A Novel Approach to Determining the Distance From a Source with a Single Measurement and no Prior Knowledge of Source Activity

For homeland security applications, it is of high importance to locate radioactive sources. This is usually done using networks of sensors. We developed a technique to obtain the distance between the source and detector using a single detector without knowledge of the source activity. The percentage of detected counts in a radiation detector with energies lower than the photopeak is used to find the distance between the detector and stationary gamma source. This method has been tested using Geant4 simulations for 137Cs, 60Co and 235U, and experimentally confirmed for 137Cs. A very strong correlation between the true distance and reconstructed distance was found. High and low air pressure simulations were also tested for 137Cs and found to retain good distance resolution.