A detector system for searching lost γ-ray source

The aim of this work is to develop a Geiger-Muller (GM) detector system for robot to look for a radioactive source in case of a nuclear emergency or in a high radiation environment. In order to find a radiation source easily, a detector system, including 3 detectors, was designed to search γ-ray radiation sources autonomously. First, based on GEANT4 simulation, radiation dose rates in 3 Geiger-Muller (GM) counters were simulated at different source-detector distances, distances between detectors and angles. Various sensitivity analyses were performed experimentally to verify the simulated designed detector system. A mono-energetic C137s γ-ray source with energy 662 keV and activity of 1.11 GBq was used for the observation. The simulated results were compared with the experimental dose rate values and good agreements were obtained for various cases. Only based on the dose rates in three detectors, the radiation source with a specific source activity and angle was localized in the different location. A method was adopted with the measured dose rates and differences of distances to find the actual location of the lost γ-ray source. The corresponding angles of deviation and detection limits were calculated to determine the sensitivity and abilities of our designed detector system. The proposed system can be used to locate radiation sources in low and high radiation environments.