m heights.