Regularized Particle Filter based algorithm for the state estimation of orphan gamma source in real time using a backpack gamma spectrometry system

Abstract

We demonstrate the capability of Regularized Particle Filter (RPF) based algorithm to localise and quantify an orphan gamma-ray source situated in an unknown area using a single radiation detection system. The radiological measurements are made in the form of gamma spectra at multiple locations using an in-house developed backpack gamma spectrometer based on a 2″ x 2″ NaI(Tl) scintillation detector. We developed an Android application based on RPF which processes the gamma spectra received from the backpack over Bluetooth along with location information acquired from the smart phone's GPS in real time to show the source location in latitude, longitude format and source strength. To examine the performance of the algorithm, the radiological source search operation is carried out with 5.74 GBq 137Cs and 2.66 GBq 60Co in two independent experiments. The sources are located within an error of 10 m in location and 10% in source strength during the multiple experiments. The experiments are conducted in an open field where the attenuating medium for gamma rays would appear homogeneous at all the measurement points. Further improvements in the methodology are required for the localisation and quantification of source in an urban environment with a single detector.